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snowman
03-03-2005, 10:03 PM
An interesting problem today.

I found that all of my van norman collets thread into the drawbar just fine, but some shell mill adapters seem to get stuck up after just a few threads. (basically, if it's a hardinge product, it's fine, some of the van norman products are screwy)

If I mic the outside diameter of the threads, I found that the ones that dont thread are bout 4 thou larger than the others (I can't find my thread wires to make the "proper" measurement).

I'm not sure if I might have pushed a chip into the drawbar thread or what. If I look at the internal threads, they all seem really clean, and using a needle, the seem smooth.

I think someone made this drawbar as a replacement...not sure why, just a gut feeling.

Any suggestions?

-Jacob

wierdscience
03-03-2005, 10:44 PM
Well at work I got R-8,BS and Nt40,all have problems from time to time.I just run a tap in them,most are not so hard on the drawbar end.

The ones that are hard,I just cut a section of allthread or use an old bolt as a lapping tool to work them out with compound.

I have found that gun brushes work good for cleaning threads.

Oh,BTW,check your mail.

[This message has been edited by wierdscience (edited 03-03-2005).]

snowman
03-03-2005, 11:03 PM
yah...a tap would be nice and easy! http://bbs.homeshopmachinist.net//smile.gif

Tap would be beautiful! Unfortunately, the smart people at VN decided to make the thread a .775 x 18 thread...anybody got a tap?

I'll have to try the lapping compound trick...I'll use one of the collets that threads in well, I've got an extra 1/2" ID.

If that doesn't work, I might just take one of my extra arbors and grind a flute on it...make my own tap.

-Jacob

snowman
05-21-2005, 06:31 PM
Weird...

FINALLY went to the auto parts store to get valve grinding compound.

It took a while, but they thread in now...really pretty smooth.

Unfortunately, for some reason each individual one had to be lapped in. Now they all come in and out with relative ease though.

Thanks for the suggestion.

-Jacob

rockrat
05-21-2005, 10:34 PM
Snowman, just caugt the thread. Glad to read that you have found a solution. I have used a thread restoring file to fix many issues. I also have and internal type thread restoring file (sort of) for the id threads.

I am curious, what type of Van Norman do you have? I have been having fun working on my 22L VN recently. Busy making an adapter to fit my #30 NMTB to the B&S 10 taper.

Cheers - rock