Calibrating a cast iron spirit level

Hello everyone, I just bought a old "Universal Boring Machine Co." 18" cast iron level. It is plainly ouit of adjustment, as the bubble position does not repeat when the level is rotated 180 degrees. The bubble appears to be of proper size. My initial reaction was to think of finding an instrument lab to calibrate the thing for me, but upon more thought I realized that I probably did not need a dead-level surface to calibrate the level, so long as the bubble is in the same spot with the level rotated either way.

I searched here and found a thread for Starrett levels where Leigh describes pretty much exactly how I would envision calibrating my level. My level has adjusting nuts that make it clear what needs to be done to adjust the level tube. So far, so good. Here's the complicating factor. One end of the level tube also has a pair of screws for adjusting the level tube from side to side as well as the up and down adjustment at the other end. I'm guessing that this adjustment is to calibrate the level when it's turned on its side, but it's hard, no, all but impossible, to see the bubble when the level is set on its side, plus there's only a very narrow strip, maybe 1/4" or so, of ground surface on either side of the cast iron body so the level can't even sit on its side all that precisely, or so thinks I.

So, that's my question. What are the side to side adjustments for, and will they complicate my effort to calibrate the level for normal orientation (flat) work? I am in somewhat of an enviable position, as the level is already out of whack and some gentle experimentation is unlikely to to make things worse. I'd like to have some idea beforehand what I'm doing, though.

Sorry if this is a dumb question, but I'm plowing new ground here.

TIA,

Steve

btw, has anyone heard of the Universal Boring Machine Co. of Hudson, Mass.? Are these levels any good? My poor old level has seen better days but is still in very usable condition, especially considering I paid $40 for the thing, complete with its original, fitted wood case. The bottom is well-scratched but shows no evidence of rust or of anyone having dropped it. The original (?) flaking is still visible. It looks to have been a handsome thing at one time.

Bill,

Thank you for the informative and encouraging reply. The base does not have any burrs, thank goodness, or any evidence of some pipe fitter having filed any away, but as to the bows and warpage, it remains to be seen and appropriate restorative actions (if needed) taken. I will search again to see what other posts I can find on this topic.

Gordon,

Don't burst my bubble! the actual tube, liquid (and yes, even the bubble) appear to be as good as new. If I replace it I am faced not only with the task of "calibrating" (for want of a better term, Bill your comments re: this are true and well taken) the new tube but also fitting it into my level. I don't see this as improving in any way upon what I have now.

If you do have to adjust the level on a non level surface I put a stop of some sort to push the side of the level against to insure it is always going back to the same spot and not reading some funny angle that is always changing.
Rob

I believe the side-to-side adjustments are to set the tube orientation within the level.

The easy way to make a bubble is to simply bend a straight glass tube. If this is the technique they used, then you must set the plane of curvature perpendicular to the measurement face. I would not touch that adjustment unless you're sure it's off.

The more difficult (and expensive) way to make the bubble is to grind a convex radius within a straight tube.
These tubes do not require any adjustment for orientation.

- Leigh

Gordon,

Puullleeeeease. He said the bubble was fine. Why replace it?

Are you just posting to increment your post count? (No reply needed.)

- Leigh

Your side to side adjustments are there to make it possible to bring the vial axis aligned to the narrow strip on each side of the body. You can go this way: 1) adjust the vial to level on a horizontal ref. surface, as you already has don. 2) Now set up a straight ruler on the ref. surface. Lean the ref. surface about 10 deg. and check that the "V" between the ruler edge and ref. surface is in level. 3) Now you can check again with the side strip on the body guided by the ruler, adjust the side to side screws until you can read the same position for the bubble when the level is turned 180 deg. With the level adjusted this way you can trust the readings better in most situations. I hope you can understand my English, I have got remarks about it earlier.
Best regards
P-O

Thanks everyone for the very informative and helpful answers. POAx, it took me several readings to get an idea what you are describing, not because of your English (which is fine) but because I couldn't envision the process. I think I've got it now - a very, very simplified functional explanation is, with the level sitting on a leveled surface (bubble centered), if you tip the level to the right a small amount (~10 degrees) and then to the left a similar amount, the bubble should remain in the same (centered) position. How'd I do?

