File this under great hardware finds. - I needed low-profile, high capacity wheels for an effect and stumbled onto these. They are load wheels for a pallet jack (the wheels pictured are Crown part number 44506 / McMaster 2670T58. The yellow caster mounts are shop built.)

44506 Load wheel specs:

• 2500 lbs load rating!
• 3” diameter x 3 7/8” wide
• Roller ball bearings
• Shore 90A polyurethane tread
• Slightly oversized 3/4” shaft (about 25/32”)
• $30 each from Mcmaster
• $45 each from a Crown distributor (price will undoubtably vary)

What makes these attractive? Comparably rated caster wheels tend to be much larger in diameter, cost more, and don’t usually feature roller ball bearings. (Mcmaster’s “High Capacity Nylon Wheels” come close, but they are a Shore 80D. That’s as hard as a hard hat!) Crown lists these wheels as “load wheels”, McMaster lists them as “Polyurethane-Tread Pallet and Lift Truck Wheels”.

Here’s a link to Crown’s wheel and tire catalogue (PDF.)

If you want to do your own research, a quick list of some pallet truck manufacturers: BT, Crown, Hyster, Lift-Rite, Multiton, Prime Mover, Raymond, Rol-Lift, and Yale.

Ever wish you were better at math? Me too. I’ve been teaching myself calculus and stumbled on Better Explained, a blog with excellent math explanations. The author’s aim is to make math concepts intuitive. Now I actually understand what the imaginary number ‘i’ is all about; it wasn’t hard at all.

Sure most people think math is boring, but that’s because they probably don’t really “get” it. Don’t worry, it’s not your fault you don’t enjoy math. For those of us who endured a crappy (though deemed “standard”) math education, I point you to an article by Paul Lockhart called A Mathematician’s Lament. In it he describes the failings of the current K-12 math educational system. I felt both vindicated and angry as I read it. This is absolutely required reading.

Danger Will Robinson! The cast iron wheels pictured below are the ones that were spec’ed in Keith Cornelius’s 1997 Tech Expo article An Inexpensive, Human-Powered Roll-Former. (Grainer part numbers are #3G262 and #3G263.)

Obviously they’ve changed a little bit since 1997; the new “feature” is a crown to the surface of the wheel. Unless you’re looking to mangle your steel whilst bending, I suggest you find flatter wheels.

I suggest finding flatter iron wheels through Mcmaster-Carr. Their 4” wheels are comparable in price, though Mcmaster’s 5” wheels are around $30 while Grainger’s 5” are around $13.

This is what a rotary milling table looks like after disassembly. Sweet.
Click the pic for a larger version.

Man, I wish I still did sound design. I got bored and made a business card. For what reason, I don’t know. Contact information follows on the other side in a similar style, but I didn’t post it for obvious reasons.

How much force does it take to bend 3”x16ga box tube to a 5’ radius in one pass? What’s the largest steel shape you can jam in a typical scene shop-built manual roll bender without cracking a roller? A week ago I didn’t know the answer to either one of these questions, now I’ve got a pretty good idea.

We’re talking about making a roll bender at work, and are waffling over whether to build a manual or motorized bender. I realized that we didn’t really have a handle on the forces involved in bending various steels to various radii; these numbers are instrumental when making this decision. (Not to mention during the design process.) Earlier this week I sat down and created an excel file to shed some light on the situation. Figured I might as well share it with my peoples.

Snag the files here: XLS or PDF

The majority of the worksheet calculates for:

1. The force required to bend a variety of steel shapes to various radii in one pass (à la motorized bender).
2. Adjustments for three different roller/die distances: 12”, 16” & 20” apart.

The manual pass sections are intended to show how much force would be needed when making the first pass in a manual roll bender. It calculates:

1. The force required to reach the yield point of each steel shape.
2. The resultant deflection and radius achieved in the first pass.
3. The above calculations adjusted for three roller/die distances (12”, 16” & 20”).

Big effin disclaimer!
Lets be honest folks, I’m not an engineer. Confidentially (just between you and me) I am confident that the calculations are fairly accurate. But under no circumstances will I claim that they are 100% accurate. The reason is this: the last thing I need is a lawsuit because someone too lazy to verify the math took it in the eye from a flying bit of steel. Don’t you dare cut corners.

This worksheet is only intended to give a general idea of the numbers involved when bending steel. It cannot be counted on to give precise data concerning specing and designing of a specific machine. There are no allowances for the inherent springy-ness of mild steel, dodgy steel quality and varying manufacturing tolerances.

Bending steel is indeed a fudgy art. But now you’ve got some numbers.

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