Turning very small diameter bar

[mooseman]

Well, I've managed to do some work!

I'm currently working on a boat powered by a tiny Philcraft steam engine....for this I wanted to make a very light prop shaft....I've used 1/8" brass round running in a copper tube. To minimise friction, I've skimmed off a couple of .01" of the portion that runs inside the tube. as the shaft is about 3" long I couldn't just chuck it, and as I don't have a fixed steady I held the loose end of the shaft supported in the drill chuck on my tail stock, with lots of oil to prevent friction....everything went OK, I only took 3 tiny little cuts, and the drill chuck didn't get hot.

I always think "if it worked, I must've done something right", but is this the right way to go about these things?

Below's a picture of my kit.

Picture of the engine, with size comparison:

 

[DickDastardly40]

Odilon,

I can't see your setup pics due to my computer not your pics, however it sounds as though you supported the 'free' end of the job lightly in the jaws of your tailstock chuck.

Check through the tooling you got with your lathe and see if there is a tailstock centre similar to this:

and if you have a drill similar to as shown in the box below.

What you would normally do is set the job in the chuck with the minimum amount protruding, face off the front so it is flat and centre drill so that just a small part of the darger diameter drill cuts. You then move the job out of the chuck and support it with the centre in the tailstock and reduce your diameter.

Hope this is clear.

Al

 

[mooseman]

Al, thanks very much - that is indeed what I did. I do have both live and dead centres, but I did not have a centre drill bit small enough to put a hole in a 1/8" bit of brass. I've just received my order from Chronos though, so as of now I do! ;-)

 

[mklotz]

Even with tailstock support, I wouldn't want to try turning a 3" length of 1/8" material.

In the past, when I've had to do similar things, my approach has been.

Chuck rod in collet (for good concentricity) with about 1/2" protruding.

Turn down exposed 1/2".

Do not alter cross slide setting, i.e., preserve tool position.

Expose another 1/2" of stock.

Repeat until done.

As more and more stock is exposed, you may still want to use the tailstock for support to prevent whipping.

 

[Cedge]

Marv
Pretty much the same technique I use here. I came to it by instinct more than anything else. It just made sense that things were much stiffer near the chuck. It also didn't take long to learn even small pieces of whipping metal are not user friendly...LOL

Steve

 

[rake60]

There is another way of turning a a longer section of thin material.

That would be with the use of a follow rest.
A follow rest mounts to the carriage and moves along the work piece
just ahead of the cutting tool.
It's kind of a PIA to use because it must be readjusted after each cut.
It does however allow support for longer straight cutting on thin material.

This follow rest is NOT set up to cut!
It's just a quick mock up to show how it would work.

If you think learning to single point thread is a challenge try teaching yourself
to use a follow rest! :

Once you've mastered it, you'll wonder how you ever got along without it.

Rick

 

[Bluechip]

Another way .. not a good write up tho'.

Did make one once to rip polyacetal from 5/16" to 6.5mm dia. in 4" lengths.

PITA, still have the mental scars.

http://en.wikipedia.org/wiki/Tool_bit#Box_tool

Dave.

 

[Cedge]

Now, if our own Tel will bring his pirate hat and drop in on this thread, I just happen to know he has a really cool little tool called a "Box Tool". It takes the worry out of having a small rod. It combines both cutter and steady rest into one purely devilish bit of cleverness. I've been meaning to build one and one of my upcoming projects will provide the perfect excuse to do so.

Paging Dr. Tel.... Paging Dr. Tel.... please pick up on the nearest courtesy phone

Steve