Chuck issues

[Seanol]

Guys,
I have an old Takang TK-105 lathe circa 1978. It came with a PUUR chuck which I am told is an old Bison and the spindle is an A1-5 mount, not common.
Lathe:

My lower jaw on one of the jaws was broken before my tenure and the previous owner just ground the rear 3 teeth off! This makes a 6.25" chuck a 1.4" chuck on the inside jaws and on the outside I can only go from 2" out!
Chuck and bad jaw:

I have a 4 jaw and a collet chuck but it is nice to have the concentricity of the 3 jaw for boring and turning the piece around. I tried dialing in the 4 jaw but could not get it close enough! I am only using a dial indicator as I broke my dti in an unfortuinate mill accident (read: I turned on the mill by accident while tramming the head)

I called a number of vendors on the web for help and most wouldn't talk to me or even return my emails because I was: A) a home shop guy, B) won't be able to swing $600+ for a new chuck.

While I am still in the market I wanted to pass along the one person who helped me above and beyond: Joel Presti of www.worldwidechuck.com
He answered my email and provided so much information in a phone call that I was almost overloaded.

I still need a chuck but I now know where I will get it and all my parts and service needs.

I still haven't purchased a thing from him!

The service he provided reminds me of the guidance I get here. While I don't post that much the tutelage here is what you would expect from the mentor in the shop except there are no mentors anymore. As Joel so eloquently put it, when the last of the old guys retire you will hear a giant sucking sound as all that knowledge is lost.

Thanks for the opportunity for guys like me to learn again!

Sean

P.S. Anyone have an old PUUR 6.25" chuck that they are not using?
P.P.S. I will also post some pics of my WIP of the crusader .60

 

[Maryak]

Sean,

BUGGER Maybe you could get a 2nd hand 3 jaw and adapt it to your lathe with a backing plate. ???

Best Regards
Bob

 

[reggie98]

Did you try and contact Bison to see if they have a jaw set that would fit? There also are companies that support certain brands that are no longer made. I'd do a web search and contact a few of them.

 

[Seanol]

Reggie98,
I contacted several vendors and was unsuccessful. Most did not return any emails b ut the majority opinion was that the chuck was too old. Bison did not return my email at all.

While working on the lathe yesterday I cleaned out the 4 jaw and tried centering again. I tried with the geartrain engaged and disengaged. I also tried another dial indicator and got the same thing. I tightened the preload on the spindle to see if that would have an effect and still I get the pointer moving around inconsistently at around 1 to 1 1/2 thou.

Still stumped,
Sean

 

[Maryak]

Sean,

What is the dial indicator running against e.g. the outer diameter of the chuck. ???

How is the chuck attached to the headstock, threaded or a backing plate and register. ???

If you were to hold a pencil against the same point as the dial indicator is running can you feel this 1-1 1/2 thou offset as a vibration
???

Is the surface against which the dial indicator is running clean and free of any burrs or dents. ???

Questions, questions, questions. Sorry but the obvious is not working so........

Best Regards
Bob

 

[Seanol]

Maryak,
Thank you for helping out. All my stock was clean and swarf free and the surfaces were just machined. The Ti turns really well and leaves a nice surface.

The 4 jaw is on a back plate and it shows about .005 runout. If I am careful when tightening the through bolts from the chuck to the backplate I can get less than a thou runout but I haven't bothered because I thought the idea of a 4 jaw was to adjust around that. I even faced the mounting surface to make sure I had no warp or pimples causing an issue (I crept up on the chuck register to avoid making it smaller).

I have some pictures of my set up and I have found a way to get it right!

First I tried mounting the indicator to the lathe cross slide:

Then I tried the lathe itself:

Still I had a mismatch when I rechucked and about .0015 to .002 needle movement that was not consistent i.e. I move the chuck about .250 and the needle would jump .001 but when I move back and again to that spot I got a different reading, usually about .0005 off of original position, somewhere between the hash marks but not in the same place. (The above pics are staged as I had already turned the snout. I forgot to take those pictures. Also, ignore the indicator readings. They are not meant to show the mismatch, just show the set up).

