Sieg C2 mini-lathe mods

[Graham Meek]

Another addition for this lathe that some readers may find interesting and worthwhile can be found here.

http://www.modelengineeringwebsite.com/Mini_handwheel_1.html

My best regards
Gray,

[spuddevans]

I might just add that to my (growing) list of mods, thanks Gray


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

[arnoldb]

Good to see you back in the shop Tim, and great going on the improvements 

And yes - I agree with you on the ball-raced ER closer nuts - an absolute pleasure to use. 

Kind regards, Arnold

[spuddevans]

Thanks Arnold it feels good to be back making stuff again.


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

[spuddevans]

Finally I have completed one of the Mini-Lathe mods - the Tailstock Cam Lock.

I didn't have much left to do from yesterday. I started by marking up exactly where I wanted the little lock/release lever to be, then it was mounted in the Stevenson's ER32 block in the vice, and indicated the centre.




I know I've mentioned it before, but someone had asked me just how good the Ball-raced ER32 nut's are. I had to drill a 4.2mm hole for tapping M5, so I used a 5mm ER32 collet. Previously I would had to have used a C-spanner to close the collet enough to grip the drill, but with the ball-race-nut I was able to close it up with just my hand.


And I am also loving the Stevenson ER32 blocks, so easy for gripping round stock in the machine vice, and now I used it to make sure the shaft was kept square for tapping.




Then I parted off the cam to length. Then I threaded a short section of 5mm steel for the handle, assembled everything and then marked where to cut the handle, and then cut it and rounded the end off.

Here's all the componant parts. The cam has about 1.8mm of "lift" (or to be technically correct, "drop").




Then I started assembling. I used a couple of E-clips to stop the Cam from moving about, the back one requires turning the block 90degrees to fit.




Then the foot was screwed on, and after checking it was screwed in enough (and not too far) a locknut was tightened.




Here's it in "Unlocked"




and Locked




As you can see, there's not much in it, and it really locks solid with very little pressure.

I totally recommend doing this mod, it is so much better than the original method.


The brass needed for the tapered gibs arrived today, so after finishing up the Tailstock cam lock I disassembled the lathe's carriage. Then I mounted the new gib brackets on and placed it back on the ways. I was wanting to check if, and how much, clearance there would be between the brackets and the bed casting.




Looks like there's about 0.75-1mm of clearance at the front, and there's about the same on the back. So the plan is to mill the gibs down to about 0.25-0.5mm wider than the brackets. Because the front and back brackets have different depths, I marked up both ends of each gib to indicate which belongs to which.




Then I milled each Gib down to their respective widths, then, using a little round-over bit, I eased the 2 corners.




This was so that they wouldn't foul in the sharp corner of the bracket




And that was all I could get done as I had to go and make some nourishment.

Next up will be milling the tapers on the gibs.

Thanks for watching.
Tim

[ths]

Nice going Tim, it's good to see people improving their machines. Although I don't have your lathe (ML7 here), I can see that what you're doing will be a great improvement. The cam lock tail stock will be such pleasure to use, and I look forward to seeing how the tapered gibs work out.

Cheers, Hugh.

[spuddevans]

Thanks Hugh

So on with the tapers. I was going to leave the brass gibs un-tapered, but then figured that they would only give the same amount of grip as the factory originals.




So over to the mill and used the bracket to hold the gib for machining the taper, this ensures that the tapers will match each other perfectly.




I took off just the bare minimum to cut the taper, and then I couldn't help myself and just had to try it on the carriage. Still needs more taken off




I took it easy with the cuts, taking the time to check each time to make sure I didn't go too far. Each time I fitted it together I would score a pencil line where the edge of the bracket was




Next was drilling for the adjustment screw in the brackets. As the screw heads are 11mm diameter I decided to space them in from the ways by 6mm. I marked up the end of the bracket and put it in the vice. To get it vertical I used bog's trick of using a engineers square on the mill's bed and shining a light on the back of it. Shows up exactly when it's square.




