I'm new to metalworking and just got a Microlux 7x14.
I'm interested in machining thin disks - about 1 1/2" in diameter by 1/16".

I see that that some lathes have soft jaws, such as
http://www.taigtools.com/c1051.html

Is there an equivalent solution for the Sieg lathe?
Any other ideas?

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Bruce Barnett wrote:

I'm interested in machining thin disks - about 1 1/2" in diameter by 1/16".

What machining operations do you intend to do?
I often clamp disks between plasic/tuffnol "mushrooms" or glue them to a
mandrel (LockTite)

Nick
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(Nick Müller) writes:

Bruce Barnett wrote:

I'm interested in machining thin disks - about 1 1/2" in diameter by 1/16".

What machining operations do you intend to do?

Hollowing - for the most part, starting from the middle out.
So one disk will nest inside a second disk.

The second operation I'd like to do is to add a different metal around
the rim of an existing disk. I can see using two mushrooms for part of
the process.


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According to Bruce Barnett :
(Nick Müller) writes:

Bruce Barnett wrote:

I'm interested in machining thin disks - about 1 1/2" in diameter by 1/16".

What machining operations do you intend to do?

Hollowing - for the most part, starting from the middle out.
So one disk will nest inside a second disk.

Hmm ... while the Taig pie-section soft jaws will work on this,
what I would think would be the best is a step collet, except that they
are rare on anything other than jeweler's lathes.

Or -- some soft collets with fairly large diameters -- but those
seem to be offered in 5C size mostly.

------------------------------ Pot Chuck Start ------------------------------

Or -- you could *make* a form of "pot chuck". Given the size of
your machine, I would suggest starting with a piece of brass or aluminum
somewhat larger in diameter than the larger of your workpiece diameter
and your spindle nose diameter. (They seem to be somewhat similar in
this case, though I'm not sure, not having seen your lathe.)

Anyway -- in a normal 3-jaw chuck, machine it to fit on the
spindle nose, and drill and tap it for the needed studs so you can mount
it directly on the spindle nose.

Mount it on the spindle nose, and mark it so you can always
replace it with the same stud in the same spindle flange hole.

Then, machine the ID a bit (say 1/8" to 1/4" smaller than the OD
of your workpiece, and perhaps 3/4" to 1-1/4" deep. Then machine a step
on the outer end just barely large enough and deep enough for a slip fit
of your workpiece.

Then, turn the OD down to perhaps 1/4" diameter greater than
your workpiece diameter, and down to the same depth that the inner bore
reaches.

Then, remove it from the spindle nose, and use a saw (a bandsaw
if you have it, otherwise a hacksaw or a slitting saw in a milling
machine.

Restore it to the spindle nose (being careful to use the same
stud per hole that you used when turning and boring it. Slip a
worm-geared hose clamp over the OD, place the workpiece into the ID, and
tighten the hose clamp to grip the workpiece.

Hmm ... you may want to drill a hole in the side of this to let
you reach the back of the workpiece to nudge it out if there is not
enough to grip.

Of course, you will have to make a different one for each size
of workpiece, but it should give you a very repeatable workpiece holding
system for this rather specialized task.

The pot chucks which I have seen in use were held in the 3-jaw
chuck, but that was on a much larger machine than you have.

------------------------------ Pot Chuck End ------------------------------

The second operation I'd like to do is to add a different metal around
the rim of an existing disk. I can see using two mushrooms for part of
the process.

I'm having a bit of trouble visualizing what you are describing
here -- especially the "mushrooms". If you intend to fit it to the
outside of something like a coin, without it extending beyond the
thickness of the coin, what I would suggest is another pot chuck for the
final OD of this, so you can bore the metal out to just too small to fit
(perhaps 0.001" too small, or a bit less.) When it is made, place the
coin (or coin equivalent) on a cold flat steel or cast iron piece, heat
the ring to an uncomfortable temperature (which temporarily expands it),
and drop it over the coin, using something like a piece of wood to hold
it down around the coin until the temperatures equalize and the ring
shrinks into a firm grip on the coin.

Good Luck,
DoN.
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Bruce Barnett wrote:

Hollowing - for the most part, starting from the middle out.
So one disk will nest inside a second disk.

I would suggest making a mandrel. Have some piece of round mild steel,
make a round recess on it's front where the disk fits into and glue it
in with LockTite. After the work, heat it up to about 150°C and the glue
will release.
Of course, you can use a magnetic chuck (with most steels) or a vacuum
chuck.


