Author Topic: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)  (Read 24829 times)

Offline stefang

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Hi again ;)

Here we go for another big project: I own a chinese made 250x550 lathe for about 4 years, but there where some points that upset me from the beginning, and now I found the courage to do something, to make it a better lathe.

Thats the lathe in its shape bevor the disassembly:

Overall a nice little lathe, a bit chinese, but ok for the money.

A few contact patterns:

Tailstock to bed:

Hmmm..

Crossslide

Uhm...

Topslide

Maybe...

Headstock to bed:

There is a hint of blue on the left...

Bedslide to bed:


Ok, there is a lot of work coming towards me...

Dirt of four years working on that lathe:


This will be a lathe again, some day...


Some parts could be cleaned and primed right away, after I have cleaned em with a pressure washer in a nearby car wash:


Here we go with the Topslide, measuring the thickness from the lower sliding way to the surface which will hold the toolholder, numbers are in 1/100mm:


I put the topslide in the milling vice and machined that surface over. I also cut a relief on the boss, which will make scraping the surface easier:


For the gib, I drilled a few more holes:


The top surface was scaped afterwards. For touching of, i made a ring-type micro-surfaceplate:


Finished:


Then, the topslide was fliped over and pockets where machined in the lower sliding surfaces. They will be filled with moglice, a special epoxy resin thats used for guideways and sliding surfaces.

With the moglice, I can use my surface plate as a reference to cast from. Only thing thats left to do before casting, is to adjust the height of the remaining material on the slideway. It is done with a file.

After a bit filling i get that measurements, this time in 1/1000 of a mm:


The Pockets are filled with the resin, a release agent is applied to the surface plate, and the top slide is put on the surface plate. I mixed a bit to much of the moglice and it squeezes out on the side, but thats no big deal.


The moglice takes 24hours to cure, after that time the part can be released with a blow from a softfaced mallet, and we get that: A perfect even sliding surface with excellent properties:

The "burr" will be filed of.

Lower part of the top slide, its also pretty off, the measurements range from -0,07 to +0,04mm


Again, scraping:


Finished, only 2/1000mm difference left:


The angular surface will also be coated with moglice, so a pocket is machined again:


This time a scraped master is used for casting:



Came out nice:


Scraping the mating surface on the upper part of the top slide:


Measuring the parallelism with a pair of pins and a mic:


Machining a new gib from hot rolled steel, as the original one was badly warped:


Chucking the partly finished gib into the topslide to machine the 60 angle:


Skinny original gib on the right, manly new gib on the left:


As i dont like drilling blind holes into a gib to hold it with the setting screws, I went another route. I assembled the whole top slide, inserted the gib and fixtured it with two wedges. Then I drilled two 2mm holes trough the side of the topslide and into the gib. Two dowel pins will hold the gib in position:


Clearance, only contacting the angular surfaces:


Here the pins can be seen:


I also made those little pieces, with an angular cut, that will go into the threaded holes in front of the set screws, that push the gib:


As the original bearing of the topslides spindle only was a hole, I went for two ball bearings. Machining a block of aluminum to size and boring it:


Flip around, mill a step and bore the other side:


Finished top slide, with the new bearing block I also gained 15mm extra travel.


Another problem was the headstock, the original bearing seats where not very precise machined..so what could I do?

But first, pulling the spindle out of the headstock:


I decided to machine a cardrige with two bearing seats, bore out the old seats in the headstock and glue it into place.
A friend allowed me, to use his lathe:


bearing seat on the first side:


Then it was flipped arround, and the other seat was machined.

Headstock and finished spindle cardrige:


Machining away the old bearing seat, roughing:


Boring to size, got a nice Wohlhaupter UPA1 boring head short time ago  :D


Same was done on the other side, and the cardrige slipped in pretty fine:


Cardrige glued in place, bearings and spindle installed, first check, everything ok. Final alignment will be done, when the bed is leveled.


Speaking of the bed, I need a new support frame and cooleant tray for it, so I went outside and weldet a bit steel together.
That will be the main support beam:


It is supported by the cooleant tray:


Primed..:


Back in the shop, the fresh painted bed and cooleanttray-bedsupport conraption got bolted together.


