Author Topic: Portable milling/grinding machine for machine way reconditioning  (Read 10753 times)

Offline PekkaNF

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Hello,

I have pretty old mill and it's ways need reconditioning. I have come to conclusion that outsourcing the work is not possible. Way too expensive and involved to work companies that really don't want to cater hobbyist. Ways need to be milled/ground to acceptable accuracy, now they have serious wear and that produces almost 0,4 mm dip in the 500 milled distance....I would be happy with 0,02 - 0,04 mm planar inaccuracy on 500 mm distance. Nothing impossible.

Ofcourse I could scrap it and start looking for a little less used, but here mills that are way better are really big industrial ones. Small hobby size (like bridgeport or such) are not often available and they are really expensive when they are.

So before scrapping my scrappy mill I might as well try fixing it and if I break it, I least learn something. Amount of metal removal necessary excludes manual scraping. I need to use power tools.

I have seen magnetic drills and mills bit like this on sites I used to go to:
http://www.hydratight.com/sites/default/files/products/images/geniSYS_II_milling_machine_product1.jpg

I never seen an linear portable mill, but apparently there are some:
http://www.hydratight.com/sites/default/files/products/images/geniSYS_II_milling_machine_product1.jpg

http://cdn.powermag.com/wp-content/uploads/2012/11/520004de14df6-Linear_Mill_-_Gantry_Mill.jpeg

Now the interesting design question: How to build "frame" which is a) bolted to milling machine frame to mill/grind milling machine upright flat ways straight, b) to mount that will hold table and it has dovetail ways, c) possibly knee.

Knee I might be able to farm out for milling least, maybe even grinding, but table is way too big.

I have been checking as much as I can without dismantling the milling machine (I need that on this condition to make some parts) and interestingly looks like there are part of the ways that still has original scraping left, I could use them as a reference to record shape of the ways and keep book how much screws and mounts have to moved to fit all parts together.

I considered plasma cut steel parts and welding....fast and easy, but I don't have immediate ways of heat treating them. I know that those structures have no long term stability, but for one-off work how much they live in a day/two time span? Or do they spring which ever way and live all the time during the stress of milling/grinding (not the rig/frame) but part?

I'm not considering concrete in any form. Makes a real mess on reuse of the metals and it shrinks first 400 years, first very much.

Most I'm considering hot rolled steel, minimal machining and all bolted joints.

I may be able to persuade one machine designer to give go/no-go advice on dimensions and such. Plan is to use some parts I have all ready and build bare minimum of structure/tools I will not have much use after.

Pekka

Offline awemawson

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #1 on: April 29, 2016, 03:33:22 AM »
What is the mill Pekka? A knee mill of some variety by your description, but a photo and rough dimensions would help us cogitate your problem a little better.
Andrew Mawson
East Sussex

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #2 on: April 29, 2016, 04:07:56 AM »
Damn. I should take pictures...it is small knee mill, about 1,5 metric tons in weight. Originally horizontal mill, but it has a universal vertical head - no drilling pinion. Maybe 3kW motor, gearbox 8-speeds from 25 to 700 rpm or so...and clutch.

Table is about 1000*250 mm and all parts are heavy :lol: Table and it's mating part are the only dovetail guide, others are flat guides, some 100 mm wide. Table/knee and horizontal flat guide have most wear.

For a German engineering lubrication is funny and and it has seen use, first school, then truck "shed" where they probably forgot to lubricate it.

Coolant tank was shot when I got and cardan shaft for feeds too, but gear and coupling works well. I will not win prizes but will shift some metal even when it is worn out. Someone had spooked the sound of the flat belts (squeeelll- clonk-clonk-clonk) and I got the cheap...delivered. I bought a new endless belt and it behaved well.

I have been looking a small mill/drill of about 300-1000 kg range, but good ones are completely out of my reach and cheap ones are crappier than mine.

Pekka

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #3 on: April 29, 2016, 12:28:04 PM »
Compulsory pictures.

Biggest and most annoying wear is on X-axle, table/knee axis. Y-axis looks weird, but has little impact. Z-axis has a dip in most used place on back of it, where the knee is hanging.

Pekka


Offline RotarySMP

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #4 on: April 29, 2016, 01:59:50 PM »
Do you have a surface plate and straight edges long enough to quantify the wear? It is extremely unlikely that you can fabricate a temporary mill or grinder able to improve this machine. You are better off downloading the PDF of Connelly's Machine tool reconditioning posted here yesterday, hacking a cheap sabre saw into a DIY Biax, getting access to a surface plate , scraping it back in.
Mark
« Last Edit: April 30, 2016, 03:31:31 AM by RotarySMP »

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #5 on: April 30, 2016, 01:53:50 AM »
I my biggest surface plate is about 600*400 mm and another 400*400 mm. Then I have three camelbacks 400, 600, and 1000 mm. I have pretty good 600 mm straight edge and 1000 mm straight edge is in order.

Table is easiest and hardest....it has few original surfaces, machined that can't have any wear, because they are no bearing surfaces, but they are on the same plane than bearing surfaces. On the other hand, it has a longitudal dovetail, that is going to need some attention and it is not trivial to measure.

Knee is hardest part....it has Z-axis bearing planes luckily on on plane (or should have) but Y-axis bearing surfaces have offset by design and it is going to complicate measurement. Good news is that it just about fits on my big surface plate - I can verify it and then check it against the knee ways.

I can borrow longer straight edges of varrying (known accuracy).

I will not try to attemp of scraping to shift the most of metal, there is simply too much of it.

