How do you support very slender shafts with tailstock

todd774 · Dec 26, 2012

When turning small diameter shafts 1/8" or less I keep rolling around an idea in my head about making an external tailstock support such as a revolving drill chuck on a bearing, as opposed to a center. Being alittle inexperienced, I was wondering how this is tackled by experieced machinists. I've never seen anything like it & was wondering if I'm just over looking something obvious. Unless I just haven't tried a small enough center drill. I'd appreciate any input. I'm building a small model steam engine from plans & I'm not used to turning such small diameters.

Thanks,
Todd K.

lbhsbz · Dec 26, 2012

Follower rest and/or a live center. If you can't center drill it, turn a female come shape to capture the end. How long are these workpieces?

todd774 · Dec 26, 2012

The one I'm about to cut is about 1" long and will be a 4-40 screw thread which will be turned to about .110" diameter.

Lyk31337 · Dec 26, 2012

todd774 said:
The one I'm about to cut is about 1" long and will be a 4-40 screw thread which will be turned to about .110" diameter.

Is this a manual or cnc? That sounds possible without a center in a cnc, also probably with a manual but it's been a while since I've used one. I'd use a 7 thou radius and take off about 20 per side, pushing it very slowly, maybe 5 tenths or so feed. Make sure that tool is dead center or it may break your part..

But I've turned plugs and bored them, center on the opposite side to use a live center, and works fine.

jkruger · Dec 26, 2012

There may be other ways to make this part. Can you post a picture or drawing?

sfriedberg · Dec 26, 2012

I'd cut this particular part with a die-head. No issues with support then! This is least convenient on a manual with only a screw-operated tailstock, but quite easy on a CNC or on a manual with a lever-operated turret or tailstock.

todd774 · Dec 26, 2012

I'm using a 9" southbend manual lathe. I' been using 1/4" diameter stock which is plenty big enough for a center. I have stock as small as 3/32" or .093". I guess the reason I was asking was because I'm building the whole steam plant & I had no idea these parts were so small until I actually stated the project. I was just thinking if I wanted to turn parts down from some of the smaller stock I had then how would you support it. I imagine not to many poeple run in to that problem, I certainly haven't until I was crazy enough to do this. I should probably have posted this on the watch makers form.

jkopel · Dec 26, 2012

Check out this cool idea for a mini follower rest from Frank Ford.
HomeShopTech

PeteM · Dec 27, 2012

Not exactly a solution to your problem, but much the same idea as yours . . . Jacobs made tail stock chucks, primarily for turning motor arbors where there wasn't a center on the end. These operate much like a 3 jaw chuck but have brass pads to allow the stock to rotate (much like a center rest contained within a chuck). These could avoid the problem of bowing a small shaft from too much tail stock pressure, but I don't see them as particularly useful for cutting 4-40 threads.

promacjoe · Dec 27, 2012

That is a neat follow rest.

When turning really small diameters from a larger diameter, you normally do it in steps. Each step would only be about 3 to 4 times the diameter in length. That will minimize the deflection.

A watchmaker might use a disk with several holes drilled in it in a concentric circle, then the discus turned so that only half the hole remains. It is mounted so that the holes are exactly on center. It can be rotated after each cut so that a smaller half circle is available for the next cut.

Hope this helps.

I look forward to seeing pictures of your progress.

Have fun and stay safe.

Joe

packrat2 · Dec 27, 2012

What size steam engine are you working on.?? I have made a few engines from castings, I use the British Association threads or BA threads.
I use the BA tap and die set to cut threads. packrat2

CalG · Dec 27, 2012

This is a VERY Useful solution

PeteM said:
Not exactly a solution to your problem, but much the same idea as yours . . . Jacobs made tail stock chucks, primarily for turning motor arbors where there wasn't a center on the end. These operate much like a 3 jaw chuck but have brass pads to allow the stock to rotate (much like a center rest contained within a chuck). These could avoid the problem of bowing a small shaft from too much tail stock pressure, but I don't see them as particularly useful for cutting 4-40 threads.

A common drill chuck (not self tightening!)
Fit the jaws to the extended stock

Perform the machining operations "between supports".

Cut off the supporting end on completion.

A simple bushing fitted to the stock can shift the wear away from the chuck jaws. A drop of lube oil goes a long way.
This can even be configured as a traveling support, with the carriage pushing the tailstock as it moves away from the head stock. (or the reverse)

I've done exactly this numerous times for small screws.

Also, a simple v support on the end of a length of retangular stock that clamps to the tail stock quill and reaches around a normal center will go a long way to supporting thin stock.

