try square question

A square without markings would be used for machinery setup, squaring wood and glue ups etc.

Some people use the square to square things and or make square marks or lines. I personally never use the markings on the square. The same could be asked why anyone would use a rule to draw a straight line. This may go back to the way Drafting is/was formally taught. You never use a measuring tool to draw lines.

I can't comment on the Footprint square, but I have about 4 try squares in various sizes and except for one, I've been disappointed in their accuracy. I now use only my Starret combination square. I would never buy one that I couldn't check for squareness prior to purchase.

Well, with me knowing my impulse ratings, that is a good thought and good advice for me to discipline myself with. But I have nothing to check one with, and the only square in town I can find is a current Stanley, sells for $17.xx, steel rule part does have measurement, wood and brass. Looks cheap too.

Alex

That all makes sense, I need a good tutorial on it, I'll get there. A drafter's T is for drawing lines. Alex

Try squares are handy to just grab and "check for 90" (ensure things are at right angles). Not a couple of things about try squares - (1) many are only claimed sqaure on one face (the side with the brass) and (2) their precision varies.

E.g. Ppl have reported their Incra try sqaures accurate; a few have said not. I'm not going to mail order any instrument that's supposed to be precise -- unless it's a Starrett (or similar brand I've grown to trust.)

A square is often used to only verify 90 degrees. Think machining.

Wes

First thing the picture in the link is of a regular square not a tri-square. A tri square will have a face that is cut 45 degrees from the blade enabling you to mark out 45, 90 and 135 degree lines thus it name tri-square.

Chris

I'ts in the words..."Try", meaning "check", and "Square" meaning 90 degrees." It's use to check for dead-on 90 degrees, that is angle measure, not for measuring length. For example, you'd check if your blade was square to the table. It is also used for marking 90 degrees.

Linear measures are added to extend the possible use on some squares, but the Try Square still serves its purpose.

Bill.

Sure you do. Remember the "perpendicular bisector" construction in semi-formal geometry? One straightedge, one pair of compasses, one sharp pencil, and you have all you need to draw a right angle and any number of other angles and constructs. These are theoretically, and if tools are good practically dead on exact. Check against that.

Bill.

Or a straightedge, although the T is [was] more commonly used.

Bill.

Ha Ha! good one!

Squares without marks are usually (but not always) more precisely square. I use my expensive squares without marks only for CHECKING squareness. I use my less expensive squares with marks for layout and scribing lines with an awl or marking knife.

Nope. The one in the picture IS a tri square. What you have described is a Combination square.

You check it against itself. Place against edge, use it as guide to draw line perpendicular to edge. Flip square over. See if it lines up with the line you drew. If it does then it's square, if it doesn't then it's not.

Most places selling squares will have a flat surface somewhere close where you can verify your desired purchase against a minimum of three others. If you think about it, take a piece of ply with a straight edge with you and use the line compare method or the 3,4,5 method to check for 90 degrees.

Irregularities in the edge can be fettled out, as can out of square, but why start at the bottom when you can start at the top?

You almost lost me on this one, but I see (I think). You mean that you'd hold the scribe or knife against the mark while dragging the two down the length of the wood? Then it makes sense to have a cheap square for that purpose. Myself, I'd rather use a tool designed for that purpose: a nice rosewood/brass marking guage.

Bill.

So, that's why the Starrett squares are so inaccurate.

The brandnametools people have mislabeled the Stanley 46-502

Never heard of a tri-square before.

scott