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Adding a 2 groove pulley to motor shaft

ARC-170

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In order to easily get more speeds from my Atlas Craftsman 101.07403 I'd like to change out the single groove pulley on the motor shaft for a double groove pulley. I currently have 16 speeds ranging from 15 RPM to 714 RPM. To get more speeds, I have to unbolt and move the motor over so the single groove on the motor pulley aligns with the other, smaller groove on the spindle pulley. Having a 2 groove pulley on the motor shaft would allow me to merely change belts from one spindle pulley to the other.

I could make one or buy one. The pulley would need to be about 1.75" OD to match what I have now. These are proving hard to find. I did find a 2.25" OD one. Are they hard to make? Could I use aluminum?

This is not a stock/original motor. It has a 1/2" shaft. It has two speeds; high is twice the speed of low.

Thoughts?
 

Alcap

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Would you be able to use two single pulleys side by side ? If so that might be easier to get the sizes your after
 

RandyMcNally

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Apr 7, 2020
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Clausing may stock the 9-428 motor pulley posted above (assuming that is the correct part as I am not sure). Clausing, which purchased Atlas some decades ago to my knowledge, still stocks a surprising number of Atlas (and therefore: Craftsman) lathe parts - at surprisingly low prices.

You can google Clausing parts to get here: https://clausing-industrial.com/partsService.asp and find their number: (800) 323-0972

I know that doesn't help your issue of the not-original 1/2" shaft size. I found a few items like this with a google search - 1/2" to 5/8" shaft adapter: https://allaroundindustrysupply.com/product/shaft-adapter-sleeve-convert-12-58-shaft/
I don't know if this is feasible or not, and I have no experience trying anything like this.
 

RandyMcNally

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I should also add:

1. There may be other considerations (DOs, DON'Ts, etc.) that I am unaware of. In fact, there almost definitely are, I would say.

2. It's confusing to me how you currently have 16 speeds using only 1 spindle pulley. To achieve 16 speeds on my Atlas 10" would entail using both spindle pulleys: 8 using one of the spindle pulleys (4 speeds in direct drive + 4 speeds in back gears) plus 8 using the other spindle pulley (4 speeds in direct drive + 4 speeds in back gears).
*Note that this is my understanding and not something I'm very intuitively familiar with. I've run my lathe at the faster spindle pulley speeds, but only a few times. I'm relatively new to this and the faster speeds scare the crap out of me :D plus I'm still chasing down some vibration issues.

3. It is also my understanding that "16 speeds" is a bit of a misnomer, as Atlas recommends against using back gears with the faster spindle pulley. Therefore, it is more accurately 12 usable speeds.

Someone may swoop in here and correct all of this (and please do, if needed), but these are my understandings which I thought were relevant.
 

mickri

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Randy, Jeff is moving the motor back and forth when he wants to change from one pulley to the other. That is how he is getting 16 speeds with only one pulley on the motor. That's a hassle and why he is looking for a double pulley to go on the motor.
 

RandyMcNally

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mickri: There it is! I wandered if I was missing something. Hell I even read that part :)
Thanks for pointing out.
 

wa5cab

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He said that his motor is a 2-speed one. 4 speeds from the cone pulleys times 2 speeds with the back gears times 2 speeds with the motor is 16 speeds. However, the standard pulleys on the Atlas 6", 9", 10" and 12" lathes and on the shapers and mills had a ratio of 2.27:1.

Two-Speed motors aren't rare but they aren't common, either. Plus, the stock motor pulley for the 10" and 12" had OD's of about 1.930" and 4.390". And a ratio of around 2.27:1. None of which is going to be achievable with off-the-shelf pulleys because they tend to be in integral inch sizes.

And the 5/8" shaft on 1/3 to 3/4 HP motors did not become common until after WW-II. During and before the War, the common shaft size was 1/2".
 
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