it was soft and crisp.I strongly suspect that the cast-iron composing your backplate is hardly befitting of that chemical analysis... Jesse
Anyone except myself hating to machine cast iron? Funny thing is that I have successfully machined a back plate made from A36 steel so I figured that the cast iron wouldn't be an issue!Here is the back plate I made from the A36 steel for my 5" 6 jaw chuck......... Today I intended to machine the back plate that came with my new chuck that has been washed, dried and lubed with RemOil. The assembly went well and the chuck is smoother than it was before the "washout" so I chucked the supplied cast iron back plate in my bench top lathe and tried to reduce the 6" diameter to match the OD of the 5" chuck. The tool holder would barely make a cut on the OD of the 6" diameter cast iron plate. Even with the lathe set to the slowest speed (max torque) my belt would slip and the cut would cut stop after tightening the belt tension if the cut was greater than .005 deep. Knowing that it would take "forever" to knock down the diameter at .005 per pass I still messed with a few passes, then stopped due to the "gritty swarf" accumulation on everything in the vicinity. I gave up on machining the case iron, found an old discarded aluminum back plate, noticed that it could be modified for the new chuck, then successfully cut a back plate from the aluminum.