PDA

View Full Version : Engineers level recommendations



blckbx
03-01-2017, 02:44 PM
Looking to buy a decent engineers level. New or used not sure but do want a quality item. Have seen these two on ebay similar price with extreme different claims in accuracy.

http://www.ebay.co.uk/itm/Moore-Wright-MAWELS-ELS-Engineers-Level-165mm-6-5in-/182470649264

or

http://www.ebay.co.uk/itm/Kinex-High-Precision-Engineers-Level-10-inch-0-02mm-1000mm-/152445820939

Any advice appreciated

Al

pinstripe
03-01-2017, 03:04 PM
Is this for levelling machines? The 0.02mm/m one might drive you crazy. I've only got a basic 0.42 mm/m one and it doesn't take much to move the bubble. Ideally you have both. The less sensitive one to get you in the ballpark, and the more sensitive one to take up the rest of the afternoon :)

blckbx
03-01-2017, 03:12 PM
Is this for levelling machines? The 0.02mm/m one might drive you crazy. I've only got a basic 0.42 mm/m one and it doesn't take much to move the bubble. Ideally you have both. The less sensitive one to get you in the ballpark, and the more sensitive one to take up the rest of the afternoon :)

Initially its for levelling my lathe. Good point on the 0.02 being too accurate for practical use. Initially thought the more accurate the better but..........Hmm..... don't really want to buy two.

Guess thats why they're selling the 0.02. Hadn't really considered that it could be 'too' accurate for what you're trying to do.

Thanks

Al

pinstripe
03-01-2017, 03:35 PM
Someone else will probably chime in about the more accurate one. I can't say because I don't have one. Remember that ultimately you should do a test cut to see if it's "level". Tony's video below does a great job of explaining it in simple terms. Tom Lipton has one too, I think.




https://www.youtube.com/watch?v=THkb-x35fwc

blckbx
03-01-2017, 03:48 PM
Someone else will probably chime in about the more accurate one. I can't say because I don't have one. Remember that ultimately you should do a test cut to see if it's "level". Tony's video below does a great job of explaining it in simple terms. Tom Lipton has one too, I think.




https://www.youtube.com/watch?v=THkb-x35fwc

It's a DSG so I get the impression that you could sit it in a hammock and it would still cut straight. However.... I levelled it with my builders level and was advised that if DSG hear they may confiscate it.:(

Al

BCRider
03-01-2017, 04:27 PM
I've never understood the reliance on a machinist's level for setting up machines. I can see using a builder's level just to get it close enough that round things don't roll off into the chip tray. But for aligning the machine? Nope, makes very little sense.

Consider that most lathes use at least one prismatic rail on the bed. Now how do you level to the contact points used by the carriage? And does it really matter if the whole length of the bed is tilted a degree or two? Not at all as long as long as it is straight.

So I say get it level with the builder's level and then do the test cuts on a big stout piece of scrap round stock. Adjust If by some chance it is sitting on an uneven floor and this is allowing the bed to twist a little then shim it back to where both ends of the test bar are cutting to the same diameter. All metal is a spring after all. Just something like a DS&G is a really heavy and stiff spring. But when you're hunting down 10's of a thou or thousandths of a mm it's not stiff enough So it may need a little help to get all four contact points on the floor sitting in the same plane so the bed can rest at it's natural flatness.

I'm sure there are other things in the shop that a machinist's grade level might be useful for. But I've never found a need for one in a home shop.

Mcgyver
03-01-2017, 04:28 PM
What's decent depends on the use. For machine tool alignment and/or scraping, the one to get is the Starrett 199. Used are reasonable, new its quite expensive.

Accuracy with a level is slightly deceiving in that its common practice to interpolate the bubble position between lines. While two models may claim the same resolution, ie the 199 is .0005"/foot.....if the graduations on one are 1/4 the distance between them as the other, I'd say it is less accurate despite the claim of the same graduations/ft.

blckbx
03-01-2017, 05:12 PM
What's decent depends on the use. For machine tool alignment and/or scraping, the one to get is the Starrett 199. Used are reasonable, new its quite expensive.

Accuracy with a level is slightly deceiving in that its common practice to interpolate the bubble position between lines. While two models may claim the same resolution, ie the 199 is .0005"/foot.....if the graduations on one are 1/4 the distance between them as the other, I'd say it is less accurate despite the claim of the same graduations/ft.

700 new 200+ second hand ouch

Mcgyver
03-01-2017, 05:26 PM
lol, well, you know you didn't pick a cheap hobby.

