Need width and thread size of threaded top end if 1.875” counterweight shafts


Mark Dearing
 

I Need the width and thread size of threaded top end of 1.875” counterweight shafts.

Thanks in advance,

Mark


M Hambrick
 

Hi Mark

I measure the OD of the threads at 1.083" with a thread pitch of 14 tpi. This is definitely not an ANSI standard thread. Maybe Roland, Howard, or George can comment on the reason this size was chosen.


Mark Dearing
 

Thank you very much for the diameter and thread pitch!
I was hoping to find a tap of the same size; 
Roland, Howard, or George are invited to comment about this not being 
an ANSI size?

Mark


M Hambrick
 

Hi Mark

That will be a very expensive tap since it is not a standard size.

I hope you are not asking because the counterweight shaft threads in the Dec axis cap are stripped. If that is the case you will probably have to get a replacement.

If you just want to chase the threads to clean them up you may be able to get someone to make a chaser for you on a lathe. It does not have to be tool steel since it will only be used on aluminum. If you are able to get the threads cleaned up I recommend using powdered graphite on the counterweight shaft to act as a lubricant. Stainless steel is especially bad about galling aluminum threads, and the powdered graphite will help to avoid this. Use sparingly ! Otherwise all of your beautiful white mount and optical tubes will soon be covered with black smudges.

FYI there was another thread on the forum not long ago where it was mentioned that all of the new mounts have a stainless steel insert in the cap. Although bronze would make a better insert material than stainless, it is still much better than aluminum. Marj mentioned that sometime before too long these caps will be available to purchase as a separate part. As soon as they become available for replacement parts I plan to buy one.


Mark Dearing
 

Thanks very much for the information!

Mark