Collet Chuck Question

[Seer]

Ok here goes: If a collet chuck keeps mandrel rods running straighter and truer what about this: I put one bushing, say a sierra in the collet chuck and use my 60 degree live center in the other bushing would this still be the same as TBC? I know the space between the blank and collet would be narrow but would this work is all I am asking?
Jerry

 

[leestoresund]

Bascally, yes.
The difference being that the bushings are not also matched for the 60 degree tailstock. That may cause some slight difference.
Depends upon how precise you want to be or can be.
In my case, 3 years ago it would not have made a difference in quality or attitude.
Today, my standards have narrowed and, I think, my abilities have increased.

Lee

 

[Russianwolf]

With a set of Johnny's bushings? Yes.

With a set of stock bushings? No. I just wouldn't trust the stock bushings to be true enough (or long enough) to put in the collet.

 

[Sylvanite]

Jerry,

You won't have much of the bushing in the collet, so you might encounter runout problems. Also, you'll be using your chisels very close to the headstock, which may be inconvenient. Lee has already mentioned that the live center may not align well with the other bushing.

I've modfied some of my bushings for turning between centers. I chuck up each bushing backwards in a collet chuck, and using a 60 degree center bit, chamfer the hole to match the 60 degree centers. Now they mate truer. To get really picky, chuck stepped bushings on the portion that slips inside the tube, not the outside. That way, if the two circumferences are not concentric, you'll be drilling the chamfer relative to the more important one.

This improves stock bushings, but the custom made ones are still nicer.

I hope that helps,
Eric

 

[aggromere]

Not sure if it the same thing and I learned it here on the forums. I use a collet chuck the same size as the steel rod for a mandrel (I use this only for finishing using some of Johnny's finishing bushings) put the flat end of the mandrel shaft into the collet chuck and use the live center on the other end. That way you can run the extra length of the mandrel shaft out the headstock for a shorter working area (like TBC). This works great for me in finishing, but you would still be limited by the quality of the bushings you use.

 

[workinforwood]

I don't think anyone mentioned this as well, but the standard bushing set has a square hole as opposed to a center bushing which has a 60 degree indent in the hole. The 60 gives the center more grip and having a square hole, is going to over time eat away at the bushing and/or the center, and not likely eat a groove into it evenly, so then you'll really get some wobbly off center turnings.

 

[KenV]

I assume that there will be some missed alignment or skew in the straight line between the connection point on the headstock adn the connection point on the tailstock. It may be larger or smaller depending on the lathe, but is is there.

If the bushing and the pen blank are a really good fit and are not flexing, the missed alignment has to be adjusted between the deadcenter and the live center. That is where the "universal joint" effect should occur for best effect. The alternative is for the bushing-blank connections to be moving.

That compromise in fit for power transfer and flex for alignment is well met in the discussion that Eric provided. Good fit for power and not too good a fit so it can move a little as a universal joint.

Works to make good pens as long as the alignment is not grossly poor.

(my big lathe has a movable bed and is effectively never in perfect alignment -- .060 is normal and 0.030 is a good day -- and it loves to turn between centers.)

 

[Seer]

Thanks for all the replies I am getting a collet set to turn with tired of mandrels and other issues and like was mentioned I can still use the rods to turn but have better control on the alignment.
Jerry