Nick
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http://www.motor-manufaktur.de
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"Bruce Barnett" wrote in message
...


I'm new to metalworking and just got a Microlux 7x14.
I'm interested in machining thin disks - about 1 1/2" in diameter by
1/16".

I see that that some lathes have soft jaws, such as
http://www.taigtools.com/c1051.html

Is there an equivalent solution for the Sieg lathe?
Any other ideas?

I machined the back of the Taig 4-jaw to fit a mini-lathe (Craftex 7x10);
this is a common and easy thing to do.

I don't like the Taig chuck as much as I thought I would - the jaws have
only a projecting tang which engages a narrow part of the adjusting screw.
This lets them tip when you have the jaws almost at their outer limit; and
then it's easy to gouge the underside of the jaw-slots when moving them
inwards, leading to the jaws never again being square to the chuck. A set
of jaws with partial threads running on screws that are captive in the chuck
would less likely to do this, I think.

What I'd really like would be a 4-jaw independent chuck, about 4", with the
soft-jaw capability. The jaws on the Taig 4-jaw are HARD.

Is it possible to edm a hole with threads?

Is it possible to edm a hole with threads?



Yep, no problem.

I'm new to metalworking and just got a Microlux 7x14.
I'm interested in machining thin disks - about 1 1/2" in diameter by
1/16".


What are you trying to do to the disks? That's going to be a pretty
challenging project for a new guy.

Depends upon what you want to do with the disks. Facing off a disk merely
requires a chuck that will leave the disk proud of the jaws when the facing
is done. This is best doe with a collet type with a backing surface.
Edging is a bit more difficult and probably the best way is to use some
doublesided tape (not the foam stuff but rather the stuff that is using a
thin plastic center with adhesive on both sides) and a live center with
alarge pad rather than a point to hold the disk in place. The finished edge
needs to stand proud of the mountings.

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Why do penguins walk so far to get to their nesting grounds?

"Bob May" writes:

Depends upon what you want to do with the disks. Facing off a disk merely
requires a chuck that will leave the disk proud of the jaws when the facing
is done. This is best doe with a collet type with a backing surface.

I looked at the collets, but I haven found one that will hold a 1 1/4" disk.

Edging is a bit more difficult and probably the best way is to use some
doublesided tape (not the foam stuff but rather the stuff that is using a
thin plastic center with adhesive on both sides) and a live center with
alarge pad rather than a point to hold the disk in place. The finished edge
needs to stand proud of the mountings.

Thanks. That's another keeper! (& Increase author's score).


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According to Bruce Barnett :


I'm new to metalworking and just got a Microlux 7x14.
I'm interested in machining thin disks - about 1 1/2" in diameter by 1/16".

O.K. What is the spindle nose on that machine?

Looking at an on-line manual tells me that the chuck has three
studs, and you tighten nuts onto the studs to hold it to the spindle
flange. That may mean a special backplate will be needed, as I don't
find that in the list at the site below.

I see that that some lathes have soft jaws, such as
http://www.taigtools.com/c1051.html

Is there an equivalent solution for the Sieg lathe?
Any other ideas?

Here is one vendor of chucks some of which might fit your machine.

http://www.brassandtool.com/Chucks-Lathe.html

Your lathe's model number suggests that it has a 7" swing, which
would normally call for a 3.5" 3-jaw chuck. You could probably get away
with the 4" size, as long as you are careful to not extend the jaws too
far so they hit the ways.

It looks as though what will be the best for you is one of
these:

Bison Front Mount Self Centering Chuck

except that the smaller chucks, (3.25", 3.3" and 4") are not available
with the two-piece jaws. Even the 4.4" one is only available with solid
jaws, and the 5" is the smallest which is available with the two-piece
jaws.

There is another, which may work:

BISON Mini Three Jaw Self Centering Scroll Chuck

with the optional set of one-piece steel soft jaws:

Set of Soft Solid Jaws 7-882-214 $58.00

But -- those chucks are made to fit the Taig, Sherline, and
Unimat machines -- with a threaded spindle. Better, to start with the
Taig chuck, since it has the more useful pie-shaped jaws available, and
they are aluminum, and easier to machine to fit. To read my suggestions
about adapting that, skip to below the line of "+++++" below.

