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Old 01-11-2013, 04:18 AM   #52
mark0ne OP
Ralle-Moto Adventure
Joined: Jun 2009
Location: central coast NSW
Oddometer: 112
Originally Posted by billdonna View Post
Quick question Vaughan...I'm assuming you're going to 100% anodize the part, thread and bores. Just wondering how you handled the allowance on the Large ID threads? How much oversize did you cut them?

I did some large camera cases and had fitment problems after anodizing due to variation on the thickness of the anodizing causing tight threads. Ended up having to use O/S taps before I was happy.
We need to keep some secrets

But we dont use taps to cut threads. We have methods to solve this as we mostly manufacture steering dampers which as you possibly know are hydraulic units with very tight clearences, valve seats, tapped holes, and mechanical seals to hold vane pressure and are all annodised. To be honest it is really not that bigger issue anymore, making thousands and thousands of hydraulic parts over the years you learn a few tricks! Like when we tried a different annodiser and got 200+ steering damper units back and had to throw them in the scrap bin - Lesson we learnt, "better the devil you know"

The only time I have seen issues like what you describe is when the annodiser is a bit rough and they etch the part way to long with either matte or bright finishes, the parts still look good but the coating is all out of spec and the annodiser will argue that the part still looks great.......... Remember most annodisers are not machinists and dont understand the work that we all put into our work to hold the sizes we do!
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