Rising to a new Level

OH ... the things we learn then we start to pay close attention to the details…

The back story…I have been working with machine tools for a long time. Up until this point, ± 0.001” has been the closest I have had to be. Typically not even that close was necessary. Now I am wanting to try some more challenging projects. While trying to work more closely, I have discovered my lathe needs a tune up. Reading about this tune up process, leveling is one of the places I have neglected. After moving a lathe to my basement several years go, not having a precision level, I used my best carpenters level, this was not good enough. Not having a precision level also makes it near impossible to correct this. This is the reason for this project.

I do not want to spend lots of money on a precision level. Since I enjoy the challenge of building something special like this…I thought I would try my hand at making one. My wife has already asked me, “Why don’t you just buy one?” I seem to hear that a lot. Searching online for vials, I discovered there are so many, some with INCREDIBLE precision specifications. I settled on a replacement vial for a Starrett 98-8. I purchased that for $15.00 with shipping I have $23.00 in it. The rest of the components I made from materials I had in my, “I will make something with this someday”, collection.

The base was a chunk of hot rolled steel, 1/2 x 1 I cut off a piece about 6 1/2” long, the longest I can fit in my 4 jaw chuck. I “faced” the 4 sides, to clean up piece and flatten the base.

The vial holder is a piece of type L copper plumbing pipe. If you choose to make one I recommend type K or L copper, type M has a very thin wall. I wish I had a piece of K to use. I cut a slot in that with my lathe using the compound rest mounted vertical on an adapter I made a while ago after seeing one on HomemadeTools.net - More Than 30,000 Homemade Tools - HomemadeTools.net Since I do not have milling cutters, I used a large center drill held in my collet chuck. It actually worked very well. The biggest problem was holding the tube securely enough without crushing it as the slot made the tube weaker. I ended up making aluminum “plugs” to slip inside the tube to prevent the vise from crushing it. I “honed” the inside with sand paper on a dowel, both before and after milling the slot.

The end caps for the vial holder are aluminum. The small end is sized to be a snug push fit into the copper tube. The small ends are center drilled just a little, because the vial has a little glass tip on one end from the manufacturing process. I had intended to use O’RIngs to make a tight fit with the copper tube, but they work fine without them. The large end is sized to match the OD of the copper tube. Flats on the large end were milled using a 1/2” carbide router bit in the collet chuck along with my “milling adapter”.

The posts to hold the vial assembly are made from 3/8-16 bolts. They are cut to length so the threaded end will not stick out the bottom and the unthreaded part is long enough to hold in the collet. The posts are drilled thru and tapped for 10-32.

The vial is cushioned in the tube with 1/2” thick foam “plugs” that were cut using a “sharpened” piece of copper tube. This is not the best solution. The vial needs to be more secure than the foam makes it. I do not want to make the installation permanent by using something more secure until I am sure the design is good. On another forum, suggested using DAP 33 window glazing compound to seat a replacement vial in their Starrett level. I may try that later.

The vial assembly went together well, the vial is held snug, but it can move, being held in place with only the friction from the foam cushions. Simply cleaning the glass with a tissue knocked the level out of adjustment.

This is how you calibrate the level. Starrett 98-12 Level

During testing I discovered that the bottom was not flat. It was tapered from the center toward the ends about .001” so, pressing down one end, made the other end, .002” high. (each time I try to get more and more precise, I learn my lathe needs a tune up) I corrected this by draw filing the base and checking with my best straight edge. Of course I never noticed this taper when facing small parts, but over the 6 “ length of this bar, it sure did show up.

Attached are photos and a sketch of the level if you want to try it. I can promise it will bring your understanding of level to a whole new level, unless of course, you are already….. on the level :)

Attachment 23812Attachment 23817Attachment 23816Attachment 23813Attachment 23814

Nice work there hemmjo
Just a useful thought though, each graduation on the vial of the level represents .005", beings you made the base of your level 6" long and your using a vial that is made and graduated for a 8" level your error would nearly double, Example:when you put a piece of paper under the level that was .003" thick it would move your bubble about .005"- .006" meaning you couldn't use the level for precise work, just as reference, look at your last photo and it shows how much the bubble moved every time you added .003"
You did a beautiful job though !

Doug

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Now how do you calibrate it? What do you have that is certified level to begin with.

It is interesting that machinist levels are "adjustable" so that you can set your lathe "level" to it's stand not that it is certified level.

Ralph

Quote:

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Originally Posted by Ralphxyz

Now how do you calibrate it? What do you have that is certified level to begin with.

