Lathe Levelling And Other Lathe Issues

ddickey

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After buying my lathe last summer (2000 13x40 Acra-Turn) I got it leveled with a lot of help from a member here. Anyway I'm waiting for a few things to come in the mail before I start my next project so decided to pull out my two collar test bar. It was out quite a bit .023". It's cold here now so I'm sure that has a lot to do with it. I monkeyed around with it for a while and decided to start from the beginning. Got the level out and started levelling. Took a while but I have levelling casters that really make it a breeze. First got the headstock leveled then move to tailstock. Took several times back and forth, as soon as I'd level the TS the HS would go out. Always kitty-cornering the same two casters.
On a side note. I put my level on the cross slide only moving the carriage up and down the bed. Once I got it leveled I used 123 blocks and put them on the flat ways out of curiosity. I had to put .011" of shims to get it level. Not sure why that is other then they are simply not level with each other. Did the same with the V ways and not even close to level.
Moving on. Chucked up my two collar test bar 2.65" Ø aluminum about 6" between collars I think it is using the 4JC. HS end is larger so I start lowering, or raising the TS, back caster. So here is one of my questions. I have to move the caster a lot to get any change in cuts. I'm not sure exactly how much I raised, or lowered that back caster but it was many turns. To me it seems like there is another issue here. The first pic is the lathe level according the bubble. The next is where I'm at now cutting very little taper.
One thing I need to mention. When I chucked up my test bar and trued it up with zero run-out on the outside collar I had four thou run-out on the inside collar. I thought that was very odd. My next test was a skim cut on a 6" 1.5"Ø aluminum bar. At this time I don't own a 1"-2" mic so used a indicator and ran the length. The next pic is my setup. And the next I my starting point and then chuck end. Now look what happened when I rotated the chuck 90°. Four Thou? I then ran the lathe touched the stock and sure enough nice and smooth on the outbound side and about 2/3 in starts to jump around.
Can anyone explain this? Thanks for responding.
Duane

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Re your first statements when using a level on the ways, if levelling the TS end causes the headstock end to 'un-level' then I have to wonder if the lathe was tweaked at some time during moving or installation. Especially if gross adjustment of the casters is required to straighten it.

For the hub tests I don't see how they can be done accurately without a micrometer.

Not sure I understood everything you wrote but maybe you should run one test at a time as required in the right sequence before moving on to the next.
 
Re your first statements when using a level on the ways, if levelling the TS end causes the headstock end to 'un-level' then I have to wonder if the lathe was tweaked at some time during moving or installation. Especially if gross adjustment of the casters is required to straighten it.

For the hub tests I don't see how they can be done accurately without a micrometer.

Not sure I understood everything you wrote but maybe you should run one test at a time as required in the right sequence before moving on to the next.
It is possible I guess. Personally I only lifted from the lifting holes on the cabinet but who knows how it was handled in the last 16 years.
I do have a 2"-3" mic so the collar test was done accurately. I agree the test bar to check taper should be measured with a mic. I'll have to check on getting one. Also, I went back out to the garage to take a look again at the test bar and the reason for the 4 thou was I didn't turn all the way around. I don't know why this would have happened.
I believe I did the correct sequence. Warmed up the machine. Took twist out of the ways with level. Ran a two collar test. Made adjustments to the casters to have equal cuts then moved onto a full length cut to check for taper.
 
Sounds good, the 2 collar test, when held in the chuck only, is the best test for discovering twist in the ways provided the headstock is aligned to the ways. Note that the outboard collar can be slightly larger even when everything is dead nuts because of deflection.
The full length cut to check for taper was between centres? If so, this only shows if the TS is aligned, and this only if headstock and ways are proven good first.

Do you have a spacer to use with the 2-3'' mic for diameters under 2''?

Do you know how much run out you are getting from the 4 jaw chuck?
 
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The full length test was not between centers.
My inboard collar was the larger one. Got that down to nil though.
I do not know about the headstock. I doubt mine can be adjusted. If you know of a test I can do.
I was curious how much movement I made so putting shims under my level I now have .024" on the HS end and .026" on the TS. Might be the other way round.
 
Re the tests you can do this might be of help.

http://cdn0.grizzly.com/pdf/G4003G_Inspection_Record.pdf

Bear in mind that some tests require precision test bars and indicators. Do what you can with what you have and see how far you can go. Ultimately if your work meets your standards then the lathe is good. No need to get bogged down in measuring stuff unless there is a problem.
 
I have a precision ground bar. Would you chuck it in a four jaw to test headstock?
 
I just got through re-leveling and "adjusting the twist" in the bed on my lathe with very good results. Fortunately, I didn't have to make any adjustments to the headstock.
Tom Lipton has a couple of videos where he goes through the lathe leveling process. He shows how to make and use a test bar and he also had to adjust the headstock alignment on his lathe, so you may be interested in watching these.

Also, I'm curious about your leveling casters. When you are leveling, is the lathe supported by the wheels or is there a separate stiff leg that supports the lathe ?


Ted
 
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I have a precision ground bar. Would you chuck it in a four jaw to test headstock?

Nope. But doing that should show how much run out the chuck has.

If your turning tests are good what is there to left to sort out?
 
Concerned about the amount of deviation from level I had to go. I guess as long as there is minimal twist it doesn't matter that they are not level to each other?
For headstock test how do you mount your bar. The Grizzly illustration looks like a chuck to me.
 
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