Welcome to Fireball Tool Europe!

Mega Square

(1 customer review)

80.00165.00 excluding VAT


All Cast Iron Squares purchased on the EU web shop come with a black oxide + oil finish for better corrosion protection.

The original Mega Square is available in a 300mm or 200mm size with two material choices: Cast Iron (FE) or Cast Aluminum (AL). All Mega 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.

Roomy joint access for welding, gluing, nailing, riveting, etc.

Whatever process you’re working with, it probably benefits from some clearance around the joint.

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. 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 workpiece to crooked surfaces.

Perfect For Angle Iron

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 Mega Square is designed to get those parts square in the first place.

Flange & Web

  • 300mm squares have a profile similar to an I Beam where the web is centered on the flanges.
  • 200mm squares are similar to a “C” channel where the web is off to one side of the flange.


Mega Square 300mm

For 50mm tubing and larger, we suggest
300mm squares (76mm wide)

Mega Square 200mm

For 50mm tubing and smaller, we suggest
200mm squares (38mm wide)

Size (mm)Weight (kg)MaterialFlange (mm)
Mega 300 FE300 x 300 x 7612,5Cast Iron76
Mega 300 AL300 x 300 x 764,5Cast Aluminium76
Mega 200 FE200 x 200 x 383,5Cast Iron38
Mega 200 AL200 x 200 x 381,2Cast Aluminium38

Aluminum vs Cast Iron

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.



  • Lightweight (Ideal for welding on the go)
  • Resistance to deformation vs aluminum billet
  • Some natural resistance to weld spatter.


  • Can be be damaged if dropped or if used in heavy duty projects.

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 Squares

  • The original Monster Square is available in a 300mm or 200mm size with two material choices.
  • The Monster Square is designed to quickly set your work piece to 90 or 45 degrees.
  • Clamping is simple with multiple surfaces for quick and rigid attachment.
  • Use the radius on the tabs to use the Monster Square as a traditional speed square for layout.
  • Use the Magic Square 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 200mm in this configuration.
  • Tall 300mm 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.
  • 150mm x 100mm x 38mm, the 100mm width is perfect for picket spacing on gates and fences.
  • Minion Square is 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.
Weight6 kg




1 review for Mega Square

  1. Vít Štěpánek


    This was my second purchase of Fireball tools. I am completely satisfied with Fireball tools. I was a Tool Design Engineer for over 30 years with a multi billion dollar company. I have graduate degrees in mechanical engineering. Fireball tools are robust and manufactured to high standards. They are designed and fabricated for versatility and are appropriately priced. They are stiff enough to control large and small assemblies. Only your imagination will limit their application. It is a pleasure to reccomend Fireball.

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