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Large diameter thread and Alodine binding

I have a threaded cap and tube (1 1/2-18ENUF) that prior to the Alodine and powder coat process mated perfectly. Now they bind after 3 or 4 threads are engaged. I believe the Alodine process does not add material. There are no visual defects to suggest handling issues. A thread sealing compound is applied before final assembly so lubrication is not an option. Has anyone experiences this binding issue? What is the cause? Is there an additional process such as teflon coating that will remedy it?

Kevin Wharton
Pacific Crest - Santa Clara, California
2005

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Alodine doesn't add thickness, but powder coating certainly does. Maybe I'm misunderstanding what you are describing

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
2005

The threads are masked prior to powder coat painting.

Kevin Wharton
- Santa Clara, California, USA
2005

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There is more to Alodine processing than just the chromate conversion coating step per se. Is it possible that the problem is not an interference fit, but the fact that these items had reasonable lubricity before, and now they are galling?

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
2005

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