If all I ever used it for was leveling, a machinists level and BCs' approach is probably the way to go....however you will do a better job of leveling with the 199. If you, as I do, use it for scraping and alignment a machinist level is not adequate....so having to have the 199 in the box means its what gets used to level the lathes.

Video Man
03-01-2017, 06:57 PM
While you're still in the common market, you might find good prices on European-made levels. I bought a Polish-made precision level (0.0005 ins) here in the states years ago for a reasonable price and it has proven accurate and well made. My semi-annual lathe leveling takes, as someone said, all afternoon and then the next day after a run-in and everything has settled into position. But that's another story. Your tool vendor may well have a new and quality level from the E.U. readily available at a decent price.

J Tiers
03-01-2017, 07:26 PM
I've never understood the reliance on a machinist's level for setting up machines. I can see using a builder's level just to get it close enough that round things don't roll off into the chip tray. But for aligning the machine? Nope, makes very little sense.

Consider that most lathes use at least one prismatic rail on the bed. Now how do you level to the contact points used by the carriage? And does it really matter if the whole length of the bed is tilted a degree or two? Not at all as long as long as it is straight.

So I say get it level with the builder's level and then do the test cuts on a big stout piece of scrap round stock. Adjust If by some chance it is sitting on an uneven floor and this is allowing the bed to twist a little then shim it back to where both ends of the test bar are cutting to the same diameter. All metal is a spring after all. Just something like a DS&G is a really heavy and stiff spring. But when you're hunting down 10's of a thou or thousandths of a mm it's not stiff enough So it may need a little help to get all four contact points on the floor sitting in the same plane so the bed can rest at it's natural flatness.

I'm sure there are other things in the shop that a machinist's grade level might be useful for. But I've never found a need for one in a home shop.

As I am sure you are aware.... it's not about "level" but about twist.

What the level (device) does is get a consistent outside reference, so you start from a reasonable point. A carpenters level is so coarse that it really gives NO good information unless the machine is in a horrible condition. A Starrett 98, at 0.005 per division per foot is good enough, and will not drive you crazy.

Without an outside reference, you can twist the bed into a pretzel trying to get it to cut the bar the same at both ends.

I just put the level on the compound and run it back and forth. Not perfect, but works because my 98 is a short one and I know it is scraped flat, with no recess in the middle. After that is good, then get with the two collar test to get it right.

If the machine has enough wear for that to be an issue, it is futile to try to get it perfect over any distance anyway, so no point in speculating on what that does to the leveling idea.

BCRider
03-01-2017, 08:51 PM
Without an outside reference, you can twist the bed into a pretzel trying to get it to cut the bar the same at both ends.

Only if the person ignores the screams of pain coming from the machine.....

If the machine is set in place so there is no diagonal rocking between the feet and with some reasonable effort made to have the load on the feet the same or consistent with the weight distribution then it's going to cut a collars on the test bar that are fairly close. And very little corrective action is going to be needed. It's a significant corrective action but it will be quite slight.

Another way of looking at it is that one would like to think that the bed feet were shaped to sit flat on a planar surface with no twist in the metal. And then those feet were held again on this planar holding points for the rails to be ground. So when we tune the bed to eliminate twist so our cuts on the test bar are identical we are actually restoring the bed to the as ground lack of twist. We are, in fact, straightening out the pretzel, not twisting it and adding salt. We are doing that by working to position the support feet in the exact same alignment they had when the bed was ground.... less any slight tweak we might induce to make up for some wear on the bed on well used machines.


The fact that it is pretty easy to see the effect of any twist or arching in the test bar for this final tuning is why I'm more a fan of the test cuts than of using a precision level. I can "see" the effect of any residual twist easily and directly from only two measurements and know which way to tweak the shimming or jacking nuts depending on how the machine is mounted.

It also takes into account the condition of the ways and more importantly the way the carriage rides on the prismatic rail.

And after seeing the price of the levels I'd also suggest that a side benefit is that I can true up the lathe using a cheaper or similar priced indicator or test gauge that I will use FAR more frequently than I would ever use a precision level.

Now I'm open to reading other uses for a precision level to aid in justifying it. But so far I've been extremely happy with my builder's level and DTI job I did on my own lathe a year and a bit ago. I recently turned a 4 or 5 inch length in the lathe and when I checked the diameter end to end it was still within a line's width on my micrometer from end to end. Not a division, a line's width of the same reading. And I did it without a precision level.

Oh I know... there's more than one road to Rome. And lots of lathes have been set up with a precision level. It's a valid tool and can do the job as has been well documented over the years. But for someone without one and that is facing that sort of cost? I'd be looking at one of those other roads.....