Machining Lathe pin/driver

Poulos Cues

Poulos Cues

AzB Silver Member
Silver Member
Folks:
I have a Taig head stock and they sell a collet closer. The largest collet is 1/4"- 5/16"

Do you think 1/4- 5/16" shank 60 deg. center is big enough to use as a driver? I don't think the thing to do is to hang a larger 2-3" od out past the collet-do you?

Another option is to buy their ER Spindle which allows for 3/8" id.

Last question:

Collets are more accurate and safer at high speeds than a chuck right? (though I will be turning at a SLOW RPM)
So wouldn't the most accurate thing to do-would be to machine an ID thread in a piece of steel or aluminum- screw it onto the threaded spindle of the head stock-and machine the shank and the 60 deg. point and then never take it off?

I have a 3 lathe station on my cnc I built, all just for od turning and tapering so I would have no need of taking the center off/out. (but if I did, I would just remachine another center).

What are some thoughs?
 
Not a cuemaker but I have a taig lathe and mill...

The main point of a chuck is to allow flexibility of holding different sized items quickly. This comes at the expense of accuracy (although you can dial in chucks if you have a 4 jaw independent or a set-true chuck), space between centers (the chuck takes up a few inches), and safety (a large diameter chuck will hurt much more if you hit it with your hand than a collet)

In your case, you will have one set up and not change it. So there is really no need to use a chuck. Collets are the way to go.

What you described about machining a drive center while permanently threaded onto the taig spindle would be extremely accurate. Only I think it would be more trouble than its worth to make. You can get the same exact accuracy by using a collet (or chuck for that matter) and machining the 60 degree center while its being held and then never remove it. What gives you the best possible accuracy is machining the final passes of your center while it is in its final and permanent holding fixture.

So to get around wanting a larger diameter than can fit in the 5/16 max taig collet, just start with a 1/2" diameter piece of steel, and machine a short length of it to 5/16. Put the 5/16 end inside the collet of the taig head, and then machine the working end of the center to the diameter you want, and put the 60 degree point on it. Now it will be dead nuts on center, as long as you don't remove it. And even if you remove it and reinstall it, it will be more on center than removing and reinstalling on a taig 3 jaw chuck.

As I finished writing this, I realized you will need a complete taig lathe to do what I stated. Because you need the taig bed and carriage assembly to do the working end machining of the 60 degree center. You will also need a compound slide which does not come standard on a taig lathe, but is available as an accessory. Go to cartertools.com to see all the accessories for taig products.
 
I just looked at the accessory list and found what you could use to go with your original idea, but without the hassle of making that 3/4-16 internal thread. Taig sells a piece that is already threaded to fit over the spindle and you machine the other end to whatever you want.

http://www.cartertools.com/catalog.html

Item is 1132 (blank arbor)
Also see item 1200 (compound slide)
 
Wanna-be cuemaker, wanna-be machinist:eek:

I do have the taig complete lathe and the compound...so thanks.

Everything you stated I already contemplated as well and I thank you ;)

As a machinist, isn't there a rule of thumb regarding weight and length ratios when hanging out in front of a collet and/or chuck?

IE- (exaggerating of course)
I wouldn't want to be hanging out 5 inches @ 1/2" od out- while only holding onto 1" of 1/4" od shank in the collet or the chuck.

Any additional thoughts?
 
It really depends on how much force will be applied to the center due to your cutting method. The rule of thumb which I'm sure you know is to keep everything as short and rigid as possible.

Now in actual turning of the shafts, a large overhang of 3 or 4 inches will probably be ok, even with a reduced diameter that fits into your chuck/collet.

But to machine the center itself and its 60 degree point, I don't think you could go much past 1 inch or so at a 5/16 diameter without getting deflection while cutting. 1 inch is probably pushing it.

How much overhang do you need so that your headstock won't interfere with your cutter when turning shafts? This distance will probably rule out a few machining options to make your center.

I have a bludworth tapering saw but not in front of me right now. It uses something like a 3/8 diameter ground drill rod as the center with a 60 degree point machined into. The overhang is several inches to clear the 10" diameter saw blade. But the 60 degree point must have been machined on a lathe with a short overhang before it was installed on the saw machine.
 
What type of "lathe dog" do you use to keep the shaft from slipping?

I use a collar on mine with a pin that fits into a band-saw groove at the end of the shaft---but it keeps breaking on me!

You can pm me if need be.

Thanks-Chris
 
You must log in or register to reply here.
Back
Top