Thats all right now, I will continue tomorrow  :)

Regards,
Stefan

Offline andyf

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #1 on: April 01, 2012, 07:23:32 PM »
 :clap: Stefan.

I have a smaller lathe also made by Weiss (not a very Chinese name, but they do paint them white). When yours is finished, please may I bring mine along for the same treatment?  :)

Andy
Sale, Cheshire
I've cut the end off it twice, but it's still too short

Offline Topos

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #2 on: April 01, 2012, 10:44:35 PM »
 :clap:

I marveled at your talent, expertise, and presentation.

Inspiring. Outstanding.

As art students are told to copy the masters at museums, so I shall
emulate you via extrapolation to my project.

I am methodically assembling an Atlas 618 out of hand selected
NOS parts, using my original Atlas 618, its milling attachment, etc
to make no longer existing factory parts.

This is an example of where each evolution of machining a machine
increases accuracy.


Offline Brass_Machine

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #3 on: April 01, 2012, 11:40:35 PM »
This is very cool. I enjoy watching a rebuild for more precision...

Eric
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Offline sbwhart

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #4 on: April 02, 2012, 01:58:27 AM »
Cracking job Stefan  :clap: :clap: :clap: :clap: :clap:

Very interesting work.

Stew
A little bit of clearance never got in the road
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Location:- Crewe Cheshire

Offline krv3000

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #5 on: April 02, 2012, 02:35:31 AM »
HI well dun

Offline Stilldrillin

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #6 on: April 02, 2012, 03:34:33 AM »
Stefan.

VERY well thought through, and carried out.   :clap: :clap:

It will be a cracker when it's finished!   :thumbup:

David D
David.

Still drilling holes... Sometimes, in the right place!

Still modifying bits of metal... Occasionally, making an improvement!

Offline AndreasL

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #7 on: April 02, 2012, 01:49:19 PM »
I enjoy watching a rebuild for more precision...

+1

This is the way to go and a greate inspriration to us all.  :beer:

Offline doubleboost

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #8 on: April 02, 2012, 03:40:39 PM »
Very nice :thumbup: :thumbup: :thumbup:
Great pictures Very well described
It should be a much improved machine
John

Offline Fredbare

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #9 on: April 02, 2012, 05:55:42 PM »
Thank you for sharing, an inspiration.

John

Offline ChadA4MG

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #10 on: April 02, 2012, 10:42:37 PM »
This is interesting, I like seeing rebuilds of machines from restorations to more accuracy.

Offline stefang

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #11 on: April 03, 2012, 06:54:22 PM »
Hey Guys, thank you for the kind words! :beer:

I hope it gets more acurate, when I am done with it...but even when not, it has a cool new paintjob :)

Here we go with the cross slide...first scraping the top surface even:

Progress...


Better...


Thats good enough, I think, the whole area has a pretty good contact pattern:


Again, machining pockets in the lower bearing surfaces, that will be filled with moglice:


The casting progress, the Tape stops the moglice from flowing all over the surface plate.


Released and cleaned:


I wanted the side of the cross slide also rectangular to the top (and automaticaly to the bottom) surface, so I had to scrape it...

First I had to check how much it was of, so I setup the dial indicator in the stand and placed my precision square against the foot of the stand (and against the feeler of the dial indicator), and zeroed it.


Now I could measure how much the surface was off. The indicator shows -0,184mm, that means, its tilted to the right.


Countercheck with a square:


Scraping...getting only a few points so far:


But I got pretty square by now.


Again, counterchecking, thats Ok :)


One little thing to the end...
The play of the main spindle is adjusted with two nuts, but they where pretty rough on one side. That made adjusting them a bit complicated...  :doh:


Easy job for the surface grinder at work:


I have a few more pictures left, they will follow  :D

good night
Stefan

 :wave:

Offline AndreasL

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #12 on: April 04, 2012, 10:26:18 AM »
 :headbang:

See you got the right lub as well.  :beer: Prost!

