Unimat for clock work?

[leeinv66]

Posted this under horological tools and have not as yet had any replies. Thought I would try my luck here :smile:

Hi, I have just purchased a Unimat SL (waiting for it to arrive) and intend to use it for mostly clock work. I would like to ask other users if the standard chucks are useable or do I need to buy the ww collet adaptor (which is quite expensive when you can find one) for clock work?

Thanks!
Peter

[leeinv66]

Posted this under horological tools and have not as yet had any replies. Thought I would try my luck here :smile:

Hi, I have just purchased a Unimat SL (waiting for it to arrive) and intend to use it for mostly clock work. I would like to ask other users if the standard chucks are useable or do I need to buy the ww collet adaptor (which is quite expensive when you can find one) for clock work?

Thanks!
Peter

[Bill Ward]

A 3 jaw chuck in decent shape should be good to within 3 or 4 thousandth of an inch, which is OK for most clock work. The more expensive brands, like Bison, are more accurate. Most clock work is custom fitted anyway, so you don't have to hold extremely tight tolerances (as you would, for example, if you were manufacturing with interchangeable parts.)
For more finicky work, like re-pivoting or fine gearcutting, you can use a 4-jaw chuck, which can be gotten as concentric as you have the patience for. It's just not as convenient as a collet. Hmm, I forget, does the Unimat have a Morse taper spindle? If so, you can also use morse taper collets, though they seem to be available in a more limited set of sizes. You might have to make a drawbar (the threaded rod used here to suspend pipes works.) One of the aftermarket suppliers of lathe equipment also sells a Chinese set of WW collets with adapters for various spindles for around $100, but the collets are soft. This would be OK if you're careful, I think.

[Mike Phelan]

The SL will have had quite a bit of use now, and the 3-jaw is probably inaccurate. I would use a 4-jaw or make up some collets.
The SL is not renowned for rigidity, either, unlike the later Unimat 3 with its cast iron bed.
Plenty of Unimat books with useful mods in them.

Bill
No morse taper - it has a parallel bore on the mandrel and tailstock.

[leeinv66]

Thanks Bill, great information. As Mike states, the Unimat does not have a morse taper, but has a parallel bore (12mm X 1.0 ID). However, there are a set of adaptors available that make it compatible with most modern chucks and accessories. Here is a link to a set on ebay if anyone is interested, I will have them made locally:

adaptors (http://cgi.ebay.com.au/UNIMAT-DB-SL-SET-OF-4-SPINDLE-ADAPTORS_W0QQitemZ250044499243QQihZ015QQcategoryZ1 3876QQrdZ1QQcmdZViewItem)

Mike, I bought the SL because it has had hardly any use (and I couldn't afford a later model :smile:). The guy brought it, used it a few times and lost interest in model building. It has spent most of its life stored in a cupboard, so wear of the chuck should not be a problem. I am aware of the limitations of the SL, but I think the work I will be doing will be within those limitations. I have also been told that there is a way to beef up the rails to diminish the rigidity issue you raised (just waiting for the specifics to be emailed to me).

Mike, when you say "make up collets", what did you have in mind?

Thanks for the replies!
Peter

[Mike Phelan]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Mike, when you say "make up collets", what did you have in mind? </div></BLOCKQUOTE>
Peter
It was just something I thought of, but never actually got around to, as my 3-jaw and Jacobs chuck are usually fine; if I want extreme accuracy I use the 4-jaw and a dial indicator.

I was going to either use commercial watchmaker's lathe collets or make my own with three cuts with a slitting saw giving six "jaws".
A female 12 x 1 threaded boss with a taper for the collets, and a threaded drawbar that screwed completely into the collet, and a knurled nut at the far end to pull them in.

Or just make the collets to fit into the parallel mandrel bore with a slight taper, and use a 12 x 1 mm cap to push the collet in.

Make sense?

PS - I am sure there is a collet system for the U3 as an accessory - the thread is the same as the SL.

[leeinv66]

Thanks Mike, that has given me plenty of food for thought :smile: I will wait until it arrives and put it through its paces and then decide what to do about collets. Yes, the collet system for the U3 will fit the SL. However, the last set I saw on ebay sold for more than I paid for this lathe!

Cheers
Peter

[Ansomnia]

Hi Peter, I know very little about the Unimat systems but as regards the costs of collets, in my experience, a semi-complete set for an 8 mm WW lathe, in good condition, will usually cost more than a similarly conditioned WW lathe.

New WW collets will make this discussion completely irrelevant as they cost at least several times the market price of good used ones.

IMO, 8 mm WW collets are the best ones for watch and clock repair because they cover the correct range of sizes needed, are robust enough, fit the greatest range of lathes, are easily obtainable and are cheap. If you want a complete set of collets on a limited budget, IMO, it's the only system to consider.


Michael