I've had a takisawa TS-15 for about a month now. I've been getting new tools and running some test parts. I've got an actual part from a friend of mine right now that has pretty tight tolerances (like -0.0000, +0.0005). This isn't all that bad of a problem. This lathe has a lot of cast iron in it and it has box ways - it's built like a locomotive. Additionally, when I run a few parts in a row, the machine repeats very well (not measurable error using mitutoyo calipers). The problem that I'm having is that if I adjust the tool offset on the finishing tool (the same tool finishes the entire OD) I can get some features in spec, but the others are out.
The part is about 2.5 inches long, and has an OD of about 0.5 inches on average. If I adjust the offsets to get the front of the part in spec, the rear of the part is about +0.0025" too large in diameter. This likely means that there is taper in the machine on the order of 3 thou per 3 inches along the Z axis. The machine's manual suggests adjusting some bolts on the head stock to remove taper. I am concerned that there can be several sources of small taper on lathes.
The machine is level, although I am thinking that I could put it out of level on purpose to twist the machine and affect the taper. It could also be the turret that is out? I REALLY don't want to mess with the turret. I also wonder if it has to do with my workholding - although I am using a nice 5C collet chuck (ATS workholding inc) in this case and it all looks pretty darn optimal. Anyone out there deal with this issue before? How did you solve it?
The part is about 2.5 inches long, and has an OD of about 0.5 inches on average. If I adjust the offsets to get the front of the part in spec, the rear of the part is about +0.0025" too large in diameter. This likely means that there is taper in the machine on the order of 3 thou per 3 inches along the Z axis. The machine's manual suggests adjusting some bolts on the head stock to remove taper. I am concerned that there can be several sources of small taper on lathes.
The machine is level, although I am thinking that I could put it out of level on purpose to twist the machine and affect the taper. It could also be the turret that is out? I REALLY don't want to mess with the turret. I also wonder if it has to do with my workholding - although I am using a nice 5C collet chuck (ATS workholding inc) in this case and it all looks pretty darn optimal. Anyone out there deal with this issue before? How did you solve it?