Help With Lining Up A Lathe Tail Stock

ebgb68

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Hello kinda new to this and need some advice .
I turned a piece of bar stock and noticed a taper from one end to another . I also tried turning a barrel and found the same . I didn't want to just start moving the tail stock with out some way of checking it so I made one of the jigs found on youtube.
I didn't have a plunge indicator so I rigged something up till tomorrow. The way I have it it shows about .002 off to the side which seems right because my bar stock had .004 taper from one end to another ?
Here's what I'm not sure of is the offset the same for 2" as say 12" ?
Here's the way I checked it tonight if the local tool shop has a plunge dial I will recheck it.
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Also I was getting a way off reading on the topside ?
Thanks Ed

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b869a5219f5d0fc742c6aaf0d47e666b.jpg

20160131_223954_zpswynwhn5z.jpg

b869a5219f5d0fc742c6aaf0d47e666b.jpg

20160131_223954_zpswynwhn5z.jpg

b869a5219f5d0fc742c6aaf0d47e666b.jpg

20160131_223954_zpswynwhn5z.jpg

b869a5219f5d0fc742c6aaf0d47e666b.jpg

20160131_223954_zpswynwhn5z.jpg

b869a5219f5d0fc742c6aaf0d47e666b.jpg

20160131_223954_zpswynwhn5z.jpg
 
Last edited:
Here's my non-expert take on what you've posted:
Regarding taper vs offset, you have the right idea. Taper is a measure of diameter, so it will be twice the radial error.
I'd start by moving the tailstock over to zero out the error, then make another test cut to verify. Adjust if needed. Rinse and repeat. Keep using diameter error as your guide. Among other things, it'll be twice as easy to measure. Assuming you don't use too short a test bar, once you're dialed in, it should be good for any length (unless there's some kind of strange warp in your lathe bed).
As for topside reading, I'd not be too concerned. The tool that does the actual cutting (forming/shaping) of the workpiece is on the side, not the top.
 
Thanks for the reply I cleaned up.my post tired eyes and oily fingers on the phone don't help.


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Here's a question before answering your question. Are you sure the tail stock was off set rather then your ways being twisted?
 
I'm assuming that the same offset with the tail stock near the chuck and at twelve inches on my bar stock would mean its not twisted too bad ? I will have to double check the barrel I made a pass on to see if its the same ?
I need to find a level made for that.
 
If the tailstock is offset it will be of the same amount at 2" as 20" so taper will be less at longer distances. Of the bed is twisted out would increase at longer distances. Also assuming your turning between two centers & touring the same distance from where the work is supported.

If it is the first then rigging a indicator to measure the push like it looks like your doing in the first picture seems like the easiest way I can think to adjust it.
 
Just a quick question, is the bed level. That would cause a taper to be turned.

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Just a quick question, is the bed level. That would cause a taper to be turned.

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Its preferable to set machines level but doesn't cause taper. Bed can be at a 45 deg angle down hill and still cut perfectly.
 
i cant figure out from the pictures how you did the measurement
in any case you did it wrong
just measure how thick the bar is at the headstock end and at the tailstock end
the difference dived by 2 is the offset of the tailstock
assuming you are turning between centers that is
to use any other means of measuring you would need a known to be streight and round bar of consistent thickness
 
Hum if lathe is out of level how will you align tailstock?

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