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  • Gantry Wheels

    Am about to start making a set of swivel wheels for a gantry, could anyone
    tell me what the correct offset should be to allow the wheels to swivel in regard to the direction of travel.

  • #2
    any offset will make them swivel. the longer the offset the easier they turn but makes the handling poor.

    Comment


    • #3
      I put locking casters on my gantry. Not the kind that locks the wheel from turning, the kind that locks the caster from rotating. That way you can lock two of them straight and leave the other two rotating and "drive" the thing much more easily. Also, you can lock wheels offset by 90 degrees so the gantry cannot move.

      The biggest problem I have with my rolling gantry is my uneven driveway. It looks flat, but it isn't. I wish I had some kind of slick adjustment to make one side of the beam adjust vertically by an inch or so to level the beam after moving it. Right now I have to roll it up onto boards, which is irritating.

      I made mine height-adjustable so it can lower down far enough to roll into my shop, or high enough so I can lift a Bridgeport onto a low trailer. Suits my needs very well.

      I used a commercial beam clamping product to bolt the beam to the legs, so the whole thing can knock down and be transported in a 5x10' trailer.

      metalmagpie

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      • #4
        May try it with two fixed and two swivel similar to my engine hoist, the fixed
        could be made to be rotated 90 degrees and pinned.
        How does between 1/3 & 1/2 the diameter of the wheels sound for the offset. Wheels have been fabricated from heavy pipe 6.5" in dia,2.5" wide, 5/8" plate centres with I.5" bosses drilled to 7/8". Swivel pins will be 1"dia.

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        • #5
          Heres the ones I bought.....the offest isn't very much, it would be nice if they had a better side view......

          http://www.princessauto.com/all-seas...ter-with-brake

          MM I would be interested in seeing that beam clamp.
          Opportunity knocks once, temptation leans on the doorbell.....

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          • #6
            If by swivel wheels you mean casters do yourself a favor and dont unless the casters retract and there are solid pads/feet in use for actual lifting. If you want a safe and dependable system otherwise use lockable rollers that have a good crown to them.
            "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."

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            • #7
              1/3 sounds good to me. I'm sure there is a magic formula "somewhere".

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              • #8
                Originally posted by hardtail
                MM I would be interested in seeing that beam clamp.
                I ordered them from beamclamp.com and I got part number BT1G12, not that I can find them on their current Web site .. but poke around there, you will get the idea.

                Incidentally, if you want to see my working sketches click here: http://www.tinyisland.com/images/temp/gantry.pdf

                metalmagpie
                Last edited by metalmagpie; 03-29-2011, 07:35 PM.

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                • #9
                  How about some crank down leveling jacks. Levels and secures at the same time...
                  Who do I think you are...?

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                  • #10
                    Originally posted by HAP
                    How about some crank down leveling jacks. Levels and secures at the same time...
                    I like the idea, HAP, but I'd have to spoil the clean lines of my gantry to do it. Still, it's worth thinking about ..

                    metalmagpie

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                    • #11
                      FWIW-
                      The offset in casters is properly called "trail".
                      I think someone along the line some time ago thought the offset was actually caster, and the name stuck.
                      Another odd thing, the industry calls them "swivel casters" and "straight casters", and I would say a straight caster has no caster, or more properly, no trail. Odd how language evolves.

                      Lets see some pics of this gantry. He He He...

                      -Doozer
                      DZER

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