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9A Headstock alignment

animal12

Hot Rolled
Joined
Apr 9, 2009
Location
CA USA
question for the pro's here . what is the best way to check headstock alignment after HS removal ? I seem to be cutting a slight taper when turning with a chuck on the HS.I was thinkin of using a length of 3/4" drill rod in the chuck if it will fit through the HS & then run a dial indicator up & down the bed till I'm happy with it . Should the HS just drop in place & get tightened down ? Am I headin in the right direction here ?
tks
animal
 
As long as the surfaces are clean it really can't get out of alignment as it was carefully fitted at the factory and doesn't wear there.

dont dink with it just make sure it's all clean and clamp it down.

BTW- drill rod isn't round or straight.
 
Most likely cause of any error you see is either wear or twist in the bed, NOT actual misalignment. As stated above, as long as everything is clean and bur free, and no one has messed with the mating surfaces, it will go back on just as it left the factory.
Check out this thread to get an idea of using the "two collar test". https://www.practicalmachinist.com/vb/general/2-collar-lathe-test-question-269116/
Pay special attention to what Forrest and Rich King have to say.

Adjusting bed twist will be your best bet, short of a rebuild, for getting the machine cutting as straight as possible.
This topic has been discussed a lot here. Do some searching and you'll find all you ever wanted to know, and a bunch of nonsense besides.
 
, yes, and the nonsense that has been bandied about has somehow got enshrined as gospel...I used to buy the bull myself...Rollie's Dad....what a load.
 
Thanks , I will pull the HS & double check the mating surface's . I did not know that drill rod wasn't round or straight . what would be recommended to use instead or DR ?
tks
animal
 
The real measure is a simple cutting test...AKA "2 collar test"

look up "monarch lathe leveling" on u tube done by Abom79

since the SB is not a Monarch, you want an easy cutting piece about 1.25" diameter chucked up so around 5" is sticking out...in any case follow the 4x diameter rule for stick out.
 
One thing id add. When indicating your collars make sure your indicator is inline with/inplace of the cutting tool when clocking your collars. If you've some wear in the bed you might get some funky readings if you're indicating 6 inches behind the tool and you're having to crank the saddle further down the bed. That seemed to be the case when Abom was checking the TS alignment on his victor, same would be true of checking 2 collars.

From 19:50
SNS 225 Part 1: Headstock & Tailstock Alignment, Starrett Wall Charts - YouTube
 
This thing about HS alignment has been a contentious issue for several years now. I believe in measurement to know for sure. Lathe alignment starts at the bed, then the headstock, then the tailstock. It isn't rocket science. Having a religious belief that the headstock could never be out of alignment is foolish.

If the lathe is cutting a taper, there is a cause of course. If you are certain the bed is straight, then the fault must be the headstock. There is nothing else in the equation. The taper could be caused because the HS is out of alignment with the bed in any direction, so that this must be measured and the reference for this is the spindle taper. Using a chuck of some sort only adds an unnecessary potential fault source. The correct technique is to use a test bar. Test bars are inexpensive and their use is fast. There is no reason not to own one.

The two collar test is just a test. It cannot identify either the direction of misalignment nor the cause and the test takes much more time and involves many other elements of the lathe which could also be a taper cause. Lastly, if the test cannot identify the fault, what good is it?
 
Do not indicate the collars. Measure them with a micrometer. When they are the
same size the lathe is well set up.

No, id level the machine as best as I could, turn the collars to equal diameters and indicate them Jim. I wouldnt blindly torque the bed trying to get the collars to match, even one with a V Flat mounted 'non adjustable' headstock.
 
it just comes down to how you apply the collar test....its a very versatile thing.
For sure, they dont even need to be the same dimension, just saves some brainache if they are. A cutting or measuring test, super simple to apply with no special kit.
 
Test bar in a good collet is a reasonable start..One that fits the spindle taper better..it can tell if tube is bent and reasonable straightness headstock..
Tube is not perfect so not a good check..many chucks wobble..even /most 4jaws indicated to zero at one place likely has wobble..

3/4" drill rod , tested on a plate for straightness and only 6" to 9" out of a collet, tried 3 times at a 120* turn is fair start but not as good as a test bar in the spindle taper.
 
thank you folks for all the input ,I did make a quick pass in the shop this am & I do have a bit of twist in the bed . I'm sure that I must have moved the bench some . were supposed to get a ton of weather in the next few days , so hopefully I can get back out there on Thurs or Friday.
thanks again for all the help & will report back with my findings
animal
 
No, id level the machine as best as I could, turn the collars to equal diameters and indicate them Jim.

Read the southbend book. Their measurements of the machined collars, with a micrometer, was the final acceptance test.
No indicator used or needed. Nice to have a fancy dial to stare at but it tells you nothing.
 
the next step of the test after machining the collars to an exact dim. is to traverse the TDC and SDC of the collars with a carriage mounted indicator.

done that way the two collar bar effectively becomes a "real" test bar, equally effective as a "proper" taper mounted one...perhaps even more so since any chucking error is cut out and you don't have to rely on bunged up spindle tapers...it becomes an extension of the spindle and is as good as the bearings themselves...bonus if you machine a step on the end the same diameter as the tailstock quill too, then you can check it in the same manner.
that is what Demon is referring to.
 
the next step of the test after machining the collars to an exact dim. is to traverse the TDC and SDC of the collars with a carriage mounted indicator.

done that way the two collar bar effectively becomes a "real" test bar, equally effective as a "proper" taper mounted one...perhaps even more so since any chucking error is cut out and you don't have to rely on bunged up spindle tapers...as good as the spindle bearings themselves.
that is what Demon is referring to.

Yes, this exactly!:cheers:
 








 
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