I have been reading of Connelly's Machine tool reconditioning, rather nice reading if you can't sleep...It is very matter of the fact of course and I much liked it. However, I haven't mannaged to google anybody first timer that has tackeled this size project solely on scarping and has a proof of succeeding.

I need whole more controlled method of removing metal than angle grinder or such and faster than scraping.

Pekka

Offline awemawson

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #6 on: April 30, 2016, 03:00:17 AM »
Get a Biax and use it with a carbide scraper insert, you'll be surprised how quickly you can remove cast iron. (Steel is a different matter)
Andrew Mawson
East Sussex

Offline RotarySMP

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #7 on: April 30, 2016, 04:19:30 AM »
Sounds like you are well tooled up to do the job. Any welded frame supporting a grinder is going to take off metal fast,with The Risk of rapidly destroying the remaining accuracy of the mill. How many surfaces are really that worn that you need to take off tenths of mm? For those you are going to have problems with leadscrew alignment, and should consider milling out and moglicing them.

Offline chipenter

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #8 on: April 30, 2016, 04:24:08 AM »
I used a flat file ground the teeth off the edges and cleaned the file with a brass brush , still took a fortnight to remove ten thou from my lathe bed , and my hands were so black the kitchen sink went rusty .
Jeff

Offline RotarySMP

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #9 on: April 30, 2016, 05:16:39 AM »
There are a few guys on the Net who have hacked cheap saber saw's to reduce the stroke and mounted carbide scraping blades a cheap Biax. The feedback from those who have done it is that it works quite well, with a significant reduction of effort verse hand scraping.

http://www.cncecke.de/forum/showthread.php?59092-Schab-O-Mat&highlight=S%E4bels%E4ge+biax

http://www.practicalmachinist.com/vb/general/power-scraping-anyone-tried-convert-makita-hk0500-metal-161099/index2.html

https://www.youtube.com/watch?time_continue=4&v=uTu2iwdiCt4

"My own Aldi variable speed recipro saw adaptation which I call "Aldix" is not quite as good, too light and too much play in the blade guide, but I've used it a lot over the past 4 years and its still going well...."



Offline Jonny

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #10 on: April 30, 2016, 03:33:22 PM »
Scrap machine already so scraping nothing to lose.

Wish had a tenner for everyone that said ive only took a couple of thou off, to correct needed 40+ thou.

Online tom osselton

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #11 on: April 30, 2016, 03:55:06 PM »
Interesting article what is the stroke on a Biax is it variable?

Offline hanermo

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #12 on: April 30, 2016, 05:53:09 PM »
This is perfectly possible, and not too hard.
Many people have done this, videos on youtube.

From 0.4 m error, you can quite easily get to 0.02 mm or near this (or less).

I have done similar, by using linear bearings, the proper profiled thk type.
Then just mounted  bench grinder onto the sled.
Worked fine.
Was maybe 0.02-0.03 max error or less.

These days, I sand ways flat.
It works perfectly well, if your process is suitable.

Ie, for me.
I use a big wide grinder. Cannot dip or groove.
Around 5" wide, iirc. Festool 1400W. Best on market. Expensive. (Sit down before You look at price).
I do lots of these.
I mark the areas to be ground "more" with felt tip. Felt tip == 0.01-0.02 mm.
Grind till its mostly gone.
All my material is wide and flat, tool steel.
Hand pressure can easily control to better than 0.01 mm error on flat steel surfaces, with some experiences.

Very important Point.
Edges get rounded with grinders. I only use centers, far from edges, so in my case its fine.
E.g. I need a 35 mm wide flat.
My surface is then 50 mm wide, and I sand flat over the total surface.
The edges are not flat, but the center part is, to better than 0.01 mm.

The Grand Old Man on precision rebuilding Richarch King has used similar and does not disallow these when used suitably.

I measure with precision ground straight edge (Vertex, 1m) and look for around 0.01 mm or less incremental error re: mount points.
You can easily feel/test/measure it by hand with linear guides.
Once they run smoothly, you know they are in range.



Offline PK

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #13 on: April 30, 2016, 06:10:00 PM »
This is perfectly possible, and not too hard.
Many people have done this, videos on youtube.

From 0.4 m error, you can quite easily get to 0.02 mm or near this (or less).

I have done similar, by using linear bearings, the proper profiled thk type.
Then just mounted  bench grinder onto the sled.
Worked fine.
Was maybe 0.02-0.03 max error or less.
Quote
I was thinking along the same lines.  We've built and bought a couple of machines using the Hiwin brand linear bearings. They are better than any of my measuring gear and relatively inexpensive.
PK

Offline Komatias

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #14 on: May 01, 2016, 06:56:32 AM »
Hi guys,
Last year i was looking to regrind my KRV and apply turcite. Having scraped a machine before and done all the messing with blue etc. I was not keen on repeating this myself. Before starting to do any thing, get quotes from professional machine tool grinders. You may be pleasantly surprised. I got 4 quotes from UK companies ranging from ridiculous to wow that is fantastic!

Typically machines require little work on the knee as it is not as worn as the X Y. So many places will tell you to ship them the knees table and saddle. Not sure what prices are for pallet shipping in your countries but here it is not bad.

It will save you so much time it is worth every dime spent and if they aplly turcite, you will have a fantastic machine!

Regards

George

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #15 on: May 01, 2016, 11:31:31 AM »
Thank you all!

Having this ground professionally is no go. I have asked prices and most said that they were not interested or I would be better of buying a new taiwanese one than paying a bit more for them to have a go on in.

One retired gearbox designer (industrial size, mines, wind turbines and such) visited me today an we plotted some ideas. It's not going to be too hard, but it might be too much work. Got three books on maching and measurement 1970-era, I'm not taking on knitting - yet.