Then to tap it M4 I clamped my tapping stand onto the mill and swivelled the head over. Worked a treat and made sure that there was no lateral flex on the taps.




In order to stop these brass gibs from moving out of place I want to put a couple of pins in each bracket and a corresponding groove in both gibs. I started off by measuring from the side of the gib that faces the bracket.




Then milled a 2mm groove in the centre of the gib




Then I poked a couple of 2mm holes in the bracket




Then a couple of short 2mm pieces were loctited in the holes




Then  it was on to the little groove that the adjustment screw fits into. I milled out a groove with a 3mm endmill, the screw head is 4mm thick, so I milled it to 3.8mm and then filed it to fit




It works!!




And it is about 1mm shy of the other end




Both done




Can I say smooth!!! It is like silk, and got better after a little oil ( always helps )

So another mod gets ticked off the list

Next up ...... I'm not sure. I'll see how the spirit moves me when next in the workshop.

Tim

[smfr]

Very nice job on the gibs there! 

Simon

[Roger B]

I agree, a very good piece of work   

[Stuart]

 Roger

A point if you can do it is a screw at the head stock end ,opposite the adjustment screw to apply tension against the adjustment screw to stop the gib moving in use , they can be loose one way and tighten up the other

The same as in a a SX3 mill Z ,and is the norm on full size machines

Stuart

[Graham Meek]

Hi Tim

You have made a nice job of those Gibs. One word of caution from my experience in rectifying two similar lathes for friends, the under face of the rear bedway is not always machined right into the corner where it meets the rear vertical face of the bed. Sometimes the gibs run on this un-machined edge and not the machined face.

There is an album below of the work I did on the two machines concerned, both were in identical condition and just over 12 months old.

http://www.model-engineer.co.uk/albums/member_album.asp?a=26835

My best regards
Gray.

[spuddevans]

Thanks Simon, Roger, Stuart and Graham

A point if you can do it is a screw at the head stock end ,opposite the adjustment screw to apply tension against the adjustment screw to stop the gib moving in use , they can be loose one way and tighten up the other

The same as in a a SX3 mill Z ,and is the norm on full size machines

That's a good suggestion, and it's not too hard to add a screw to the other end. That may be the next mod to be made. Heh!! A mod for a mod!!

One word of caution from my experience in rectifying two similar lathes for friends, the under face of the rear bedway is not always machined right into the corner where it meets the rear vertical face of the bed. Sometimes the gibs run on this un-machined edge and not the machined face.

There is an album below of the work I did on the two machines concerned, both were in identical condition and just over 12 months old.

http://www.model-engineer.co.uk/albums/member_album.asp?a=26835

Funny you should say that, I did notice that the carriage does tighten up a little at the headstock end. Hmm I thought I had left enough clearance (about 1.5-2mm) but maybe I need to skim half a mm off the thickness of the rear gib.


Thanks for those pics, they will be a good reference.

Can I ask if doweling the top-slide gibs brought about much improvement?

Tim

[Graham Meek]

Hi Tim,

Any Gib that is adjusted with set screws that are locked by nuts will benefit from dowelling. Especially if the adjusting set screw has more of a point on the end rather than a radius. The pointed end allows the gib to move fore and aft as the slide changes direction and rapidly wears the point down, usually dubbing the point over. Which of course makes future adjustment very interesting. Another bonus with the dowelled Gib is that should you need to remove the slide the Gib stays put and usually does not need readjusting. I did the Gibs on my Emco Maximat Super 11 just after I purchased the machine in 1986, I cannot recall having touched them since then, and my lathe has done a lot of work in the meanwhile.

My best regards
Gray,

[spuddevans]

Hi Gray,

Thanks for the info, I may add doweling the cross-slide gibs to the growing list of mods, they sound a worthwhile improvement


Tim

[ths]

Tim, I dowelled the top slide gibs on my ML7, and it has made a great difference. I must do the cross slide as well. Hugh.