I think I’ve shared this one before when I first made it. I use it now and then still. Tonight was one of those nights.
I call it a poor-mans fireball square. (Which I had one before too but I left it in Hawaii.
The goal was to make a clampable square for fixturing while welding. The fireball versions are nice but big $$.
I took 3 of the small Harbor Freight squares, held them all tight and stacked perfectly on top of each other. Then drilled a few holes through all, and then spaced them apart with nuts to keep them parallel. The spacing apart allows them to be a wide enough area to be clamped with a C-clamp on each leg.
I also chamfered the outside corner of the squares when I first made it. That gives a little extra corner clearance to maybe clear any weld beads or anything when using it on the inside of the material corner.
Works great, but it does take a little fine tuning to get everything positioned perfect and ready to weld. The Fireball version comes with tabs that help keeps the square parallel to the material which speeds up the setup time.
The Harbor Freight squares are at least a cheap version of stainless steel which helps with keeping the rust at bay and any weld spatter to fall off a little easier.
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If anyone wants one I could make you one for time and materials. Or they are obviously easy to make yourselves.