Manual lathes and tailstocks
- Thread starter Mr. Atoz
- Start date
Booze Daily
Active member
Pretty sure yes, but not as much.
Dualkit
Well-known member
I would suspect the same thing as it will affect the centering of the tool along with possible variation of surface finish.
DavidScott
Active member
Depends on how far off your tailstock is and the diameter of the workpiece. If your say .01" off on a 1" shaft I doubt you're going to notice a difference unless you're holding a few tenths. It is something to be aware of but it's a bigger deal when your drilling than turning.
Like David said, it depends on the diameter of the workpiece. The smaller the diameter, the worse the error. In general, the error is much smaller than taper due to horizontal misalignment.
The error is not a taper, but more of an elliptic curve, with the smallest diameter at the point where the tool crosses the actual centreline, and increasing in diameter either side of that, but not linearly.
The error is not a taper, but more of an elliptic curve, with the smallest diameter at the point where the tool crosses the actual centreline, and increasing in diameter either side of that, but not linearly.
Yeah, but that seems to only be a problem in really cheap poor quality lathes that weren't made right.
If trying to dial one in, make sure you use a short and very solid indicator(no mag base) that doesn't droop at all.
On a good lathe that is level, straight bed and made right, you'll wear out your arm moving the tailstock back and forth sooner than you'll wear down a couple thou off the bottom.
If trying to dial one in, make sure you use a short and very solid indicator(no mag base) that doesn't droop at all.
On a good lathe that is level, straight bed and made right, you'll wear out your arm moving the tailstock back and forth sooner than you'll wear down a couple thou off the bottom.
Plastikdreams
Well-known member
We have an old leblond af work, 1.500 2024 getting turned down to 1.375 over 8.500 inches, .006 diameter runout from tailback to jaws. I actually take the center out for the last pass of about 5k to get it down to .0015ish then finish with Emory. It makes things difficult lol.
You are taking the last .0015 X 8.500 to finish with emory ? Apparently, you are not in a hurry.
Plastikdreams
Well-known member
It actually doesn't take that long, maybe a few minutes at the most. I hit it with 180 then 320 and finish with green scotchbrite. I use wd40 to help it cut, spin around 800 rpms.
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Machtool
Well-known member
I'd blame Dr Georg Schlesinger He largely wrote the standard of inspecting machine tools. Which went on to become the DIN standard, and many other agencies followed, including JIS.
For ever more that stated that a tail stock could only be higher by an amount of 0.05mm. Never minus. Reason being the tail stock would wear in before it wore out. The Japanese take that literally. I've lost count of how many sub spindles and tail stocks, I've found to be 0.05mm 2 thou high. Even on the same set of rails.. Sub spindle picking up off a main.
Getting back to your high / low issue. Isn't that just the cosine error, which should amount to Sweat F All. I'm wondering how you blokes are adjusting for UP & Down, just like requested in post #1
Regards Phil.
Herding Cats
Hardplates
As others have said a small amount of high or low doesn't mean shit unless you are turning very small parts.
There are even lathes out there that the tail-stock quill is ground eccentric to the taper and you rotate the quill to adjust taper and you are expected to ignore the Y axis change and only pa attention to the X. Shitty design if you ask me but what do I know
There are even lathes out there that the tail-stock quill is ground eccentric to the taper and you rotate the quill to adjust taper and you are expected to ignore the Y axis change and only pa attention to the X. Shitty design if you ask me but what do I know
Plastikdreams
Well-known member
The leblond is dead accurate if I can machine only in the 3 jaw...for obvious reasons. I've made some bronze bushings that I was able to hold a few tenths with by machining the od first then the id...for obvious reasons. Add the tailstock and it's a train wreck lol.
But it's not like I'm doing anything any other lathe operator would do though, it's a pretty standard operation. No horn tooting
As far as my other post...
I'm making a handle for a wax injection mold, my coworkers said just leave the taper because it doesn't matter. I look at it as a) good practice and b) even though no one will notice, I'll know it's not done right...and that just doesn't sit well with me.
But it's not like I'm doing anything any other lathe operator would do though, it's a pretty standard operation. No horn tooting
As far as my other post...
I'm making a handle for a wax injection mold, my coworkers said just leave the taper because it doesn't matter. I look at it as a) good practice and b) even though no one will notice, I'll know it's not done right...and that just doesn't sit well with me.
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Ya, emory can be a pretty fast finishing tool provided the mat isn't too hard. With a lean back into the emory roll it will remove some mat fast. I wouldn't want to do it all day, but for a 1-2-3 off, easier than comping the tool and trying to make it cut the last .001" IMO
Plastikdreams
Well-known member
Exactly
For up-down adjustment on a manual lathe tailstock you shim it somehow. It's kind of a crapshoot because when you know the tailstock is low from wear you know you can't trust it's alignment anymore either. By that point the quill/bore and taper are probably shit as well. You're into a complete rehab of every surface/alignment of the entire thing at that point.
And for what reason? If you need a perfect manual lathe go buy one. Much cheaper/easier.
One of my manual lathes is dead on tight, great condition. The other has some way wear near the chuck, tailstock is pretty beat, some things don't work, etc. Both machines can do perfect work. Just takes a little more fuss with the worn one.
If I'm doing a part that requires a long straight section on my knackered lathe and I don't want to fuck with tailstock offset I measure the taper while roughing and then I lay out tick marks with a Sharpie on the bed for every 1/2 thou. When I'm doing the last couple passes I just take the taper out by hand. Every sharpie mark I bump a 1/2 thou and it's not really perceptible.
And for what reason? If you need a perfect manual lathe go buy one. Much cheaper/easier.
One of my manual lathes is dead on tight, great condition. The other has some way wear near the chuck, tailstock is pretty beat, some things don't work, etc. Both machines can do perfect work. Just takes a little more fuss with the worn one.
If I'm doing a part that requires a long straight section on my knackered lathe and I don't want to fuck with tailstock offset I measure the taper while roughing and then I lay out tick marks with a Sharpie on the bed for every 1/2 thou. When I'm doing the last couple passes I just take the taper out by hand. Every sharpie mark I bump a 1/2 thou and it's not really perceptible.