Brake Drum Micrometer?

6

62BillT

Well-Known Member
I've got this posted on another board (not CT) and I thought I would post it here as well.

I've been in the market for a Brake Drum Micrometer. I like the Ammco 8500's but they are pretty expensive new and used ones aren't real cheap either. Then a lot of used ones need to be Re-calibrated and that tool is about another $100.

I've decided to try to make my own out of a Dial Indicator that I bought. I'm going put an extension on it to equal the inside measurement of an 11 inch Brake Drum.

My question is, is the inside measurement of a brand new drum Exactly 11 inches?

I'm planning on having it set to about zero on a brand new drum, and I should therefore get a pretty accurate reading on a used drum.

I'm going to try to make it as accurate as I can.

Any input would be appreciated.

Thanks

Bill
 
Most dial indicator have a 1 inch travel. You will need some pre-load, so why not start with a total length 10.9 inches.

Do you have a brake lathe???
 
Right, the Dial Indicator I have has a 1 inch travel.

No Brake Lathe, just want to get a more accurate idea on the condition of them, other than going by eye sight. I've got quite a few Brake Drums to check.

Bill
 
I wouldn't worry about it being exactly 11", most drums are stamped with a Maximum Diameter. That number really determines the largest
SAFE diameter for that brake drum. Look over the drum, inside and out for this stamp, it might be abbreviated "Max 11.060"
 
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