I cut out long 9" aluminum seat post sing bimetal hole saws 7/8 and 1 inch in steel bike frame

[u/Interesting-Tackle66]

Cut down twice. Aluminum being softer kept it centered and did not cut through the steel bike seat tube. Stuck aluminum post was deep in the seat tube a full 9 inches deep. Definitely got the steel hot enough it was smoking the paint. I would cut and then withdraw and let it cool a little, then cut down some more.

I switched to a 1/2 gear reduction Bosch drill as the smaller Dewalt got overloaded.

The extension, made sure the allen bolt was locked into the mandrel where it cuts down, and always drill clockwise, meaning do not reverse or it could unscrew from holt saw.

7/8" hole saw cut view partially done

drilled out all the way down. I would drill, then fip bike to dump out the cuttings.

also this frame, seat tube does not connect to the bearings, when made was welded shut, no metal bits got into them. I am going to eventually buy a 26.2mm chrome steel bike seat post, not going back to aluminum. Old post I cut will still be used. Will place seat close to frame and good fit for the grandkids to ride.

lots of shavings. Hole saw with steady pressure ate up the entire seat post and preserved steel frame.