Leigh, I hadn't thought about the rotational alignment of the arched spirit tube. I can see where having the tube out of plane could make a difference to very precise measurements in some situations. But the adjusting screws do not cause the level tube to rotate, rather they adjust one end from side to side. Maybe this side to side adjustment has the same effect as rotating the tube? I am 100% on board wth your advice to not touch these screws at this time. If I have problems with getting the level to adjust properly (after checking the bottom of the iron for flatness as Bill mentions) I will ask again with more specific questions.

Thanks, all!

Steve

btw, I just was looking at the tube to figure out if it was the formed or ground variety. I don't have many clues but the inside of the glass does appear to be slightly milky (not optically clear) and when you can see the glass clearly (inside the actual bubble), it does appear to be ground.

(Tongue firmly in cheek): Gordon, if I determine that the bubble is defective and does indeed need to be replaced, how do I get it out of the tube, and how do I get the replacement bubble back in? Can I use generic bubbles (as sold at the grocery store diswashing detergent aisle) or must i find NIST-certified, instrument-grade bubbles?

Hello Steve,
Your simplified explanation is good and what I suggested was a way to perform that. Instead to lean the ref. surface to the right and then to the left, you can lean the ref. surface to one fixed position. Then you turn your level 180 deg. back and forth and makes your readings and adjustments. That way you creates the right and left leaning for the level. To get the 180 deg. precise and repeatable, you need the fixed ruler as a guide for the levels sides. (The levels sides has to be parallel).
Some good levels has a vial in a cross position. That is very good in many cases as it allows you to see and understand what is going on when you, for example, are working to adjust a lathe or mill to level.
Regards
P-O

Steve --

I'd explain the side-to-side adjustment screws this way: These side-to-side screws enable you to rotate the vial so that its lengthwise axis is parallel to the long edge of the level body. Why? Well, if the vial is not parallel to the long edge of the body, the bubble will change its lengthwise position in the vial as the level body is rolled about its long edges.

As for the Universal Boring Machine Company, they were bought by Bullard Machine. My understanding is that Bullard operated Universal's Massachusetts factory for a couple of years before shuttering it to move horizontal boring mill manufacturing to Bullard's VBM plant in Bridgeport, Connecticut.

Here's a link to a website that I suspect you'll find interesting: The Universal Boring Mill Page

John

POAx,

I must confess I was a bit unclear on the actual methodology you were describing to check the level, especially what you were doing with the ruler, but your second post was all I needed to clear it up completely. Thanks again!

John Garner,

Thanks for the further explanation and the information and link to the Universal Boring Machine Co. The fellow who created that page is a serious hobbyist!

Steve

I've been following this thread with the hope that some photos of this old (and perhaps beautiful) instrument would get posted......<sigh>.....

Best Regards

That would be nice. We always like pix.

- Leigh

I will take some pictures of the level tomorrow and post them. I like pictures, too. I "leveled" the level today. I was off by a couple of lines on the tube when rotated end for end and the adjustment required was all but nonexistent, a stern look as much as a twist of the adjusting nuts. I must admit I have no prior experience with precision levels so I was wondering about their accuracy. (Curiosity and the desire to level my machines were the reasons I bought it in the first place.) So, I slipped a .0015 feeler gage under one end of the level and the bubble moved TWO graduations. I am impressed.

Steve

sa100 said:

I slipped a .0015 feeler gage under one end of the level and the bubble moved TWO graduations.

Click to expand...

That's about .0005"/foot, same as the Starrett 199Z. Pretty decent.

- Leigh

Here (I hope) are some pictures of the Universal Boring Machine level. The case is a little shabby but I think it will clean up all right with some mild cleanser.

Glory be to me, I think I did it!

Steve

That's quite a nice item, Steve. Similar to the Starrett 199Z but a bit longer.

- Leigh

Thank you for the photos, Steve. The original carrying case too!! Ooooh!!!!

Best Regards

My manners must be slipping. I neglected to say Thank You to everyone who took the time to share their wisdom and help educate me on this subject, and to help me get my level set up properly. What a great bunch!

Steve

Some Murphy's Oil Soap will do wonders for the wood case!

Nice Level!

The real Leigh said:

I believe the side-to-side adjustments are to set the tube orientation within the level.

The easy way to make a bubble is to simply bend a straight glass tube. If this is the technique they used, then you must set the plane of curvature perpendicular to the measurement face. I would not touch that adjustment unless you're sure it's off.



- Leigh

Click to expand...

I agree, Dont touch side to side adjustment