I started measuring parts. It's nice to know which size parts are how much space I'm going to need.

Next step would be to figure out how to tackle each part and how to do it. Then I would have pretty good idea how big rig I need for it.

Some advice was really usefull, any pictures or links to projects members have done to regrind ways would be nice.

I did consider using a bench grinder as a grinder head. No way ideal, but it could work. I'm not too keen on routers or any die grinder....way too small stone and too much dressing.

Pekka

Offline Jonny

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #16 on: May 01, 2016, 12:37:39 PM »
What you have to bare in mind is no amount of beefiness unless a proper way oversized machine will be accurate. Typically these machines are solid objects weighing by the tonne and around 16 foot long.
C Linear bearings your limited by the frame beefiness and runout plus dia of bar used, terrible flex even for woodwork, soon as It starts theres no stopping it just gets worse and worse trying to correct even with a small dia cutter.

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #17 on: May 01, 2016, 01:10:07 PM »
Not sure if I follow you Johnny.

I agree that normal milling machines and even more grinding machines are a hefty affair. But that is greatly because the working envelope is big and they are designed for production = ability to shif crapload of metal in no time.

I have seen whole lot of amateur routers that are designed for huge work envelope and 600w chinese router....

I'm aiming here lower. Only one movement is large (X-axis), one axis has feed of 20-50 mm, cutting depth adjustment in order of 1-3 mm. 1,1 Kw motor and that's pretty much it. Rails have to be pretty close to cutting point here or there will be problems.

Pekka

Offline hanermo

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #18 on: May 01, 2016, 01:42:48 PM »
I used a glass dining table as my reference surface, for 2 m long surface.
The v1 linear bearings ran on it.
Worked ok.

Then, a wood tabletop, with 20 mm thk linear bearings bolted to it.
Worked very well.
The grinder was the typical 30€ desk grinder.
Flatness had about 0.02-0.03 mm or less error, for 600 mm travel, +/-.

A grinder has tiny loads, if you are hand feeding it.
Typically, it might be 0.2-1 kg at most, of tool pressure.

*Because* everything is floppy, it actually works pretty well.
You dont get tool bounce, etc. It just bends off.

And a 350W motor has little mrr.
Grinding about 600 mm with 2-3 disc widths took maybe 1-2 hours, back in 2006 or so.

I had zero linkages.
Just a steel sled, rigid mounted grinder, linear bearings.
Push by hand.
Works fine.

The low-power grinder is (or seems to be) quite safe by hand.
It just bogs down.

As Pekka said, an industrial grinder thats used for grinding machine ways, is 20-30 tons.
But that because is has a 30 kW spindle and does one pass.. done.





Offline Pete.

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Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #20 on: May 02, 2016, 03:43:32 AM »
Pete....Looking for a hobby, not profession.....Hmm. if i retire on country and fill one barn with old slow oversize tools.....

Hanermo. Thank you for your pointers. I'm working on same size of envelope.

Luckily I have one real designer to help me with forces, deflections and such, because even I have a cursory knowledge on these things I'm too thick to be able to calculate them correctly. He can not only calculate, but he has these on his head and I make question like. I want to make a hydraulic broach of 4 tons of maximum force and I need a beam of 70 mm wide, 20 mm bolts on both ends - 250 mm apart and hydraulic cylinder rod of 25 mm must go trough it. How much I need thickness for it. he calculated/questimated few key figures and came out result that was very close to calculated one and exactly the prefered dimension I went to buy on junk yard. I could not solve those on few minutes no matter what I had at my hand!

Nevertheless, there is always some surprices.

Pekka

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #21 on: May 04, 2016, 05:28:01 AM »
I think I will lash up something Hanermo said, I'm going to try it first on scrap or something whole less critical to try it out and measure what sort of stuff it will be capable of doing.

I did measure a little of floor quality MDF and bit over 22 mm thick is not even near rigid enough to mount anything. But I can saw few strips and when deep beam is mainly on compression it looks rather doable, based on hasty measurements and numbers I am finding on MDF mechanical properties. My concern is now on how stable it will be....mainly on moisture. Looks like there are some P-grades and some are more resistant on moisture than others.

I basically could buy some, make small body that will fit on surface plate and easily check if it stays straight any time.

Pekka

Pekka

Offline PK

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #22 on: May 04, 2016, 06:21:58 PM »
Re reading, I realise I may not have conveyed the correct message in my previous post.
When I sugguested Hiwin linear bearings, it wasn't to construct a grinding jig. I was thinking about attacking the ways with an angle grinder, slapping a couple of cups of metal filled epoxy on them and bedding the linear bearings in as replacements for the dovetails...
You gotta think big, that's the key...
:-)

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #23 on: May 05, 2016, 03:20:23 AM »
Hi PK, you are right on thinking "big". That would do, specially if I could glue the whole thing upside down over a very big surface plate.

My reluctance stems due to fact that I work for a comppany that uses linear rails and bearings all the time to build machines and there is a learnig curve. Anyway, if you build something like 9-20 m long and 6-12 metres wide machine that has multiple ways every and each direction. On welded and machined frame. I know that the frame is not straight, but linear machine ways are machined pretty straight before installing the linear ways there. Because the rails are not straight either and no long linear ways is made out of one continous piece, but segments, there is a methology.

Unfortunately we have no more manufacturing on our location, therefore there are no extra pieces floating around.

On short distace linear way is pretty straight, but usually a large r, that they are easy to fit on stiff straight surface. Nothing magic there everything usefull is on linear bearing assembly and mounting instructions.

