Straight, true, and square...

[John Dykes]

I'm going to attempt to build a 42" diameter round dining room table top with my planes. To that end, I'm not sure my cheap Home Depot combination square will be accurate enough for my education. However, in looking at upgrades - I'm not sure what to consider. There are combination squares, double squares - 4", 6", 12"....

With what I'm trying to do (restore my own planes, relying further on planes, flatten stock, square and joint edges), what type of quality squares \ rules should I be considering?

Again, my thanks -

jbd in Denver

[Pam Niedermayer]

First determine whether your square is square. On a surface such as a table that's square, place your square and draw a line. Then flip the square and draw another line. If the lines are parallel, your square is square. If not, look for a replacement; but be sure and do the same test before buying.

Pam

[Larry Laffer]

Follow that advise. The table doesn't need to be square. It just needs a straight edge. I imagine that's what she meant.

Rich Man: Get a Starrett combination square that is forged, not cast. The cast ones are just as accurate. But they break when you drop them on concrete floors. They make them in 4", 6", and 12' Lengths. If you're really rich, get all three. The small one is great for the apron pocket. So is the Starrett 4' double square.

Poor Man: Buy an Auger file, which has safe edges, and test the square as before. Some judicious filing on the casting where the straight edge bears will allow you to correct the problem.

Poor Man part deux: Got to a stationary or art store like Blicks and get some plastic triangles. They are very accurate. 30-60-90 and 45-45-90 in various sizes.

For larger sizes, get a Carpenter's square (I use the aluminum one by Stanley) and correct any inaccuracies with the punch and hammer trick. Add one of these--they are very useful:

http://www.leevalley.com/wood/page.aspx?c=2&p=44624&cat=1,42936,42944&ap=1

You can find the Starrett forged squares at ToolsforWorkingWood

[Greg Cole]

A cheap metal one can be made fairly accurate via some lapping as well. But seriously, most of the el-cheapo plastic squares are better than the no-name (ie not Starrett etc) ones.
There was a great thread in the general ww'ing forum not too long about "squares not square & levels not level" subject IIRC.
Maybe I'm lucky, but I have a 12" Stanley that's within .003" over 12" of the Starrett version of the same thing..... but notice I have both cheap & not cheap (one stays in the shop, the other can be on the roof, on a ladder... building a deck etc etc etc). With the pricier offerings you're much more likely to get better accuracy out of the box, but there's no guarantee..... :rolleyes:

Cheers.
Greg

[Jim Becker]

While you may be able to get an inexpensive square square, IMHO, buying a good one is a worthwhile investment. You kinda need more than one size, too. Small square are very useful for both machine/tool setup and marking small parts. The larger combination squares have a lot of versatility. The really important thing in addition to things being square for real is the scale on the rule...etched, like on the Starrett is preferable to anything slathered in paint. The lines are thinner and crisper, for more accurate measurements.

[Bill Brehme]

Groz makes a box set of three different sized engineer's squares.
Oh, look... A link!!!
http://www.woodcraft.com/family.aspx?FamilyID=20413

Pretty handy little kit for $35.;)

[jonathan snyder]

I just recently picked up a Starrett 6" double square. I highly recommend it, It is very handy. I reach for it more often than my engineer squares. LV makes a 4" double that is a bit cheaper that the Starrett.

Jonathan

[Bill Brehme]

I could also agree w/ Johnathan on the starrett double square..
I have been drueling over one of them, 4" or 6", for a couple months now.
Just having a hard time finding one locally (I really dont want to buy an adjustable square without testing it for 'square').

[harry strasil]

I have found that the triangular shaped layout squares are very accurate. They are easy to use, and have the angles marked on them.

[Tim Knight]

If you decide to pursue the Starret combo's, be sure to get the matte finish on the rules. The std finish is to shiny and you will find the measurements can be hard to read due to light reflections. I have both regular and matte finished Starret rules and find I use the matte finish rules 90% of the time.

Tim

[Jerry Olexa]

Starret IMHO