spirit levels

[-MIKE-]

The point he's making is that close enough is close enough for most uses of a 2 or 4ft level. If you need more accurate, you go to a 6 or 8ft level. I have a few 4ft levels and more, for whatever reason, is much more accurate than the others. In many situations, I don't use it because it is a bit of a PITA. I don't need to be scootching an 8ft wall back and forth to try to achieve plumb to within 1/64". That's what happens with this particular level. The center of the spirit vials is much flatter requiring much more precision in movement to get the bubble dead-center. Whereas, the other two have a much more pronounced curve to the viral meaning the precision of movement needed to get the bubble dead center is much more forgiving. When that level is dead center, it might be accurate 1/16" in 8ft, which is plenty enough for framing.

It's like using the course adjustment instead of the fine adjustment. Just like with a framing square. It needs to measure decent framing angles, not send a space probe to mars.

[Clare Snyder]

I've addressed it. There ARE different "sensitivities" of level - call it "accuracy" if youi like - or "resolution".

It is specified by number of degrees per unit of measurement bubble displacement - such as .05/2mm, or in units per unit of deflection - like .2/1 - 0.2 inch bubble deflection with one end of 3 meter level raised 1 inch.

Can also be metric. An engineer's precision level (machinist's level) or a survey transit may be as accurate as .005 degree per 2mm bubble deflection, while a carpenter's square is tiypically closer to 1 degree - and a plumber's level may have 3 or 4 vials of different accuracy for measuring different "drops" for different drain or pipe installations

As far as a level being able to measure totally level both ways on a surface that is not level - not possible. Even the cheapest level will only read level on a level surface, both ways, if it is level to within a VERY small limit of error - if you can read the bubble accurately

[Clare Snyder]

A 6 or 8 foot level is not necessarily more accurate than a 24 inch level - and in fact there are 4 inch or 6 inch levels that are MORE accurate than the runof the mill 4 or 6 foot level

You figured it out!!! It's not the length of the level that makes it more accurate, it's the radius of the vial.

Or close a survey within 1/10 of an inch over 2000 feet.

[Bill]

Yes you did. Thank you! I knew there were different "standards", but I wasn't familiar with the underlying physics. I appreciate the thoughtful lesson!

Happy New Year, Bill

[Emanuel Berg]

So what level should one buy for general purposes? I won't abuse it. Today I made a fence with planks to three horizontal bars (ribs?) if you want an example application.

By the way, here I might also ask what way to put the planks with respect to the age rings? I thought I'd put them with the imagined circle away from the bars, so that the plank will naturally bend that way (toward the bars) over time. I'm not sure that will happen tho or if this is something to care about at all?

Third question, the posts down in the ground, does it really help if you first put them in to a barrel with a fire?

[-MIKE-]

I didn't say it was, nor imply it. You get a more accurate reading per the application by using the longer level. It also helps you find a more accurate reading because it bridges the bow in a stud farther than a 4footer. As an example, my 6' level is less accurate than my 4' level, but in the above application, it give me a more accurate reading, in context.

[John Grossbohlin]

Stabila has specs for each of their levels and all the ones I looked at say "±1/32in @ 72in." I did not find specs for Stanley levels.... Irwin guarantees vial accuracy for the life of the product at .029 degrees but say nothing about the accuracy of the placement of the vial in the level's beam.

One issue I haven't seen mentioned is that longer levels tend to give a better overall indication of level as they average out the irregularities in the surface being tested. For example, if you use a 2' level to plumb a 2x4 stud wall you run the risk of placing the level at different points in the curve (no matter how slight) of the stud upon which the level is placed. A

6' level would tend to give a better indication of overall plumb in such cases but a 4' probably suffices. Same kind of issue with laying bricks or blocks... a 2' level would be subject to the variation within the few units it's touching rather than giving an overall indication of the course... again a 6' level would be better but a 4' probably suffices.

Put another way, there is the accuracy of the level itself (to include the vial, the beam, and the placement of the vial in the beam) and then there is the accuracy of the application of the level. I dare say that the level in my Starret combination square is highly accurate but it would be pretty much useless for use in plumbing and leveling the framing of a house.

[krw]

Good point and something worth considering in the future. My benches are on wheels, so it's not possible to (keep) the front level. I'll have to check them for straightness. I can use my saw table for that, if needed, though.

The instructions for my RAS showed how to do this as a setup step. Works well.

[krw]

"Rails" I'd use at least a 4' level for this. An "I-Beam" or "Box" level is probably the best. "I-Beams" tend to be cheaper, at least here. If you aren't going to abuse it, don't spend a lot of money, just buy (test) a good one. Find a place to keep it where it won't get dinged (and where you'll remember where it is ;-). A 4' level is good for the posts (vertical part), too.

To lay out a fence, I'd use a "water level", described elsewhere in this thread.

Center of the tree down.

Good plan. Also, splinters down, if you're not going to keep them well painted/stained. Up if you don't want people climbing the fence (e.g. around a pool).

Never heard that one before. I'd make sure they were rated for ground contact. Also, put the bottom few inches in sand or, better, gravel. Paint all cuts with "green" stuff and cut the tops (perhaps after the fence is done) at an angle so water doesn't sit on the post tops. They also sell post covers, here at least, to keep water off the post ends. They're a worthwhile addition and can be quite attractive (and pricey). I'm partial to the copper ones. ;-)

[Clare Snyder]

a 2 or 3 ft level is the handiest - if you are only going to have one, I'd have a 2 footer

Not critical, but I usually put the concave side to the post if using screws.

A charred end MAY have some advantage

[Clare Snyder]

A high precision "square level" is only about 3 inches long, but when snapped onto a 2 foot framing square it is HIGHLY accurate. On a 4 foot drywall square, even better - yet it is only THREE INCHES long. Similarly, using a 2 foot level with a good straight "guage board" of whatever size you like makes the 2 footer "accurate" over the longer distance - while a 4 foot level id totally useless if the space available for lefeling is less than about 47 inches - - - -

Your Starrett combination square could well give you better accuracy used in this way than your 4 or 6 foot level - and it will level a 8 inch surface as well.

[Emanuel Berg]

Stainless, self-drilling deck screws with a "milling" (? - direct translation). I put them in with a drill driver (torx 25 head) without drilling first - very easy...

... you don't sound very convinced? :) Anyway thank you and krw and everyone else for answering.

[whit3rd]

Or, adjust it (for old levels, with replaceable vials, this was always possible). Nowadays, the adjustment feature is sometimes absent.

Many manufactured items look 'fixed' though a litle hot vinegar would dissolve the matrix around the vial, and allow adjust/replacement. Every bent old level is a source of replacement vials when one cracks...

[Leon]

Most any level is going to be accurate enough for wood, especially construction grade material.

Are you asking which way to place the pickets? Does not matter, a nail about 1" in from each side and one in the middle if it is a wide picket.

Whuuut???

[krw]

Try going through the levels at HF sometime. I've found some real stinkers at the Borg, too.

Uh, Leon, the picket points go *UP*. ;-)

I think the idea is to carbonize the outside so it tastes bad to critters. It might even work (burn off the sugars) but I'd think it would be pretty hard to control.

[DerbyDad03]

[Leon]

Makes sense, wood rots or is eaten because it is a food source. Charring it would get rid of the nutrients.