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oldwilly wrote: Hi again,
I sort of got side tracked with some home reno stuff ( happy wife) but the late is looking really good and I could not agree more with your comments about making parts on the Unimat, it can be done but........
Some tings I have learned about 3 jaw chucks,
They don't run true, ever, They are great for quickly grabbing a piece of stock and turning something and what you make will be concentric to it's self but if you want to remove the work one must be very careful about marking it to get it back in exactly the same place in the chuck or it will not run true again. Mine or any I have used have some degree of run out but it should be consistent when you tighten it up, mark it and check.
Most 3 jaw chucks I have seen have the tightening screws marked, some with 1,2,3 but some just have one screw marked, a V or a dash or just a round center punch mark, I have been told this is the screw that will give the least run out when you are tightening it up, so when giving it that final tighten use that screw, check yours, it should be marked. If not find it and mark it.
Also you can use that fancy new test bar to check the back of your chuck if it was really off ( have only found this problem with really cheap off shore stuff), put the bar in the head stock, give it a tap to seat it and clamp the chuck backwards on the bar. You could also take a light facing cut if you think you need to.
Try changing the chuck position on the mounting plate see if it gets better and what ever is the best be sure to make marks for future reassembly.
Personally I don't think your run out is that bad, if you want it perfect you need to get a 4 jaw chuck and get good at centering a work piece with your dial indicator.
Speaking of that other new toy, put your test bar in the headstock and mount the indicator to the carriage then set the dial and move the carriage the length of your test bar to check that the head stock is aligned to the bed, might need a bit of shimming, my Logan did. This will stop you from turning pieces that are tapered.
So there is my 2 cents again.....