Recommended spindle speed using a boring head on a Bridgeport

[ironwrx]

Just got a 50X, used a 5/16 rod in the eye cast into the right side of head.

That’s a neat, simple solution, but according to the Tapmatic recommendations, “the torque bar installation must be stronger than the largest tap in the capacity range of your tapping attachment”. So, my concern would be if the 5/16” rod would be strong enough?


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[MrWhoopee]

That’s a neat, simple solution, but according to the Tapmatic recommendations, “the torque bar installation must be stronger than the largest tap in the capacity range of your tapping attachment”. So, my concern would be if the 5/16” rod would be strong enough?

I've only been using it for 10-32, so not a problem. The shank of a 1/2-13 tap is .367 diameter, which is going to be the weak point. Being HSS, stronger than mild steel, but still worth considering.

 

[ironwrx]

Success! I ended up using the lowest speed on my mill (80 rpm), as I was cutting with a fairly long boring bar (the only one I had for my Yuasa boring head), with hss cutter. The next speed up was 135, and I decided that I was getting a decent finish with 80. Thanks for all the helpful advice!

All I’ve got to do is cut off the excess material, and drill a couple of holes for the torque bar clamp itself which I’m making out of a u-bolt I stole from a wire rope clamp.


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[ironwrx]

All done. I decided to cut a 1/16” deep groove with a ball end mill to keep the torque bar straight. Other than that, all done, very happy with the project.

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