Author Topic: Sieg C2 mini-lathe mods  (Read 30423 times)

Offline spuddevans

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Sieg C2 mini-lathe mods
« on: July 08, 2014, 04:06:55 PM »
So after too long a break from posting up anything, I've decided to chart my progress as I try and improve my little mini-lathe.

Let me introduce the patient.



It is a Sieg C2A mini-lathe, badged by Axminster (I doubt if that makes any difference) I bought it about 5 or 6 years ago (I think :scratch: ) and up to now the only mods I have made to/for it is to chisel off the majority of the anti-rust "dragon fat" and to install a QC toolpost.

I have been quite happy with the lathe, it has done most of what I wanted from it. However, parting anything harder than warm moist butter has always been a little "Buttock-Pucker" inducing. Also the carriage has always been a little stiff, and the gears are constantly jammed up with swarf. The topslide (compound :scratch: I'm useless with proper terms) DRO has stopped working and the action has always been so poor I have just kept the gibs fully tightened up to lock it solid.

So what's the plan? Here's the list in no order of importance.

Tapered gibs on the carriage,
Carriage lock
Replace gibs on cross-slide and topslide with brass gibs (or learn how to scrape the existing gibs to fit properly)
Build a replacement QC mounting block to replace the Top-slide (I don't use the Top-slide/compound except on rare occasions, when I will re-mount the top-slide)
Convert the tailstock to a cam-lock.
Maybe change the headstock bearings to Angular Contact.



So I've made a start on the 1st item, the Tapered gibs.

Because I have only one lathe I made a start by making the gib-adjustment screws (it's pretty hard to turn them when the lathe is in bits)

The screws are M4 threaded, with a 11mm diameter head. Rather than wastefully turning down a long section of 12mm brass, I decided to follow (of a fashion) C.Fellows and make it out of a socket cap screw. Not having any M4 cap screws I used the next best thing I had, a couple of M4 Pozi screws, and a couple of 12mm "washers" I turned up and tapped M4.




Then I fluxed them up and set them up to silver solder in my little hearth.




In the interests of honesty, only one actually "took", I think that the screws may have been Zinc plated, which caused one not to stick, funny as the other one seems fine. So I had to redo one, but this time I turned the end of the screw down to 3mm, then drilled another brass "washer" to fit and then silver soldered it.


Then I chucked them back into the lathe and cleaned up the faces and turned them down to 11mm.




Then it was over to the mill to mill a screwdriver slot.




Resulting with this,




Having a little more time before the call to dinner, I started on cleaning up the hunk-o-rust that will become the gib brackets.




That's as far as I got, stay tuned for (ir)regular updates.


Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline Stilldrillin

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Re: Sieg C2 mini-lathe mods
« Reply #1 on: July 08, 2014, 04:18:09 PM »
Nice to see a useful project underway Tim!  :thumbup:

I'm in. Looking forward to watching your progress.......  :)

David D
David.

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

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

Offline Brass_Machine

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Re: Sieg C2 mini-lathe mods
« Reply #2 on: July 08, 2014, 05:14:58 PM »
Nice! I will be watching closely as I have some of these mods lined up for mine.

Eric
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Offline S. Heslop

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Re: Sieg C2 mini-lathe mods
« Reply #3 on: July 08, 2014, 06:49:54 PM »
I'm interested in this. I did a little 'tuning up' on my own Axminster SC2 lathe, shimming the carriage gibs and convincing the cross slide gibs to sit flat (they were a wider angle than the dovetail, so I filed them to a narrower angle (kind of over-did it!) and it seemed to do the trick), and it really made the world of difference. I can take a bit over a 1mm cut on steel now without any problems, which is huge to me!

I've also been tempted to replace the compound slide with a block too. I'm thinking about getting a bigger lathe in the near future and adapting the mini lathe for rapid turning of small parts. So i'll be interested to see how you do it.

Offline Stilldrillin

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Re: Sieg C2 mini-lathe mods
« Reply #4 on: July 09, 2014, 03:34:41 AM »
Anyone tempted to replace the compound, with a block.

Don't forget to offset the toolpost pivot stud, outward, and to the right......... http://madmodder.net/index.php?topic=2464.0

Gives much improved stability, and greater diameter capacity.  :thumbup:

David D
David.

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

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

Offline spuddevans

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Re: Sieg C2 mini-lathe mods
« Reply #5 on: July 09, 2014, 02:48:37 PM »
Anyone tempted to replace the compound, with a block.