It is really not that big problem if they can be mounted on relatively flat structure, if gringing flat ways on same axis...who cares about 0,1 mm arc on sideways on 1,5 m distance - when it is on same plane than flat ways. Dovetail problem could be reduced to same problem when the dovetail flat is jigged ont same plane with ways.

Only problem here is that I don't have 1,2 - 1,5 m long linear ways at my disposal. Could buy them, but it would make pretty expensive rig for a one off. And I have no plans for a CNC hobby now.

I have a plan of buying some metres of key stock, that has been rolled into standard spesification and glue it on a frame. Have to device a method, I don't have a big eneough flat plane to rig it straight on one go, I have to think somehing.

I know the spesification, it's not great, but least is not bigger tha on bad grinding spindle. Have to keep eye on big picture here, no point of chasing the last 0,01 mm/m if something else produces bigger error. Local 0,01 mm I can scrape, but 1m long and 50 mm wide area of 0,5 mm are I can't.

Pekka

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #24 on: May 10, 2016, 04:06:09 AM »
Bit testing shows, that key stock over really deep section of the MDF might just do.

Has anybody done anything small succesfully out of epoxy concrete (granite/mineral)?

Found some links and lot of enthusiam, but very little end results and practically no long term follow up. This might be canditate for it :lol:

Something like this, but whole lot crappier for "cross slide":
https://youtu.be/-0Cn0WRXPKs

If I understand correctly, it's about aluminium density, compression strength is enough, tensile strength sucks and absorbs vibration about 3 times better than cast iron. Values to very good hobby grade mix.

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392008000400003

"According to Ashby & Jones13, granite has a density of 2.6 Mg/m3, a Young Modulus of 60 to 80 GPa, a tensile strength of 23 MPa and a compressive strength of 65 to 150 MPa."

Aluminum alloy (7075-T6) density of 2.7 Mg/m3, a Young Modulus of 70 GPa, a tensile strength of 510–540 MPa.

Pekka

Offline RotarySMP

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #25 on: May 10, 2016, 05:02:42 AM »
Not sure if it is successful, as I haven't finished machining  and installed it yet, but I made a new head support for my Deckel G1L from E/G...
http://www.cnczone.com/forums/epoxy-granite/305018-epoxy-granite-mill-head-support-beam.html

My summary:
1/ You need strong vibration to compact it, and you need to tune the frequency to the mold. A concrete vibrator on a VFD works well, but needs to be well bolted to the mold. Clamps just fall off.
2/ I used Thomas Zietz's Spreadsheet for the recipe, as I couldn't get SILIMIX 282 graded aggregate. It is now available for a decent price from this web vender in Germany.
http://www.moertelshop.com/SILIMIX-282-guenstig-kaufen
4/ If you make your own recipe, the finest fine needs to be a super fine powder, and the largest aggregate needs to be about 1/5 of the thinnest section. Fine play sand is too course to be the finest part of the mix. It is the second aggregate in mine.
5/ I used a cheap casting epoxy off Ebay.de. The lower viscosity the better. I use 8% epoxy. The mix is very dry. I put too much in the mold before starting to vibrate, and didn't get all bubbles out. Next time I will use vibration from the start, before adding E/G.
6/ This stuff sticks like **** to a blanket. I waxed my mold, but the wax just gets abraded off. Coating the mold in brown packing tape makes for an easy release though.

Tensile and compressive strength is largely irrelevant for a machine base. Stiffness, damping then stability are the main figures of merit , and they are dependent on the youngs modulus and inherent damping and aging characteristics of the material. The advantage of E/G, is that it has fantastic damping, far better than cast iron. Once cured it is very stable (Concrete keeps shrinking for years). As it is a cold casting process with insignificant shrinkage,  you can cast sharp corners, thick sections,  big changes in thickness etc which would rip an iron casting apart during cooling. It has a quite low youngs modulus, but you just achieve your target stiffness by making thicker sections.

It is pretty cheap. Epoxy and the fine alumina were the only significant costs in my mix.
http://www.cnczone.com/forums/epoxy-granite/30155-epoxy-granite-machine-bases-polymer-concrete-frame-407.html#post1772512

Mark

« Last Edit: May 10, 2016, 06:43:34 AM by RotarySMP »

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #26 on: May 10, 2016, 06:16:38 AM »
Thank you Mark. Great info.

How do you think I should approach if I want to make a "cross slide" to this one out of mineral casting? I need to get two set of rails X and Y. X on bottom and Y on top. These axis are square to each others, about 50 mm apart (thickness) and on parallel planes. Something like 350*200 area, maybe 3,5 litres of volume, maybe scale up to 10 litres and that would weight something like 8-23 kg? Does it sounds completely bonkers for first project on epoxyconcrete?

I was thinking of using key-stock (or pre machined bar) that comes proud of surface few millimeters to allow machining them straight for rails/gibs. Accurately ground spacers between them to ensure top and bottom are reasonably parallel during curing. Just need small reasonably straight plate as a form bottom to make everything reasonably straight.

If I understand form making, pretty much no no traditional release agent works? You said that packing tape works. Hmm. maybe a self adhesive PVC film would work too?

Pekka

Offline RotarySMP

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #27 on: May 10, 2016, 07:21:01 AM »
Hi Pekka,

I used cheap brown packing tape on my test mold, and it releases well. Problem you have with larger parts is that you need very little adhesion, to give a huge removal force required over the large surface, and you have a rigid lump. The guying doing E/G professionally on the CNCEcke consider a wooden mold sacrificial. They use coated printers Multiplex (Siebdruckplatte), but still have to destroy it to demold. Fro the permanent steel molds, they designed in threaded features to break the mold, and say enormous force is necessary.

