level mystery

[Silvan]

I ran into a curious situation today. I have some trivial but significant alignment problem with the left wing of my table saw. I was attempting to gauge how far out of whack it is by comparing two levels.

For the first level, one of those orange deals with three vials in it. I used this to level the saw initially. It reports the saw as being level all the way around. If I move it out to the waffle wing in question, and position it appropriately, it also reports the wing as being level all the way around. Whatever difference there might be is too small to gauge with this method.

So I thought I'd look at two levels simultaneously. I grabbed the head off an old combination square, that I use for sundry low quality purposes. Put it on the table, and it showed a huge amount of tilt. Put it on the wing, and it showed the same huge amount of tilt.

Then I got the head off my good combo square, and it showed the same as the first one. Grossly out of whack level wise.

I just don't get it. Why would one show perfect and the other show that the left side of the saw is almost 1/4" higher than the right? That's a huge difference. My first thought is length. The orange 3-in-1 level is about

3/4" longer than the head of a combo square. My second thought is the size of the bubble. The bubbles in the combo squares are a bit larger, and the vials are a bit larger too.

Just for kicks, I also tried with a bullseye level. It shows level all the way around too.

Weird. No, there's nothing stuck to either of the square heads, no hardware protruding; no reason I can discern why both of them show such a huge difference from the other two levels.

[bridger]

sounds to me like you have some bad levels.

first, check the levels against themselves. put a couple of drywall screws in something immoveable, like the floor. twiddle the heads in and out while checking with a level until you get it level, then turn the level end for end and check it again.

some levels can be adjusted, some can't. the ones that can't, and are out, throw away. if they are also something else useful, like a square head that *is* square, mark the level as bad.

[Katrina & Derrick Bradford]

Once verified the levels for accuracy, then cover the top of the TS with some MDF (cover the whole top) and make sure the TS is level in all directions. Then take off the MDF and check individual areas, you will find out where you have just a section out. Adjust and your done.

significant

[Charlie Self]

Silvan asks:

Simple answer: the levels in the combo squares aren't worth the dynamite to blow them over a squatting flea. They're crappy when new and the first knock they get sends them totally over limits.

Charlie Self "They want the federal government controlling Social Security like it's some kind of federal program." George W. Bush, St. Charles, Missouri, November 2,

2000

[Groggy]

I agree with Bridger's suggestions. I am going through the same thing. I made the mistake of buying a new No98 Starrett Machinist's level (cheap off e*ay) and now I can't find a level that is close to doing its job - except the Starrett (thanks to UA100). One level has gone to landfill and my other (reasonably new) Lufkin level I'll probably be taking back.

[Dave]

The advice already given is good. The levels in the heads of combination squares aren't usually that good. Another thing to consider is the length of the reference surface on the level. I don't know what sort of orange level you are talking about but if it has three vials, it must be longer than the face on the combination square head.

The orange level may report a level surface but keep in mind that could be just between the two ends of the device.

If you want to confirm what your first level told you, you use another level of the same length.

If you want to adjust the wing with the table, you should be using a different measuring device. A level, even an accurate one doesn't have a very high resolution.

If you are concerned about the wing sagging or riding high out at the ends you should use a long, accurate straight edge and reference off the table. Better would be two used as winding sticks to see if one corner is higher.

If your concern is the wing being level with the top right at the seam, a dial indicator on a base would be an appropriate tool.

G'luck.

[George]

Assuming you're talking about similar spans on the level, there is the waterglass option. Broad glass, compare meniscus, go with the level that's closest.

Of course, in my house, it's flush, not level, that counts in tablesaw wings. That only requires a straightedge.

[Andy Dingley]

Make a water level. Clear hosepipe, duct tape and a squeeze bottle of water with a drop of dye in it. Take you 10 minutes, guaranteed accurate.

[TWS]

and don't plug up the ends of the pipe. Air has to flow to both ends. TWS

[Dave Hinz]

Always turn the level end-for-end to make sure that the level itself isn't crooked. If it shows up as level one direction, but when you swap ends shows as not level, then the measurement tool is what is technically known as "crap".

Do you know anyone with a machinists level?

[Silvan]

True. I was just looking to get some idea how obvious the difference is with a level, because, well, because the idea occurred to me at the time basically. :)

I'm actually concerned about the wing being machined wrong. It's flush at the edge, but it seems like the far end is too high, or some of the surfaces of the waffle pattern were not ground down to the same plane as the edges. I'm having trouble figuring out which is which. If the wing is flat all the way around, then maybe the edge of the wing or the edge of the saw needs touching up or shimming, but if it's a high spot, then I guess I need to think about grinding it down.

[Ed Clarke]

You too? Bwahahaha!!! Join the club. Damn Starrett anyway...

[stifler]

A straight edge works great for checking flushness with the main table If you want to check for level as with respect to gravity, set ballbearing on the table and see which way it rools

-- stifler

[TWS]

I'm with Dave. I don't think it is important for the top to be 'level' to any significant degree. It is much more important that it be flat and this you can find with a couple of straight edges or winding sticks as Dave suggested. A single long straight edge, referenced to a single corner and then moved to all three other corners will give you a corner to corner check and then sliding the straightedge along with it perpendicular to the fence will show up any high or low spots.

TWS

[Larry Jaques]

On 26 Jan 2005 10:02:03 GMT, the inscrutable [e-mail] (Charlie Self) spake:

--snipomatic--

Right. If you want to level a machine, use the proper device, a precision machinist's level such as this Starrett:

the wider, shallower vial.

--- After they make styrofoam, what do they ship it in? --Steven Wright

Comprehensive Website Development

[max]

The way you check a level for accuracy is to place it on a fairly level surface ( level not being critical) and check where the bubble sets. Turn the level around (180 degrees) and check it again. IF the bubble is in a different place the level is not accurate. This happens all the time. max

[Silvan]

I like this answer best of all. "...aren't worth the dynamite to blow them over a squatting flea." Wunnerful.

[Tom Watson]

Interesting use of language.

OK.

Why? It was an alignment problem, not a level problem.

I realize that you are a linguist, rather than a logician, but does the concept of "category error" have any resonance at all?

You are using a verb to solve a noun problem.

watson - who likes to solve noun problems with nouns.

tjwatson1ATcomcastDOTnet (real email)

(webpage)

[loutent]

Hi Silvan,

I set up my new (1 month old) TS to what I think is almost perfection without picking up any one of my half-dozen levels.

Don't care much if it's level (as long as the boards don't slide off!).

It's pretty damn flat tho.

Lou

[Andy Dingley]

_one_pound_ ($2 !) 8-)