Don't forget to offset the toolpost pivot stud, outward, and to the right......... http://madmodder.net/index.php?topic=2464.0

Gives much improved stability, and greater diameter capacity.  :thumbup:

David D

I forgot about that thread, thanks for reminding me  :thumbup: :thumbup: That mod is definitely on the "To-Do" list


Nothing much to show for today, I just removed the rust and squared up 2 lumps of steel, and in the process flattened a section of my carbide lathe tool that I used in the flycutter. ( I'm glad I wasn't using a HSS bit, I'd have been sharpening it every half inch )

Next will be stripping down the lathe carriage to measure up exactly where the mounting holes should be installed, then it will be onto milling the taper into the brackets.


My playtime in the workshop was cut slightly short today as I had to go to the post office to pick up a little bundle of toys from Arc  :headbang:

I got a new Digi-vern (one of the new orange screen ones, bought to replace my last 2 that had suicidal tendancies and threw themselves off the workbench, which somewhat negatively affected their accuracy/use) a set of Stevenson's ER32 blocks (what a great idea) and a ballrace ER32 nut, and a couple of small items.

So, onwards and, Umm........  sideways

Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline chipenter

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Re: Sieg C2 mini-lathe mods
« Reply #6 on: July 09, 2014, 03:04:14 PM »
I keep looking at those ER ballrace nutts , please let us know iff they are any better than the plane ones .
Jeff

Offline spuddevans

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Re: Sieg C2 mini-lathe mods
« Reply #7 on: July 09, 2014, 03:09:43 PM »
I keep looking at those ER ballrace nutts , please let us know iff they are any better than the plane ones .

Will do, I will be trying it out the next time I'm in the workshop  :thumbup:

Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline Stilldrillin

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Re: Sieg C2 mini-lathe mods
« Reply #8 on: July 09, 2014, 03:19:13 PM »
I keep looking at those ER ballrace nutts , please let us know iff they are any better than the plane ones .

Jeff.
I used ER32, on my last mini mill.

One of those replacement nuts made a big difference in gripping power. But needing less tension on the C spanner.......  :thumbup:

David D
David.

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

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

Offline Pete W.

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Re: Sieg C2 mini-lathe mods
« Reply #9 on: July 09, 2014, 04:34:11 PM »
Hi there, all,

I keep reading mentions, here and elsewhere, about tapered gibs.  I don't understand what it's all about!   :bang:   :bang:   :bang: 

Please could somebody post a couple of sketches or photos (cross sections, I assume) showing the before and after?   :mmr: 
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline awemawson

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Re: Sieg C2 mini-lathe mods
« Reply #10 on: July 09, 2014, 04:49:07 PM »
The Bridgeport saddle is an example - it's pushed in to adjust

http://www.icai-online.com/table-to-saddle-gib-x-axis.html
Andrew Mawson
East Sussex

Offline Pete W.

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Re: Sieg C2 mini-lathe mods
« Reply #11 on: July 09, 2014, 05:07:39 PM »
Hi there, Andrew,

We're not talking about dovetail machine ways then?

And I assume that the Bridgeport saddle itself has a corresponding taper?  And if that gib controls the lateral fit, I assume that there's another to control lift (i.e. at 90 degrees)? 
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline spuddevans

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Re: Sieg C2 mini-lathe mods
« Reply #12 on: July 09, 2014, 05:08:23 PM »
Hi Pete,

Here's the link to the sort of thing I am doing with tapered gibs, this is where I have got some plans for what I'm doing.

http://warhammer.mcc.virginia.edu/ty/7x10/vault/Lathes/7x10-7x12-Projects/TaperedSaddleGibs/


Bogstandard wrote up a great thread about fixing up Darren's mini-lathe, sadly all the pictures are missing, but I managed to print out the thread before the pics went down, so that helps too.

Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline awemawson

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Re: Sieg C2 mini-lathe mods
« Reply #13 on: July 09, 2014, 05:28:30 PM »
Hi there, Andrew,

We're not talking about dovetail machine ways then?

And I assume that the Bridgeport saddle itself has a corresponding taper?  And if that gib controls the lateral fit, I assume that there's another to control lift (i.e. at 90 degrees)?

They are dovetails, but with non parallel sides - the gib strip having a corresponding angle to bring them back parallel
Andrew Mawson
East Sussex

Offline Brass_Machine

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Re: Sieg C2 mini-lathe mods
« Reply #14 on: July 09, 2014, 09:33:38 PM »
You can read about another who did the tapered gib mod:

at MEM

Eric
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Offline spuddevans

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Re: Sieg C2 mini-lathe mods
« Reply #15 on: July 10, 2014, 01:09:05 PM »
I started today by reducing the brackets down to the dimensions I needed, 19mm x 15mm. I decided to leave them a little longer than the carriage width for an idea that will be explained later (or if the idea turns out to be rubbish it will be forgotten about :lol: )

Then I dismantled part of the Carriage in order to be able to measure it up. For those who may be wondering what the underside of a mini-lathe carriage looks like, wonder no more...