That sounds like a very doable sized first project.  I mixed up about 10kg of E/G in two batches. Using a mixer/swirler on a normal electric hand drill, more than about 5kg per batch gets pretty difficult to get the largest aggregate wetted. A normal concrete mixer would be useless. The stuff is too dry, and would just stick to the sides and spin around. At least with the epoxy I used, you have plenty of time. I think it had about 4H till it jelled. Once the aggregates are added, there is so much mass, that you don have to worry about the epoxy heating itself up.

I got too complicated with trying to add rebar. Unnecessary. As you suggest, steel strips bolted in routed slots in the bottom of the mold, sealed with silicon, spacers attached to hold the top rails/pads in place during casting. One it is all cured (Thomas suggested I leave it a week before demolding) mill/grind/scrape the surfaces parallel, drill and tap the attachment holes.

I have only ever seen threads of people who were semi successful at making grinding sleds. With 0.4mm to remove,  grinding is not a hogging process.

I am sure you have seen this one...
https://www.youtube.com/watch?v=7NGEQFJdmo4
http://www.practicalmachinist.com/vb/general/my-way-grinder-225515/

Another challenge with a grinding sled running on the lathes ways, is that there is no overtravel, so you are left with unground bits, so you need to design you sled to allow for that.

Mark

Offline hanermo

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #28 on: May 10, 2016, 09:15:31 AM »
I believe nothing sticks to HDPE (?) aka trash bags and or "elmukelmu" kitchen plastic wrap.
Aka plastic builders tarp also, I think.
The thin wrap would probably stick to crevices and chemical/mechanical means would be needed to take it off, if you need t.

I made some concrete bits 10 years back.
The 7x minilathe lathe bed was a huge technical success. 9.5/10.

70x12x90 cm, 15 mm rebar, preloaded, 12 mm thick mild steel torsion box in permanent heavy tension.

I made the mild steel box, flats are on side, 120 mm tall/thick, 900 mm long, 700 mm deep.
2 sets of 3 rebar, inside, crossed, welded onto one side only of box, at end and at front, wleded at center onto heat other.
Box is finish welded. Cool.

Then heat rebar with propane torch for 10 mins or so. Now weld last 2 ends of rebar, back side on x axis and left side on z axis.
Leave propane torch on, in middle, 3 mins == till welds cool.
Take off torch.
Leave to cool.
The cooling rebar is an enormous spring, and the hole box is really tight, with very heavy (== 5-10 metric tons, by my estimate) preload.

Flip on old tabletop, with flat plastic melamine (does not stick to concrete).
Leave granite 40x40 flooplate at bottom, to be catch pan, dropped == 20 mm from center to collect swarf.
I made a hole in middle, and left a plastic tube through box, to allow liquids aka coolant/oil to leak out, == 15 mm.

Filled with concrete, vibrated with chicom hammer drill.
Turn out really well.

Lathe == 45 kg.
Box == 200 kg.
Excellent results.
70-80% less noise, 300% more rigid.

Lathe was flat mounted, very rigidly, onto the steel box, before concrete.
I used 2 sets of flat legs, in x axis, ie 2 flats at HS, 2 at TS.
120x70x12 mm, one on top of the the other. Bolted SHCS, 6 mm.

How to get lathe to be flat.
When the lathe was flat, mounted to top legs rigidly (bolted), but top legs are floating, ie not mounted to anything.
The legs align the top plate, HS end, since its not fixed at all.

The bottom flat plate, same 120x70x12 mm (xyz) is now bolted onto the top flat (previously drill &t through both at same time).
Now, the bottom plate is bolted, perfectly flat, onto top plate.
As the 2 legs together are far apart, ie contact points are 700 mm between front end x++ and back end x--, now spot weld bottom plate only, onto frame, ie the steel box. From below, only.
Onto bottom flat, only.

The spot welding is really small, and the thermal mass is so large of legs and frame, it cannot move or twist anything.
Then add a few more spots, and unbolt top plate, and lathe.
The two flats will always get maybe 0.01 mm or better registration, one on top of another.
6 mm shcs == 240 kgf (2400 N) x 4 and easily bends the 12 mm thick plates flat one onto the other, in step one.

Spot welds cannot distort the frame, of maybe 100 metric tons breaking strength, or load carrying ability in the middle.
Finish weld bottom piece onto frame.
Then do the concrete.

Involved, some work, lots of plan.
Not hard to do.

The lathe and legs will now always bolt flat onto the legs.

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #29 on: May 11, 2016, 03:48:17 AM »
Hanermo: Thank you very much. Some places picture or drawing or any kind of illustration would have helped. Part I got, part I got lost, I'm that fluent on mechanical construction. My first <60 kg lathe was bolted on 30 mm hot rolled steel plate. It did help great deal.

....
I have only ever seen threads of people who were semi successful at making grinding sleds. With 0.4mm to remove,  grinding is not a hogging process.

I am sure you have seen this one...
https://www.youtube.com/watch?v=7NGEQFJdmo4
http://www.practicalmachinist.com/vb/general/my-way-grinder-225515/

Another challenge with a grinding sled running on the lathes ways, is that there is no overtravel, so you are left with unground bits, so you need to design you sled to allow for that.

Mark

I have seen those bits. I'm sure he used unworn ways (or parts of ways) like tail stock way is pretty much always intact near head stock -and vice versa.

What I did not like on that setup is small grinding stone and I didn't see any calibration of the stone face with diamond. That contraption does not oscillate....how did he stop it from producing stripes?

