About Those Carpenters' Levels

[slugger]

For most guys using the average machine, A very good carpenters level, like my Stabila, will get you so close that you will probably not have any issues with your machine. There are many other factors in other than a clean room environ that can affect machine accuracy (temp fluctuations come to mind) so if a guy doesn't have a master precision level, he can still get pretty dang close with a good carpenter's level and some careful methodology.

[oldtiffie]

Heavy metal.

Jeez, if you wan to test for level, just pour some Mercury on it and adjust til it stops moving in all directions.

Good move ligito.

A dozen or so ball-bearings will do as well.

Watch out that the OHS/"heavy-metal" police don't getcha thou' with all that mercury around.

[SHADOW]

I have dealt with a number of vials over the years needing replacement or resetting. They were filled with alcohol and ether, the colored ones just have added dyes. Bubbles can indeed stick. I was told the mixture coagulates over time and it forms small clear blobs that naturally find their way to the top and when the bubble comes along it hits these and stops. These then become a constant problem. They have usually been stored in extreme conditions and are somewhat older.

I aquired an engineer's survey level, a Deitzgen (cira '50's) with a 6" vial, having a 2 1/2" bubble. It was formerly a government item and in it's box was a spare unmounted vial (unexpected bonus). It basically needs fastening to an appropriate base.

[oldtiffie]

Get it as right as you need to.

For most guys using the average machine, A very good carpenters level, like my Stabila, will get you so close that you will probably not have any issues with your machine. There are many other factors in other than a clean room environ that can affect machine accuracy (temp fluctuations come to mind) so if a guy doesn't have a master precision level, he can still get pretty dang close with a good carpenter's level and some careful methodology.

Agreed Slugger - absolutely.

Your method will do most of the time at best result for minimal cost and effort.

Using a "super level" on its own is a problem as there is too much effort (and frustration) in trying to get the bubble into the vial at all let alone into the centre only to have to have it upset as you go onto leveling and adjusting elsewhere.

It is far better to use a "staged" approach - using "coarser/less-accurate" levels as you go on a progressive basis up to the standard that you are satisfied with and that meets your needs.

There may well be compromises that have to be made as well as things that will "have to be lived with" and/or "worked around".

There are many other factors in other than a clean room environ that can affect machine accuracy (temp fluctuations come to mind) so if a guy doesn't have a master precision level, he can still get pretty dang close

That is a very valid practical point that is often over-looked or ignored.

The "level set-up" will change with ambient temperature changes. It may even change between "cold" (before starting work) and hot-warm (after the machine has been running both under and free of load).

It would be unrealistic to expect otherwise or to attempt to re-level with every temperature change.

Perhaps its best to do the leveling at the average temperature in your shop when you use your lathe/mill or what-ever.

[Evan]

In the thread that Fasttrack started about levels mounted on ball bearings I described a way to level a lathe using a cheap line laser level and two 90 degree prisms from a cheap pair of binoculars. Back when I did the thread on qualitative flatness testing using a laser level I went on to develop the method that I described in Fasttrack's thread. Last fall I was extremely fortunate to buy not just a horizontal mill at a very good price but also a box full of the highest quality Swiss and German instruments, including a good frame level.

Now, you would think that as soon as I got my hands on that level I would be running around checking things like my lathe. To tell the truth, I haven't used it to measure anything until tonight. I already knew that lathe was straight both from it's performance and the fact that I had optically aligned it a year or two ago.

Because of this thread and the previous one I decided to check and see just how effective my dirt cheap laser system is. I put the master level on the cross slide with a shim to bring the bubble on center and then ran it to each end waiting several minutes for it to settle.

You can see for yourself what the difference is from one end to the other.

[lazlo]

You can see for yourself what the difference is from one end to the other.

That Swiss frame level is very nice Evan -- it's 0.02 mm per meter, or 5 second accuracy. That's twice as sensitive as the Starrett 199 Master Precision Level.

It looks like your lathe is leaning backward (away from the operator) at about .135 mm per meter at the headstock, and .11 mm per meter at the tailstock.

[oldtiffie]

Machine level.

That Swiss frame level is very nice Evan -- it's 0.02 mm per meter, or 5 second accuracy. That's twice as sensitive as the Starrett 199 Master Precision Level.

It looks like your lathe is leaning backward (away from the operator) at about .135 mm per meter at the headstock, and .11 mm per meter at the tailstock.

Sorry laslo.

Nope - don't think so.

If you have a close look you will find that the level is centred/zero-ed on the long lines/graticules with the black "spots" at each end.

It is only 3 of the divisions/graticules "off" = 3 x 0.02mm/m = 0.06mm/m = 0.06/1,000 = 0.00006 = atan 0.0034 arc degree = 0.2063 arc minute = 12.3276 arc seconds.

It would not matter if the lathe were out 10 degree at that setting as the ends are within a "whisker" of being parallel and so are co-planar. If Evan's lathe bed is straight and he gets a similar reading in the centre of the bed then that lathe is as good as can be asked for and will meet any spec of any modern lathe of any size from any country and from any manufacturer.

Evan's lathe and set-up just has to be the bench-mark.

I will be interested to see if any can better it.

Further, Evan's Machine Square is German and at least as accurate as any machinist's level - "Starrett" or otherwise.

My "Chinese" "Measuremax" machine square is of the same specification as Evan's and I have every reason to be confident that it is as accurate as Evan's.

