What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Precision machinist levels

captainron

captainron

Well Known Member
I had been watching for a precision level on Ebay, and after seeing an old one sell for almost the new price I bought one here:

http://www.mansontool.com/cart/shopexd.asp?id=160

These are made by Starrett, and are graduated to read .005" per foot. I have an electronic level, but trust these more! If my math is correct, 1 degree= 3600 seconds. If the electronic level reads to 1/10 degree, that would read to 360 seconds. Plus, since it only reads to 1/10 degree, it could be on the high or low end before it "flips" to the next number. So, you could be looking at 530 or so seconds before it decides to give you the higher number reading. The machinist level is graduated to read to 80-90 seconds! Much better accuracy.
 
Last edited:
Nice! One can never have too many tools!! At least that's what I say every time I find myself in Northern Tool, Ace, HD, Lowes.....

Thanks for the link.
 
Now you just have to figure out where to put that level to measure whatever you are measuring on an RV that needs that kind of precision. No doubt more accurate, but your not building a watch, your building a kit designed to be built by amatuers like me!
Are those longerons really level to the reference? Are those tooling holes really centered on the chord? Hmmmm???
 
JonJay said:
Now you just have to figure out where to put that level to measure whatever you are measuring on an RV that needs that kind of precision. No doubt more accurate, but your not building a watch, your building a kit designed to be built by amatuers like me!
Are those longerons really level to the reference? Are those tooling holes really centered on the chord? Hmmmm???
Click to expand...

A forum is just an exchange of information. I'm not selling anything here, just pointing out a tool probably few amateur builders knew even existed. The electronic levels have been highly touted here; I was just pointing out some concerns that I had with their accuracy and suggesting an alternative. This information is worth, to you, what you paid for it. To others who are contemplating tool purchases, it may have more value.
 
Thanks, but..

I am one who did know about this and always am happy to learn of another tool. So, thanks.

That said, the electronic device is not only accurate enough for me, but more importantly, it allows me to get two objects in alignment without having to level the airplane and it allows measurements of change in flaps, ailerons, elevators. It's more than a level, more like a protractor, I guess.
 
Ron,

I have the Starrett level you mentioned in your post and agree with you on the level of precision that it provides. I have used it on several friends RVs while trial fitting the wings and setting the angle of incidence. It provides a measure of precision that some may feel unnecessary ---I personally like knowing I have done all I can to "nail" something as important wing angle.
YMMV

Cheers,

Dave B.
RV9a/ECi0360/James cowl/Catto prop---106 hrs and a permanent smile!!!!!
 
Ron,

captainron said:
. If my math is correct, 1 degree= 3600 seconds.
Click to expand...

I think your math is fine but your assumption that 1 degree=3600 seconds is off. My recollection was there were 60 seconds in one degree and 3600 seconds in a full circle. I double checked myself on a couple of web sites including http://geography.about.com/library/howto/htdegrees.htm to verify my recollection.

If the electronic level reads to 1/10 degree, that would read to 360 seconds. Plus, since it only reads to 1/10 degree, it could be on the high or low end before it "flips" to the next number. So, you could be looking at 530 or so seconds before it decides to give you the higher number reading. The machinist level is graduated to read to 80-90 seconds! Much better accuracy.
Click to expand...

The Smart Tool, often called an electronic level (but really its an electronic protractor) reads to 0.1 degree. That would be 6 seconds, about 10-15 times more accurate than the Starrett level. Not knowing the precision and the accuracy of the Smart Tool has left me wondering how much the readings are worth. In my limited experience with the Smart Tool I can consistently get readings to vary by 0.1 degree. In other words, I can get a reading of either 0.0 or 0.1 degree with the unit in exactly the same position, depending on when I turn the unit on (before or after I set it down). I take this to mean the unit gives me a reading within 12 seconds (or 1/5th of a degree) of the true value. I fully expect this is enough to keep my RV-9A from flying in circles when I finally complete it.

Having said all this, I can't imagine calling anyone using a bubble level (Starrett or not) to construct an RV, a Luddite. Like you, I want to get as close to the parametric value as possible while realizing all the while there's room for a lot less precision without creating a problem. I think the Smart Tool is probably going to get closer to the true value - but it sure doesn't have the nice feel and look of the Starrett.
 
Don, I think you may be confusing things here. You wrote:

"My recollection was there were 60 seconds in one degree and 3600 seconds in a full circle."

There are 60 seconds in one MINUTE and sixty minutes in one degree. A full circle is 360 degrees which is 360 degrees x 60 minutes/degree x 60 secs/minute = 1,296,000 seconds.

best regards

erich weaver
 
Don said:
Ron,

The Smart Tool, often called an electronic level (but really its an electronic protractor) reads to 0.1 degree. That would be 6 seconds, about 10-15 times more accurate than the Starrett level.

Having said all this, I can't imagine calling anyone using a bubble level (Starrett or not) to construct an RV, a Luddite.
Click to expand...

One degree=60 minutes. One minute=60 seconds. Therefore, one degree equals 3600 seconds.Sorry, But I believe my calculations to be correct. In fact, since the Starrett level has graduations of 80-90 seconds, with the bubble one half or one third of the way to the graduation, this level would be able to show you somewhere in the area of 45 seconds or less! Since we have determined that the electronic level can only read to 360 seconds, plus or minus as much as half that much before it "flips", this makes the Starrett around TEN times as precise as the electronic level.

