Adjusting a machinists level?

[ttabbal]

If you have a "regular" level (carpenter's level, hardware store level, etc)... Use that first. Get close, then use the machinist level.

Note that to calibrate a level you don't need a level surface. You need a somewhat FLAT surface. Your workbench is probably good enough, though a real surface plate is ideal. You rotate till it reads level, then flip 180 degrees in the same exact spot to prove the level calibration. It took me a bit to get my head around why it works, but it does. The downside to these hyper accurate levels is the accuracy itself. Put a hair under one side, and it detects it. And don't touch it too much, heat expansion matters too.

You might try getting both ends across the ways reading the same on a normal level, then use the 2 collar test to dial in the lathe's twist. You want the lathe to cut without a taper, the actual "level" isn't really that important other than the "round stuff rolls off it" factor. I would want it "regular level" for that alone, but for cutting straight it's not the most important bit.

Note this is all from me reading a LOT of stuff while I wait for my lathe, I've never done it as I don't own a machine yet, so I may need to be corrected.

 

[f350ca]

Finding a surface area level to the accuracy of your tool will be virtually impossible. Use something solid as a base, as suggested mark the position of the level. Now add shim stock to the end till you get the bubble to centre. Measure the shim stock, then replace the stack with exactly 1/2 the thickness. Then on this created surface adjust the bubble to centre. Rotate the tool 180 degrees as a check. Repeat as needed.
I've never calibrated my 0.0005 in 10 inch one, as long as it reads the same at both ends on the bed I know there is no twist and thats all I care about.

Greg

 

[mikey]

In order to calibrate a precision level you need two things: a level surface and a reference to orient the level precisely when you flip it 180 degrees.

I suggest you make a leveling table. This can be a simple piece of plywood. I use a 3/4" thick piece of Melamine coated plywood with three threaded inserts in a triangular arrangement. Bolts with nylon feet are used to level the table. In use, I clamp a small aluminum framers square to the table and then roughly level the table with a bubble level. This takes me all of 45 seconds. The table is now level and the square gives me a reference so that when I flip the machinist level end for end, it is exactly the same place.

Then follow the instructions provided in the attached document.

My Kinex level is one of those really sensitive ones - 0.0002"/10" - and I use it often to check the level of my lathe. Before I use it, I check the calibration and most of the time it requires no adjustment but at least I know that it is reading true. I guess I'm in the minority but I happen to think that these sensitive levels are quite useful because they save time. I also own a Starrett 98 and my Kinex bubble will move an entire unit without the bubble in the Starrett even budging. When the Kinex says the lathe is level, I am maybe a cut away from dead level using a 2-collar test. So, for me, it is faster to have a good level.

 

[epanzella]

I have a chinese machinist level .0005 x 10". It's pretty close but not dead on. As I only use it to set up my lathe I couldn't care less that it's slightly off. It has a red mark on one end and I always use it in the same orientation across a cupla 123 blocks on my ways. It doesn't matter if the lathe is absolute level to .0005, all that matters is that the level reads the same over the length of the bed and there's no twist. When done with the level turn a test piece and if that's good you're done.

 

[RJSakowski]

Hello,
I just got a PM1236 lathe and now I want get it leveled.
I bought an Accucize Master Precision Level, number S908-C687 from Amazon. It was not calibrated out of the box.
It has instructions for adjusting it but it looks like they are a very bad translation from another language maybe...
Anyway the instructions don't make any sense to me.
A tool was included with the level. It looks like a tiny hook spanner. I don't see anything on the level to use it on.
There are 2 slot head screws. One on top and one on the bottom. They seem to be be pushing on something inside but it doesn't change the bubble position.
Any Ideas out there?
thx,
Jim
Edit,
I got brave and just started taking it apart. Bingo,
Now it all makes sense. I just wish the instructions would have been better. Even just a picture would have been enough.
Oh well.
Now I can go level my level and then finish leveling my lathe.

