Optimum dimensions for 12" beam setup?

I’m designing a steel bolt together frame with a wood waste panel. It will attach to the underside of one of the runways on my 4 post Bendpak car lift, when it is fully raised and locked. Instead of a beam, I plan to make motor brackets with a 15 degree angle that will bolt directly to the runway underside 12’ apart. I have a metal maslow on order with longer chains.

I have a couple questions:

  1. for a 12’ motor shaft to motor shaft spacing, what is the optimum height above the cut area (assuming a 4’ wide sheet)? I read somewhere on an older topic that for 10’ spacing the distance should be 18". Metal Maslow says this should be a foot higher than “normal” but that just seems a bit rough (and I’m not sure if 18" is considered “normal”) when they sell a laser cut jig to ensure the spacing of the motors are 12’.

  2. I understand the motor sprocket should be such that the chains are parallel to the panel being cut. I also understand CG of the sled comes into play. When I machine the brackets for the motors, should I make them adjustable to compensate for panel thickness, or am I over thinking this? I could easily create slots for the motor bolts and have an index line on the motor mounts and several lines stamped on the bracket for say 1/4", 1/2",3/4".

  3. I just thought of this question. I’m assuming that I will mess up the calibration if I remove the chains from one use to the next? Should I plan to clamp the chains on the sprocket when I disassemble the unit to keep them in the exact same location from one time to the next?

Thanks in advance.

  1. 30"
  2. beam depth usually is only set once. if you can slot and stamp, there is no harm in that. It may or may not be needed. If you assemble your sled first and do the hang test (manual reference) you can set your ring height which will tell you how high the motor should be out from the wasteboard.
  3. if you don’t keep the chains on, you can always reset them by going to 12:00 on the sprockets, and putting the chain on at your marked link and pressing reset chains.
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unless you are significantly changing the thickness of the material you are
working with (by >1" thickness or so)

David Lang

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Thanks guys! I’m looking forward to this project. I’ll be fabricating as much as I can before the kit arrives.

If you haven’t bought your materials yet, I’d recommend using Aluminum framing instead - much lighter

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