Offline grayone

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #13 on: April 04, 2012, 01:08:26 PM »
Just amazing talant :jaw:
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Offline David Jupp

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #14 on: April 04, 2012, 01:22:55 PM »
On what basis did you decide how big to make the pockets for Moglice ?

Offline stefang

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #15 on: May 23, 2012, 07:55:18 PM »
Resurecting from the dead...

Sorry for the long period for the next post, but I had a lot of work other than my homeshop ;)

Quote
On what basis did you decide how big to make the pockets for Moglice ?

I made the pockets almost as big as the bearing surfaces, leaving only a small border of castiron so the moglice will not run away while beeing molded to the surface plate. Moglice has also a minimum thickness of 1mm or it wont hold up to the surface.

And I saw, that I used a wrong picture up there, as measuring the perpendicularity of the side of the cross slide, here is the right one:
http://gtwr.de/hbm/IMG_0234.jpg
Only 0,016mm out of true on the whole lenght after scraping..


But there are also a few new pictures:

The reworked feed-gearbox, painted on the in and outside, new bearings, new seals, all cleaned out:


I found that old electric cabinet at my machine supplier and got it cheap (and he was relieved that he got rid of it..):


After a bit of rebuilding, wiring and a brand new Omron VFD, I got this:


Put on the machine, notebook hooked up for programming:

The Omron is pretty nice to program, and with the notebook hooked up it just looks cool ;)

The bedslide got also fitted to the bed, here with the overworked crossslide and the new gib:


Machining the new closing gib for the bedslide from a piece of hot rolled steel:



I also made a new, more massive gib:

New one on the left, original chinese made on the right, I think you can tell the difference ;)

Fits on the bedslide:


Here is another problem of the original design of the topslide, the mounting to the crossslide:

Its just idiotic, as, when the screws of the clamp are tightened, the cross slide is warped. And to top it all of, the topslide has very little support.

So i made a new baseplate and clamp...

Here is the clamping plate:




And the new base plate:

Boring to final size:


Fits :)


Now the top slide is supported on a broad base and the mount to the cross slide will not warp it any more.


Thats the lathe so far:


At least now I have a partial lathe to make parts for itself...still not finished :D

I made a set of new scale rings for the bed, cross and top slide:

Machining on the lathe:


Engraving on the cnc milling machine:


Top slide done:


Bed slide:


Cross slide:


The numbers are not engraved, as I have no cam system that supports a rotary axis, so I stamped the numbers manualy with stamps, a hammer and the MK I Eyeball :loco:

And now I have something special: I thought that a rack and pinion style tailstock would be very cool on my lathe...after a few beers and consulting a good friend of mine I got a plan, so I ordered a round rack and a 12 tooth gear:



The rack got machined down:


The tailstock ram got bored out (oversized to the rack) and I aligned it all together and glued it with JB Weld:



After setting and cleaning, it fits the tailstock:


A bearing block for the gear is machined from a chunk of hot rolled steel:


Milling out and boring the hole for the rack:



The hole for the gear is machined out:



Testfit:


The bearings in their flanges:


The shaft that will hold the gear, note the surface finish my lathe now produces  :wave:


Drilling the holes for the handles, note the very sturdy setup ;)


All put together:


Thats it for today, I hope that were not to much pictures..good night :)

Stefan

Offline philf

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #16 on: May 24, 2012, 03:21:59 AM »
The numbers are not engraved, as I have no cam system that supports a rotary axis, so I stamped the numbers manualy with stamps, a hammer and the MK I Eyeball :loco:
Hi Stefan,

Super work - again!  :clap:

I haven't tried it yet on my CNC but you can simply draw out the scales flat including the numbers and substitute the A axis for the Y. Calibration is simple.

Does the round rack on the tailstock have a hole through it? If not, how do you eject tools from it?

 :beer:

Phil.

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Location: Marple, Cheshire

Offline ieezitin

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #17 on: May 27, 2012, 10:54:29 AM »
Stefang

Nice job there fella I just got to reading the whole thread today and it was an enjoyable experience.
Can you clarify one thing for me, when you milled out the hollows on the base and then you poured the Moglice in did you have to machine that surface or is the pour the finished product.  If it is the finished deal can Moglice be machined?

