Where to purchase and learn to use a lathe TEST BAR?

HMF

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EVER WONDERED WHY YOU GET A SLIGHT TAPER WHEN TURNING OVER A LONG DISTANCE. ITS USUALLY BECAUSE YOUR TAILSTOCK IS NOT IN LINE. TO ELIMINATE THIS THE TEST BAR FITS BETWEEN YOUR HEAD STOCK -TAILSTOCK. UNIT IS HARDENED AND GROUND PARALLEL TO 0.0002" AND CENTERED AT BOTH ENDS. SIMPLY PLACE BETWEEN CENTERS SET UP DTI TO RUN ALONG LENGTH, RE-ALINE TAILSTOCK TO SUIT. 2MT TAPER AT ONE END

Sold by RDG Tools located in the UK:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370461331479

Two Videos on HOW TO USE the test bar by Tubal Cain:

[video=youtube;QADD2XQFDds]http://www.youtube.com/watch?v=QADD2XQFDds[/video]


[video=youtube;1EZh8SUoA4o]http://www.youtube.com/watch?v=1EZh8SUoA4o[/video]

 

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Re: Where to purchase and learn to use a lathe TEST BAR?

HP,

They ship to the US! I know someone in California who bought one!

Best,

Nelson
 
Re: Where to purchase and learn to use a lathe TEST BAR?

That's great Chip, but it doesn't compare to a hardened and center ground finish that my lathe is incapable of producing. :(

I've tried making my own before, but running a good DTI down the length of the turned finish bar, you would have thought is was an old corn cob. :-[
It LOOKED good - but......
 
Highpower link=topic=1434.msg8406#msg8406 date=1301671588 said:
That's great Chip, but it doesn't compare to a hardened and center ground finish that my lathe is incapable of producing. :(

I've tried making my own before, but running a good DTI down the length of the turned finish bar, you would have thought is was an old corn cob. :-[
It LOOKED good - but......
Maybe try a Harbor Freight indicator, lol
 
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Re: Where to purchase and learn to use a lathe TEST BAR?

I know that this is a popular method of checking a lathe, but being the practical guy I am, I do it differently. I make a shaft. I if it is tapered, I stick an indicator on the tailstock end and offset it half the error in the appropriate direction. Take another cut and check again. As long as I get a servicable piece of of it, or in tolerance, I'm good with it. I guess the practicalities of trying to get a lathe true to within 0.0002 just doesn't work for me. Insert wear, tool pushoff on delicate turning.....too many other things are involved. Haven't seen a lathe yet that would do that.
I guess it comes down to this for me: No lathe is really capable of maintaining that sort of accuracy for any length of time in normal use. That's why they build grinders. If you need that kind of accuracy occasionally, then you will probably end up with a file and paper if you don't have a grinder. It's admirable for guys to learn the method, and it can get you lined up pretty good, or turn up some alignment issues that need to be resolved, but seems to me to be something only seldom done, perhaps after the very, very, very infrequent wreck. Or on a newly acquired second hand lathe. Again, I simply machine a piece and see what it does.
 
Re: Where to purchase and learn to use a lathe TEST BAR?

I know where you guys are coming from, and I agree.

That said..... there is a motto in one of my other "hobbies" that applies equally to machining as well.

"Aim small - miss small." ;) ;D
 
Allthumbz link=topic=1434.msg7783#msg7783 date=1301260550 said:
EVER WONDERED WHY YOU GET A SLIGHT TAPER WHEN TURNING OVER A LONG DISTANCE. ITS USUALLY BECAUSE YOUR TAILSTOCK IS NOT IN LINE. TO ELIMINATE THIS THE TEST BAR FITS BETWEEN YOUR HEAD STOCK -TAILSTOCK. UNIT IS HARDENED AND GROUND PARALLEL TO 0.0002" AND CENTERED AT BOTH ENDS. SIMPLY PLACE BETWEEN CENTERS SET UP DTI TO RUN ALONG LENGTH, RE-ALINE TAILSTOCK TO SUIT. 2MT TAPER AT ONE END

Sold by RDG Tools located in the UK:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370461331479



Hope this helps!

Best,

Nelson
Well I rolled the dice and ordered one in a MT3 taper. Hopefully it won't look like a pretzel by the time it makes it's way through the postal systems .... ::)
Will post further if and when it arrives. ;D
 
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Re: Where to purchase and learn to use a lathe TEST BAR?

Mounted directly in the spindle taper, you can get a measurement of the headstock alignment. Need to account for sag though. I believe RandyC (where is he??) had a good thread on using a bar.
 
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