Teknatool precision midi chuck accuracy?

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Andrew_K99

Andrew_K99

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I just picked up a Teknatool/Nova precision midi chuck and measured the run out to see how accurate it was.

I measured 8 thou!!! Which seems rather ridiculous!!

FYI I also measured the lathe without the chuck and it didn't have any run out (well the needle moved a tiny bit, 1/2 thou if that).

Is this normal for a wood lathe chuck? Did I get a dud? Is there something I am missing?

Thanks,
Andrew
 
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I should have noted that the chuck body had 1 thou run out, the 8 thou was observed at the jaws and on multiple known round objects mounted in the chuck.

AK
 
On the objects you know are round, have you formed a tenon or recess for the jaws to grip onto or have you just been resting the objects on the bottom of the jaws? Also have you been using the tailstock to support the other end or is it just free spinning?
 
Andrew how far out were you measuring from the chuck, .008 does seem a bit much, that sound more like the runout on a Barracuda 2000 than a Nova Midi. But the distance out from the chuck also makes a bit of difference, you said at the jaws, were these the 50mm jaws or on pin jaws.
 
Hi Andrew,

I'd posted last week with a similar problem with a supernova chuck, fitted with pin jaws. The chuck body is within 2 thou, but the four pin jaws are 'out to lunch'. I've quit using the pin jaws, and am back to drilling at the drill press.

Extremely frustrating...

Steve

Andrew_K99 said:
I just picked up a Teknatool/Nova precision midi chuck and measured the run out to see how accurate it was.

I measured 8 thou!!! Which seems rather ridiculous!!

FYI I also measured the lathe without the chuck and it didn't have any run out (well the needle moved a tiny bit, 1/2 thou if that).

Is this normal for a wood lathe chuck? Did I get a dud? Is there something I am missing?

Thanks,
Andrew
Click to expand...
 
There could be a lot of things causing the run out from a tiny chip of wood in the threads to not having the jaws in the correct locations. Did you make sure the jaws are in their correct numbered positions? May sound like a silly question but I've met folks who didn't have a clue as to what I was talking about when mentioning the dots or numbers on the bottom of the jaws.
 
Yes, the numbered sections were the first thing I checked. Also:

- dissassembled and checked for debris in the locking channels
- assembled loosely, tightened on a perfect piece of round stock, then cinched down the jaw mounting screws...

The tops of the slides to which the jaws attach are perfect (as measured on their tops).

The 50 mm jaws seem to be fine, so the chuck is okay -- it's some aspect of these pin jaws. Andrew (Maxwell Smart) pointed the other day, that there is just one machine screw that holds each pin jaw in place, compared to two screws for the 50 mm jaws.

I'll have to examine them carefully and see if one of them has bent or something.... :frown:

How about you Andrew -- do any of these apply to your chuck?

Steve

Texatdurango said:
There could be a lot of things causing the run out from a tiny chip of wood in the threads to not having the jaws in the correct locations. Did you make sure the jaws are in their correct numbered positions? May sound like a silly question but I've met folks who didn't have a clue as to what I was talking about when mentioning the dots or numbers on the bottom of the jaws.
Click to expand...
 
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Thanks everyone for the input.

I wasn't measuring the jaws that screw on, I was measuring the fixed jaws.

I haven't had time to play with it again but will hopefully this weekend. I thought it was odd that the chuck body was good but the jaws were out.

As for where I was measuring, I mounted a couple different drill bits in the chuck and measured as close to the jaws as possible.

AK
 
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Andrew, how are you measuring the runout and what sort of runout are you measuring? Is it axial or circular? Also, are you clamping something in jaws first? I would clamp a cylindrical guage pin in the jaws and measure that. You can get by with a regular hardened dowel pin in a pinch. I did machine set up for 13 years as a machinist and I have to say that .008 runout, jaw to jaw, if that's it, is pretty minimal if the chuck is loose.
 
AlanHil said:
Andrew, how are you measuring the runout and what sort of runout are you measuring? Is it axial or circular? Also, are you clamping something in jaws first? I would clamp a cylindrical guage pin in the jaws and measure that. You can get by with a regular hardened dowel pin in a pinch. I did machine set up for 13 years as a machinist and I have to say that .008 runout, jaw to jaw, if that's it, is pretty minimal if the chuck is loose.
Click to expand...

I was measuring in the fixed jaws (not the bolted on accessory jaws) and I mounted a few different drill bits in to check for run out.

I'm not sure what you mean by axial or circular run out. The way it was reading the piece would be oval, I'm guessing only one jaw is actually to blame.

AK
 
i can't help but wonder. what does is matter if the jaws have run out? put a piece of wood it the chuck and round it, then check it. it does not move with the jaws causing an oval. it will matter only if you turn a piece and then rechuck it. am i missing something here?
 
I own 3 nova chucks Super Nova Supernova II And a nova midi. no problems with run out. In The Nova chuck manual it recommends that the jaw screws be left loose the chuck closed completely then tighten the screws. I find this works best. Of course it is imperative that all mating surfaces be clean. Lastly, mark the work piece so that it can be re chucked in the same position.

Tim

Doing the same thing the same way and expecting different results is the definition of insanity.
 
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