Truing up headstock

[Standingbear]

After moving my Lathe I leveled the lathe, then made a 6” barbell to check headstock. It measured .007 off. After jacking with the Jack screws on the side of the lathe and taking another cut it is reading .0005. Two questions here is that good, the OCD in me wants to keep going. Second question is did I mess up because I did this with a 3 jaw chuck, not sure how much runout the chuck has. Or does it matter

 

[benmychree]

If you recut the test bar with a fine finish cut each time you make an adjustment, it will be OK; if you machine the ends of the test bar to the same size, and use the indicator, that should be OK also. The runout of the chuck should make no difference as long as the test bar is trued after chucking. I would be happy with .0005" in the distance you are spanning.

 

[pacifica]

You might want to use a4 jaw, or the morse taper in spindle nose is even better. I can't tell from photo if tail stock is involved.
I would also check how level the ways are by themselves.
First I would want to know the runout on the inside of the spindle nose with a test indicator.
But, how likely is it that you need more precision than 5 tenths variance over 6 inches?

 

[Standingbear]

Ok so I made one more small adjustment then made another cut and going to stop while I’m ahead. I did level first front to back starting with the headstock side then tail stock side. Now I have to try and align the tail stock. Is it ok to use a center on both sides and align the points or better to drill this bar I just cut for HS?

thank you benmychree and pacifica

 

[ddickey]

You should be checking the the diameter with a micrometer if you're checking for a taper.

 

[Standingbear]

I cut a dead center and mounted my bar from earlier headstock adjustment. Ok question, do I need to take fine cuts again? Or just use the dial indicator until it’s on adjusting the tail stock?

small goof, almost didn’t give myself enough room when I cut my bar of lol.

 

[Standingbear]

Dicky I did check with a micrometer too and it was .989 in both spots I was cutting. I was cutting a bad taper prior to this. I’m hoping to get it all cutting true today.

 

[Technical Ted]

As John said above, you can use just the indicator without taking another cut as long as the two shoulders are the same dimension. Holding the test bar in a 3 jaw, 4 jaw, collet or between centers makes no difference.

I wouldn't worry whether the lathe is still level or not.... the reason we level our lathes is so they cut true. When checking my lathes, I check with the level but then tweak, as you are, by using a test bar. The test bar is the king! If I find when I'm taking a cut, without using the tail stock, I am starting to get a taper I will tweak the leveling screws (without getting my level out) to correct the problem.

Ted

 

[mikey]

@Standingbear, I'm curious about what your depths of cut were when taking cuts on the 2-collar bar. Also, what are you trying to accomplish with the bar between centers?

 

[Standingbear]

@Standingbear, I'm curious about what your depths of cut were when taking cuts on the 2-collar bar. Also, what are you trying to accomplish with the bar between centers?

Morning Mikey, I had two goals I was trying to to do. First one was true the headstock due to cutting tapers. For that part I chucked up some one inch mild steel in the three jaw only, no tail stock. I made the tests bar which showed to .007 bigger on the tail stock side. Took measurements both with DTI and micrometers then would recut after each adjustment. Once that was completed I wanted to zero my tail stock so I cut a taper in the three jaw and used the bar I made from truing up the headstock to mount between centers to check. Found out the Jack screws were loose on the tail stock during this lol. For both tests I would cut .002 of each end of the test bar. On my lathe that is one mark one the wheel.