"Large" try square

ptschram · Mar 12, 2021

Gentlemen and Ladies (I'm sure there are a few ladies amongst us)

While this is very basic and elementary, I haven't had much luck finding what I'm needing.

I'm currently working in a cabinet shop as Facilities/Maintenance Engineer and I have frequent need for a larger scale Try-Square than I have and can find easy access to.

The facility has numerous fences on saws, assembly tables, and other things in the shop where two surfaces must be perpendicular to at least 1/64". Yes, I know, we hold much tighter tolerances everyday, but this IS a cabinet shop.

All of the squares I have found have been T-Squares, folding (that sounds precise, accurate, AND repeatable), or costing several thousand dollars-I'm a Starrett man through and through, but my boss and management are not going to approve a ~$5000 square!

Ideally, I'd like three individual Try Squares with blade lengths of three, four, and six feet, in "Workshop Grade".

Any suggestions? If I put this in the wrong category, mods, feel free to move!

PT Schram
Facilities/Maintenance Engineer
Dutch Made Custom Cabinetry
Grabill, IN
USA

Booze Daily · Mar 12, 2021

You may just have to have something custom made. What are other cabinet shops doing?

RC Mech · Mar 12, 2021

I have a 36" Starrett master square at my shop and just looked up the new price. You're correct, that's a $5k square!

I'd have the required geometry laser cut from 1/4" plate if I were you, potentially stainless cost permitting. Draw some L's with 4" x 72" legs x 30" or whatever your short leg is, and leave a small radius undercut at the inside corner for clearance.

ptschram · Mar 12, 2021

RC Mech said:
I have a 36" Starrett master square at my shop and just looked up the new price. You're correct, that's a $5k square!

I'd have the required geometry laser cut from 1/4" plate if I were you, potentially stainless cost permitting. Draw some L's with 4" x 72" legs x 30" or whatever your short leg is, and leave a small radius undercut at the inside corner for clearance.

I was shocked to find that my six inch Starrett square I got from a Grandfather's Estate was nearly $500!

One of the machine shops where I worked in 2019 had a square with a six foot beam, I didn't fully appreciate it until I started here.

I am afraid that given management's mindset, I'll be using a $50 folding square or cutting the leg off of a drywall square...

Cyclotronguy · Mar 12, 2021

Starrett has a large machinist square the 8H I think. A bit more spendy than I wanted so I took one of the off she shelf drywall squares and amputated the blade back to what to me was a more friendly length and then trued up the head on the mill referencing off the blade.

Cheap, fast, easy and good nuff to get accurate scribe lines on sheet metal

ptschram · Mar 12, 2021

Cyclotronguy said:
Starrett has a large machinist square the 8H I think. A bit more spendy than I wanted so I took one of the off she shelf drywall squares and amputated the blade back to what to me was a more friendly length and then trued up the head on the mill referencing off the blade.

Cheap, fast, easy and good nuff to get accurate scribe lines on sheet metal

I'm afraid that is what I'll likely end up doing, however, the Bridgeport "Drill Press" i have here is pretty well clapped out.

Phil in Montana · Mar 12, 2021

I just made one used alumium flat bar and 3,4,5 drilled holes and tight bolts worked great...Phil

wesg · Mar 12, 2021

ptschram said:
Gentlemen and Ladies (I'm sure there are a few ladies amongst us)

Yes, but not a single 'Gentleman'.

Not nearly as big as you'd like, but likely as accurate as you'd need:

https://lambtoolworks.com/square

pavt · Mar 12, 2021

I did a similar job once, by making a 3-4-5 triangle out of 2x2 angle iron, welded. Make sure the angle is reasonably straight first. Might have to brace the completed job in the middle.

neilho · Mar 13, 2021

If it were me, I'd make something like a large version of a speedsquare. Start with 1/4" 6061, add 1/4 x 1 "edges" if needed. Waterjet with lots of lightening holes. One could check them against each other with a large surface plate or straightedge.