There was nothing on the work piece to cause this issue. When I turned on the lathe with the indicator bearing on the stock you could see the needle swinging .003 to .005 on either side of zero. But when I did it by hand I would be within .001 to .0015. i could not swing the chuck fast enough to get the deviation. I tried to measure any runout of the spindle axially or in thrust and found no movement at all.

I decided to get it close and machine the snout anyways. Here you can see the mismatch:

The swarf you see are particles of paper towels used to wipe off the oil. The surface is very smooth.

I drilled a .295 hole through the case and swapped ends. This time I used a mt2 center in the hole I just drilled and brought my mt3 center to bear on the arbor:

(This is before I added the parallels. I added them to insure I could machine the sides concentric to the snout)

Pushing against parallels on the chuck face for pressure (and gap to turn to the edge) I was able to snug the work in the chuck. Once snug I was able to get the needle to barely flicker around one of the hash marks with careful tightening of the jaws.

(this is the setting of the piece in the jaws before centering)

I turned on the lathe and the drill bit I used for the original hole passed through without removing any material at all! I did have to remove about .020 off of the side of the case to true it up. :shrug:

Since all my remaining machining of the bore will be in one chucking I think that I will be fine on concentricity. A 3 jaw will have to wait as my wife did not buy the home shop stimulus package I presented :rant: :rant: :rant:

Thanks,
Sean

 

[Maryak]

Seanol,

Gotcha, I notice that one jaw has #3 stamped on it. The only thing I can come up with is to try the jaws in another position and see if it's better or worse. Also try them reversed. There maybe a burr or something in the jaw guides or on the jaw itself.

I am happy you achieved concentricity with the parallels.

Good luck.
Bob

 

[Seanol]

Maryak,
I removed all the jaws and looked for any kind of burr. I did not swap them as I noticed that they were all stamped with corresponding numbers on the chuck itself.

Next time I remove it I will try the swap and see if I can dial it into a particular jaw or set of jaws.

Thanks you again for all your help,
Sean

 

[reggie98]

Since I can't find the name and # of the chuck repair service I had used, I can only suggest that a call instead of an email might get more response from Bison.

 

[Seanol]

Reggie,
Thanks. I took apart the 4 jaw and cleaned it really well. I am going to go back over it this week to see if it gets better. A question:
Do you spin the chuck by hand and look for the high spot or do you just indicate at 90 degree intervals? My problem is when I disengage the gear train to the spindle there is always a gear attached. I spin the chuck with my hand and look at the indicator. I stop when I see movement and adjust the jaws. I can get between the hash marks on a .001 indicator but I still have some run out. Am I trying too hard? it seems if I go back and then forward I will have about a .001 movement on the indicator. If I go only in one direction it seems fine. No measurable spindle run out axially or in thrust in either direction.

Thanks,
Sean

 

[thezetecman]

I spent many hours messing with old worn chucks thinking a good make must be better even if old. then finally i bought a cheap Chinese chuck mounted it. No looking back will never spend the time trying to fix a worn out chuck again.

Why not look at reusing the mounting plates and buying some new import chucks.

I have seen 6" new one for £40 - £60 all in with key and inside and outside jaws.

The one i got was a 5" and it is very good.

good luck with the lathe.

Another thing that can cause problems is the tightening and condition of the headstock bearings.

 

[reggie98]

It's a longshot, but try: http://www.worldwidechuck.com/Chuck_Sales/chuck_sales.htm

 

[Seanol]

Reggie,
That is who I contacted and he was great! As I said in the initial post, he talked to me about everything under the sun and taught me more about chucks in one phone call than all the researching I have done in the past.

He will be the vendor I choose for my next chuck, that's for sure!

Thanks for the help,
Sean