Fw: [C0 Lathe] Fitting the drive center

[David Halfpenny gmail]

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From: "Jensmith" <jensm...@googlemail.com>
Sent: Tuesday, May 11, 2010 9:25 PM
To: "Sieg C0 Baby Lathe" <C0-L...@googlegroups.com>
Subject: [C0 Lathe] Fitting the drive center

> Hi, I'm back again :)
> Pen turning stuff is sorted so thanks for the help.
>
> I've got a drive center for the headstock with the woodturning
> attachment but I'm surprised that it just seems to slot in with no
> fixings. Is this correct or should there be something to screw onto
> the thread?
>
> I can see how it would work with a morse taper and friction but with a
> parallel shaft will it really drive ok?

Yes, it works by friction in that tiny little 60 degree cone, arising from
the
end load from the tailstock. That isn't a problem because you can't
actually use the thing without the tailstock.

What isn't obvious is that the Morse Taper isn't all that much different:
a
Morse taper will work its way out if subjected to a side load. Therefore
all Morse applications subject to side load (such as holding a milling
cutter or for turning without the use of the tailstock) must have either a
drawbar or a screw-on ring. (Model engineers sometimes take the risk,
which
is why Model Engineer magazine has to keep repeating the warnings year
after year after year.)

If you end up doing what the majority of woodturners in history have done,
i.e. make your own chucks, you have got several options:
- hold the home-made chuck in the three jaw
- fit it into the 10+mm hole but with a screw or other drawbar through the
spindle
- fit it into a collet (Arc will sell you a choice of good collet chucks
that will hold dowels etc)
- screw it onto the nose.

Here's another tip for holding smaller stuff - you can use a Sieg or
Unimat
(the other kind) fit drill chuck to the headstock spindle.
BUT it won't fit properly - notice that your headstock and tailstock have
the same thread but (annoyingly) a different parallel section behind the
thread. For small work I just put a thick washer between the drill chuck
and the spindle like this attachment.
That washer is really important or the chuck may jam on at a drunken
(technical term) angle.

David 1/2d




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