I rarely have an issue parting on my 8.5x20 Sieg C4 lathe but when I do it’s when I get less than an 1/8” away from the part falling off or right was I first start the cut. The blade either stops cutting or it doesn’t cut at all. If I apply more pressure to make it start cutting this long flat pile of what looks to be microscopic pieces of metal comes off. It slowly builds up and works its way back on the tip of the tool. I have sharpened the parting tool numerous times (I get it razor sharp) and messed around with the height as well. It seems to cut the best when I have it slightly above center.
I am using a Somma Tools T-15 .094” thick T-type blade in an Aloris AXA parting tool holder (I believe its a #71) and a solid tool post and my carriage locked down. Just in case anyone asks, yes I have checked the height after I locked the carriage. Lastly, I made sure that the blade is perfectly straight and not leaning or tilted. The material I seem to have an issue parting is 1018 CRS, 12L14, and general low carbon steel. I do not have this issue with tool steel or aluminum.
My parting speed is usually around 230-350 rpm’s and after the cut is finished the part is not so hot that I cannot touch it. Don’t get me wrong, it’s hot but not to the point that it will burn me. Also the motor does not bog down at all.
Oh, I almost forgot to add that I use a moderate feed. I make sure that the chip keeps rolling off. If I have to stop to put more oil on my brush I back out so that the tool does not rub and potentially work harden the material, or at least I think that is what’s going to happen if I let the tool rub without feeding.
Here is a picture of the swarf that I occasionally get.
Here is a picture of the part. Can anyone see what’s going on judging by the face of the material? This is the part that falls off. I should probably add that when I face off the part still left in the chuck I do not notice it being concave or convex. A few thou cleans up the face.
I am using a Somma Tools T-15 .094” thick T-type blade in an Aloris AXA parting tool holder (I believe its a #71) and a solid tool post and my carriage locked down. Just in case anyone asks, yes I have checked the height after I locked the carriage. Lastly, I made sure that the blade is perfectly straight and not leaning or tilted. The material I seem to have an issue parting is 1018 CRS, 12L14, and general low carbon steel. I do not have this issue with tool steel or aluminum.
My parting speed is usually around 230-350 rpm’s and after the cut is finished the part is not so hot that I cannot touch it. Don’t get me wrong, it’s hot but not to the point that it will burn me. Also the motor does not bog down at all.
Oh, I almost forgot to add that I use a moderate feed. I make sure that the chip keeps rolling off. If I have to stop to put more oil on my brush I back out so that the tool does not rub and potentially work harden the material, or at least I think that is what’s going to happen if I let the tool rub without feeding.
Here is a picture of the swarf that I occasionally get.
Here is a picture of the part. Can anyone see what’s going on judging by the face of the material? This is the part that falls off. I should probably add that when I face off the part still left in the chuck I do not notice it being concave or convex. A few thou cleans up the face.