Or, even less expensive, buy a sheet of aluminum, check for square across the corners, lop the corners off with a skilsaw. Instant squares. Lightening holes a bit more difficult, maybe unnecessary.

AdamC · Mar 13, 2021

Your boss is right. You don’t need any of those squares. Get a decent straight edge and tape it to a flat table. Place a framing square against the straight edge, draw a line then flip it over and draw another line. The two lines should be parallel. That will verify the square. You could stone or file the square to adjust. Then use the framing square and a couple straight edges to check whatever you need.

Measure across corner to check rectangular tables. Table saw fences aren’t set square to the table. They are set parallel to the blade.

I understand why you might think you need large machinist squares, but I think there’s another way to do what you want without them. That’s what everybody else does.

neilho · Mar 14, 2021

He's looking for a square with a side 6' long. A framing square is just a wee bit undersized....

wheels17 · Mar 14, 2021

I have no idea of the accuracy of this sort of square. Certainly not machinist grade, but with testing you might find it is good enough. You are only risking $14:

https://www.homedepot.com/p/Johnson-48-in-Aluminum-Drywall-T-Square-JTS48/100353817

These are more akin to the old drawing T squares, but come in large sizes. Price is reasonable, but shipping is apparently an expensive problem:

96" x 2"Heavy Duty T-Square 8ths,16ths

The accuracy of a T square is easily checked by flipping it.

Pattnmaker · Mar 14, 2021

I would just make a square out of Baltic birch plywood. I made some several years ago for a rail car manufacturer the size he's looking for and made one for myself while the job was loaded on the router. Way lighter than the other options which is important for handling a square this size. The plywood is stable enough to hold the tolerance he's looking for. Unless measurements really need to be taken on the inside leg going with a triangular support on the inside leg is a good idea. Strips can be added to make the square like a speed square if wanted.

ptschram · Mar 16, 2021

neilho said:
He's looking for a square with a side 6' long. A framing square is just a wee bit undersized....

Six foot would be great, but I found a 36” for less than $200!

Waiting on purchasing now

As for gentlemen, not only am I a gentleman, I am a “Well-Experienced Gentleman”

You kids, get orf my lawn!

Ries · Mar 16, 2021

I have 4", 6", 12", and 18" Starrett adjustable squares, speed squares, a bunch of framing squares including a copper plated one that weld wont stick to, aluminum sheet rock squares, drafting squares including flourescent orange ones that are up to 24". Bigger stuff, we usually use geometry, often I have built things that need to be square up to 20' on a leg- 3/4/5 triangles are good for that. Hanson actually makes an aluminum square that is 3'x4'x5'. 8' t squares are out there.

adh2000 · Mar 16, 2021

If you’re interested in antiques there are lofting squares like this one that I have:

Hard to find these days they go back to when the wooden ships components were drawn full size in the loft. Who knows, Herreshoff himself may have had his hands on this square.

Sent from my iPhone using Tapatalk

Dresden · Jun 21, 2021

make a pair out of very good straight grained dense wood, a guy on Utube shows how, and as a Millwright I agree with him

the wood ones are light and self proving, the fences ect can be checked for straightness with tight fishline and a Starrett fule, use a optivisor 5X

thermite · Jun 21, 2021

Phil in Montana said:
I just made one used alumium flat bar and 3,4,5 drilled holes and tight bolts worked great...Phil

3-4-5 works well with ignorant poly packaging twine and eyelets for a stylus, too. Or metal. Or wood. And rivits or shoulder bolts.

"BFD" IOW.

"Nature" is actually helping..... for a change.

BHolcombe · Jul 27, 2021

I am a professional woodworker.

I had Darrel Smith (older brother on PM) scrape me up a boxed straight edge. Along with that I use an 18” Mitutoyo, 6” starret, 3” mitutoyo and a couple of angle blocks that Darrel scraped for me.

This has been used to setup my equipment, and check it periodically and saves me considerable time and energy precious wasted ‘fitting’ parts that now fit together perfectly every time.

"Large" try square

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