Keeping threads square

[d-m]

I bought a nice key less chuck a short time ago from a shop that was closing its doors, not a name brand but it looked well made. I got it home and chucked it up in a collet and was disappointed that the arbor was bent it was set on a shelf. Today I was off work and got some shop time after getting a few small things out of the way i pulled it off the shelf to take a better look at it. i removed the arbor by unscrewing it and separated the body in the same manner. I realized that this would be an easy fix( I thought) just take a piece of .500 drill rod thread 1/2 fine thats it! chucked up the rod, the lathe was all ready set up for threading so off i went. i made about 6 passes to get good square start and got my adjustable die out, set it loose and started the cut. After the threads were done i assembled the chuck and ran it in the collet only to find it was running out about .025 not what I was after. So whats the trick here it looks to me like it the threads that are knocking the chuck out of square.
Dave

 

[Blogwitch]

Dave,

Usually for a screwed arbor, you must also have a flange that the chuck screws up to, just like a screw on lathe chuck.

It is that flange which squares up the chuck rather than relying on the threads being straight.

Bogs

 

[portlandron]

Set up your lathe up to cut the thread and use you die to clean it up after lathe cutting it almost to proper depth.
It's my experience that it is darn near impossible to get a die to cut on center.

 

[d-m]

John glad you caught this question I am going to take some pic's of this chuck that will help I think. the arbor that was on the chuck has a shoulder but it in no way could have ever contacted the top side of the chuck. I will go take some pic's and show you what I mean
portlandron
Thats what i meant when I stated in the post that I made several passes with the cutter on the lathe then finished up with a die

 

[d-m]

Hi all
this is better the wife is done working for the day and I can use a real computer lap tops are nice but not that nice.
here are the pics of this chuck I am trying to save as I said there is a shoulder on the arbor that was in the chuck but as I was taking the pic's I thought it may not be the original arbor. I see no witness marks on the top of the chuck to indicate a shoulder was ever there. First pic is the chuck with the arbor that came in it. Next is with the arbor screwed in and bottomed out the jaws in the chuck are also bottomed.The next is the top of the chuck. And the last is of the inside of the body.I am thinking that it may just be a POS and should bite the bullet and order up a good one.
Dave

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[winklmj]

Why not just turn up a new arbor where the threads die right up right up next to a flange? Then, as Bogs says, the flange is what will align the chuck. If you end up buying a new chuck, you can donate the old one to me

 

[d-m]

Why not just turn up a new arbor where the threads die right up right up next to a flange? Then, as Bogs says, the flange is what will align the chuck. If you end up buying a new chuck, you can donate the old one to me

winklmj
I agree with you and ,and as Bog's commented a flange would keep all square to the world but its is the arbor that is screwed into the body of the chuck and pushes the jaws to close. so the only way would be a nut to lock up to the top of the body after the bit is tight. Any one have a chuck like this ?
Dave

 

[winklmj]

So the threaded end of the arbor pushes on the jaws? I was thinking that tightening the knurled part of the chuck (outer-body) would be what closed the jaws. But in this case it's also got to be threaded further onto the arbor to get them to close? That doesn't seem right. Might help to see a pic of the chuck "inner-body"--minus the knurled part--so we can see what that looks like from both ends.

 

[d-m]

winklmj
Good point I haven't looked at it that way I will thread a nut on it and try that it will also give me something to make measurement's from if that's the way it works.
Dave

 

[Ned Ludd]

Hi Guys,
It would appear that the chuck is from an old hand cranked drill, which never needed to be true. When the drill is only turning at a few score RPM with a wobbly hand holding the other end, why spend money making a chuck more accurate than is needed?
Ned

 

[stevehuckss396]

Could you chuck the chuck in a 4 jaw chuck and indicate it true, then finish turn the arbor and never unscrew it from the chucked chuck.

 

[Hilmar]

I have a chuck like that.
The arbor screws in and out to tighten or loosen the jaws.
Don't mess with the threads or it will loosen even more.
It is not the most accurate chuck.
Is the shaft may be bent????
Hilmar

 

[d-m]

Hi guys
I put a nut on it and useded it as a shoulder to tighten against. unfortunately It is vary in accurate am thinking that Ned made the I D on the chuck correctly and it still has run out on it I will be hunting ebay for a precision chuck. Thanks for looking and the help pulling my well you know
Dave
stevehuckss396 LOL and thanks ,and are we going to see more of that V8 build soon vary nice stuff !!!!!
Hilmar yes the original arbor was bent I made a new one and thats were the trouble started at least I'm not out much more than a 5.00 bill and an hour of time to get to the point that i realized i'm a dumb a## and it's a POS LOL
dave

 

[stevehuckss396]

stevehuckss396 LOL and thanks ,and are we going to see more of that V8 build soon vary nice stuff !!!!!

Hopfully soon. The Peewee needs minor repair before Zanesville in 2 weeks. Work has been picking up and i have only been getting one day weekends. I did spend 3 days cleaning the garage so i can find everything real easy now. Hoping to get at it as soon as Monday.

 

[dsquire]

Could you chuck the chuck in a 4 jaw chuck and indicate it true, then finish turn the arbor and never unscrew it from the chucked chuck.

How much wood could a wood chuck chuck, if a wood chuck could chuck wood? Oops, sorry wrung type of chuck :big: :big:

Just had to do that. Sorry for the off topic, now back to the other kind of chuck. :bow:

Cheers

Don

 

[Blogwitch]

Dave,

I hould have realised it was one of those types of chucks. Dremel do those type as well for screwing onto the nose fixture of their little drills, but I think they are made a lot more accurately, and do seem to keep very good concentricity.

Bogs

 

[arnoldb]

Like Bogs said, the small Dremel chucks work the same way. I made a little arbor for one that I can grab in a collet in my mill to use for tiny drills, and have drilled many 0.8mm and 1mm holes using it without breaking one of these small drills. That attests to the fact that they are made fairly accurately.

For these types of drill chucks, I'd say one of the primary considerations for accuracy is a close-fitting and very concentric thread on the arbor, and the face of the arbor that operates the jaws must be well faced to apply even and equal pressure on the chuck jaws when closing.

Regards, Arnold

 

[rcmadness]

I have one of those chucks too. The best I have ever been able to do was chuck up a 3/16 bit in it, put the bit in the lathe chuck, set a center point in the end and turned the shank true. Now with all that said its still not perfect due to the mechanism itself. None the less it works really well when I need to chuck up something really small for polishing or taking a file to.

 

[d-m]

Good point RC I went ahead and finished the arbor and assembled the chuck today placed it in a on the shelf near my lathe I will chuck it up with some drill rod and see if it trues up any better.
Thanks Dave