Furthermore my problem with mill ways is that there are no unaffected ways left....least not on same axis.

Pekka

Offline RotarySMP

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #30 on: May 11, 2016, 06:58:15 AM »
If I read it right, your longest slide is 500mm with .4mm max wear. Why not use a mill or shaper to hog it, then scrape the rest?

Mark

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #31 on: May 11, 2016, 07:45:10 AM »
Table is the longest item, it has 1000mm of guide ways - dove tail type. I asked around and 500 mm would have been easy on table size, but 1 m is bit long for any of my friends. And then there is then knee, it does not fit on normal milling machine.

I have been checking the dimensions and the knee is awkward. Then there are the flat upright square ways, about 1000 mm long on the milling machine frame. Plan is to measure first to see how much and where wear is, before doing anything on it.

Anyway, most wear is on the table x-axis and that is most challenging: longest, most wear, dove tail and even if I pull it off, I still have to refit the screw.

Pekka

Offline RotarySMP

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #32 on: May 11, 2016, 09:32:20 AM »
How about milling  out pockets in sections on a smaller mill, to get the necessary depth for Moglice? Moglice wont care if the bottom of the pockets have steps, and this way you can keep the screw centerline.

If the Knee is not as badly worn, just scrape it.

Mark

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #33 on: May 11, 2016, 03:18:51 PM »
How about milling  out pockets in sections on a smaller mill, to get the necessary depth for Moglice? Moglice wont care if the bottom of the pockets have steps, and this way you can keep the screw centerline.

If the Knee is not as badly worn, just scrape it.

Mark

That is like plan B vs, scrapping it. I don't like moglice, because I don't know what it is how it works. Makes me feel iffy.

Is't it stuff that has big part epoxy, some solvent and then some lubricants like MOS, graphite and some metalic bearing material like coppermetals and maybe teflon?

Solvent makes it shrink and deform a little, metalic particles need oil lubrication and teflon - I don't get it.

Logical step would have something like that to cast over epoxyconcrete. And it looks like it has been considered. Even googled recepies of home made moglice type castable bearing material. It's distracion in it's own right.

Hanermo: Where you got that "elmukelmu"? It's Finnish for a cling film wrap. Not very international word. You got me thinking that I have seen very nice surface quality on samples poured into a disposable plastic cup. Those are made out of PET, PP or PS. Probably more. PP and PET family seems to be difficult to glue with epoxy and therefore pretty nice material to prevent polymer casting from gluing into mould.

Pekka

Offline hanermo

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #34 on: May 12, 2016, 05:59:13 AM »
You could also solve it easily, and for maybe 200€, in one hour (or even less, depends).

Contact Grönbloms, the local HFO or Haas rep for Finland.
Ask, from sales, for a recommendation to one of their clients with a HAASF VF5 or bigger, who would be happy to do a small one off job, and plane the ways.

They are nice guys, and are ime, imho, always happy to recommend clients who will/can do work like this.
Ie recommend a machine shop that is happy to work with one private individual, on a one-off, and who has a big enough machine, with 1 m+ table travel.

The machine shops tend to do these jobs in between, or on slack time, and if you are not in a big hurry they can do this cheaply.
They also get favourable publicity, and this tends to bring in more work, later, and good word of mouth.

A single pass with a suitable cutter should leave the ways within 0.01 mm or so, overall.

Eiks kaikki sitten puhu suomea, vai mitä ?

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #35 on: May 13, 2016, 02:42:43 PM »
Hannu? Jorge? :lol:

It's not even nearly DIY...but when I'll take it appart I'll might change my mind. Specially if it turns out that I have whole lot less than 12 surfaces to plane.

Today I checked 20*20 mm and 22*14 mm keystock. Unbelievable straight. All of them had a bow, max. 0.05 mm / m, about the same than linear bearings. That sort of bow straighten easy with finger pressure. Unbelivable luck. Would need superstructure and where it would be easy to bolt down.

Young's modulus seems to be max. 4GPa, or 4 KN/mm² for MDF. P6 MDF (floor grade) 20-25 mm thick is 2,5 KN/mm²

Nylon 2-4
Al 70
Steel 210
Concrete 10-40

Therefore MDF would need to be pretty deep structure to resist deflection.

Epoxy concrete Young Modulus is pretty good in comparison 60 to 80 GPa (KN7/mm2)

Did I got the numbers on ballpark? Looks about there...

Pekka

Offline hanermo

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #36 on: May 14, 2016, 11:00:01 AM »
The most rigid, specialist epoxies with titanium or stainless steel paste in them are something like Hysol (locktite) 3478 et al.
About 1100 kg/sq cm crush resistance.

But strength =/= load  =/=  crush resistance.

What happens is that the load is spread over a largish area (technically) and the point load or kgf push is low .. approx 3-5 kg, imo.
= 500 N or less.

So, even wood carriages work well (on rail grinder), because the linear guides do geometric averaging on them.

For the same reason - geometric averaging..
I have overconstrained rails on the front, impact side, of the new VMC.

Ie 4 rails, of Hiwin 35 mm profile, 1000 mm tall, on front. 2 at back. 2 cars each rail, 12 total.
A single car has 4000 kgf load capacity, +/-, for 50.000 kg or 500.000 N rated capacity.

I cannot, easily enough, make the assy to much better than 0.01 mm (this level is easy. Assemble so cars don´t bind, by hand. Shim as needed)).
The geometric averaging makes the actual accuracy be about 2-4x better.

I don´t have 50 metric tons push load on my VMC (  I wish).
I hope to do 3 kW spindle power, at most, => 300 kgf push, or 3000 N.
2 kW is fine.

