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-----My anodizer says they can't rack my part
Q. My part is a simple aluminum angle that is radiused. The overall length is about 5 inches long. We are not allowed to have rack marks on the outside of the angle. The parts came back from anodizing with rack marks on the outside.
We threaded a 4-40 hole and threaded in an aluminum rod with a cross hole and they say they still can't rack it. Any recommendations?
Scott DordickEngineering - Pomona
January 21, 2026
A. Hi Scott,
Are those two round bright areas through-holes? If so, a rack with properly spaced spring clips should work fine.
I don't think the device you built will be practical. If built of aluminum it may carry enough current, but will anodize and lose conductivity, requiring stripping every cycle. If made of titanium, a #4 rod may not carry enough current; it would require calculation. Additionally, it looks like it might unscrew enough to lose conductivity.
Please get back to us with whether the part has through-holes because I'm thinking that maybe the issue is simply that the anodizing shop does not want to buy special racks for this particular need, and and you don't either. If they are not through holes, what are they?Thanks.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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Q. Hi Ted,
The anodizer said if I added a couple of blind holes he could rack in them and the he changed his mind. I added a 7/16 threaded aluminum rod that threads into the part with a 4-40 thread. I can't have through holes and the part is only .100 thick.
Engineering - Pomona, California
January 22, 2026
A. Hi Scott
Are you saying that those two round bright spots are blind holes which are not part of the product but were added for racking purposes?
I would suggest that you speak to a titanium anodizing rack manufacturer and see what they say. If those blind holes are not part of the product, but were added for racking, I think the rack manufacturer will prefer to see them placed something like 1" apart rather than (looks like about) 3" apart. I think they will offer encouragement that sharply pointed titanium spring clips, pushing apart on blind holes will prove workable.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
Q. Yes, the silver blind holes were added at the request of my anodizer and then he said they won't work. He then said we could try some more slightly farther apart. They are a big company but somehow can't figure it out.
Scott DordickEngineering - Pomona
January 22, 2026
A. Hi again.
I still feel you should talk to a titanium anodizing rack supplier, alone or with your anodizer. Your anodizer has experience with racks but not nearly as much wide-ranging experience as the suppliers specializing in them. I think if you offer to pay for a prototype rack things will change.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
Thanks Ted, This is a prototype run of 3 parts. I can't justify the expense of a special rack. But I will see if my anodizer will give me the info on the manufacture of their racks so I can contact them.
Engineering - Pomona
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