The machinist square has capabilities beyond the machinists precision level - but with equal accuracy - as it will show vertical and square to very high orders of accuracy as well. It is my precision level of choice as my machinists level is only a "one trick pony".

I thought Evan's use of the cross-slide (or saddle) - as suggested seperately by J Tiers - was excellent thinking as the "shift" of the saddle as opposed to just measuring the deviation/wear in the bed was brilliant. In other words the "error" was determined where it counted - at the tool position.

Evan's pics are repeated here.




Pics of my "MeasureMax" machine square (as posted previously) - for comparison - follow:

[Evan]

It looks like your lathe is leaning backward (away from the operator) at about .135 mm per meter at the headstock, and .11 mm per meter at the tailstock.

(edit)I make it as no detectable difference. Both ends lean the same. But that is dependent on the shim I placed.
Which of course doesn't matter since it all leans together. One thing I discovered when running my seisomgraph is that the foundation of the house is quite flexible. The siesmograph I built is essentially a very sensitive tiltmeter and can detect the effect of somebody walking near the house. I had problems maintaining the alignment of the instrument when it snowed or rained because of the effect of the multi tons of water deposited around the house had on the bending of the earth under and around it. Of course it wasn't even, especially when it rained because the rain that landed on the house was directed off the roof and onto the surrounding ground.

I can't quantifiy the actual amount of deviation from level this causes because the seisomometer is uncalibrated in that respect. That isn't relevant to it detecting earthquakes. It would be nice to know but I can't think of an accurate way to determine it because the instrument is so sensitive.

[added]
I should say that when I said I brought the bubble on center I didn't mean exactly on center, just to where it was readable as you see it in the pics. I also made similar measurements directly on the lathe bed with the same results. It doesn't vary appreciably anywhere along the length of the bed.

[John Stevenson]

I have a 18" builders level here that I use daily in the shop.
It's the only tool that comes to hand where I can reach over and scratch my back with it.

Next question? How will I know it's level as it's behind my back and will changing over to a machinists level improve the quality of the itch ?

Seriously I do use it for that but in the course of buying up job lots of gear at sales, and measuring equipment here fetches zilch for some reason I have loads of levels of all sorts, some are supposedly very expensive and accurate.
Simms Sons and Cooke spring to mind here as a manufacturer but not certain.

Scrap man gave me a frame level [ although I didn't know they were called that ] about a year ago, still wrapped, have to dig that out and see just what it is.

Edit got the wrong name

http://www.ast.cam.ac.uk/~ipswich/History/Troughton_and_Simms.htm

[lazlo]

It looks like your lathe is leaning backward (away from the operator) at about .135 mm per meter at the headstock, and .11 mm per meter at the tailstock.

If you have a close look you will find that the level is centred/zero-ed on the long lines/graticules with the black "spots" at each end.

When the legend says ".02 mm per division", I've been interpreting that to mean each tick on the level, where the major ticks are there to help you count how many divisions off you are. Can someone (John Garner?) confirm?

So at the headstock end of Evan's lathe, he's off 6.75 divisions x 0.02 mm per division = .135 mm per M.

At the tailstock end of Evan's lathe, he's off by 5 divisions, or .11 mm per M.

It is only 3 divisions "off" = 3 x 0.02mm/m

Evan's Machine Square is German and at least as accurate as any machinist's level - "Starrett" or otherwise.

It's Swiss, not German. And as I posted above, it has 5 second accuracy, which is twice the sensitivity of the Starrett 199 Master Precision Level, and half the sensitivity of the 2.5 second level in the Kingway Alignment system.

I thought Evan's use of the cross-slide (or saddle) was excellent thinking as the "shift" of the saddle as opposed to just measuring the deviation/wear in the bed was brilliant.

Yes, we all know you're in love with Evan -- do you want to be alone now?
Not only did Evan invent the idea of putting the level on the cross-slide, but he invented the level too.

[Evan]

Robert,

The bubble is in the same position at both ends. Where are you seeing a difference?

[lazlo]

From your pictures in post 35, it looks like the reading are different by 1 - 1 1/2 divisions, but maybe that's the angle you took the picture. In any case, I was just reading off the vial scale in the middle of the night -- my 5 month old was up sick last night... In either case, your lathe is extremely well leveled.

By the way, you say that the lathe was leveled with a laser setup -- did you do the laser autocollimator thing with the binocular prism? Do you have any pictures?

[Evan]

I don't have pictures of the process as I wasn't intending to post about it at the time. Perhaps I will replicate the setup and do a thread about it. I know you may find this hard to believe but I don't post about all the shop related things I do, even if they work.

[lazlo]

I know you may find this hard to believe but I don't post about all the shop related things I do, even if they work.

I thought the HSM Forum was your personal Blog?

Seriously, I have several commerical laser line generators and little first surface mirrors (from when I built the ubiquitous laser alignment jig for my Mill/Drill). It sounds like I need a beam splitter, and I'm not sure how the combining/interference setup looks?

[Evan]

No beam splitter of interference is used. It is simple geometry and one of the reasons I didn't post about it previously is that you need sufficient distance in front of the lathe to obtain sufficient resolution. I will put up a drawing of the setup later but right now I have some work to do outside.

To put you on the track just do the math on the possible visible angular displacement of a beam over 30 feet. That's the length of the arm I have with the laser 15 feet from the lathe. I can even go to about 30 feet x 2 by going to the end of the hall in the basement.