It is interesting that machinist levels are "adjustable" so that you can set your lathe "level" to it's stand not that it is certified level.

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Levels are self-calibrating.

Set the level on any flat (not necessarily level) surface. Mark around its base. Note the position of the bubble.

Now turn the level 180 degrees and place it on the marks made previously. If the bubble returns to the same position as in the first orientation, the level is calibrated. If not, make adjustment and iterate procedure until it is.

Rather than marking around the base, I prefer to make a corner pocket into which to fit the level. Clamping a machinist's square or similar to a mill table works well.

It's very easy to set or check the level Raplhxyz
Set the level on a semi level surface, it doesn't even have to be perfect, just make sure your surface you set the level on is level enough that the bubble is close as possible in the middle, use a surface plate, milling machine table ETC. look where your bubble is, now turn the level around 180° the bubble should be in the same place it was before you turned it around , if it's not then unloosen the two locking nuts and raise or lower the vial until the level reads the same every time you rotate it 180°
Doug

Another thing to remember, Ralph...

The lathe does not need to be level*. What is needed is to remove any twist from the bed. A level is just a convenient tool with which to measure twist.

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* Lathes are regularly mounted in ship machine shops where level is something that only happens when docked.

Marv is 100% correct. If a level repeats after 180° reorientation it is correct; even with some apparent displacement of bubble. If not, either base or surface have an interference, some imperfection out of plane to their respective surface.
Process he describes is the procedure, by textbook and in practice. There are conditions that increase accuracy; a master level will displace its bubble just breathing on the vial [temperature change].

A good quality carpenters level can be very reliable too. In their normal use, the check combines level [or perpendicular] along with straightness of a surface; over an extended area of contact. That combination may not always be the best indication of information sought.

Try this experiment. A kitchen table, counter top, etc...demonstrates this as well if not better than a precision surface.
Place a level on a clean 'flat' surface, obviously longer than the level. Observe reading.
Now, level still in same location, place thinnest feeler gauge, shim stock, tissue, number size drill etc, at one very end. Observe new reading.
Next, place level on two identical items at very end; gauge blocks, drill blanks, shim stock. Don't be surprised when a third different reading occurs.
You could with little effort determine practical accuracy by a little math here, working the overall length by the known thickness of spacer.

On many levels, the intermediate pair of marks indicate a slope of 1/4" per foot, critical in generation of dependable drainage.

While base of a precision level can support itself decently in full contact or at its ends, I use that second tendency in leveling machine tools. I suspend the level on good 1-2-3 blocks or reamer blanks. With the spacers separated by a known distance, it is quite simple to better estimate what amount [and direction] of movement is needed to get a machine on two [X & Y] truly horizontal planes.

I used 2 levels, an 8' carpenter for X and 12'' magnetic torpedo for Y on the bandsaw support. To get accurate cuts for long material used in machine frames, this and improved leveling of the saw itself had to occur.
Attachment 23835
As no table connects machine and support there likely is a sag in the level, regarded negligible by reversing level for the same reading. I found imperfections in the concrete floor experimenting with the distance and approximating the Airy Points https://en.wikipedia.org/wiki/Airy_points

Thanks, I knew that, duh well I knew that 55 years ago.

I need a "level" surface to calibrate my cell phone.

Ralph

Quote:

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Originally Posted by Ralphxyz

I need a "level" surface to calibrate my cell phone.

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Float it in a pan of mercury.

The surface of the mercury is not precisely flat. It will have a radius equal to the radius of the earth but since that is 6371 km, it'll be close enough for government work. If you define "level" to be perpendicular to the local gravity vector, then it's just as level as any surface "leveled" using a bubble level.

Oh Marv..... that raises a WHOLE NEW conglomeration of issues. Imagine the government using a pan of Mercury as a reference for level. The EPA would have to get involved, there would be men in hazmat suits, with respirators. Yellow tape strung up all over. They would double bag Ralph's cell phone so they can haul it to an EPA approved Hazardous Waste Disposal Site. ......

Seriously though. This was a very enlightening project for me. It is fascinating to have an instrument as sensitive as this one is. After calibrating my new level, I set up my 6 foot, aluminum bean level on my bench. I used shims under each end until it was "level" then placed this new level on top only to have the bubble almost pegged against one side. Thinking that surely I must have messed up the calibration of my new level, I turned it 180º and had the same reading. Being about 3 graduations from center, each graduation represents .005 per foot. 3 x .005 = .015, my level is 6 feet, 6 x .015 = .090. Putting .090 shim under the low end brought my new level into the center, and barely moved the bubble on my carpenters level

I was able to tweak a bit of twist from my lathe bed already. I have to wait a few days to see how things settle since I made those adjustments.

