Try square vs engineer square

[LCHIEN]

I have in my toolbox a metal 6" engineer square which I use for checking square jointer fence, table saw blades and miter fence and rip fence, band saw table to blade, drill press table to bit etc.

I was thinking it would be nice to have a slightly smaller one for when the clearance is not real high as for the band saw and drill press. They generally are made with 2, 4, 6, and 8" and sometimes bigger, those four often being sold as a set.

I was looking on the internet, woodcraft, Rockler, amazon, ebay for engineer square and try square. the names Try square and the engineer square are often used interchangeably, usually the engineers square is made entirely of carbon steel and the try square is made of rosewood and steel and brass rivets and facings.

The rosewood and brass fitting make a try square look classy, I thought for the small additional amount it might be nice to have.

But Woodcraft had an article which points out the main shortcoming of a try square:
http://www2.woodcraft.com/PDF/77A33.pdf

While I did find a try square with two brass facings, the wood movement makes it a less accurate instrument especially for making outside measurements which is primarily how I use the table saw, drill press, band saw tunings.

I guess the engineer square calls for careful 90° machining for both the outside and inside edges and to each other. This also makes sure that the blade and foot (for lack of the proper terms) have perfectly parallel and perpendicular edges.

One disadvantage of the engineer square is the carbon steel... it tends to rust esp if you leave fingerprints on it after handling on a warm day (sweaty hands - almost everyday in Houston). Anyone have a good solution to this that doesn't leave the tool greasy or oily or filmy feeling? I imagine a stainless steel one would be more expensive both because the material cost and because machining stainless is much harder than carbon steel which is very easy to machine to fine tolerances.

I suppose I should look up exactly how much movement you can get in a rosewood piece 1" thick...
P.S. according to an on-line wood movement calculator, Rosewood is a more stable wood than most. one inch will expand about .002 to .004" from 8% humidty to 20% humidty - that will throw the outside of the square with a 3" leg off by about .07 degrees... That'll probably do just fine.

[cabinetman]

The article specifically discusses try squares with Rosewood handles. Might be that it's what they sell. I've had many try squares some with Beechwood, Hickory, or Maple handles. I check them for square for both inside and outside, and haven't experienced movement issues that affected squareness.

It's possible to get absolutely anal about woodworking accuracy. It's not metal working, like tool and die making. For however close some milled piece of work or joint is at the end of the day, can measure differently in the morning. Engineering squares (all metal) do minimize the possibility of movement.

For all intents and purposes, plastic drafting templates work just fine for checking sawblade square to the table, 45°, or miter gauge to the blade or fence.

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[RAFlorida]

For carbon steel, I use

Johnson paste wax to control rusting. Not the best, but it doesn't leave the tool oily.
Thanks for posting about the two squares. All that's in my tool box is the try square w/hickory.

[woodturner]

I have in my toolbox a metal 6" engineer square which I use for checking square jointer fence, table saw blades and miter fence and rip fence, band saw table to blade, drill press table to bit etc.

No square will ever be "perfectly" accurate - and even if it were, the adjustments in our tools would limit achievable accuracy.

When I truly need accuracy, as some aspects of woodworking require, I use a a caliper or micrometer. One can use a caliper to determine square, using a 3-4-5 triangle of measurements, but it's really overkill.

What I find more productive is to use techniques that will give accurate results, regardless of the tool accuracy. For example, when cutting two board edges on the tablesaw or jointer that will be glued together, run one on one side of the blade and the other on the other side. This results in one board having a positive error, and the other having a negative error - so when the boards are glued together, any error cancels out and the surface is true.

[Knottscott]

...Anyone have a good solution to this that doesn't leave the tool greasy or oily or filmy feeling? ...

Apply a low voltage, or store it in a cloth bag with a dessicant.

[LCHIEN]

...

For all intents and purposes, plastic drafting templates work just fine for checking sawblade square to the table, 45°, or miter gauge to the blade or fence.
...
The article specifically discusses try squares with Rosewood handles. Might be that it's what they sell. I've had many try squares some with Beechwood, Hickory, or Maple handles.
...
.

good point, in a pinch or on a tight budget they (plastic drafting triangles) will certainly do.
The engineer square stands on edge and is a bit weightier and the edges hold up better than plastic. I have a pair of plastic triangles on hooks on my pegboard where I keep a combination square, and push shoes and some other layout tools including circle template. But for critical machine setups I like the engineers square.

I looked up expansion tables and rosewood is much lower movement than your average wood. I would also imagine but didn't look up hickory, Beech, maple would also be fairly low in relative movement rate for wood compared to average. I imagine the low rate of expansion/contraction is why rosewood is very popular for measuring tools, but being a localized wood has often been substituted for with the other woods mentioned.

by my calculations the movement of a rosewood base would cause less than a 1/10th of a degree change in a 4-inch square with a 3-inch long base and a 4-inch blade for an 8 to 20% humidity change. Which is probably better than needed for woodworking.

[pelligrini]

When I first saw that Woodcraft article I immediately thought that the movement wouldn't be much at all. Probably still within most manufacturing tolerances for woodworking squares.

I have a set of Groz engineer squares which I use quite a bit, and a couple larger sizes. I like the heaver base of steel squares. Paste wax or Boeshield works pretty well for rust prevention. The 2" one is really handy.

You could make a square too, but most all of the wood ones I've seen are larger than you're wanting:
http://www.popularwoodworking.com/wo...old-try-square

http://www.popularwoodworking.com/wo...nd-a-slideshow

http://www.popularwoodworking.com/wo...-layout-square

[cwsmith]

I'm a "plastic triangle" fan. I've got several of them from my many days on the drawing board.

From an accuracy point of view, almost anything made of the graphic arts/drafting business will be quite accurate. Arguably, a top-quality machinist's square will be better, but I question whether woodworking setup to 0.0001 is practicable. But each to his own.

I actually have a set of those cheap aluminum HF "machinist triangles" and they are not bad. But since I pretty much only use the outside angles for setup, a plastic triangle works well for me.

Good quality does come into question though and I'm not sure what "brands" are even available today. "Deitzen" was the preferred brand when I was "on the board".

I do have a set of "Theo. Alteneder & Sons" stainless steel, machined triangles (30-60 & 45 10" length) that were grossly expensive, even back in the 60's when I purchased them. But, they are too big and combersome for most uses and are primarily used to check the accuracy of other squares and triangles that I have.

Tri-squares have never been a favorite of mine. Simply I don't find them all that accurate. Framing squares are of course notorious. I do have a "rosewood" tri-square that my father had, but it is way out of alignment and worn to the point that it must be something that perhaps his father had. It is a "Stanley" but is worn to the point where you can hardly identify that... but it was "Dad's" and thus it has value in keeping.

CWS

[cabinetman]

I'm a "plastic triangle" fan. I've got several of them from my many days on the drawing board.

From an accuracy point of view, almost anything made of the graphic arts/drafting business will be quite accurate. Arguably, a top-quality machinist's square will be better, but I question whether woodworking setup to 0.0001 is practicable. But each to his own.

+1. 'Alvin', 'Graphic', and 'Pickett' brands come to mind.

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