Here is where the backplates for the chucks are listed.

http://www.brassandtool.com/Backplate-Adaptors.html

If they have not yet added one to fit your lathe (which is a
fairly new one in the US, I believe), you will have to get something
like a:

Bison Semi-Machined Rough Opening Adapter

and first machine it to fit your lathe, and then machine the other side
to fit your choice of chuck.

++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++

To adapt the Taig chuck, what you will need to do is to first
machine a piece of steel to fit your spindle nose, and fit it with the
proper studs (same metric thread as the ones on the existing chucks).

Then, mount it on the spindle, turn a portion of the length to
the OD for the thread used for the Taig and Sherline chucks (3/4-16
thread.) Make sure to leave a larger diameter to tighten the chuck back
against, and ideally, you should also leave a register diameter behind
the threads to match the register hole in the back of the chuck.

This won't be as strong as a normal 3-jaw chuck with two-piece
jaws, but it should be adequate for your project. And those pie-fan
jaws for the Taig lathe will probably be better for your task than any
soft top jaws available from Bison at present.

The main weak point on the Taig chuck is that you don't have a
key to tighten it. Instead, you have a "tommy bar" to stick in a hole
in the rotating scroll plate on the chuck, and to grip the chuck body
and jaws to keep it from rotating. (There really should be a hole in
the chuck body for a second tommy bar, but there is not one -- at least
on the rather old example which I have.

I hope that this is some help. Now I go to see what others have
answered.

Good Luck,
DoN.
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(DoN. Nichols) writes:

I hope that this is some help. Now I go to see what others have
answered.

Great info, DoN!!! Another keeper! Thanks!!!


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Bruce Barnett wrote:

I'm new to metalworking and just got a Microlux 7x14.
I'm interested in machining thin disks - about 1 1/2" in diameter by 1/16".

I see that that some lathes have soft jaws, such as
http://www.taigtools.com/c1051.html

Is there an equivalent solution for the Sieg lathe?
Any other ideas?


Are you starting with a thin disk and machining the edge or face
OR
are you starting with a bar and want to part off thin disks?

Most of the good advice here has presumed the parting off. If you are
actually starting with thin disks you can stick them to a face plate
with double-stick tape or superglue. Hit superglued disks with hot air
or a gentle propane torch flame to release.

You can also fasten a disk of MDF to the faceplate as a sacrificial
layer if need be. Stick the disks to the MDF and have at it.
--
Fred R
"It doesn't really take all kinds; there just *are* all kinds".
Drop TROU to email.

Fred R "spam writes:

Are you starting with a thin disk and machining the edge or face

Yup. In particular, I am using medallions with artistic designs -
think of it as a coin.

Most of the good advice here has presumed the parting off. If you are
actually starting with thin disks you can stick them to a face plate
with double-stick tape or superglue. Hit superglued disks with hot air
or a gentle propane torch flame to release.

Ah. Good to know, but the opposite side may not be 100% flat.
So superglue might not hold it well.

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Sending unsolicited commercial e-mail to this account incurs a fee of
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Bruce Barnett wrote:

I'm new to metalworking and just got a Microlux 7x14.
I'm interested in machining thin disks - about 1 1/2" in diameter by 1/16".

I see that that some lathes have soft jaws, such as
http://www.taigtools.com/c1051.html

Is there an equivalent solution for the Sieg lathe?
Any other ideas?


http://www.dunhamtool.com/step_chuck.html

Tom

Tom writes:

Is there an equivalent solution for the Sieg lathe?
Any other ideas?


http://www.dunhamtool.com/step_chuck.html

Thanks! (Bookmarking THAT page.) Hmm. I don't see a price.



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According to Bruce Barnett :
Tom writes:

Is there an equivalent solution for the Sieg lathe?
Any other ideas?


http://www.dunhamtool.com/step_chuck.html

Thanks! (Bookmarking THAT page.) Hmm. I don't see a price.

It looks as though they have online sales, but I can't get the
price information, even after adding one to the shopping cart. (Nor can
I see any other information about the item.) Perhaps it insists on only
talking to Microsoft's "Internet Explorer". :-)

There's another problem. It is designed to fit into 5C collets
or 16C collets -- with a bore of 1". I don't think that there is one of
that size available for your machine, as a 5C collet needs at least a
1-3/8" spindle through hole for the collet drawbar.

Good Luck,
DoN.

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