Tail Stock Issue

Coos Cues

Coos Cues

Coos Cues
Looking for the correct answer to this problem with my jet lathe tail stock. I am not a machinist but I know many of you are. Aligning it horizontally is easy peasy but this thing is pointing down. Has no affect on turning between centers but does on drilling. I have been drilling undersize and boring which of course is precise but I would like to make this better if possible. Not all holes require boring precision but I would like a little bit more from the tailstock accuracy. See Video https://rumble.com/v1jihsd-jet-lathe-tail-stock-issue.html
 
Have you tried the same with a quality dead center in the tailstock? You need to start removing variables. Is your lathe nice and level?
 
Move your tailstock to different positions on the bed and do similar readings with a more stout and more ridged mandrel. If the readings move with the tailstock then it's your tailstock. If not, you likely have wear in the bed.

The video just shows that the long skinny rod is not straight at the end, nothing more.
 
Sorry I should have given more details. I bought a precision mt2 alignment bar to verify it wasn't the chuck
S4110006 [1600x1200].JPG
and it gives the same results about .004
S4110005 [1600x1200].JPG
" over 12 inches of travel.
 
Renegade_56 said:
Move your tailstock to different positions on the bed and do similar readings with a more stout and more ridged mandrel. If the readings move with the tailstock then it's your tailstock. If not, you likely have wear in the bed.

The video just shows that the long skinny rod is not straight at the end, nothing more.
Click to expand...
Sorry I just put that thin rod in my chuck there for illustration I knew the results were the same but forgot to elaborate. So with my thick alignment rod in the tail stock mt2 and all locked in place I can move the tail stock pretty much anywhere along the bed and read a thou drop every three inches. Is there a remedy for this a non machinist like myself could partake in? Can I separate the tail stock and shim the front with a cigarette paper or something?
 
Deruki said:
Sorry I just put that thin rod in my chuck there for illustration I knew the results were the same but forgot to elaborate. So with my thick alignment rod in the tail stock mt2 and all locked in place I can move the tail stock pretty much anywhere along the bed and read a thou drop every three inches. Is there a remedy for this a non machinist like myself could partake in? Can I separate the tail stock and shim the front with a cigarette paper or something?
Click to expand...

Is there only a drop along the rod or is there side-to-side runout as well?
 
Deruki said:
Sorry I just put that thin rod in my chuck there for illustration I knew the results were the same but forgot to elaborate. So with my thick alignment rod in the tail stock mt2 and all locked in place I can move the tail stock pretty much anywhere along the bed and read a thou drop every three inches. Is there a remedy for this a non machinist like myself could partake in? Can I separate the tail stock and shim the front with a cigarette paper or something?
Click to expand...
That sounds more like a problem with the tailstock than the bed. Try some kind of temporary shim under the low end of it and try the same tests by moving it to different places. If those readings are consistent then your tailstock centerline axis is not parallel to the tailstock base, and so would require permanent shimming or possibly resurfacing, depending on whether or not you have a low end or a high end.
 
Renegade_56 said:
That sounds more like a problem with the tailstock than the bed. Try some kind of temporary shim under the low end of it and try the same tests by moving it to different places. If those readings are consistent then your tailstock centerline axis is not parallel to the tailstock base, and so would require permanent shimming or possibly resurfacing, depending on whether or not you have a low end or a high end.
Click to expand...
I experimented with shimming thank you. .002 under the front made it parallel to the bed but it was still .002" low of the centerline of the chuck so I made the front .004 and shimmed the back to .002 with notebook paper strips. Seems like it is as close as I can get it now I think I will just leave the paper in there and check it again after a while.
 
My cheapo China lathe tailstock was the same way. I found the correct feeler gauge needed and cut strips out of it and left them there, so far so good 👍
 
Deruki said:
I experimented with shimming thank you. .002 under the front made it parallel to the bed but it was still .002" low of the centerline of the chuck so I made the front .004 and shimmed the back to .002 with notebook paper strips. Seems like it is as close as I can get it now I think I will just leave the paper in there and check it again after a while.
Click to expand...
In the meantime maybe get some brass shim stock, it will hold up better over the years. This is an assortment starting at 0.002", but a little more searching and you should be able to find packages with 0.001" included.

Amazon.com: Brass Strip, Brass Shim Stock Assortment, 1" Width x 6" Length, 0.002", 0.004", 0.006", 0.008", 0.012" and 0.016" Thickness, 6 Pieces : Industrial & Scientific

Amazon.com: Brass Strip, Brass Shim Stock Assortment, 1" Width x 6" Length, 0.002", 0.004", 0.006", 0.008", 0.012" and 0.016" Thickness, 6 Pieces : Industrial & Scientific
www.amazon.com

Dave <-- shims everything :(
 
Rotate your chuck in the tailstock half of a turn and see if it reads the same. If so it is the tailstock. If it changes it is the chuck.
I just re-read the above statement. The headstock being mentioned was a typo. Please re-read. It is the tailstock chuck that is being rotated.
 
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cueman said:
Rotate your chuck in the headstock half of a turn and see if it reads the same. If so it is the tailstock. If it changes it is the chuck.
Click to expand...
I faced the chuck when I got this lathe and it's pretty good. About a thouTIR with my hardened rod chucked up at 10 inches from the chuck.

Since I shimmed the tailstock yesterday my 3 flute carbide drill bits are squealing and it's snug to turn them around and stick them in the hole they just cut which is a good sign.
 
cueman said:
Rotate your chuck in the headstock half of a turn and see if it reads the same. If so it is the tailstock. If it changes it is the chuck.
Click to expand...
I just re-read the above statement. The headstock being mentioned was a typo. Please re-read. It is the tailstock chuck that is being rotated.
Rotate your chuck in the tailstock half of a turn and see if it reads the same. If so it is the tailstock. If it changes it is the chuck.
 
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