John

Seems few of the places I've worked had "real" levels. I regarded my investment as a useful treasure. One feature; the best evidence possible when a discussion heats up about why certain lathes run well or not.

Often like this. "What ARE you doing?"
This lathe isn't turning straight.

(Now, one of two things happen. #1 is "Wow, can you fix it?")

Or

"Don't waste time dammit, set the tailstock"
I tried that, thinking your shop was set-up correctly. It's not.
"No one else says that!"
Any of them still work here?

and where would I get a pan of mercury?

I used to love playing with it in my hands when I was a kid, we got it from broken thermostats, which luckily my Dad had
a Plumbing and Heating business so we always had lots of old thermostats.

Later on found out that wasn't such a good thing to play with, of course I was always the one tending the lead pot so maybe the
layer of lead on my hands protected me from the mercury.

Ralph

When we were kids we could walk into most any country rx/all drug store and buy just about every chemical known to man and powdered raw elements or even a small bottle of mercury. we could also buy beakers of varying shapes or sizes glass tubing Bunsen burners petri dishes you name it if it had to do with chemistry it was available. The town nearest to where I lived was about 10 miles from our house, it was a small town population of maybe 500 but it had a 2 story drug store 1 wall had shelves from floor to ceiling with small bottles of most everything. Some of the stuff required an adult to present for us to be able to buy it if the drugest didn't know us kids very well. OH yeah there was also a soda fountain on the other side. A very popular hangout as well.
It was probably guys like me always blowing up our home experiments that caused those to disappear.

Probably anyone over the age of fifty played with mercury as a kid, yet you seldom hear of any of them dying of mercury poisoning. The reason is that they were playing with elemental mercury, the liquid, silvery metal form, which isn't particularly dangerous. It's the mercurial salts that are dangerous to humans. Unfortunately, the combination of an uninformed press and health nazis plus a paranoid population has turned mercury, and lead too, into their most recent bugbears. Wait until they learn that ordinary table salt is composed of sodium, which catches fire in contact with water, and chlorine, a poisonous gas used by the Germans in WWI.

Mercury has long been used to float scientific equipment. One example is the floating collimator...

https://en.wikipedia.org/wiki/Floating_collimator

I admire Marv Klotz's ability to clarify topics. Some responses might be intense, and certainly out of range for me, but his effect on the forums is undeniable.
Not to say other contributors are lessened in my eye, there are many.
This particular morning, re-read several; and finally sunk in.

I've used Plaster of Paris for mounting a vial in an antique level, which had no adjustment.
I set it up on the mill table (already level with a precision level), and carefully shimmed with whatever was handy.
Poured the pasty mix in, then did the 180º check before allowing it to set up.
Worked good and the Plaster of Paris is cheap at the local hobby store.

I guess that depends upon how you define “need”. Having the main ways level, on any machine tool, is an advantage for many setup challenges. As for lathes in general, yes removing twist is a major justification for leveling.

Quote:

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Originally Posted by mklotz

Another thing to remember, Ralph...

The lathe does not need to be level*. What is needed is to remove any twist from the bed. A level is just a convenient tool with which to measure twist.

--
* Lathes are regularly mounted in ship machine shops where level is something that only happens when docked.

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This is true. The point I’m trying to make is that a level machine tool aids in setup work. While it might upset a traditional machinist, I’ve used an electronic protractor on many occasions to get a “good enough” setup. That does require a level table to begin with.

I might be a bit obsessive here as I even leveled the little bench my grinders are on.

Quote:

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Originally Posted by wizard69

While it might upset a traditional machinist, I’ve used an electronic protractor on many occasions to get a “good enough” setup. That does require a level table to begin with.

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Set the level on the (unlevel) table and press the "zero" button. From then on all angles will be relative to the table and not to the local gravity vector. It's one of the nice features of an electronic level, as opposed to a fluid bubble type.

Yes, it's certainly good to have a work surface relatively level to prevent stuff rolling off, etc. but one doesn't need a precision level, the type used to untwist lathe beds, for that degree of "leveling".

I [whilst patting oneself on the back] am fairly traditional, until point new things offer solutions unavailable before. I like digital levels, like setting angles on my new brake, which has no calibration at all, just stops.