Accuracy of Machinist Levels

ChandlerJPerry said:
Thank you everyone for the advice! Are these the inexpensive levels on eBay that everyone is speaking of? I can find what looks like the same 8" level from any number of sellers for around $60. I am concerned that I won't be able to level my lathe very precisely, I'm bolting it to a 2" thick industrial countertop made of very heavy particle board, which I think is rigid. However the legs are 4x4 posts that are braced with 2x6, I am worried that with the tendency of wood to expand and contract that this could introduce twist. Will using such a precise level with my chosen mounting method be a hopeless endeavor?
Click to expand...
Well, yes, that is why God made cast iron.
 
If you're not hung up on names like Starrett, Mitutoyo, Brown & Sharpe or other more common names you might want to check out Moore & Wright. While they are less popular in the US they are a little more accurate (.0035" per foot) than the Starrett 198 series. In most cases they are also less expensive. They are more often referred to as "Engineers Levels" rather than "Machinists Levels"

I purchased a 12" model on eBay earlier this year and have been very happy with it's performance. It's in like new condition and came complete in the original box. Like anything on eBay prices are all over the country side. I paid $110.00 with shipping included
 
VIS is the brand of Polish levels.
They made xlnt micrometers as well.
 
I wouldn't use that board you speak of for mounting a lathe. I have 2" think butcher block Over the last 2 years with a lathe placed on it, well, it's not flat enough anymore to even approach it with a machinist level. If you have some solid supports under the wood, spaced not TOO far apart, that may help greatly. I am considering ordering the manufacturers table to fix my problem,
 
Mikey's explanation is good. I'm always bothered by the term "leveling." The use of a level is just an aid in getting the bed to not have a twist. The level can be off by a lot and not matter in the least as long as you keep it in the same orientation and get the bubble to settle in the same spot for each end of the lathe. The sensitivity of the level is what determines the repeatability. We are getting off into an area of discussion beyond what is necessary for your lathe truing up. Everett's workshop has an easy to follow video for making and using the bar Mikey is talking about.
.
When you use one of those bars it is best to make sure the cross slide has been advanced into (to eliminate backlash) the work then ideally locked so there is no creep. It's worth keeping in mind that your lathe, or mine for that matter, was never intended to be tool & die maker accurate.

Now back to your bench. I can't see the underside of the top. But if there is no framing below the top you will have a bigger problem. Particle board will sag over time with the load of the lathe on it. PB is also compressible. So the force necessary to take any twist out of the cast iron may be more than the PB can resist and it may simply dent rather than move the cast iron. The 4x4 legs are OK since wood moves very little in the length wise direction. A steel bench would be better, maybe some day. Concrete moves so don't put the bench over a control joint or crack.
 
ChandlerJPerry said:
What is everyone's preferred minimum accuracy for a machinist level? I see the Starrett 98 mentioned a lot which I believe is .005" per graduation on the vial. I know quality measuring equipment isn't cheap, but my budget is unfortunately tight (laid off due to covid related slowdowns), so I was wondering if anyone has any experience with other levels and what accuracy is really useful for the home shop. Something tells me a .0005 level might just lead to ripping hair out in the garage! :grin big:

I was looking on eBay and found a 4" Stanley No. 34 for a reasonable price, it looks very similar to a Starrett 98 but I can't find any published statistics on the accuracy of that model. There are also plenty of Stanley No. 36, 37, and 237 on eBay which have adjustable precision ground glasses, but are marketed more towards high precision carpentry and plumbing, etc. in vintage Stanley catalogs. So what levels are everyone using for their machines?

Just for showing off's sake, here's my newest level that I purchased on a whim before realizing it wasn't nearly precise enough. :p
It's a Stanley No. 39 1/2, 6" long, marketed as a machinist level in their catalog but definitely more suited to general leveling tasks, it may be more precise than a similar carpenter's level, as the glass seems significantly longer to me and it is enclosed in a heavy cast iron body. However it lacks adjustability and fine graduations for precision leveling, as well as the glass not being precision ground. It is very pretty though! The logo dates it as being from 1922-1935.
Click to expand...
This is a good price and quality for new : https://taytools.com/products/kinex-86-2-precision-inspection-machinist-spirit-level . I have several of their machinist squares and they follow the specs exactly and are well made.
 
I just bought this one from Accusize in Canada. I'm sure it's Chinese but then so is my lathe, I've been happy with other stuff I've bought from them.

John
 
I have the Accusize level. It for sure works. I am interested to see Chandler try and get his lathe level. With my 2" thick butcher block table and a level that is too sensitive, it was impossible. When I got it close enough and then tried then to use it on the ways.....forget about it. I think newbs just work on getting it to cut equally on the 2 collar test and screw everything else. I will say, getting the Tormach level was MUCH easier, but there is no twist to deal with. I really want a solid metal table/stand for the lathe....and to add something like @RJSakowski added to the lathe as adjusting feet.
 
GunsOfNavarone said:
I have the Accusize level. It for sure works. I am interested to see Chandler try and get his lathe level. With my 2" thick butcher block table and a level that is too sensitive, it was impossible. When I got it close enough and then tried then to use it on the ways.....forget about it. I think newbs just work on getting it to cut equally on the 2 collar test and screw everything else. I will say, getting the Tormach level was MUCH easier, but there is no twist to deal with. I really want a solid metal table/stand for the lathe....and to add something like @RJSakowski added to the lathe as adjusting feet.
Click to expand...

I really have to wonder why you are having so much trouble leveling your lathe because there really isn't a whole lot to it. There are only a few principles that need to be attended to and leveling should go pretty easily.

If you think about it, what we are trying to do is twist or untwist the bed so we can get it aligned. In order to do that, we have to have some mechanism that applies or relieves pressure on the bed. On larger lathes with solid stands that are free standing on the ground, we use leveling mounts/feet to apply pressure to the lathe that is solidly bolted to the stand. Some smaller lathes, like my Emco lathe, use adjustable levelers under the feet of the lathe AND under the cabinet/stand. Many hobby lathes require shims or the fabrication of adjustable levelers under the feet of the lathe; these are often mounted on tool chests or shop-made stands of various designs. The common factor here is that there must be some method of adjusting or applying pressure to the lathe structure in order to move it, and it must be finely adjustable enough to do the job.

When leveling the lathe, the level must sit on a common surface that is available at the headstock and tailstock ends of the bed. Most folks seem to use the ways of the lathe as this common surface. Others, like myself, prefer to sit the level in a precise position on the cross slide. Using the cross slide is common when the front and rear ways are not at the same elevation. Whichever way you choose to do it, you need to do it consistently and precisely. This is especially true for lathes that may have some wear on the ways.

Finally, you have to understand that trying to twist a large piece of cast iron does not happen in seconds. It can take minutes to hours for the bed to move, and the bigger the lathe the longer it can take. This is not a consistent thing; some lathes move more readily than others. My Emco lathe will move within 10 minutes and then settle. I've leveled a little Compact 8 lathe that took almost an hour before it settled and a SB13 that took several hours for the bubble to stop moving. If you make an adjustment and the bubble moves, watch it for 5-10 minutes to make sure that the bubble doesn't move further. If it does move further, wait until it stops.

All lathes move over time and need to be adjusted. This is just the nature of the beast. You should check your level-ness every so often and especially if you turn a large work piece or something that was out of balance. Guys who think they only have to level once are just naive because the reality is that lathes move.

So, if you're having trouble I suggest you look at how your lathe is mounted and how you're adjusting it. It isn't the level that is the problem.
 
You must log in or register to reply here.
Back
Top