Red_R · Dec 27, 2012

They make drill points as small as small as .010" in diameter. Even that small, I would still use a center.
Take a look at this. McMaster.com part number 2915A83

You could turn your part with an extra quarter inch of material on the end of it which you would use to engage your center and then cut it off as a final step. So instead of cutting threads on the end of the shaft, you could cut them in the middle and then part off the rest at the end of where you made the threads.

Blob · Dec 27, 2012

todd774 said:
When turning small diameter shafts 1/8" or less I keep rolling around an idea in my head about making an external tailstock support such as a revolving drill chuck on a bearing, as opposed to a center.

Thanks,
Todd K.

To answer this part of your question, yes, there are revolving tailstock chucks - I have one, a 3" three jaw made by Bison. It has a MT2 mount so it fits directly into the tailstock taper, and has ball (or roller, I don't remember which) bearings to allow the chuck to rotate with the work, independent of the mount. I got mine a long time ago for a reasonable cost, but I think they've gotten pretty pricey since then. If you're interested, I think Enco still sells them.

B

jkruger · Dec 27, 2012

Why not purchase some 4-40 screws long enough to do the job and modify them as necessary?

davycrocket · Dec 27, 2012

Hi Tod

How much thread are you putting on ?

One solution to your question is to start off with bigger stock, say 1/4" in the chuck, and sticking out just a bit longer than you need for the item that you are making . No need then for tailstock or steady support .

Then simply turn down a short bit on the end, and thread it with a single point tool, putting on a slight taper to allow for later accurate and concentric application of the correct die .

Turn down the rest of the shank of the item ready to complete the thread with the die .
Finally finish to length by removing the slight tapered extra bit that you made .

Really sharp tool, dead on centre and fast speed for the initial turning essential.

Use a split die quite open at first, and then gradually closed on successive passes will give you a perfect, non sloppy fit in a nut .

Die nuts can give a sloppy fit as you don't know the exact size of commercial nuts untill you try them with the adjustable split die method of threading ..

Davycrocket

Lucky13 · Dec 27, 2012

I would use a drill chuck in the TS. But drill a brass bushing that fits the stock tight enough to hold it but still let the stock spin free in the bushing. Put the bushing in the drill chuck. Once the stock is cut to diameter (except for small nub in bushing) part the nub off and run your die for threading.

All though that neat little follow rest made on the tool holder looks like a neat and quick way of doing this.

Jess

Ohio Mike · Dec 28, 2012

todd774 said:
...I keep rolling around an idea in my head about making an external tailstock support such as a revolving drill chuck on a bearing, as opposed to a center.

If you'd like to make one there's a very nice article in the Jan/Feb 2013 issue of Home Shop Machinist magazine on building a tailstock live center. The example is a Morse tapered live center with a 1-1/2" x 8TPI threaded spindle.

Mike

nel2lar · Dec 28, 2012

todd774 said:
I'm using a 9" southbend manual lathe. I' been using 1/4" diameter stock which is plenty big enough for a center. I have stock as small as 3/32" or .093". I guess the reason I was asking was because I'm building the whole steam plant & I had no idea these parts were so small until I actually stated the project. I was just thinking if I wanted to turn parts down from some of the smaller stock I had then how would you support it. I imagine not to many poeple run in to that problem, I certainly haven't until I was crazy enough to do this. I should probably have posted this on the watch makers form.

The size of what you are doing is questionable. You need collets and to cut the stock down to 4-40, how long are these pieces. You do not need a follow rest, it is too small for the follow rest made for that machine. Your question does not have enough information to make a plan. To make small bolts (4-40), you will be using a magnifier to just see the part. Maybe you need a watch makers lathe instead of a South Bend. But in the quest for the plans you have, scale it up so the smallest parts are 8-32. The size would be more manageable.
Good Luck, make some chips
Nelson Collar

todd774 · Dec 30, 2012

I want thank everyone who took the time to respond to my question. I have to admit, I was a little hesatant about asking a dumb question, but am I glad I did. The answers I received were very good, I couldn't have asked for better answers. I read each one carefully & followed the links that were suggested. I guess I came to the right forum after all. p.s. I tried to down load pictures from my cheap cell phone, but I guess I need to learn more on how to do that too.
Thanks again,
Todd K.

How do you support very slender shafts with tailstock

Plastic

Cast Iron

Plastic

Cast Iron

Stainless

Diamond

Plastic

Stainless

Diamond

Stainless

Hot Rolled

Diamond

Aluminum

Hot Rolled

Stainless

Hot Rolled

Aluminum

Titanium

Aluminum

Plastic

Similar threads