Levels

[samualt]

Paul Simon once had an album that contained a song about a man who thought too much about writing a song. On the flip side of the album was the same song done a different way. LOL.
I feel that I am also thinking too much about something so simple...Levels:

A water-level is cheaper than a Starrett Machinist's Level, but wouldn't a 6" Starrett be better (or is that too small)? Also, the water-level measures actual height, in a fashion, whereas the Starrett measures only if the level is exactly parallel to the earth. Still, I think the Starrett Machinist's Level would be easier to use and more precise.

Any thoughts?

[duluthboat]

Unless you’re setting up high end machine tools get yourself a 12” carpenter’s level, about $10 at the big box store. Or use the one in the tri square base, if you have that. You’ll be fine.

Gary

[samualt]

duluthboat:
"Unless you’re setting up high end machine tools..."

The beauty of a CadCut machine is that you can make it as high-end as you want. I ain't going to this much trouble unless I go all the way. A 4x8 router is no small task and I don't ever want to have to build another one! Steel frame, THK rails, peak 1500 oz-in servos, and as level as I can possibly make it.

[HuFlungDung]

Something to consider before purchasing the level is what quality is the surface that the level is going to be used upon? Machinist levels are meant to be used on a machined surface, but would not do a good job of finding the average level of a long surface, which may be rough and/or bowed slightly.

If you are levelling the table, an ordinary level is likely good enough to get your table in the ballpark. Actually mounting a dial indicator on your gantry and moving it around to test the depths is likely a much better method of setting it up for the conditions that actually exist in your machine.

[samualt]

HuFlungDung:
It has to do with two very long precision machined aluminum rails (tolerence of .005") that go on either side of the machine. The idea is to get them as perfectly parallel and level as possible.
The steel frame on which it sits isn't that big a deal because it has tabs on it which the machined rails sit. Once you get the rails perfectly aligned then you use some kind of epoxy stuff to make it all solid.
Bob (the guy who wrote the plans) wanted mucho accuracy! Incidentally, it was one of the reasons I chose his plans.

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"If you need a machine and don’t buy it, then you will ultimately find you have paid for It, but don’t have it." - Henry Ford.

[duluthboat]

This is what I addressed my response to.

“I feel that I am also thinking too much about something so simple...Levels:”

I can appreciate the fact that you are concerned about getting your machine level. But a bubble level is just a reference tool and the accuracy is in the operator not the tool. I didn’t know you had such a large machine, I would now suggest a 48” carpenter’s level. I think you could get a nice one for under $20. Please don’t think I’m making a joke. I spent some time setting up $500K VMC’s, we used carpenters levels. After all was leveled we would check things with the expensive level. I don’t recall ever changing anything. Save your money for 1 or 2 good indicators.

Gary

I love the H Ford quote.

[HuFlungDung]

Sam,

I don't know about "epoxying it down". One of Murphy's corollaries is this:

"Anything which must be permanently assembled with great difficulty must always be disassembled once more, immediately after the shrink fit forms, the Loctite gets hard or the epoxy sets. Only then may it be assembled permanently"

[Max]

Sam,
I'd like to butt in here concerning the leveling of your table. I'm just thinking outloud ... so to speak, but I'm looking at your question from a different angle (I tend to do that with most things)

Instead of worrying about the level of your rails in relation to each other, I think it is more important to be concerned with the level of your rails in relation of the z axis spindle to the the table.

An idea would be to build the table (I haven't seen the plans for yours if it's possible) with the ability to adjust the rails from time to time as needed for maintenence. Shims and spacers come to mind here.
Then, run your gantry back and forth across y as you move across x checking for distance from the z (spindle) to the table with a micrometer and adjusting the rails as you go.

In addition an idea is to run a routine to mill the table flat after the machine is finished to get rid of any bumps or imperfections in the surface if accuracy is important.

You can check on the shopbot forum and they have discussed this to great length. I think the shopbot software even has a routine just for this (not sure ... don't have a shopbot either) but you can use their procedures to aid in your project.

I just don't see where having the parallel rails level to each other in relation to earth is as important as it is to being level to your work surface and the rails being true to themselves to prevent binding of your linear bearings.

[samualt]

Max:
Good ideas, but not what the plans call for. The reason you must get the two machined rails exactly parallel and level is because the gantry sits on them. If the rails are perfect then the gantry will be perfectly aligned. It's so well aligned that a single finger-push can cause the gantry to travel the length of the table. I'm hoping mine is that accurate.


HuFlungDung:
Once this table is built there is no disassembly. Heavy steel frame that is welded together, machined rails that are epoxied to the frame, and a pretty heavy gantry mean you arn't moving it much either. The guy who wrote the plans looked at all the commercial machines and tried to figure out why they built them the way they did. He then incorporated all those ideas into this machine. Its more of a business machine than a hobby machine. In other words, this ain't your Mama's router! LOL.



But, we digress:
Has anyone here ever used a water-level vs a Starrett Machinist Level? Which did you think was better and why?

[Mr.Ed]

I have had numerous level gauges in the past. Expensive ones, cheap ones. When i had to put something against a wall wich needed to be level i tried my very best every time.

Then, one time i used a level, and the mounted object still looked "not-level". Then i figured out that when i turned the level gauge around, it would show a different measurement than the way i first started out with.

This can mean only two things. 1) I have an el-cheapo level gauge wich needs to be thrown in the garbage can, or 2) No level gauge in the world is exactly LEVEL. (wich i doubt).

The thing i learned : I'll never trust a level-gauge just like that.

Lately, for rough measurement i used a long hose filled with water, holding both ends near the measured object. That seemed to work well, but a lot of hassle.

Good luck, get level

Ed.

[Stevenpats]

I relocated and installed equipment for about 10 years, we used Starrett Precision levels 12" long .0005" per foot accuracy. I have also used water levels for fences and such, and there is no comparison to a precision level. Mills and toolroom lathes get only a torpedo level job, precision Grinders and large machining centers got the Starrett levels. I am building a router table but only using a 2' level for the frame, the rest will be dial in with indicators. There is no use in buying a 500 dollar level when the surface you are leveling is rougher than the level tolerances. A good practice when using a level is to check it by flipping it over and also turning it around, if the bubble moves, the level is no good.
Hague

[lsfoils]

You can get a reasonably accurate precision level from Grizzly for $80. Thats what I did. It comes with adjusting screws and a booklet to explain how to zero the level in. It is calibrated to .0005" per foot. I set up my rails with it. Took all day but was worth it and the money spent. Finish hooking up my first axis Sunday and when my friend wanted to see how much slop was in my ball screw he moved the whole table; there was so little friction from the rails that he back-drove the screw with about 5 lbs. of pressure! I'm sold. In the end, I'd have to say its all about what you're after, how much time and money you're willing to spend....