Using 32/4 mm screws, 1200 (1600 mm max) for now.
32 screws are max 1500 kgf max, +/-.

Similar to modern medium VMCs with 1-1.5 m table travels (they do 25 kW).

X axis is the long one, 2200 mm long end-end with 1600 free travel.
Beams are 2200x20x200 mm, with 35 mm rail on top, for 235 mm total height.
Over 1600 mm free span, a 235 mm flat steel beam, 2 of, can probably carry way more than 50 metric tons without failure, in theory.
(Its actually not on top of the beam, but..)


Hannu.





Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #37 on: May 29, 2016, 04:51:42 AM »
Huh! That is a big plan. Very nice to read on how differently people approach different problems. Hope to hear more from that project progress.

I have been doodeling on paper some spindle designs. Goal is to make a simple spindle that will allow a little of axial and radial grinding.

Basically I need a fixed bearing near grinding stone and free bearing near pulley at the other end of the shaft.

I considered first classical pair of angular contact bearings, but very few are offered with any dust shields. I'm setling on dual angular contact bearing with 2RS shields, this I might just get away with the loading and RPM I need here.

I draw two slightly different basic designs, which one is prefered and why?

Is there better, easy to make design?

* Addition: The square on very left is a polyvee belt pulley - free bearing end - ball bearing. Grinding stone will be on right hand side (not drawn) on locating bearing side.....just to clarify my doodle.

Thank you,
Pekka
« Last Edit: May 30, 2016, 02:42:41 AM by PekkaNF »

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #38 on: May 31, 2016, 02:10:33 AM »
I'm thinking on using fat shaft design....toss of a coin. Grinding stone on right next to double angular contact bearing and poly-vee belt on left to load the free tail bearing.

Pekka

Offline RotarySMP

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #39 on: June 01, 2016, 05:11:39 AM »
Does a surface grinder really need the thrust control of paired AC bearings? My Clarkson T&C grinder only has deep groove ball bearings. Since you are grinding a surface, with no precise shoulders, I'd think you only need radial stiffness, and could make the spindle more simple.

Mark

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #40 on: June 01, 2016, 05:33:36 AM »
Flat surfaces and there would be no problem with deep groove ball bearings. Or even with bench grinder that was suggested before and I did consider it.

However: I have dove tails to grind too and they probably will not be done in  one go. Another sightly problematic surface is back of the vertical. only way I can imagine reasonable size grinding wheel there is a cup/face type wheel in reverse. I.E. I might need radial and axial loading in both ways. I tried to resist the latest one, because othervice I could have got away with two opposing angular contact bearings, tail one spring loaded. Pretty much same than Quorn type grinder, GREAT BOOK BTW.
http://s164.photobucket.com/user/rtgeorge_album/media/broadley.gif.html

Pekka

Offline RotarySMP

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #41 on: June 01, 2016, 09:58:56 AM »
A couple of years ago I picked up a Fischer Precise FAV 80L grinding spindle off Ebay.de pretty cheap. there are a few options on Kleinanzeign.ebay.de (Craigslist in Germany) if you are interested:

https://www.ebay-kleinanzeigen.de/s-anzeige/schleifspindel/413146499-84-13826

My Fischer looks similar to this one (€70 for a new spindle! - you couldn't even get the bearing for that price)
https://www.ebay-kleinanzeigen.de/s-anzeige/schleifspindel/225839568-298-4254
Mark


Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #42 on: June 01, 2016, 01:56:00 PM »
A couple of years ago I picked up a Fischer Precise FAV 80L grinding spindle off Ebay.de pretty cheap. there are a few options on Kleinanzeign.ebay.de (Craigslist in Germany) if you are interested:

https://www.ebay-kleinanzeigen.de/s-anzeige/schleifspindel/413146499-84-13826

My Fischer looks similar to this one (€70 for a new spindle! - you couldn't even get the bearing for that price)
https://www.ebay-kleinanzeigen.de/s-anzeige/schleifspindel/225839568-298-4254
Mark

Those are nice. Last one looks about right, speed is ok, physically is's tad too big. But price is right.

Trawled net and found some new (to me) info post #87 plus much of that thead is interesting.
http://www.practicalmachinist.com/vb/general/making-very-good-bearing-fits-2-3-microns-lapping-281292/index5.html

Pekka

Offline hanermo

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #43 on: June 04, 2016, 03:18:08 AM »
I may be of interest that I am "hanermo" and the spindles are my project.

The spindles are not done, but the VMC is getting there...
Painted the last major assys last week, 2 vertical assy that support the bridge (== 700kg).

And the lathe is now running with C axis..
Need the lathe, to do the spindle mount for the VMC to do the flats for grinder, to make manufacturing spindles fast and easy...

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #44 on: June 06, 2016, 02:37:40 AM »
Went on swap meet this week-end. There was a guy with spindles, but they were massive. Mainly used in wood working machines ISO40 and one 1/3 of that but something like 30 mm bearing shaft and the AC-bearings were shot.

I have two open issues:

1: Grinding wheel type/spesification? I never have used grinding wheel to cast iron, but talked to few guys who did a little and lit looks like aluminium oxide abrasive (White....) and fairly coarse like 46 and bit open/friable would be worth of trying. looks like I have to settle on normal disc type wheel, dress it somewhat slant to negotiate around dovetails and that must do.

I could buy russian boron nitride small sharpening wheels, but they are cup or saucer type. Problem is that they are very fine, mostly 80-100, very few #60. Would that work "kissing" on cast iron?