Many thanks  Anthony.
If you cant fix it, get another hobby.

Offline stefang

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #18 on: May 29, 2012, 09:37:30 AM »
 :wave:

Quote
Can you clarify one thing for me, when you milled out the hollows on the base and then you poured the Moglice in did you have to machine that surface or is the pour the finished product.  If it is the finished deal can Moglice be machined?

If molded from a ground surface, or from the stone surface plate, it is ready to go. But it is able to be machined and handscraped, no problem there. If cast from the surface plate or a ground surface, oilpockets are a good idea to be scraped or machined in.

Quote
Does the round rack on the tailstock have a hole through it? If not, how do you eject tools from it?

Right, drilled a hole trough it and insert a loooooooong screw with a handle on its end to eject the tools :)

Stefan

Offline Noitoen

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #19 on: May 30, 2012, 02:34:25 PM »
Do you have a braking resistor on that Omron VFD? It doesn't handle quick decelerations very well especially with some inertial load.
I have one at work, driving a magnetic cylinder and every time I had to change to a lower speed, it would trip due to the over voltage from the motor's regeneration. The braking resistor solved the problem.

Offline steamer

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #20 on: June 03, 2012, 01:48:53 PM »
Great Job Stefan!   I hope my 9" SB comes out as nice!

Dave

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Damned ijjit!

Offline Davo J

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #21 on: June 04, 2012, 11:12:17 AM »
Nice work Stefan, coming up really nice.

Dave

Offline BillTodd

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #22 on: June 04, 2012, 01:17:40 PM »
This is not just reconditioning Stefan, it is a complete rebuild an redesign.   :clap:

I am sure you will have improved the machine a hundred fold  :headbang:
Bill

Offline stefang

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #23 on: June 05, 2012, 09:13:53 AM »
Quote
Great Job Stefan!   I hope my 9" SB comes out as nice!

Want to trade against my chinese lathe?  :D

Quote
Do you have a braking resistor on that Omron VFD?

Not yet, at the moment i run a pretty long stoping ramp to prevent the VFD from goint into an over voltage fault...

Stefan

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #24 on: June 05, 2012, 11:48:51 AM »
Hi Stefang  :bow: :bow: :bow: :bow: :bow: :bow:

Your doing an excellent job and showing great skill in your workmanship ,,,,,,,,,,,,,,,,,very interesting thread ,keep the photos coming  :thumbup:

The rack tail stock  will be a good mod to the lathe  :med:


Rob

PS ,,,,,,,,,,, you cant beet a  Wohlhaupter  boring head  :)

Offline steamer

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #25 on: June 06, 2012, 09:49:02 PM »
Quote
Great Job Stefan!   I hope my 9" SB comes out as nice!

Want to trade against my chinese lathe?  :D

[


 :D

No Need Stefan!  Your's will be perfect!   You will be very happy with the slides now that they fit properly....it really does make a big difference!


 :thumbup:
Dave
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Damned ijjit!

Offline Robin Bull

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #26 on: February 27, 2018, 02:49:44 AM »
Hi, I'm a newbie here to this site. I cannot see any pictures on Stefang's post.  Have they been removed?  I believe I might be talking to myself as this is an old post! 
Regards,
Robin

Offline awemawson

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Re: Project: Reconditioning of my 250x550 Lathe (Very Picturheavy)
« Reply #27 on: February 27, 2018, 03:51:25 AM »
Robin, welcome aboard  :thumbup: Would you like to put a post in the Introductions section to tell us all about yourself?

. . . pictures dissapearing. Sadly with pictures hosted either by members in their own web space, or on a commercial site like Photobucket then we are not in control of their destiny. Recently photobucket destroyed thousands of threads on hundreds of forums as they tried to hold people to ransom wanting to charge if pictures appeared on forums.


This is why I always advocate uploading pictures directly to the forum (at 800 x 600 resolution please) so they will stay visible as long as the forum exists.

Incidentally Photobucket seem to be getting increasingly desperate to gain market share, with new 'offer' emails coming out most days. So much so  now that they are on my 'blocked sender' list and go straight to the spam folder  :lol:
Andrew Mawson
East Sussex