8mm driveshaft to 1/2" bore pulley

Submitted by Ag99JYD t3_zd9dna in DIY

I have a worm drive motor with an 8mm D driveshaft. I am trying to connect it to a shaft that has a 7/8" OD on roller bearings to turn a display feature with either a vee belt or something similar. I tried connecting with a 6mm timing belt but that was not enough to turn the display. I have found v belt pulleys with a 7/8" bore, and corresponding pulleys with a 1/2" bore, but cannot find one that has an 8mm bore.

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TLDR:

So how do I connect an 8mm shaft to a pulley with a 1/2" bore?

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Comments

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Thud2 t1_iz0ewst wrote

how about these. They have less slippage than a v pulley also.

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Ag99JYD OP t1_iz0jzo9 wrote

I tried those with timing belts. It seemed they were not strong enough to turn the display, which isn't that heavy, maybe 30 pounds total (roughly half a sheet of plywood).

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dr_xenon t1_iz0f052 wrote

I’m guessing this isn’t high speed or high precision movement.

8mm is 0.315”. 5/16” is 0.3125”. You could probably use a pulley with 5/16” bore and hit it with a 8mm drill bit. Set screw will take up the rest of the slop in it.

McMaster sells pulleys with 5/16” bore for under $20. Get the drill bit there too.

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Ag99JYD OP t1_iz0ksoc wrote

5/16 is a good idea, thanks. I think the problem I'm having is everything I'm finding for a v belt (mostly A type, 1/2") is on a 1/2" or larger bore, while the smaller pulleys (6mm and up) use PU Round belts.

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dr_xenon t1_iz0lz21 wrote

McMaster has them for 2L or 3L belts which are 1/4” or 3/8”, with 5/16” bore.

Try part 6245k314 for example.

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Ag99JYD OP t1_iz0ni1n wrote

Oh, that is awesome! Thanks!

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John_B_Clarke t1_iz1uybs wrote

Is the display balanced? Doesn't have to be exact but the closer it is the easier it is for the motor to turn.

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Thud2 t1_iz1diah wrote

What happened when you attempt to turn the display with those belts? The ability to turn the feature depends on the torque of the motor and the ratio of the pulleys. If your sign is mounted on free turning bearings it should only have to provide enough torque to overcome the inertia of the feature. It should take minimal power to rotate it once it's moving. How much does the feature weigh, what type of bearings is it mounted on, what ratio are your pulleys, how much torque does your motor supply, how many RPMs does the motor turn at and how many RPMs would you like your feature to turn at?

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