Universal support arm Adjusting Nut

[rustic]

Hi I am sure this question has been asked many many times but I will ask again. Can anyone tell me the thread size for the adjusting nut for the support arm. When Googled it comes up as ACME and I know the bar size is 12mm but no further info can I find. I am trying to take the slack out of the support arm by adding a second nut on the base.

[RickKrung]

Welcome to the forum, Rustic,

The USB thread is M12x1.25, but it is not really ACME.  ACME has a squarish bottom, whereas the Tormek version has a rounded bottom.  It would be fairly easy to turn this thread if one has a lathe capable of turning metric, but making such an odd-ball internal thread would much more difficult.  A metric ACME tap is hard to find and expensive if you could.  I tried.  Plus, in thinking about the mating of external and internal threads, I thing an ACME would not work, unless you could make the "peaks" of the internal thread rounded.  Or so short/shallow that the sharp corners didn't interfere with the rounded "bottoms" of the mating external thread profile. 

I gave up (my lathe doesn't do metric) for the much easier and cheaper ($10 US) option of buying Tormek Micro-Adjust nuts from Advanced Machinery.  I installed these extra nuts to serve as spacers for keeping my calipers parallel when setting the USB distance. 


I don't set the USB height that way any longer, so they are moot.  I now use the direct distance from the USB bar to the stone/wheel, using a rubber band as a visual reference.  Faster and more accurate, in my opinion (thanks Curtis).


One may notice that I am not using calipers for the setting of this distance.  I use a woodworking marking gage. I like the wide fence as it is a positive in positioning on the bar.  I've removed the marking wheel and use the square end of the bar when touching the grinding wheel.  I definitely do not like touching the grinding wheels with the end of the depth rod on my calipers. 

I like the rubber band also as it is easier to judge when the gauge is parallel, than just by eye. 

...I am trying to take the slack out of the support arm by adding a second nut on the base.

I do not get what you are trying to do with the additional nut.  What "slack" are you wanting to take out?  Could you please elaborate? 

Thanks,

Rick

[rustic]

Hi so when having the USB on the horizontal base there is movement laterally even when the clamp screw is tight the photos show this better, I am thinking of using another nut to secure the USB better see second photo for position. |And thanks for your reply.

[jimdbird]

Would this solve the problem?

Tormek XB-100  Horizontal Base
https://advanced-machinery.myshopify.com/products/62-horizontal-base

Jim

[Ken S]

Excellent suggestion, Jim. The two locking screw version, introduced years ago, is a real improvement. The top surface, which is drilled and tapped, is thicker and more substantial with the new version. For thirty bucks, it is worth it to get the upgrade instead of trying to adapt the older version.

Ken

[rustic]

Hi thanks for all the help I had thought about adding another locking screw to the free USB arm but the metal thickness seemed to light.  The new design base seems the option to go for. Thanks.

[cbwx34]

...
I don't set the USB height that way any longer, so they are moot.  I now use the direct distance from the USB bar to the stone/wheel, using a rubber band as a visual reference.  Faster and more accurate, in my opinion (thanks Curtis).
...
Rick

Final... It's about ti...  You're welcome!      

[Dutchman]

Final... It's about ti...  You're welcome!      

[RickKrung]

...
I don't set the USB height that way any longer, so they are moot.  I now use the direct distance from the USB bar to the stone/wheel, using a rubber band as a visual reference.  Faster and more accurate, in my opinion (thanks Curtis).
...
Rick

Final... It's about ti...  You're welcome!      

Ha Ha!  You are welcome in return...  for the opportunity to gloat a bit...   

Rick

[Ken S]

I think the rubber band sighting guide idea is clever. However, being part Neanderthal (and proud of it), I find the flat bearing surface of the kenjig quite adequate for my needs.

Ken

[ega]

I see that Tormek's description for the US-105 is " a square cut Acme style thread" which is interesting since the diameter is to a metric dimension; the corresponding metric thread is the trapezoidal which, amongst other differences, has a 30deg included angle as opposed to 29deg for Acme.
There have been numerous variations on the Acme thread and without knowing what "style" has been adopted it would be difficult or impossible to produce the corresponding internal thread.
The essential "point" of the flat-topped thread is, of course, that it resists damage from the pinch screws and avoids the need for a separately-machined flat along the thread as per the previous generation of supports. I have modified my pinch screws by the addition of a small brass insert in the end which bears on the support.