EMF / Jacob hub motor polyurethane development

Yes, so if you can have it cast like the real inner cores of skate wheels it may hold up. But if you 3d print it will crack. I troed sleeves from .4mm to about 8mm think. Just giving you a heads up.

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Thank you so much :smiley:

I wonder what is the length of the green bar and the red bar? Green bar: from the centre to the reference point of R4.5 Red bar: from the centre to the middle of the screw hole

Also, what is the size of the screw hole?

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The hole is a m3 sonits 3mm thread. From that you can add and subtract and figure it out.

so the mid point of the m3 hole is at the circumference with radius=32.7? also I dont think the R4.5 arc is a half circle, in this case I can’t simply calculate it out

please guide me if I have anything wrong

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From the centre to the mid point of the M3 is 33mm (or 1.3 inch) The “arc” in real is not R 4.5, it is about 2.5. With the bumps the diameter is about 71 mm, but I can not measure it exactly, because my urethane is glued on the rotor.

Guys im making 114mm wheels for the jacob motors to go the biggest size Abec 11 wheels which is 107mm.

Who’s interested in a set ? Price is $120 a set shipping included in the USA and like prior sets it will have the s.s. hardware and the s.s. plates. They will only have 4 rods per wheel unlike the 8 the 100mm had.

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With two 107 flywheels or without?

No its without them. But i am working on a strategy to cast the clone front ones that are 97mm up to 114mm.

First prototype of the 114mm wheel. I feel good about this setup and looking forward to testing once i complete a full set to roll 114mm wheels all around.

Screw the 107mm abec11 wheels we will have the BIGGEST BLACK ONES!

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Holy sht. Bigger is better in the world of electric motors.

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Damn…can i still buy a set of these @ralphy ?

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Yeah guys anyone can buy them I am just showing you my process. Im very curious about current draw at such a large diameter. Im also certain the urethane will last a long time and you can run the plate on the outside since there is so much urethane.

All these bad ass hub motors coming out… I want all of them!

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Fun Fact : My 100mm wheels after months of riding and burnouts and pure torture have been worn down to 99mm. Pics will follow tomorrow so you can see how the urethane is behaving and the actual diameter reading of 99mm on the caliper.

YES alot of motors and wheels are coming out but I still have the biggest one! lol

Some data on the 100mm vs the 114mm

---------------- 100mm SOLIDS ---------------- Mass: 17.01830851 lb Volume: 17.01830851 cu in Bounding box: X: 607.48486070 – 611.44486070 in Y: -31.51834258 – -27.55834258 in Z: 15.34888950 – 17.77888950 in Centroid: X: 609.46486070 in Y: -29.53834258 in Z: 16.56388950 in Moments of inertia: X: 19550.14061501 lb sq in Y: 6326108.16096940 lb sq in Z: 6336303.18388407 lb sq in Products of inertia: XY: 306373.49180521 lb sq in YZ: 8326.54512187 lb sq in ZX: -171801.67265478 lb sq in Radii of gyration: X: 33.89352561 in Y: 609.69145789 in Z: 610.18254309 in Principal moments (lb sq in) and X-Y-Z directions about centroid: I: 32.24902397 along [0.99999893 -0.00145953 0.00000000] J: 32.24902544 along [0.00145953 0.99999893 0.00000000] K: 47.74948109 along [0.00000000 0.00000000 1.00000000] Write analysis to a file? [Yes/No] : Cancel Command: MASSPROP Select objects: 1 found Select objects: ---------------- 114mm SOLIDS ---------------- Mass: 25.56560430 lb Volume: 25.56560430 cu in Bounding box: X: 598.37327168 – 602.86327168 in Y: -31.78334258 – -27.29334258 in Z: 15.34888950 – 17.77888950 in Centroid: X: 600.61827168 in Y: -29.53834258 in Z: 16.56388950 in Moments of inertia: X: 29376.18278820 lb sq in Y: 9229664.94992261 lb sq in Z: 9244987.48941407 lb sq in Products of inertia: XY: 453566.24430772 lb sq in YZ: 12508.47918596 lb sq in ZX: -254341.32363304 lb sq in Radii of gyration: X: 33.89765456 in Y: 600.84843810 in Z: 601.34697766 in Principal moments (lb sq in) and X-Y-Z directions about centroid: I: 55.60178526 along [0.99999787 -0.00206257 0.00000000] J: 55.60178676 along [0.00206257 0.99999787 0.00000000] K: 86.04318255 along [0.00000000 0.00000000 1.00000000]

What have you done to fix the issue of the threaded rods backing out of the urethane? Very dangerous design flaw that only took a few miles of riding to start happening.

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Well i wouldnt call it a design flaw. Some people have realized that the rods do not displace on their own. It takes a latteral impact to cause the bond to break. One person showed us how you can shave them down on the outside and i also recomemened you periodically inspect them visually. You can also use epoxy or retaining clips to prevent any displacment in the most extreme situations.

Most importantly if you feel the design isnt suitable for your application buy the other manufactures products. The whole purpose of this thread is not for me to sell items but for everyone to offer design solutions you find useful for your motors.

Thanks for the input!

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This is certainly not true. I rode my board all of 10 miles and the rods on both sides had moved laterally, some more than others (anywhere from 2-4mm). I can assure you that there was no lateral impact to those rods during that time. Luckily I caught it and decided to simply not ride them anymore out of fear that it would cause a major problem. I believe one user had them back out enough that they got caught up on the phase wires, shredding them, frying their VESCs as well.

I’m certainly aware that I can just buy other products, which is exactly what I ended up doing. I just hoped that this problem had been addressed for future buyers. Fortunately I can take a $350 loss and write it off as a “learning process” without any real impact to my life, but other forum members aren’t exactly in the financial situation that I am, and I want to ensure that they are aware of the problem (whether you consider it a problem or not) prior to purchasing, that’s all. Or ideally, there would be a design modification that made my post completely irrelevant.

I’m all for supporting people with their DIY designs, but I like to think that when a flaw is identified that they will address it rather than continuing to sell it knowing of the “problem”. This post isn’t meant as an attack by any means. Moreso a push to keep innovating and improving, that’s all.

Ok there is no need to take any $350 dollar loss buddy.

Everyone is entitled to a full refund so im not sure about your learning expense allocation to my product.

Good luck as far as my design there is no problem.

Got two ready to test in the next couple days.

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