A couple of weeks ago I picked up a very nice Criterion DBL-203 boring head with a case and 5-6 unused Criterion boring bars, for a very low price. The only flaw with the boring head was a slightly damaged R8 shank, which at the time I figured wouldn't be much of a problem to change out. Well in the last 2 days I've broken one 5 inch bench vice, dislodged my work table from the wall and broken four 3/4" boring bars and that shank is still attached to the head.
Yesterday afternoon I began my attempts to remove the shank which uses 1-1/2"-18 Threads to screw into the top of the boring head. I placed the shank in my bench vice, tightened down the vice and placed an old 3/4 inch boring bar into one of the side holes. At first I tried to get the head turning with a couple of hits with a 2 pound hammer on the boring bar. The only thing this did was make the shank rotate in the vices jaws. Next I tried the same thing but first applied some heat using a MAPP gas torch. Once again the shank rotated in the vice jaws but the head didn't rotate on the shank. Then I decided to grind some flat on the shank to prevent it from rotating. This did stop the shank from rotating, but at this point my vice cracked and became useless. So into the dumpster it went, and I then drove to Harbor Freight where I picked up a nice 6.5 inch Doyle vice. Side note, I've been wanting to get a new heavy duty vice anyway, so it was $250 well spent. Upon arriving home I installed the new vice on my garage workbench right where my old one had been. At this point I thought I had a chance of defeating my adversary. Nope, I placed a piece of 1 inch square tubing over the protruding boring bar and began to turn the boring bar head CCW. The only thing this did was dislodge my workbench from the wall and lift the benchtop from it's mounts. I was not at all amused. I once again tried heat but had the same negative results. I used 2 boring bars stuck in both side holes in the boring head and used 2 pieces of 1" tubing so I could both push and pull the head CCW. Nothing. I even tried turning the head CW as I thought it couldn't hurt, but once again no movement. I conceded that my adversary won the day and began plotting my next move.
Today I devised what I thought was a cunning plan that I thought for sure would work. I would weld the shank to a 2" square trailer ball hitch, install the hitch into the receiver hitch on my tractor's front end loader and then install a boring bar into the boring head and place the 1" square tubing over the boring bar. I would then use the downward force of the front end loader to force the head to turn CCW. My first attempt ended when the boring bar snapped in half. I then tried again after first replacing the boring bar and heating the shank and top of the boring head, but once again the boring bar snapped. At this point I slid part of the boring bar out of the hole and began hitting the shank end attempting to rotate the head CCW. This caused the welded shank to rip from the trailer hitch. I rewelded the shank to the hitch and tried again but this time I attempted to turn it CW. Nope, no movement at all.
Surprisingly the boring head is still in good shape, but I'm at a loss as to how to get the shank off the head. And before someone asks if the shank and head are machined as one piece, they are not. Before I destroyed the Criterion shank it was clearly visible on the shank what threads are used to attach it to the head, 1-1/2"-18. So I'm up for suggestions anyone may have on how to defeat my foe.
Yesterday afternoon I began my attempts to remove the shank which uses 1-1/2"-18 Threads to screw into the top of the boring head. I placed the shank in my bench vice, tightened down the vice and placed an old 3/4 inch boring bar into one of the side holes. At first I tried to get the head turning with a couple of hits with a 2 pound hammer on the boring bar. The only thing this did was make the shank rotate in the vices jaws. Next I tried the same thing but first applied some heat using a MAPP gas torch. Once again the shank rotated in the vice jaws but the head didn't rotate on the shank. Then I decided to grind some flat on the shank to prevent it from rotating. This did stop the shank from rotating, but at this point my vice cracked and became useless. So into the dumpster it went, and I then drove to Harbor Freight where I picked up a nice 6.5 inch Doyle vice. Side note, I've been wanting to get a new heavy duty vice anyway, so it was $250 well spent. Upon arriving home I installed the new vice on my garage workbench right where my old one had been. At this point I thought I had a chance of defeating my adversary. Nope, I placed a piece of 1 inch square tubing over the protruding boring bar and began to turn the boring bar head CCW. The only thing this did was dislodge my workbench from the wall and lift the benchtop from it's mounts. I was not at all amused. I once again tried heat but had the same negative results. I used 2 boring bars stuck in both side holes in the boring head and used 2 pieces of 1" tubing so I could both push and pull the head CCW. Nothing. I even tried turning the head CW as I thought it couldn't hurt, but once again no movement. I conceded that my adversary won the day and began plotting my next move.
Today I devised what I thought was a cunning plan that I thought for sure would work. I would weld the shank to a 2" square trailer ball hitch, install the hitch into the receiver hitch on my tractor's front end loader and then install a boring bar into the boring head and place the 1" square tubing over the boring bar. I would then use the downward force of the front end loader to force the head to turn CCW. My first attempt ended when the boring bar snapped in half. I then tried again after first replacing the boring bar and heating the shank and top of the boring head, but once again the boring bar snapped. At this point I slid part of the boring bar out of the hole and began hitting the shank end attempting to rotate the head CCW. This caused the welded shank to rip from the trailer hitch. I rewelded the shank to the hitch and tried again but this time I attempted to turn it CW. Nope, no movement at all.
Surprisingly the boring head is still in good shape, but I'm at a loss as to how to get the shank off the head. And before someone asks if the shank and head are machined as one piece, they are not. Before I destroyed the Criterion shank it was clearly visible on the shank what threads are used to attach it to the head, 1-1/2"-18. So I'm up for suggestions anyone may have on how to defeat my foe.
