Ok trying to level this lathe. I have a 2in bar 11 in stick out and I have both ends within .0002 but the middle dips in about .0005? All my adjustments are made on the outside tail stock end. Is there something with the head stock leveling bolts that's doing this
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Pm 1440 get leveling
- Thread starter BCwoods
- Start date
- Joined
- Sep 10, 2022
- Messages
- 930
May I suggest removing the center of stock. Make a dumbbell shape. Maybe 1” raised section on the ends. Then take a light cut.
As that is sticking out quite a long way. You might be getting some harmonic vibrations in the center. Over 11” having only .0002 is really really good.
Cutting oil is my blood.
As that is sticking out quite a long way. You might be getting some harmonic vibrations in the center. Over 11” having only .0002 is really really good.
Cutting oil is my blood.
- Joined
- Jan 6, 2017
- Messages
- 1,214
To prevent yourself from dialing out headstock misalignment by twisting the bed, or the opposite, start with a level bed.
First, use a Machinist level such as the Starrett 98-6 at least, preferably something even more accurate, sitting on a set of 123 blocks on the way flats to level the bed. Even easier with 2 levels.
Adjust untill it reads level in both directions at each end of the ways. Hopefully the middle gives the same reading.
Once the bed is level, then take test bar cuts to check/adjust the headstock alignment. Even if they aligned it perfectly at the factory, it's been on a ship, a truck bouncing down the interstate, and moved multiple times with a forklift.
Once your confident that the bed is level and the headstock is aligned, use a bar between centers to align the tailstock.
And be careful with that much part sticking out. Even with light cuts, the bar will deflect enough to give bad readings.
First, use a Machinist level such as the Starrett 98-6 at least, preferably something even more accurate, sitting on a set of 123 blocks on the way flats to level the bed. Even easier with 2 levels.
Adjust untill it reads level in both directions at each end of the ways. Hopefully the middle gives the same reading.
Once the bed is level, then take test bar cuts to check/adjust the headstock alignment. Even if they aligned it perfectly at the factory, it's been on a ship, a truck bouncing down the interstate, and moved multiple times with a forklift.
Once your confident that the bed is level and the headstock is aligned, use a bar between centers to align the tailstock.
And be careful with that much part sticking out. Even with light cuts, the bar will deflect enough to give bad readings.
Last edited:
Those numbers are good.
You have a carbide insert that may not like spring or light passes
That long of unsupported stock may do may moving things so call it good.
Or, get a non carbide cutter and make it very sharp and repeat a few spring passes without changing any depth of cut.
When it does not remove any metal check again.
I would call it good as that is far above normal hobby work.
For each Decimal point of accuracy the amount of extra work goes way up.
Granted sometimes you need it but most of the time not so much.
For setting up your tail stock you can make a spool or 2 collar test.
Start with facing then center drilling opposite ends of handy round stock, maybe 3 to 4 inches long. By 2 inch diameter, not critical.
Clamp in 3 jaw on one end and remove the middle, make it look good.
Place between centers, no dog needed, you make light cuts, start from end and single pass for whole part in ONE go until continious cutting (cutting true to center).
Measure and adjust tail stock as needed, repeat cut.
When both collars are exactly same size your tais stock center is in alignment with head stock center such that the interface with the cutting tool are same.
Sometimes the tail stock may be tiny bit high or low, with this action the measurement is of the cut object so it may be offset to compensate for height difference.
It is relative, And unless the stuff you are making goes into something that requires certification it is close enough.
When finished you NEVER cut again, you use dial indicator in tool post, put this between centers and adjust tail stock until both ends in same place relative to tool post.
Keep in the tool box, you will use it many times, ours was made on an Sears lathe 30 years ago and use it on current ones to quickly center the TS.
Looks like this.
Sent from my SM-G781V using Tapatalk
You have a carbide insert that may not like spring or light passes
That long of unsupported stock may do may moving things so call it good.
Or, get a non carbide cutter and make it very sharp and repeat a few spring passes without changing any depth of cut.
When it does not remove any metal check again.
I would call it good as that is far above normal hobby work.
For each Decimal point of accuracy the amount of extra work goes way up.
Granted sometimes you need it but most of the time not so much.
For setting up your tail stock you can make a spool or 2 collar test.
Start with facing then center drilling opposite ends of handy round stock, maybe 3 to 4 inches long. By 2 inch diameter, not critical.
Clamp in 3 jaw on one end and remove the middle, make it look good.
Place between centers, no dog needed, you make light cuts, start from end and single pass for whole part in ONE go until continious cutting (cutting true to center).
Measure and adjust tail stock as needed, repeat cut.
When both collars are exactly same size your tais stock center is in alignment with head stock center such that the interface with the cutting tool are same.
Sometimes the tail stock may be tiny bit high or low, with this action the measurement is of the cut object so it may be offset to compensate for height difference.
It is relative, And unless the stuff you are making goes into something that requires certification it is close enough.
When finished you NEVER cut again, you use dial indicator in tool post, put this between centers and adjust tail stock until both ends in same place relative to tool post.
Keep in the tool box, you will use it many times, ours was made on an Sears lathe 30 years ago and use it on current ones to quickly center the TS.
Looks like this.
Sent from my SM-G781V using Tapatalk
- Joined
- Dec 26, 2015
- Messages
- 2,079
Excellent point here. You want to make sure your depth of cut with carbide inserts is at least 1/2 the nose radius of the insert.
Ok yes carbide was not a great choice on light cuts and gets finicky. As for stick out I figured as much as I could get away with. As far as accuracy maybe I fell into that trap of trying to be dead on vs what is practical. But ok I'll make a pass with some hss. Get it close and call it good
- Joined
- Apr 30, 2015
- Messages
- 11,333
Also, your bar of material might have a soft spot in that middle zone- when you get into tenths anything can affect the numbers
-M
-M
- Joined
- Oct 7, 2020
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I have a question. My lathe is level from side to side at both the tail stock end and the headstock end, but the tail stock end is a little lower than the head stock. Is there a reason that I would need to level up in that direction? As long as the headstock is level with the bed it shouldn't matter should it?
- Joined
- Dec 26, 2015
- Messages
- 2,079
Tim, as long as the spindle axis is coplanar to the bed, and the bed is level along it's length in the X-axis (front to back), then it shouldn't matter. More precisely, I would check that the spindle axis is coplanar to the travel of the carriage. Here is one method of checking that using a precision MT5 alignment bar (there are other methods as well):
Aligning the Headstock of PM-1340GT Lathe
Click the image to see the text description below the photo.
flic.kr
Here is one-such alignment bar: https://www.ebay.com/itm/233818331689
I'd be happy to lend you mine if you pay postage both directions.
- Joined
- Jun 12, 2014
- Messages
- 4,817
Leveling is relative, the goal is not to have bed twist, so as long as the bed measures the same front to back the same along the ways, that is all that matters. When cutting a test bar one usually uses a sharp insert or HSS cutter, a standard molded insert will not work well for a shallow cut. You are also limited by the nose radius vs. DOC. You can see some banding in your cut, part of this may be the steel but it can also be not enough feed, DOC and /or speed for carbide. You can also get some oscillation of the unsupported rod so as you get toward the end you are pushing the rod as opposed to cutting to depth. This would also make it appear to dish in the center. Overall I would be very happy with those numbers if your bed is level.