The LocTite'd screws should not be touched . My level has two end caps which can be removed by inserting an M4 screw and pulling. Inside, you will see the adjustment nuts.You have to turn the both the same way, first loosening on and then tightening the other. I would suggest that you take some pains to get you surface close to level. While you can rotate the level on any surface to find a horizontal line, the level is affected somewhat by the level at right angles. That is why there is a cross level vial.
I use my 9 x 12" surface plate and place shuims at three points under it to level it. I find that a couple of feeler gages work well. Place a washer under the plate at the center of one side and the feeler gages at the corners on the opposite side. Adjust the shims yto level in all directions. It isn't necessary the the plate be perfectly level. If it is off by a couplr of divisions, the calibration will still work, You're just looking at having thwe same reading when you flip the level 180º.

 

[scattermaster]

Well,
I did my 1st test cut last night. I chucked up a piece of 3" alum. bar stock and cut about a foot of it down about .040".
I checked the new diameter with a dial caliper and couldn't see any taper. I know that's a really crude way to check but I was in a hurry and didn't feel like digging for my mics. For now it looks like I got it pretty straight.

 

[Technical Ted]

The LocTite'd screws should not be touched . My level has two end caps which can be removed by inserting an M4 screw and pulling. Inside, you will see the adjustment nuts.You have to turn the both the same way, first loosening on and then tightening the other. I would suggest that you take some pains to get you surface close to level. While you can rotate the level on any surface to find a horizontal line, the level is affected somewhat by the level at right angles. That is why there is a cross level vial.
I use my 9 x 12" surface plate and place shuims at three points under it to level it. I find that a couple of feeler gages work well. Place a washer under the plate at the center of one side and the feeler gages at the corners on the opposite side. Adjust the shims yto level in all directions. It isn't necessary the the plate be perfectly level. If it is off by a couplr of divisions, the calibration will still work, You're just looking at having thwe same reading when you flip the level 180º.

I just got one of these: https://www.amazon.com/gp/product/B00K1NOK3E/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

Seems to be pretty nice and so far is working well. I just finished calibrating it and will be using on my lathe soon. Mine is similar in that it has the removable end caps, but it also has a removable cap directly under (on the side of the level) the LocTite'd screw, that is used for calibration. You reach in the opening and turn the collar with the spanner. Mine only has one calibration screw/collar to tweak. I, like others, wondered why they gave me that little spanner wrench when there was a screw on top that appears it could be for calibration. The instructions that came with it were USELESS! So, I pulled one of the plastic end caps off and looked inside. That told the story.

Ted

 

[arvidj]

My solution is similar to the one Mikey suggests. I use a surface plate with three machinists jacks under it. A few quick adjustments of the machinists jacks will get it reasonably level in two directions using either a carpenters level or even the level I am trying to calibrate. The engineers level are are never THAT far off that I can't at least get the process started and I can refine things as I go.

The other thing I do is put two strip of masking tape on the surface plate at a right angle to one another and located on the plate such that the base of the level to be calibrated will (a) be in the center of the plate and (b) one side and one end of the level will 'catch' on the tape. Note that the base of the level is definitely on the surface plate but I can gently slide the side and edge of the level up against the tape when I swap it 180 degrees. That seems to make for quick and easy yet very repeatable positioning of the level on the plate.

Once I get the level reasonably close I can then use it to fine tune the leveling of the surface plate and wash, rinse, repeat until I am satisfied.

 

[tq60]

For leveling a lathe the calibration does not matter a bit...follow me here.

Only thing relevant is the ways are straight and not twisted. Period.

So place a piece of tape on top of one end if there is not an obvious difference.

Place the level in different places as needed but ALWAYS use the same way.

Meaning if resting level across the ways near the chuck place the level either way but choose one that allows the bubble to just touch a line if it is different.

Note which end is towards the front then move it to tail stock end and have it same directiin and adjust until bubble touches same line or is in same place.

Regarding calibration it is same as a square, simple to do.

Place it on a stable and solid place like across the ways.

Note where the bubble is then rotate it 180 and see if it is in same place.

Adjust 1/2 way to where it was if it moves and repeat until turning makes no change.

Once this is done you can find a level spot or make one via a chunk of 2 X 4 with 3 screws then rotate and adjust for no change and exact center.

Easy to do but takes time.



Sent from my SAMSUNG-SGH-I337Z using Tapatalk

 

[Bob Korves]

Only thing relevant is the ways are straight and not twisted. Period.

Ultimately, the only thing needed is for the lathe to cut straight and square and without taper. Whatever it takes to get it there works. Straight and parallel ways are probably the best place to start.