And before you ask, yes it did come with one cap screw missing. Setting these gibs up requires the employment of an octopus in order to loosen 3 screws while tightening 1 or 2 others. Hence the attraction to upgrade to a "single screw" operated tapered gib.

After removing the original gibs I set about measuring up to transfer the holes to the new brackets. I first up measured the diameter of a M6 capscrew, and then halved the result. Then I set my digi-vern to this value and zeroed it. Then by measuring from a datum edge (I chose the edge that would normally be closest to the headstock) to the far side of a M6 cap screw in each of the holes like thus,




And by repeating the same procedure but using the front or back edge I was able to note on the plans exactly where the centre of each mounting hole should be installed. I guess in the factory they just drill these holes without any real reference as no two holes were aligned!!




So after measuring, noting, drilling and de-burring I ended up with this.




Next up will be cutting the tapers, Thanks for watching



Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline vtsteam

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Re: Sieg C2 mini-lathe mods
« Reply #16 on: July 10, 2014, 09:39:35 PM »
....Next up will be cutting the tapers, Thanks for watching

 :coffee: :coffee: :coffee: :coffee: :coffee: :coffee: :coffee: :coffee: :coffee: :coffee:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline spuddevans

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Re: Sieg C2 mini-lathe mods
« Reply #17 on: July 11, 2014, 04:10:41 PM »
Warning!! Epic tome ahead.


I had the day off work today, so I got to spend much more time in the workshop.  :headbang: :headbang:

Before I start on cutting the tapers I wanted to cut out for the gear, as you can see it will not do as it is at the moment.




Also I tried the fit of the new gib brackets on the lathe and found that the front bracket fouls the rack by just a little.




So I took about 1.5mm off that bracket and then, after measuring the offending gear as being 17mm, I used a 16mm endmill ( the biggest I have ) and made the cutout.




And here it is in place.




Now that's done it was on to cutting the tapers. In Bog's thread about Darren's lathe he temporarily glued a 1.5mm pin on one edge to set the taper, and I was going to do the same when I discovered I didn't have any superglue. So I came up with an alternative version, and verified it using my little digi-angle-finder. I used a 1.3mm drill bit to space one end ( circled in red )




Then I rough milled it with a 3/8" roughing endmill and then finished it with a 10mm carbide cutter. Then I did the same on the other bracket, remembering to get the taper going the right way.





I was hoping to mill up the gibs themselves, but when I looked through my stash-of-scrap I didn't have any suitable pieces of brass. ( I did have some that was way too big, but the price of brass is too much to mill that much into swarf )


So instead I decided to press on with another little mod, the cover for the handwheel gears on the carriage. As supplied, it looks like this.




I was going to get all technical and start measuring up and marking datums, but then I realised that I could do it much simpler. I measured the shaft to be 17mm and, after cutting out a suitable piece of 1.5mm ali sheet, I bored a 17mm hole in what seemed to be roughly the right place. Then I had to file a little radius on one corner (red circle) so that I am able to manipulate it in and one edge fits nicely under the half-nuts.




Then, while holding the ali in place, I traced out the outline of the casting with a pencil. (actually I had to do this twice as I smudged it the 1st time )




Then I rough cut it on the bandsaw, remounted it on the casting and held it in the vice and carelessly filed it to shape, and then drilled the cover for mounting screws (and gently marked the casting too)




Then it was over to the mill to align by eye and then drill 2.5mm. I was only able to get one clamp on it so I took it really gentle when drilling. ( this casting drills and taps like a dream )




I seem to remember seeing someone else doing a similar mod and they found that the gears sit a tiny bit proud, and their solution was to mill a recess in the cover to prevent the gears from binding. My lazy streak kicked in and I thought I could make it a little simpler. Both gears have shoulders to space them out from the casting, and I measured the shoulders at just over 1mm.




Now if only I had a working lathe !!! But I do have a vertical lathe, of sorts.




As you saw, I even aligned the tool with the very same ruler I use to set the toolheight on my lathe. Actually I had to do this twice as the above tool was the wrong geometry.

It worked just fine, all I needed to take off was 0.25mm from each gear's shoulder.





Then after tapping the m3 holes in the casting I was able to mount the cover.




This what it looks like in situ





Sadly the brass I've ordered for the gibs wont be here until at least tuesday, so I will have to think up some other mods to be getting on with in the meantime.


Tune in next week to see what happens.

Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline spuddevans

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Re: Sieg C2 mini-lathe mods
« Reply #18 on: July 12, 2014, 02:51:35 PM »
After some thought as to what "mod" to start on next (while I await delivery of brass) I started today by cutting a chunk-o-rust off in the bandsaw (thank goodness for bandsaws, I would really hate to cut this 63mm steel bar with a hacksaw)

I then popped it in the vice and used another offcut to make up for any unevenness/out-of-square-ness, and picked a roughing cutter. I'm now using the Ball-raced ER32 nut and I have to say that I am a convert. My collets are metric, and I used to have to juggle with trying to hold the cutter in place (it is 3/8" and the collet is 10mm) and keeping the spindle "lock" button held in while trying to tighten up the ER32 nut with a collet spanner. Now I can close up the collet nut just by hand until it grips, then finish off with a little tweak with the spanner. Well worth getting, I will be getting another one for my lathe.




