mounting a backing plate to an adjust-a-chuck

M

mike in co

Guest
well i bought a 3 jaw adjust a chuck, and it requires that i turn the backing plate to fit.
there is a dia that fits into the chuck. this is where the 4 adjusters ride against. the question is: how much clearance ? there must be some for the adustment.....how much ?
there is nothing in either packaging, nor the chucks manual.


help.....

mike in co
 
Mike

Ours all came with the backing plate, and they have about .015 clearence between the male and female spigot. I suppose a little more will not hurt anything, it will give you a little more adjusment.

But with that, you also get an out of balance situation, which is why the Factory might only give it the .015.........jackie
 
thanks jackie. i'll call the supplier monday and see what they know, thought i'd pick brains here first.

mike in co
 
Mike, A 6-jaw ,,6''Buck I recently purchased recommend no more
Than a total of twenty, or .010 each way. My spindle nose was
an odd size in metric , so I made the backing plate. As jackie says
the out of balance would be significant, especially in larger chucks.
 
If you are cutting the backplate, then you are in control. Start with zero clearance as if it weren't adjustable, and measure runout. If there is runout, cut half that amount off the backplate and adjust it out.
 
guys,
thanks for the replies.

but i find myself lost.

i thought the chuck would move on the adjusters, independent of the bolts holding it to the backing plate. well it aint so on this chuck. the bolts go straight thru front to back. i see no way for movement with the six attaching bolts tight.

yep i'm call for the numbers...but it looks like i have to lossen the bolts, adjust, retighten and hope you are still in toleramce........

what am i missing?

thanks
mike in co
 
Ajust Tru Backing Plate

Mike,
When you machine your backing plate make sure you also face off the chuck mounting surface. This will make the chuck perpendicular to your spindle. If you are using a cam lock set up make certain that you always orient the chuck in the same manner it was machined or things won't repeat.
I generally will mark the adapter plate in line with some feature on the lathe spindle.
 
When you ordered your new chuck, that was the time to order the matching face plate for the chuck. That facing the face plate is the real deal. Don't forget to take the facing cuts. Truly the most important thing you can do.:D
 
yes, all my cam loc tooling is marked to the lathe. yes i made sure all parts were clean before mounting. yes i checked it all , and made the decision to reface. i did order a mounting plate with the chuck....it was the wrong one. the sales flyer did not have correct parts listed. MSC gave me a deal on the right part and paid shipping for both.

thanks guys
i do appreciate the help
mike in co
 
?????

I am a little confused about one posters response. The object of a set true chuck is not to get the chuck running true, but to get what ever you are chucking up running true.

Maybe I am missing something here.

Also, I rarely loosen the four bolts that secure the chuck to the backing plate. The adjusting screws can easilly overide the friction that these bolts
induce.

It is understood that these types of chucks are not intended for rough interrupted cutting, or banging around on. They are designed for light work where it is required to get a certain item running as dead true as possible.

Barrel work falls right into this category..........jackie
 
so maybe i have them too tight ...thanks jackie

i'll go get out an in/lb torque wrench.

mike in co
 
Adjust thru?.

After reading this form I have decided not to get an adjust thru chuck and do like we did in the past.Put a set of soft jaws in the chuck bore them to the dia. we want to hold and the piece should run dead on.
 
Bentwood said:
After reading this form I have decided not to get an adjust thru chuck and do like we did in the past.Put a set of soft jaws in the chuck bore them to the dia. we want to hold and the piece should run dead on.
Click to expand...

do more reading...soft jaw is not the answer for BENCHREST quality chambers.
 
Bentwood

You don't understand the problem. If you chuck a piece up by the OD, and the ID, (which you must get running dead true), does not run dead true with the OD, then the bored jaws are useless.

The vast majority of the questions concerning the usage of these little chucks revolves around doing precision barrel work. If you chamber barrels, you will see the worth of one of these types of chucks.........jackie
 
so back from the lathe.
removed the chuck from the adapter, and took another cut. went from the 0.010 i had to the 0.015 jackie reccommended(still have not heard from enco). cleaned it all, reinstalled with bolts only tightened to "two fingers" on the small end of an allen wrench.. put my test bar in the chuck, and easily and quickly dialed it into less than 0.0005.
sucess.....

thanks

mike in co
 
I'm getting ready to do the same thing as Mike. I have a Bison set-tru and a Bison 5C that have to be mounted to adapters. As far as I can determine I have the correct adapters. The first thing that I noticed on Saturday was that the boss on the adapter was 98mm in diameter and the recess on the 5C chuck was 94.8mm in diameter. Haven't checked the depth yet. Imagine I'll have the same issue on the set-tru. Guess it's a measure six times before very careful cutting situation.
 
I haven't adjusted mine in ages, and I don't want to go out and look, But, I'm pretty sure there are four setscrews which bear on the backplate from the side to actually set the chuck, and then you lock it down with the through bolts. And, yes, of course you dial in a bar held in the chuck, not the outside. One nice thing about a Buck, or other quality chuck, is that the chuck tends to hold its setting at different openings. Some chucks change their runout a bunch as you open them up.
 
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