unimat sl/db headstock stem

Hello,
I have a question about the Unimat SL/DB headstock stem -
I wander how it is attached to the body of the headstock?
I want to reuse the stem but don't want to ruin the headstock.
I assumed that connection is threaded but weren't able to
unscrew. What else could it be - there is significant force
pulling stem out when you tighten the locking bolt. What could
you suggest to detach the stem?
Thanks,
Archi
Reply to
Archi
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Wow, nice pattern! Unintentional...
Archi
Reply to
Archi
Don't know how it's connected, but it could be cast in place?
Reply to
Jordan
It's different metal. So did you mean that stem (provided it has some 'fins') had been placed into the mold and the possible used as the mandrel to machine the bottom of the headstock (for example)? Then it means that there are no ways to extract the stem w/o destroying the headstock :( By the way stem looks heat-hardened - doesn't it suggest it wasn't heated later even to the AL temperature?
Thanks, Arcady
Reply to
Archi
Archi: What part of the Unimat head stock are you calling the "stem"? I have my owner's manual here and once I figure out what part you are referring to I might be able to help.
Jim Chandler
Reply to
Jim Chandler
The round one going down from the main casing - to be clamped to the base. This is the e-bay picture of it -
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or here if long link would not survive -
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Thank, Archi
Reply to
Archi
Things are sometimes made that way. My MZ motorcycle for example had an iron brake disc, but the centre of it is aluminium alloy - must be cast in.
Here's a blow up from a DB200 parts list. It shows the stem as a separate part, and the method of holding it with a pin in a groove. Note that the SL has a different method of clamping the headstock/stem assembly to the bed, but it's likely the DB method is the same as on the SL, as regards the stem to headstock question. Worth checking?
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Reply to
Jordan
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Note that this is only one of the two styles of mounting pin for the Unimats which you mentioned in the subject line. The one shown is the one with the SL-1000. The DB-200 (based on what I have read and seen) had a different system. The pin has a tapered hole which is encounted by a tapered pin with a threaded straight section on the small end. It is installed/removed by the same metric Allen wrench, but the two are not interchangeable -- and the base into which the pin is placed is also sufficiently different so you can't interchange any of the headstock, the base, or the screw between the two styles.
And I would be willing to accept that the pin (on the SL-1000 at least) was machined, probably with fins for gripping, heat treated, placed in a mould, and the headstock casting poured around it. I'm not really sure whether the headstock casting is Aluminum or Zamac (zinc casting alloy which pours at a lower temperature)).
In any case -- instead of trying to extract it from the headstock, I would measure the part which extends from the headstock casting, and then machine my own replacement for it. That replacement could attach to whatever you want to use it on in whichever way is convenient for you. I would probably thread the hidden part.
Good Luck, DoN.
Reply to
DoN. Nichols
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O.k. I thought tht as what you were referring to but I wanted to be sure. The manual won't be of any help here but tomorrow when I get home from work I'll take a look at mine and see what i can come up with. I have to say that I have never thought of taking it off so I haven't looked too closely at it. I'll let you know what I come up with.
Jim
Reply to
Jim Chandler
My wrong - I have SL, but got incorrect idea that this part has been shared among SL/DB.
Do not have a lathe :( It is 20 mm so I could use the drill rod (If I got lucky with it in this non metric country) but there still be question of groove (as well as good enough threading).
Thanks, Archi
PS Which model has been first - SL or DB?
Reply to
Archi
DB came out first.
Reply to
Jordan
Why don't you sign up on the Yahoo Unimat SL/DB group. A lot of good information there and a nice files section as well. Dave Foreman
Reply to
David L. Foreman
Sure thing, Dave! Where was my head - if there is something, then there is Yahoo group (possible more then one) about this something!
Thanks, Arcady
Reply to
Archi
A lot of things were shared between them, but not all, such as the headstock/pin design, and the mating base. (And, presumably, the milling adapter.)
That does make things more difficult. Do you have friends with a lathe of sufficient size? BTW -- you could use inch drill rod say 1", or as small as 13/16" if you can find that -- and turn it to the needed diameter -- once you find a lathe to handle it.
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The DB is first. And it needed the two-part arrangement of headstock and pin so the headstock could swivel (when loosened) in spite of the transverse screw through it.
FWIW -- the SL-1000 is the easier to machine without production fixtures and jigs. That tapered transverse hole -- with threads perhaps in the base, or perhaps in the pin -- would be more difficult to make.
Good Luck, DoN.
Reply to
DoN. Nichols

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