4 jaw chuck problems

[timbertoes]

somethings going on with my D1-4 4 jaw..

it will come loose from the lathe..

granted, it does this when:

A minor crash. this happend last night, when I miscaluted and did not get the threading bit out of the way fast enough, so under carriage feed power let the bit get to far to a shoulder,took a big chunk. here, maybe I should be glad it happened ?

have had it happen with a on-purpose 20 or 30 thou bite of metal.

also with unsupported somewhat long stock - 14" out the back and about 6 in front.

will try adjusting the camlock pins out 1 turn, once the current work is off the lathe.

they are adjusted to the witness mark now, and I get about the same amount of a "turn" when tightening, as my 3 jaw. which I cant recall ever coming loose.

 

[jscandale]

This is the reason I always thread away from the chuck. Impossible to crash and never have to woring about disengaging the half nut. Can also cut threads at 300-400 rpm without ever having to worry again and the finish is excellent.

JS

 

[Erik Cortina]

This is the reason I always thread away from the chuck. Impossible to crash and never have to woring about disengaging the half nut. Can also cut threads at 300-400 rpm without ever having to worry again and the finish is excellent.

JS

The downside is that you have to do a relief cut to do that, and in my opinion, it does not look good.

Other than that, you are correct.

 

[timbertoes]

This is the reason I always thread away from the chuck. Impossible to crash and never have to woring about disengaging the half nut. Can also cut threads at 300-400 rpm without ever having to worry again and the finish is excellent.

JS

yes. Of course. Thanks for that. darn thing is, I now recall reading this similar advise before. and esp with metric, where the half nut stays engaged. would have been so much safer. relief cut, yes I did have that anyway, the original wby barrel uses one.

and would'nt you know it....it happened on the VERY LAST PASS!! arrghh.
(fixed it all though, thank goodness)

 

[jscandale]

Yes, there is a relief cut, but it does not in introduce any additional compromise to the strength of the tenon since the relief cut is no smaller in diameter than the root diameter of the thread itself, so it's a non issue.

JS

 

[timbertoes]

does anyone think there might be a QC problem with Chuck, or is it somewhat normal to have a D1-4 sit itself under too heavy of a cut ?
In one respect, i can imagine the difference in holding power now, between a D1-4 and the its bigger brothers.
even as a begineer, I can already appreciate spending more on a lathe.

I will admit I have not taken the time to pull the jaws ands find its best position, at least with repsect to balance and vibration inducing..
Now is the time.

 

[paperpuncher]

When you tighten the camlocks the indicating line on the camlock should stop between 3 oclock and six oclock, you may need to adjust the pins on the chuck. You may want to check the camlocks as well have seen them crack. I have never had a camlock chuck loosen up on me. I always tighten the camlocks about 90% and then go back over them and snug them up. You may also want to check the registration between the chuck back and the spindle nose. It is possoble the chuck back is machined improperly and it doesnt seat on the spindle nose correctly. I had a backplate like this and while it never came loose the chuck would always be "out" when I removed it and remounted.

 

[shortgrass]

Buy yourself 3 new D-4 studs. Spend some $$ on 'um, don't buy the cheapest you can find. Learn how not to crash. If it's a cheap Chinese chuck it may have other problems. There is no substitute for quality when it comes to lathe chucks.

 

[milliron]

be sure that you are turning the camlock squares the correct direction. on my sb big 10 and maximat v 13 they turn clockwise to engage properly and move about 180 degrees to full engagement.snug around the first time , tighten fully on second time. don t use a cheater to tighten them.henry

 

[timbertoes]

thanks. these camlocks dont rotate more than 90 degrees, on any of the 2 chucks and faceplate.

As I mounted the face plate tonight, I noticed they were set with the witness line at least a turn higher.

 

[paperpuncher]

The camlocks need to rotate at least 90* and less than 180* from the 12 oclock position. If you arent getting to 90* that could be an issue

 

[eww1350]

Oh No...Cam Locks MUST turn more than 90 degrees (180 degrees is best)...MUST... ...take your chuck off and adjust your cam pins out 1 full turn..then try again...your Cam Locks must turn more than 90 degrees to be safe...

DO IT ASAP...!!

also when mounting your chuck clean the tapered recess to remove all debris and then as you start to turn your cam locks use a dead blow hammer (nylon type) on the chuck to ensure it seats squarely as you tighten your cam locks...

 

[timbertoes]

will do, thanks. safety is #1.

 

[jscandale]

will do, thanks. safety is #1.

Especially when you have such a large hunk of steel rotating at a high rpm relatively close to your head. I hope you have solved your problem.

JS

 

[timbertoes]

I am sure all the good advice will work out

Chuck wont be used until its good to go.

and Thanks very much for the help.

today was spent bedding the 257wby project.
and making a bedding alignment screw using a morse taper collet in the headstock, that was fun.
in the end, the screw/pin was not all that much required.