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oxford
11-30-2017, 08:29 PM
I need to make a broach bushing for a 2.5" diameter hole using a 1/2" D broach. Does anyone know deep the slot where the broach rides? For others that I have made I just measured the depth on the same letter bushing of a different diameter. I don't have any bushings for a D size to measure.

I plan on just ordering the correct shims for the broach so I would like to keep the bushing standard. Thanks.

J Tiers
11-30-2017, 09:11 PM
if you order the shims, the basic bushing slot depth is the broach height to the highest tooth, plus the shim thickness for final pass, less the keyway depth outside of the hole diameter.

wierdscience
12-01-2017, 12:28 AM
I need to make a broach bushing for a 2.5" diameter hole using a 1/2" D broach. Does anyone know deep the slot where the broach rides? For others that I have made I just measured the depth on the same letter bushing of a different diameter. I don't have any bushings for a D size to measure.

I plan on just ordering the correct shims for the broach so I would like to keep the bushing standard. Thanks.

I can measure one for you tomorrow since I have the full 2-3" set at work to confirm it,but the way I normally do it is to cheat a bit and use an online key depth calculator.
http://www.cncexpo.com/KeywayArc.aspx

Measure the width of the Broach body and add .001" for clearance and use that for the W dimension.The diameter is obvious at 2-1/2 that will give you the A dimension height that needs to be milled off.

Once that's milled off,zero the knee,measure the height of the lead in section of the broach and mill the slot to that depth. De-burr and you're done.

Here's a few I did back in September of this year,4-11/16 4-3/4 and 4-15/16" all for 1-1/4 keyways in coupling bores.

http://img.photobucket.com/albums/0903/wierdscience/003_zpsjaks3kil.jpg