Monster Square

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  • Monster Square
  • Monster Square
  • Monster Square
  • Monster Square
  • Monster Square
  • Monster Square
Frequently bought together:


The original Monster Square is available in a 12 or 8 inch size with two material choices: Cast Iron (FE) or Cast Aluminum (AL). All Monster Squares feature a stiff “flange and web” design that is fully machined on all outer edges with tapped holes on the sides for mounting tabs.

Made in USA, Patent Pending

Designed to quickly set your work-piece to 90 or 45 degrees

Speed squares and machinist squares are made for visual inspection and checking AFTER setup, the Monster Square is designed to get those parts square in the first place.

Tabs help eliminate twisting and warping in the final work-piece

The machined squares and tabs always create the perfect plane for your work-pieces to rest on. Bonus: The tabs also let you easily hold round tubing.

Clamping is simple with multiple surfaces for quick and rigid attachment

Stop spending your time and focus figuring out clamping strategies, or worse, clamping your straight work-piece to crooked surfaces.

Use the radius on the tabs to use the Monster Square as a traditional speed square for layout.

Flange & Web

  • 12” squares have a profile similar to an I Beam where the web is centered on the flanges.
  • 8” squares are similar to a “C” channel where the web is off to one side of the flange.

Customer Reviews
"I love these squares I'm planning to buy a few more. Especially the adjustable angle square. I'm an artist and have difficulty angles to weld or figure out. These squares help to ensure one step of a process will be free of errors. Thank you for creating these squares."
Alma L.
"I’ve had this square for not long at all and already I’ve used it a ton! Either at work at a fabrication shop or at home doing side work. It makes getting things square the first time so effortless, no more cutting tacks and re-squaring!"
Patrik K.


Monster Square 12"

For tubing 2 inch and larger, we suggest 12” squares (3” wide)

Monster Square 8"

For tubing 2 inch and smaller, we suggest 8” squares (1.5” wide)

Size (in) Weight (lbs) Material Flange (in)

Monster 12" FE

12" x 12" x 3"


Cast Iron


Monster 12" AL

12" x 12" x 3"


Cast Aluminum


Monster 8" FE

8" x 8" x 1.5"


Cast Iron


Monster 8" AL

8" x 8" x 1.5"


Cast Aluminum


Cast Iron


  • Great for heavy duty projects
  • Excellent resistance to deformation and raising burrs when scratched.
  • Some natural resistance to weld spatter.


  • Heavy (Not ideal for mobile welding)
  • Susceptible to rust.

Included Accessories

4 Edge Location Tabs

Our revolutionary tabs allow you to align your material up so that you don’t even need a welding table! Don’t spend thousands on a flat table, just use our squares! Tighten the tabs onto the front or back of your square and you can immediately get to work. Sure, there are different jigs out there, but can they line your material perfectly in seconds?

4 Tool-less Thumbscrews

But it doesn’t stop there. We reinvented the game by introducing our thumbscrews. Say goodbye to your hex keys and Allen screwdrivers and freely adjust the tabs with only your fingers!

Optional Add-ons

Edge Alignment Pins

Install our edge alignment pins on any square to create a large, overhanging edge which can be used to index the square on a different plane. Depending on the square, this allows you to create edges which are 90 degrees (perpendicular), 45 degrees, parallel, and even 60 and 30 degrees from the edge.

  • Use it with our Monster squares to create a speed square for layout.
  • Use it to hang the square off the edge of a table for working vertical or perpendicular to table surface
  • Use it to elevate the squares off the ground or table for extra clearance when you’re fitting and welding entire frames
  • Tip! If trying to create a parallel edge with the mega square for marking, use our shims to get that perfect distance!

What is Black Oxide?

Black Oxide, blackening, oxidizing, oxiding, black passivating, gun bluing . . . these terms all refer to the process of forming a black iron oxide on the surface of ferrous metals.

The black oxide process is a chemical conversion coating. This means that the black oxide is not deposited on the surface of the substrate like nickel or zinc electroplating. Instead, the black oxide coating is produced by a chemical reaction between the iron on the surface of the ferrous metal and the oxidizing salts present in the black oxide solution. These oxidizing salts include penetrates, catalysts, activators and proprietary additives which all take part in the chemical reaction. The result of this chemical reaction is the formation of black iron oxide, magnetite (Fe3O4), on the surface of the metal being coated. Black oxide has a range of unique properties and benefits including corrosion protection & reduced friction.

Our Other Square

  • The Mega Square is designed to quickly set your workpiece to 90 or 45 degrees.
  • Tabs help eliminate twisting and warping in the final workpiece.
  • Clamping is simple with multiple surfaces for quick and rigid attachment.
  • Roomy joint access for welding, gluing, nailing, riveting, etc.
  • Use it as an ordinary, adjustable angle square that adjusts from 40 to 180 degrees.
  • Right Angle 90 Degree Square with generous weld accessibility. Total height of 8” in this configuration.
  • Tall 12” square when fully opened and locked into place
  • Remove the fasteners to get two individual squares
  • Use the large V-groove to hold large round tubing or pipe
  • Compact configuration for use in tight spaces.
  • 6" x 4" x 1.5", the 4" width is perfect for picket spacing on gates and fences.
  • They are the first square we offer which has a built in 60/30 degree angle.
  • The cutout provides just the right amount of joint access when using it to clamp things at 90 degrees.  
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53 Reviews

  • 5
    Monster Square

    Posted by Zach on Aug 12th 2021

    An absolute must have for fabrication. These save so much time squaring up tubing; what an incredible game changer in the welding community.

  • 5
    Monster Square

    Posted by Emmett Secrest on Jun 14th 2021

    Excellent product. I don’t know how I got by without it. I’ll definitely be buy more of this product. One is just not enough.

  • 5
    just what we needed

    Posted by Steve Lester on May 6th 2021

    We love these squares we will purchase more in the future

  • 5
    Monster square & minions

    Posted by James Duff on May 5th 2021

    makes fabricating frames easy square corners are always perfect would have made things easier when i started but never to late great product

  • 5
    fits my needs

    Posted by mervin j shaffer on Apr 23rd 2021

    I would like to see you design an outside corner square

  • 5
    Great tools!

    Posted by Anthony Perez on Apr 21st 2021

    Fast shipping and perfectly square. Going to speed up production significantly

  • 4
    Aluminum square

    Posted by Jamie on Apr 19th 2021

    Great product was very impressed. Would have given 5 star if I would have received sticker with product. Will definitely be ordering more.

  • 5
    This absolutely perfect!

    Posted by Mike W on Apr 16th 2021

    This absolutely perfect. It has a strong robust feel to it. It is precise, no flex, and the pin and tabs are much more sturdy than I thought. I really love this tool.

  • 5
    Monster square

    Posted by Michael Billian on Mar 23rd 2021

    At my welding shop we make railings on the regular, I have no idea how we ever accomplish this without these squares. It made the job go twice as fast with zero headaches. my next purchase will be the minions!

  • 5
    Monster square

    Posted by Steve Lauer on Mar 18th 2021

    What a great tool
    As a master cabinetmaker this tool exceeds my expectations

  • 5
    FE Monster square

    Posted by wolf schwarz on Mar 10th 2021

    well built and very accurate. made my cart frames look factory built without elaborate jigs

  • 5
    Cast iron black oxide

    Posted by luke coady on Mar 9th 2021

    An awesome product, it will be a staple in my shop. I’ll definitely be buying more!

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