2: I'm considering gluing the fixed front bearing on bearing housing. It is one part bearing (no adjustable preload). It would make nose of the spindle whole lot more easy and more compact.

I checked some ready made spindles and they are great for something a little larger. I'm in a hunt of something like dumore tool post grinder size.

Last weekend went on my daughte's graduation (primary->seconday) and showeling/wheel barrowing few tons of gravel around my front yard....no swarf was being produced, but looks like I have all the necessary steel to make spindle looking object.

Pekka

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Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #46 on: June 08, 2016, 04:11:37 AM »
Did you see this solution...
http://bodgesoc.blogspot.co.at/2015/08/rivett-lathe-slideway-refurb-as.html?m=1
Mark

No, I didn't see that one. Thank you. Got some ideas to mull over.

As with other lathe type solutions the problem with milling machine is that you have no redundant ways to reference with.

Lathe DIY way methods rely on the fact that most of the lathes have separate guide surfaces: Two for tail-stock and two for cross slide. And they hardly never wear at the same spot.

Offline awemawson

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #47 on: June 08, 2016, 08:06:42 AM »
Pekka,

I have been having a clear out and an Arrand spindle has surfaced - I've had it donkeys years but it is brand new in its box complete with two MT adaptors, a drive pulley and even the belt and belt joiner to drive it.

Before I put it on ebay is it any use for your conundrum?
Andrew Mawson
East Sussex

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #48 on: June 08, 2016, 11:42:26 AM »
Andrew, That looks about right size and all (providing that cutting mat has metric graduation, not imperial).  I remmember that brand poping up in UK mags -90s.

Is it made for grinding or does it has other uses? The draw bolt on taper hints for milling. Is that MT taper or something special? Need to device something to clamp the grinding stone and 180 mm dia, 20-25 mm width seems to calculate close to keep all simple.

Bearings might need changing, it's probably imperial?....but bearing boys is as close to me than it is to you.

Looks about right. Care to take aproximate lenght and width, by eyeballing is not calibrated.

Pekka

Offline DMIOM

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #49 on: June 08, 2016, 12:53:13 PM »
Andrew, That looks about right size and all (providing that cutting mat has metric graduation, not imperial).......Pekka

Pekka,

I think they're 10mm squares on the cutting mat - some pictures show where the corner of an A4 and an A5 page would go; they are a little bit more than 6 squares apart in one direction, and about 8¾ squares in the other direction - so I reckon that's a pretty close match for 10 mm squares as A4 is 210 x 297 mm, A5 is 148 x 210 mm which would be 62mm difference x 87mm

Dave M.

Offline awemawson

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #50 on: June 08, 2016, 01:09:20 PM »
Pekka, I think Dave is spot on but I'll check absolute size next time I crawl over to the workshop. The bore is 1MT

Just at the moment I'm recovering with a can cans of Old Speckled Hen having been squirting unbelievably expensive vetmeds down lambs throats (£150 for a 1 litre bottle  :bugeye: ) against coccidiosis. They didn't want it to happen and are amazingly agile and fleet of foot.

The later Arrand spindles called themselves 'milling and grinding' spindles. The only difference apparent is a lubrication fitting screwed in the side !
Andrew Mawson
East Sussex

Offline awemawson

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #51 on: June 09, 2016, 11:24:09 AM »
Here's a C o C of the spindle for your delight and delectation
Andrew Mawson
East Sussex

Offline awemawson

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #52 on: June 19, 2016, 04:19:51 PM »
Pekka, glad its arrived  :thumbup:

Have a laugh at this ebay listing for an Arrand spindle like yours:

http://www.ebay.co.uk/itm/Arrand-milling-and-drilling-spindle-for-a-myford-lathe-/272279443631?hash=item3f651e98af:g:sqUAAOSwnNBXZvhU

£250  :bugeye: :bugeye: :bugeye: :bugeye:
Andrew Mawson
East Sussex

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #53 on: June 20, 2016, 05:21:01 AM »
Holly crap, does word "Myford" 10x price immediately?

Had a quick look at it. Feels like never used and grease is not gummed up. I was prepared to change the bearings first, most of the greases has self life less than 6 years.

The spindle is that small that I got an idea on how to grind the upright body ways on far back, there is very little space for anything but that seems to do it if rigged bit unorthodox and when using small worn grinding stone.

I have been working lately on front yard. Did last round of leveling and teach my daughter to use plate compactor and how to level crushed rock bed. Even got done first two pallets of concrete concrete paving blocks. It's all downhill now when the base is done.

Pekka

Offline awemawson

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #54 on: June 20, 2016, 05:46:25 AM »
Oh yes it was brand new when I bought it, and I never got round to using it  :med:

Andrew Mawson
East Sussex

Offline j1312v

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #55 on: September 06, 2016, 02:20:48 PM »
Hi Pekka,

Just came across a thread in practical machinist that may give you a few more ideas... :coffee:

http://www.practicalmachinist.com/vb/general-archive/fixing-hardened-ways-77879/

Best,

Joe

Offline PekkaNF

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Re: Portable milling/grinding machine for machine way reconditioning
« Reply #56 on: September 07, 2016, 01:56:03 AM »
Thank you. I glanced it trough and looks like it has some usefull stuff and some pointers on what to watch. Pity he did not go trough it all the DIY route. I would have liked to read more about the last bit on what went on it after regrind.

I'm still using the mill, but it prevents me doing anything accurate. I still have some time, this could be my winter project. I don't want to pull the mill apart before I know what to do on and on which order.

Looks like pretty much all lathe DIY regrinds trust that parts of the ways are not worn and can be used as they are for regrinding.

Pekka