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Turning very small diameters

elwinbender

Plastic
Joined
Jan 28, 2021
What is unsed as a follow rest when turning/threading small diameters. Normal followrests with rollers seem like a major overkill. I've never used one (mainly because I don't have one).

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2/56 threads. I don't have a watchmakers lathe

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#000-124 have been done on Hardinge #00-90 on SB nines, tens of thousands per year.
Every one of them silly SHORT though.

What are you trying to do as NEEDS support?

Coupla inches of 2/56 leadscrew for a teeny-tiny optical stage?

Better to just buy it - or a metric "cousin" - precision-ground in a suitable alloy, heat-treat, hardness, accuracy ....etc., etc.. from the experts who "just do" that stuff every day, all day as a market niche they may have invested a great deal of sweat and money in to get GOOD at.

It not only has to be small. It has to be RIGHT .... to be of any use... not to mention durable.
 
OK. Lathe is 13x40 Clausing/Colchester. Material is stainless maybe 316??? Diameter is .089. At an inch from the chuck there is a lot 9f flex. Threads are 2/56. In comparison that's probably not small but I am trying to learn something.

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Buy cylindrical 316 (1.4401) pins. Have them warm roll threaded. Why the pain on a lathe thats made for way larger work?

If you want or need to do them yourself, install collet chuck and cut thread in two passes with dies. The point is to diminish DOC in that sort of steel and be able to give plenty oil on.
 
This is a scale model. Some of the parts are not standard off the shelf parts. That would ruin the asthetics. Sometimes There are only a couple threaded parts that don't make it worth buying a set of dies for. I followrest to prevent flexing of small diameters would be ideal solution.
e1601ffe142d1bdb3419b7486444157a.jpg


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OK. Lathe is 13x40 Clausing/Colchester. Material is stainless maybe 316??? Diameter is .089. At an inch from the chuck there is a lot 9f flex. Threads are 2/56. In comparison that's probably not small but I am trying to learn something.

understood, the pushback was because without complete info no one can help ...hopefully that was learned :)

A drawing and sense of volume is also good to included. If this for the model you mentioned, you have a lot of latitude in how you come at it. You have discretion and the volume is low, say one or two. For example you could just not turn the long skinny part: silver solder, soft solder or glue (e.g loctite) an assembly of material the right size. Also, with said discretion, pick a better material. 316 is worse than 304 which is gnarly enough to machine ....if I have choice which I do with a hobby project its going to be 303.

There are a variety of ways to machine a small diameter long section such as advancing a bit out of the collet at a time (poor mans swiss lathe), start with a large diameter and make one big cut or make a piece attached to the tool bit/post that acts as support...sort of a traveling box tool steady thing. Probably other ways but who knows what to recommend without seeing the drawing
 
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OK. Lathe is 13x40 Clausing/Colchester. Material is stainless maybe 316??? Diameter is .089. At an inch from the chuck there is a lot 9f flex. Threads are 2/56. In comparison that's probably not small but I am trying to learn something.

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@ 0.809'' dia the parent stock will need no OD turning for a 2/56 thread, so just run the thread with an ordinary button die in a tailstock dieholder, and the job is done
 
This is a scale model. Some of the parts are not standard off the shelf parts. That would ruin the asthetics. Sometimes There are only a couple threaded parts that don't make it worth buying a set of dies for. I followrest to prevent flexing of small diameters would be ideal solution.
e1601ffe142d1bdb3419b7486444157a.jpg


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2-56 dies and taps are not that hard to find or afford, sure a lot cheaper than a 5/16's die head and inserts. Neither is threaded rod stock. Hells, for short sections, cut the rolled threads off little cap screws.

Drill a hole, tap it 2-56, insert appropriate length of thread, with or without some thread locker to make it a permanent install.

Then you will have 2-56 taps and dies for the next time you need.

It's not that you can't do it on a 13 inch lathe, it's just that your odds of screwing it up a dozen or so times before getting it right, seems to me that a set of taps and die, will look pretty cheap in comparison to the lost time spent re-doing the same little piece.

If you really insist, though, just how tight is your lathe? Can you count on it to not be out of position by a couple thou, when you are trying to feed it in only one, or a half thou at a time?

As for a follow rest, for that small a part, make one. It's not magic. Can be as simple as a notch in some brass sheet stock, or you can equip it with little brass screws.

Another suggestion would be to remove the overhang. Drill out some stock to fit the round section of the shank of the part, larger in OD than the other end. Saw a split in it so you can grip the part up close in a chuck or collet, with no overhang.
 
An explanation of what a traveling box tool/tool/toolpost support might be helpful as well as how do you turn a .003 diameter. I have heard of people putting threads on a pin (pin size) under a microscope. Sorry if I havn't given a better explanation. Even threading a 3/16 rod has some flex to it if there is much hangout. How do you turn a small diameter that can't be supported with a steady/follow rest without purchasing expensive tooling for just a few parts?

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An explanation of what a traveling box tool/tool/toolpost support might be helpful as well as how do you turn a .003 diameter. I have heard of people putting threads on a pin (pin size) under a microscope. Sorry if I havn't given a better explanation. Even threading a 3/16 rod has some flex to it if there is much hangout. How do you turn a small diameter that can't be supported with a steady/follow rest without purchasing expensive tooling for just a few parts?

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I think they are talking about one of these.

Redirect Notice

I don't know about .003", but we have a guy that turns .01-.015", of course only maybe 3-5x diameter.
 
This is a hobby/learning situation. I'm retired so I am in no hurry. Yes a tap and die isn't that expensive but add a little postage + a couple days delivery and I would rather see what other means there are. And many times there might be only one time I may use tgem. Some great suggestions but I'm not quite understanding some of them.

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I think they are talking about one of these.

Redirect Notice

I don't know about .003", but we have a guy that turns .01-.015", of course only maybe 3-5x diameter.
Yes this is what I am looking for but I don't need to buy one. Is there a way of making something mounted on a tool/toolpost that would do the same thing?

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I don't know about .003", .

was being slightly smartassish, but that's the smallest I've made; a watch balance staff pivot (think journal on a rotating shaft)

How do you turn a small diameter that can't be supported with a steady/follow rest without purchasing expensive tooling for just a few parts?

I gave a few ideas. The support one doesn't have to be expensive, as trev suggests, just a piece of brass fixed behind the tool supporting the work - e.g. brass with a hole that the finish dia passes through. That or as I suggested, cut a little bit, advance it out of a collet, repeat.

Question....you're saying you don't want to buy a die, ok, then is the plan to single point the thread? This goes beyond learning and becomes masochism. I may have some 2/56 ready rod.....how long a piece to do need? My pleasure to send it.
 








 
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