Machining thin disks on a lathe


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
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Is there an equivalent solution for the Sieg lathe?
Any other ideas?
Reply to
Bruce Barnett
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What machining operations do you intend to do? I often clamp disks between plasic/tuffnol "mushrooms" or glue them to a mandrel (LockTite)
Nick
Reply to
Nick Müller
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?
Reply to
jtaylor
Bruce,
I have 4-soft jaws on my Grizzly 7x12 (bascially same lathe as yours).
Get the Taig 4 Jaw 3 1/4" dia. self centering scroll chuck (steel body) with aluminum soft jaws 3/4-16 thd. Then get the 3MT to 3/4-16 thread adapter from LittleMachineShop.com. Then make your own draw bar from threaded rod to hold the 3MT taper adapter in the spindle.
Ed
Reply to
cascadiadesign
Yep, no problem.
Reply to
Dave Lyon
What are you trying to do to the disks? That's going to be a pretty challenging project for a new guy.
Reply to
Dave Lyon
Yebbut...
I want _independent_ jaws...
Reply to
jtaylor
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.
-- Why do penguins walk so far to get to their nesting grounds?
Reply to
Bob May
According to Bruce Barnett :
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.
Here is one vendor of chucks some of which might fit your machine.
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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.
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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.
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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.
Reply to
DoN. Nichols
His lathe(which is the same as mine) is supposed to be able to take a 5" chuck(with adaptor): I was getting ready to purchase the following until this thread, now I'd better wait and see.
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Though I have no idea what how much of that chuck's capacity can be used, I always thought that X inches meant that "X" was the largest diameter the work piece could be.(That shows what I know).
Darren Harris Staten Island, New York.
Reply to
Searcher7
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.
Reply to
Fred R
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.
Reply to
Bruce Barnett
Thanks!!
Reply to
Bruce Barnett
I looked at the collets, but I haven found one that will hold a 1 1/4" disk.
Thanks. That's another keeper! (& Increase author's score).
Reply to
Bruce Barnett
Great info, DoN!!! Another keeper! Thanks!!!
Reply to
Bruce Barnett
Yup. In particular, I am using medallions with artistic designs - think of it as a coin.
Ah. Good to know, but the opposite side may not be 100% flat. So superglue might not hold it well.
Reply to
Bruce Barnett
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Tom
Reply to
Tom
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
Reply to
Nick Müller
Thanks! (Bookmarking THAT page.) Hmm. I don't see a price.
Reply to
Bruce Barnett
According to :
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Note -- he was wanting to get a three-jaw chuck with soft jaws. The general practice is to have the diameter of a three-jaw chuck half the maximum swing over the bed.
This is because at some settings, the jaws (which are *typically* not reversible) can extend out far enough to risk hitting either the bed, or perhaps the arms of the carriage.
Four-jaw chucks typically can have each individual jaw reversed at need to hold awkward shapes.
Three jaw chucks also have the additional mechanism of the scroll plate and the gearing from the keys to the scroll plate, which makes for a longer and a heavier chuck.
As an example, on my 12x24" Clausing, I'm happy with a 6" (actually 6-1/4") three-jaw, but I use a 10" 4-jaw. And -- they are of similar weights.
Note that is a 4-jaw chuck, not the three-jaw which he was looking at. And soft jaws on a 4-jaw (with independent motion of each jaw) don't really work out well.
"X" inches is the overall diameter of the chuck body. To that must be added the extension of the jaws when they are adjusted to hold larger workpieces.
Some (typically quite small) three-jaw chucks come with reversible jaws.
More often, they come (or are at least available with) two sets of jaws, one the normal set for gripping relatively small things on the outside, and for gripping larger things on the inside. The second set is the reverse, and is primarily for gripping larger things on the outside, with a reduced length of grip.
The ones which can accept soft jaws are typically two-piece jaws. A hardened set of master jaws which remain in the chuck, and sets of jaws which bolt onto the masters. What typically comes with the chuck is a hardened set of top jaws. Soft jaws are available to fit the same master jaws. They can be either aluminum (really soft jaws), or a mild steel (which is more common, except in the little 3-jaw chucks for the Taig, which are non-standard in several other ways as well.
BTW I tried to answer an e-mail from you on the 21st, and my mail server was unable to establish communications with your mail server. So, I did not ignore the e-mail, your mail server does not like me for whatever reason. Here are the headers:
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[ ... rest snipped because as usual it was large ... ]
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It is the same e-mail address which you use in your newsgroup headers. But I can't reach that system, even with a ping.
Enjoy, DoN.
Reply to
DoN. Nichols

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