In article ,
Mike Henry wrote:
DoN and I have different models of Clausing lathes and we both have bed
turrets. Mine (on a 5914) must be different than his, though, as there is
1" of daylight all the way through the bore on one station to to the bore on
it's opposite side.
Yes -- quite different in that. There is a threaded stud up
through the center of my turret, which passes through a disc and has a
nut with a single lever handle to tighten down so there is *no* play in
the turret head for heavy cuts. Thus on my turret, the limit is about
3" plus whatever extension there is beyond the turret's face.
IOW, it would be possible to thread a pretty long piece
with a die head, providing the OD was small enough to fit therough the die
head shank bore.
*And* as long as you had some way to capture and steady the free
end of the workpiece as it passes through the turret. The other problem
is that the total travel of the turret ram is about 8-10" (I think --
maybe a full 12"), and if you use the back-most two inches, you will
pick up the pawl which will try to rotate the turret as you pull back --
which could be very awakward with a long workpiece passing through it.
I guess that you could limit the travel and use the lever collet
assembly to lock and unlock the collet to pull more stock through the
headstock.
But we really don't know what kind of lathe the original poster
) has, nor whether it has a turret of any form, or
what the diameter is. Though we now know that it is an Acme thread, and
I've never seen a set of Acme chasers for a Geometric die head. I guess
that they could be purchased, but I would think that you would want a
larger die head to handle the extra cutting load for the Acme thread
form -- let alone the extra cutting force needed for a good bronze.
"Larger than a standard diameter" may well mean also "larger
than any die head which will fit in my turret", and thus "possible
problems in most lathes which will fit in a typical home shop." My
largest die head which I've used is a 3/4", with a 1" diameter shank. I
think that it may have a full 3/4" diameter clear through the shank,
though I've never actually measured it. But that could be a limiting
factor.
"jim rozen" wrote in message
...
In article ,
says...
Not sure why it matters, but it's an acme thread that is larger in
diameter than a standard diameter/pitch and must be in bronze.
Like don asked, how long a piece do you need? Longer
than a few inches and a die head won't do it.
If it is a non-standard thread you proably won't be able
to purchase off-the shelf chasers anyway. Single point
it with a follower rest would be the way I would do it.
I agree. I can handle up to 24" long between centers, and with
a single point tool, plus a follower rest, I can cut Acme threads on
that up to perhaps 6" diameter. If it is 1" diameter or less, I can
pass it through collets, and with a steady rest replacing the turret or
tailstock, I can single-point any 24" long section. Beyond that, by
unclamping and reclamping, and taking a lot of time tuning the feed to
pick up the previous pass, I can probably continue the thread -- but
each re-clamping increases the chance for a mistake which would spoil
the whole thing.
Using a chuck, I could pass a full 1-3/8" through the spindle,
but could thread somewhat less length at a pass, thanks to the loss of
space taken up by the chuck.
The longer it gets, the more likely to have problems with
whipping -- (and the smaller the diameter the more likely to have those
problems -- but if you have whipping with a large diameter, you have major
destruction -- including possibly of the lathe or yourself.
So -- yes, knowing about the approximate dimensions -- *and* the
size of your lathe -- do make a difference. The more we know, the
better our advice can be.
But if you have to be secretive about it for whatever reason
(perhaps a non-disclosure agreement?) so be it.
Knowing that it is larger than the largest die head your lathe
will handle is one important thing. Knowing that the overall threaded
length is greater than the travel of the carriage on your lathe is
another important thing.
If you're trying to do this with a 1-1/2" die head, and a
Sherline lathe, we will all turn our backs and wait for the final
outcome. :-)
Enjoy,
DoN.
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