After a short while I had somewhat distributed part of the steel all over the place



I need to rig up some swarf barriers




Anyway, after a little while and lot of swarf I ended up with this. Anyone guess what it is?





Maybe this will give you a clue.




A new foot for the tailstock, I'll show you a pic of the old and new together a bit further on. My dilemma was how to accurately position the hole for the clamping screw. The hole in the tailstock casting is about 12.7mm, so I routed in my scrap-box and found this




So I chopped the end off that was threaded, inserted a sharpened grub screw into it thus,




With the new "foot" in place I used my very expensive marking system to blue (black) it up. and popped the sharpened grub screw holder in place.




Worked pretty good eh?



Then by measuring from the end of the casting to the point of the grub screw and transferred that to the new foot. Then drilled 10mm through, and counterbored from the underside to give room for a nut and big enough for a socket to fit over it too. (although I'm toying with tapping it M12 and doing away with the nut altogether)

And here is the promised pic comparing old and new.





I also re-installed the lathe's original gibs and re-assembled the carriage, as the next parts of the cam-lock need to be turned.


Thanks for watching,

Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline vtsteam

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Re: Sieg C2 mini-lathe mods
« Reply #19 on: July 12, 2014, 08:58:22 PM »
A custom transfer punch!  Or transfer scriber, properly.
Worked well!  :thumbup:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Sieg C2 mini-lathe mods
« Reply #20 on: July 12, 2014, 09:00:15 PM »
The mill is CNC?
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline spuddevans

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Re: Sieg C2 mini-lathe mods
« Reply #21 on: July 13, 2014, 03:28:59 AM »
The mill is CNC?

Yea, I converted it a few years back. I don't actually use it in full CNC mode very much, but most of the time I use it just in manual control mode, sorta like a glorified DRO system.

I did use a Mach3 wizard to cut the pocket for the nut in the tailstock foot.


Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline spuddevans

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Re: Sieg C2 mini-lathe mods
« Reply #22 on: July 14, 2014, 04:52:28 PM »
I got started today by rescuing a piece of very rusty steel (reclaimed from a bent earth spike dug out of the ground and carefully disposed by BT in my back hedge) and lopping off a short section. Then it was a simply a matter of taking very fine cuts (my re-assembled lathe is even more delicate as the old gibs are needing adjusting) to reduce it to 12mm.

Then I spent too long single point threading a 20mm section M12 ( this rare "Scrapbinium" is murdering my Hss threading tools)

Then I cross drilled the other end.

Anyway, on to (slightly) more interesting stuff.

In looking at the tailstock casting, nothing is even close to square.




The area around the hole for the clamping nut is especially bad, I stuck on a 6" rule with a thin magnet to illustrate the angle.





So after deciding that I needed to correct this, I then had to figure out a way of actually correcting it.

After a little thought I remembered that I had a small Angle plate thingy that I've never used up til today. So I dug it out and bolted it on my mill. Then with a little shimming and a couple of toolmakers clamps I ended up with this.




This may not seem very secure, actually it was rock solid. Even so, I took only light cuts, quite a few light cuts as I ended up removing about 1.6mm to get it squared up.




I also took some 8mm steel and offset turned a 12mm section near one end in the 4jaw (sorry no pic, will take one next time of all the componants of the tailstock camlock mod)

Then I got another small bit of 20mm square steel and poked a couple of holes in it.

Then I put all the bits together for a test, gave the sticking out bar of steel a twist with some pliers, and surprise surprise, the tailstock is locked solid.




All that's left to do is to cross drill the sticking out rod of steel (and shorten it) and attach a handle to it. (clear as mud I know, but hopefully it will all come clear in the next update)

The Idea for this kind of tailstock camlock system came from here :- http://warhammer.mcc.virginia.edu/ty/7x10/vault/Members/RickKruger/Tailstock/

Thanks for watching,

Tim
Measure with a micrometer, mark with chalk, cut with an axe  -  MI0TME

Offline Kjelle

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Re: Sieg C2 mini-lathe mods
« Reply #23 on: July 15, 2014, 02:33:44 AM »
Keep it up, buddy, sooner or later I have to do some of this to my lathe (the blue Einhell version)

Kjelle

Offline Meldonmech

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Re: Sieg C2 mini-lathe mods
« Reply #24 on: July 15, 2014, 04:27:42 AM »
Hi Tim

                You have some very interesting solutions that you have executed on your little lathe.

                                                     Well Done,  David