Re: Mach2GTO counterweight shaft stuck midway #Mach2GTO

Cheng-Yang Tan

Hi Carl,
   The mechanical engineers and techs that I work with have extensive knowledge of stainless steel. We work with stainless steel everyday because it is used for high vacuum. Stainless steel bolts and nuts seize easily unless we use "never seez" compound which is a mess. Instead we prefer to silver plate all the stainless steel fastening hardware to prevent seizure.

   Anyway, I had started a thread about this problem a year ago and got some info about how to mitigate this problem. See this link:

Anyway, I agree that having an insert is a good idea, but a change of material will certainly lessen or eliminate the cross threading problem.



On Tuesday, August 9, 2022 at 04:29:59 PM CDT, Carl Björk <carl.bjork@...> wrote:


I just wanted to give you guys an update.

My shaft is seized solid to the insert and the thread is visibly damaged (look at the first thread on the first post). Unfortunately nothing works.

I must say AP has been extremely responsive and will send replacement parts to me tomorrow.

Now for the insert.
For what I know about it, cold welding is something that can only happen with very pure metals. Metals so pure that even oxydation will make it impossible. IMHO, the reasons for seizures are somewhere else. But besides the design, what counts is solutions and downtime minimisation.
More importantly, as per my shameful experience of damaging aluminium threads, I really see stainless steel inserts as an advantage.

But that is only my own opinion in this given situation ;-)

Yes this is a hassle, BUT yes AP has probably has the best support out there! For me it totally makes up for it.

Cheers everyone!

Looking forward to share great things with my Mach2 ;-P

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