- Joined
- Nov 27, 2012
- Messages
- 7,865
Woah, if you didn't make a typo & it's out .0040" that's a lot! Although possible it shouldn't be that much out of alignment, especially for a Taiwanese lathe. My PM1236 is only outr a few tenths over 7-8" or so, I haven't bothered to adjust my headstock yet. Not sure if your adjustment screws for the headstock is the same as mine but all the asian import lathes in this size are similar. I would do some more investigating before messing with the headstock adjustment.
It's not the chuck, if you suspect it is you can try it with the stock chuck. But it doesn't matter even if the chuck is holding the test piece crooked, it wouldn't matter cause you are taking a cut along the spindle axis. Try it again with only 5-6" hanging out for that 2" piece of alumn & see if you get similar results. You need a sharp cutter & take very light cuts, what you want is to avoid tool pressure & pushing the stock. Although it's only a light cut, take the backlash out of the compound slide & lock it before making the cut.
You leveled the lathe pretty well with a machinist's level right? Side to side & front to back doesn't have to be level with the world. What you want is the headstock side of the ways to be level with the tailstock end of the lathe front to back. Use 2 123 block on the flat part of the ways for the machinist's level to sit on so it clears the V, you don't want to measure off the crest off the V. Where ever the bubble settles, you want it to be the same on the end of the lathe, this takes the twist out of the bed.
It's not the chuck, if you suspect it is you can try it with the stock chuck. But it doesn't matter even if the chuck is holding the test piece crooked, it wouldn't matter cause you are taking a cut along the spindle axis. Try it again with only 5-6" hanging out for that 2" piece of alumn & see if you get similar results. You need a sharp cutter & take very light cuts, what you want is to avoid tool pressure & pushing the stock. Although it's only a light cut, take the backlash out of the compound slide & lock it before making the cut.
You leveled the lathe pretty well with a machinist's level right? Side to side & front to back doesn't have to be level with the world. What you want is the headstock side of the ways to be level with the tailstock end of the lathe front to back. Use 2 123 block on the flat part of the ways for the machinist's level to sit on so it clears the V, you don't want to measure off the crest off the V. Where ever the bubble settles, you want it to be the same on the end of the lathe, this takes the twist out of the bed.