Even taken at face value, with the Starrett showing to 90 seconds and the electronic level indicating to 1/10 degree, or 360 seconds, and assuming that the electronic level was "dead nuts on", the Starrett is still four times as precise as the electronic level!
 
Last edited:
Take a Starrett and a Smart Level. Sit them both on a bar such as the straight edge of a 4 ft level. Shim either end of the bar until the Starrett shows level and the Smart Level shows 0.0 (be sure to calibrate the Smart Level first). Now take a piece of paper and shim one end of the bar. The Starrett will show deflection--the Smart Level wil still show 0.0. Keep doing this until the Smart Level moves from 0.0 to .10 degrees off--the Starrett will show significant deflection. Is the level of precision provided by the Starrett necessary?? -- maybe not -- but if you can achieve that level of precision should'nt you???---Personal choice !

BTW, I have both!!

Cheers,

Dave B.
RV9a/ECi0360/James Cowl/Catto Prop--106 hrs and a permanent smile!!!!
 
I want both. The smart level is designed for hanging pictures not wings. However, it is the real deal when it comes to measuring control surface deflection. It's only money. :p
 
Last edited by a moderator:
I've been pondering this for a couple of days while watching this thread...

The level shown is 12" ... what do you put it on to measure things? I have my doubts that I would be able to find anything 4' long that is consistent / flat / true enough to make the precision of that level useful. Certainly any wood in the shop would be out, and I'm not even that sure about the metal frame of the 4' levels I have.

How are you guys dealing with that?

Thomas
 
Just set it on a standard carpenter's level. That way you'll get "close" and "exact"! Also, I've found that 1" square aluminum tubing like you buy at Home Depot is very true.
 
Last edited:
captainron said:
One degree=60 minutes. One minute=60 seconds. Therefore, one degree equals 3600 seconds.Sorry,
Click to expand...

Ron, No need to apologize for being right! My apologies for the goof. Perhaps I should worry about my 9A turning in perpetual circles when it eventually flies.
:)
 
Don said:
Ron, No need to apologize for being right! My apologies for the goof. Perhaps I should worry about my 9A turning in perpetual circles when it eventually flies.
:)
Click to expand...
Don, looks like you snapped-up a great deal! Sometimes you just get lucky!
Ron
 
Poor man's level

If you get a cheap laser level and set it 35 5/16" from a yard stick, 1" = 1 degree. I used it to check my bubble levels. I was surprised how accurate they were.
To check a level, turn it end for end and the bubble should not change position. Once you confirm your level is level, then you can see how far the bubble moves to get 1 degree etc. You get the idea. Was fun to play. Now for the wheel alignment.....

Bob
 
captainron said:
Don, looks like you snapped-up a great deal! Sometimes you just get lucky!
Ron
Click to expand...

Ron,

Sometimes it's better to be lucky than right! I think this was one of those times.

Don
 
Comparison

The Starrett precision machinist's level that I purchased from another VAF forum user arrived yesterday and the Starrett beats the pants off the Smart Tool for precision and accuracy. If anyone is debating which way to go, get the Starrett.
 
Levels

Second what's been said here. I can see a smaller change on any good bubble level that with my electronic levels, but they are really useful for reading a change, for example in a control surface, setting stops etc. Both kinds are useful. In my garage the Smart level and the Sears unit seem comparable in accuracy. Good tools are fun! Bill
 
I agree with both camps - I like a bubble to find "level", and a digital "level" to use as a protractor (measuring an angular change, like control surface range).

paul
 
Level

I borrowed my local airports precision digital level that was used to set up the new PAPI lights. It reads in hundredths of a degree not tenths! Rivals the bubble for accuracy. Was afraid to ask what it cost so I was very careful!
 
At this level of precision we are far beyond useful for MOST tasks on building the airplane - these tools are sensitive enough to tell you whether you made 3 swipes with the sandpaper on your primed surfaces, or 4...
 
mannanj said:
I borrowed my local airports precision digital level that was used to set up the new PAPI lights. It reads in hundredths of a degree not tenths! Rivals the bubble for accuracy. Was afraid to ask what it cost so I was very careful!
Click to expand...

I wonder if the guy on the lawn mower knows about the precision setting of these lights!!!:eek:
 
Aren't we getting a little carried away here?

I can't measure and trim within 1/100 of an inch, and we are obsessed with better than 1/10th of a degree accuracy? What about all those pre-prepunched RV-6's, Rv-3's and RV-4's that fly perfectly well? I doubt that anyone building those was able to get such accuracy. And look at your skins along your rivet lines. They aren't always perfectly flat and smooth.

Seems to me that the Sears unit is probably better than needed but nice to have and anything fancier is just a waste of money.
 
Clearly the best option is to talk your buddy into buying one and then borrow it!!:D

This is where your local EAA really should come in. I plan to talk with the 'elders' about buying these expensive and rarely used types of tools for members to use. Tubing benders and flaring tools fall into this category too IMHO. Indispensable for 10 minutes then worthless???
 
RScott said:
Aren't we getting a little carried away here?

Seems to me that the Sears unit is probably better than needed but nice to have and anything fancier is just a waste of money.
Click to expand...

Well said and I intend to use mine not so much for absolute leveling but more as a digital protractor which you can't do with any normal bubble level.
 
Good suggestions and advice. I also believe 'absolute' accuracy is not necessary for homebuilding aircraft. However, speaking for myself, I really enjoy getting things perfectly straight and level (OCD or what?:D) so buying anything other than the most accurate of the digital levels is a waste of money to me.
 
You must log in or register to reply here.
Back
Top