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11th Nov 2010, 03:37 PM #1Golden Member
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Lathe headstock and tailstock are out of alignment
OK, so I was already suspicious that my tailstock wasnt lining up properly and now I have confirmed it. I cut a 400mm long bar at 20mm diameter the other day, and the tailstock end of the bar was about a quarter of a mm smaller than the headstock end.
So I put a bit of steel in the three jaw and turned it to a point. Then I put a live centre in my tailstock and wound it up to the point. To the eye, it looked perfect. Then I did something that I read on here somewhere, I put a thin shim in between the two points and wound the tailstock in gently. The shim tipped from right to left, indicating that the tailstock is slightly lower than the headstock.
So, what do I do next to determine the problem and go about fixing it?
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11th Nov 2010, 04:12 PM #2Most Valued Member
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What sort of lathe? new old?
Stuart
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11th Nov 2010, 04:15 PM #3Golden Member
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20 years old made in india. I assume ill need to test some parts for wear. Is it possible the bottom of the tailstock has worn? How do you test the ways for wear?
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11th Nov 2010, 04:19 PM #4Most Valued Member
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How far off Vertical is the shim?
Do you have a Vernier Height Gauage?
Do you have Parallels that will span your Lathe bed?
Do you have Depth Micrometers that will measure from the Top of your Tailstock Spindle to the Bed of your lathe?
Do you know the Actual Centre Height of your Lathe?
Have you checked the Tailstock Spindle to make sure that it travels Parallel to your Bed?
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11th Nov 2010, 04:26 PM #5Golden Member
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How far off Vertical is the shim? - About 18 degrees
Do you have a Vernier Height Gauage? I have a vernier caliper and a dial indicator. thats it.
Do you have Parallels that will span your Lathe bed? No
Do you have Depth Micrometers that will measure from the Top of your Tailstock Spindle to the Bed of your lathe? No
Do you know the Actual Centre Height of your Lathe? According to the manual its 125mm
Have you checked the Tailstock Spindle to make sure that it travels Parallel to your Bed? No.
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11th Nov 2010, 04:44 PM #6Most Valued Member
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I'm not sure the shim test between two points is valid. Its normally done between a point and curve(the side of a round bar)
Its possible the ways have worn but I wouldn't worry about the vertical alignment yet, as it has much less effect on turning tapers then front to back alignment.
Are you sure both ends of the bed are level?(Ok they don't have to be level just on the same plan but most people set that plan up as level so level I'm going to cal it).
Stuart
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11th Nov 2010, 04:47 PM #7Golden Member
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"Are you sure both ends of the bed are level?(Ok they don't have to be level just on the same plan but most people set that plan up as level so level I'm going to cal it)."
No im not - how do I check? I basically got this thing second hand from my old school, dragged it home, plugged it in and started using it. I havent done any setting up or anything. Is there a standard procedure for setting up a lathe in a new home?
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11th Nov 2010, 04:53 PM #8Dave J Guest
Hi Brendan,
I would wind the tail stock spindle out 3/4 of the way and clamp it down, then put a indicator base on the carriage with the indicator touching the top of the tail stock spindle. Wind the carriage back and forth and check the reading to see if it sloping down either way.
After this test shim between the tail stock and base back and front as necessary to bring it up level and to height, then re test it as above and as you did with the shim.
If you don't have shim material you could use coke can, aluminum foil and things like that.
I will try to chase up the thread that gives the exact difference between the height being out and how much it affects the work.
From memory it was something like 0.001 in height= 0.0000??
Dave
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11th Nov 2010, 04:54 PM #9Most Valued Member
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"Does it need setting up in its new home" Yes.
More than anything both ends of the bed need to be "level". If they aren't "level" and the tail stock is set correctly, it will turn a taper. You could move the tail stock to off center to make it turn parallel but you then need to adjust it again if you change the position of the tail stock. So its best to get it "level" and then see what you have.
Does it have 3, 4 or 6 mounting points? Got a picture?
I guess you don't have a machine level?
Stuart
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11th Nov 2010, 05:28 PM #10Dave J Guest
A carpenters level will do to level it, for years I used one before getting a machinist level.
If you don't have parallels you can use the shanks on your drill bits on the way flats to get the level up to get over the V's of the bed each end.
When going from one end to the other just make sure you keep the level the same way and the drill bits on the same sides so you get a true reading. You are not really tying for level, only to get each end the same so there is no twist.
CTC have machine levels if you want to go that way, they are $81 posted for a 200mm one.
Dave
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11th Nov 2010, 06:15 PM #11Member
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A fellow student at TAFE wanted to check his tailstock alignment on his lathe at home.
The basic procedure was to get a testbar turned up on another lathe and put it between 2 centres on the lathe to be tested. Then you use a dial indicator on the carriage.
You're meant to check with the tailstock spindle wound both in and out in case the spindle is not parallel.
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11th Nov 2010, 06:22 PM #12Dave J Guest
I had a look for that thread and couldn't find it but came up with these for you
Frank Fords one is a good one as long as your tail stock is running parallel
HomeShopTech
These 2 are from another forum and the first one describes the test I spoke about above.
Tailstock Alignment Question - Page 2 - The Home Shop Machinist & Machinist's Workshop BBS
Centering Tail Stock Quill ????????? - The Home Shop Machinist & Machinist's Workshop BBS
I think if you want to fine tune your lathe you really need to start at leveling it first as Stuart said above, then go from their.
My shed is concreted pretty true and my lathe was leveled and bolted down for the first 5 or 6 years of it's life. About a year ago I unbolted and moved it 12ft, just in that short distance it started to turn a taper so I built the feet for it to adjust the twist out.
http://www.woodworkforums.com/f65/la...ctures-114836/
These lathes may seem solid and rigid, but they do twist.
Dave
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11th Nov 2010, 06:41 PM #13Most Valued Member
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Edster
Using a test bar will tell you if the alignment is out, but I wont tell you why. If the bed is twisted and you line the tail shock up with a test bar it will only be right at that lenght.
Stuart
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12th Nov 2010, 09:25 AM #14Golden Member
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Thanks for all the help fellas, especially the links and stuff. Ill have to do some serious measuring of this machine and post back with results. I think ill get one of those machinists levels from CTC. It will come in handy for other projects too I imagine.
Brendan
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12th Nov 2010, 10:19 AM #15Distracted Member
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Brendan, I'm in much the same boat, so I've been following with interest. I'm thinking of paying a bit more for one of the square frame levels, because it could be more useful later for things like mills or shapers. shars.com have them for $80.