DIY Motor Mount Pulley Measurement

Hi All,

I’ve got a question about creating a motor mount out of 1/2" thick 6061 aluminum plate. I have a 6374 192kv turnigy motor and have measured its shaft to be approximately 25.5 mm in length The diagram of the pulley I ordered (on its way) is shown below. From the drawing below it looks like 16 mm of the 25.5 mm long motor shaft(can’t tell exactly from drawing, can any of you tell? :sweat:) will be occupied by the pulley hub leaving around 9 mm of available space for the motor mount plate thickness. I’m basing my design off of torque boards motor mount and their plate is 12 mm thick. I was wondering if 9 mm thickness is enough? I could always let the pulley slide a little further down, use loctite and a grub screw with notched keyway. Let me know what you guys think. I’m thinking I’ll just slide the pulley down enough to where the grub screw will still grip the shaft with a keyway and the plate will be able to have a 12 mm thickness.

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Where’s the legend for dimensions?

My bad. Here they are: A=28mm B=18.5mm C=you can choose D=33.5mm E=16mm F=1.5mm G=M4

Do you have the ability to remove the shoulder where the grub screw is? I just got a really nice gear set (motor and wheel) from @Titoxd10001 - where the motor gear has the grub screw in the gear teeth itself - so you have more flexibility on the gear placement (especially on shorter motor shafts) without needing to flip the gear so the grub screw can secure to the motor shaft.

quick search - here’s an example of an aluminum one on aliexpress i think:

No shoulder and grub screw(s) in-between teeth.

Thanks for the mention @sl33py @westonbe if your building a single drive, 15mm is the way to go. I have 15t steel motor pulleys for longevity.

Thanks for the replies! I actually ordered a shoulderless 15 mm pulley off of alliexpress (thanks @sl33py !) . I’m not sure if this will solve my problem entirely but it looks like my only option is to leave a little of the pulley hanging off of the motor shaft, use my dremel to create a small notch for a grub screw to grip and hope it sticks with some loctite. I don’t feel comfortable grinding a full on keyway into my shaft so I’ll stick with a grub screw grip. Wish I would’ve ordered a motor with a keyway @Titoxd10001 but oh well. It’s a bummer my shaft is short by only a few millimeters but that’s the price you pay for a 15 mm belt on a 6374! Thanks for the tips and advice guys, I appreciate it.

I have those alluminum pulleys. They lasted me a week (in a dual drive board) before the teeth had worn down excessively. That’s why I purchased steel pulleys for durability.

Do you have pictures of the mount? The actual plate that connects the motor could be as thin as 6mm in alluminum

Hey I I’ll definitely look into steel pulleys in the future. I’m currently designing the motor mount and will post it here soon! I’m using these trucks: on account of their grip ability. Unfortunately the side profile isn’t a perfect rectangle like I had hoped so it’s taking me a little longer to design. I didn’t know that about the 6 mm limit as well. Right now my calculations come out to 9 mm of available space for the plate, but I’m planning to make it 12 and have the pulley slide off a little. If there isn’t enough contact surface/grip with the loctite and grub screw (the pulley slides off while testing) of the pulley, I’ll probably sand the plate down to 9mm. I think as long as a majority of the 17mm pulley (15mm + ~2 mm accounting for flanges) is in contact with the shaft I should be good, but we’ll see.

Wow those are some tiny trucks. Space is going to be tight. You building a mini by chance. Here’s my mini with 150mm Ronin’s.

You can see what I mean about motor mount, the plate that connects to the motor is 6mm, but the part that connects to the truck is 15mm thick. Also both motor pulleys are close to 19mm in width for reference

Wow that’s awesome. Yea, I’m building a cruiser and space is definitely tight but there’s enough room.

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Here is my first draft of the clamp plate… Those angles doe. I’m going to need some revisions for sure.

Are you going to weld it or clamp it on?

I’m gonna clamp it. It’s going to be vertically cut 30 mm from the short back end piece.

I would recommend designing for manufacturability. This design would likely have to milled in three separate operations to achieve the 90° angles, which are probably not even necessary. And it would tricky to machine the cutout with all the sharp angles. Consider adding filets so this could be milled in a single operation

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Yea do you mean filleting both the outer and inner edges? If I fillet the weird angles off won’t they lose some grip ability with a straight edged truck? I’m going to get this cut with a waterjet.

Is there another piece you’re going to attach to this? What type of motor you going to use

Yea there’s a motor plate which I’m not worried about. I will post everything soon. I actually just cut out the piece above from a paper printed version. The piece fits pretty much perfectly and can be adjusted with a file. I’m not sure if fillets are the best option here because the truck doesn’t have any round edges. If the waterjet gets to 60$ + I’ll probably just use a hacksaw and a hand drill with carbide bits. Also I’m using a 6374 turnigy motor 192 kv.

Maybe getting everything cut except the axle hole would be optimal. I could probably cut the axle hole myself with a drill and hacksaw.

These are the final drawings minus the weird angle axle cut. I had to do several printouts to get everything right!

Just talked to the waterjet cuttter owner and he said the angled cut should be no problem. Stoked. Thanks for the assistance yall