My buddy and I are building two English wheels out of 3/8 ' plate HRS. The "C" frame outside and inside flanges have been rolled to shape , the center web positioned and then welded in place. Each is about 6 feet tall with a throat of 40 in. The width of each of the flanges that comprise the "C-frame" is 3/8 by 6 in. PROBLEM: When you stand facing the machine (as if you were forming a piece of metal) and take your index finger and push in on the outside dia of the wheel, the top half of the "C-shaped" frame flexes very easily with just the slightest pressure.You can see the entire upper half and 1/3 of the lower half of the "I-Beam" C-shaped frame flex back and forth in a harmonic motion like the pendulum of a clock. It will stop moving after about a minute. Needless to say this is most distressing as we had not anticipated this. Any ideas on why this is happening and possible remedies are very much appreciated. All frame pieces were water jet cut. Photos attached. Thanks, Jim
I-beams truly suck for torsional rigidity. They are stiff, but don't deal well with torsion, which is exactly what you are applying when side loading the upper portion of the frame. I would say the best solution is to plate the outside of the frame. It may not look as cool, but you will gain stiffness in all directions. From the sounds of the material used, you might even be able to get away with plating the outside with 16ga. Just my thoughts. Tim D.
i think i would try boxing it with plates with the same holes you have, and if that still doesnt do the trick you could weld tubes in the holes, also i wonder if there is tension in your frame that could be removed by a little time in a powder coaters oven?
What he ^ said. "What if" you had two more center "C's water-jet cut and boxed them on the outside"? Kind of like if you used both of the original "C's" to build one stand. ' just thinking.
We thought about that ( laying one "C-Frame on top of the other and welding them together flange to flange) but were not absolutely sure it would solve the flexing problem and thought it might be too massive. Thanks. Keep the ideas coming!
Seems like you made a cool looking coat hanger. Trianglular sections are far better for torsional rigidity. a bitch to make but any type of box section is better than an I beam. The reason they get away with an I beam cross section on the old machines is because they were made from cast Iron.
Massive is good, but there comes a point where it is unuseable! Kerry Pinkerton (of Imperial Wheeling Machines fame) built a wheel with a 65" throat that actually has Belleville washers in the adjuster because it is too stiff to wheel over lumps without them! The good news is that, with the spring washers, any deflection is straight up and down with no angle change on the wheels - a really, REALLY smooth machine. You can also fully compress the washers and just stretch the snot out of a piece of sheetmetal! Ok, actually, mass does not = strength, but you know what I mean. Plating the sides with 3/8" might well be overkill. 1/4" would be much better - and you might be able to go 3/16" or even thinner since it only needs to close up the I-beam and control the torsional stress (and maybe add a bit of vertical stiffness as well). Cutting it with the same holes and then welding tubes into the holes would retain the cool look and might help stiffen things torsionally by controlling flex in the side plates. Make sure to cut some slots in the side plates so they can be welded to those stiffeners you've added though - it will tie everything together even better. Tim D.
As per above, although, as a suggestion, rotate the two wheels 90 degrees such that instead of feeding the metal from the 'side', your pushing/pulling from the end, which will dramatically improove the situation. I'd personnally add the 2 side plates (even in a reduced plate thickness), but you'll need that torsional rigidity given the large scale. Cheers, Drewfus
The outer and inner curved pieces that form the ibeam might have helped more if they were tapered. Lets say starting in the middle inside and outside with a width of 6" and taper down to 3" to give the ibeam some triangulation. Also thicker plate might have been better. Changing the direction from side to side to in and out may be the only answer other than boxing the sides. Like the other poster said make plates with the same holes to keep the cool factor, and add slots for welding the connecting pieces.
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