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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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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".
 

ARC-170

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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
I hadn't thought of that! Thanks. I'll look into it and see if that is a viable option. However, there might not be enough room on the shaft and it might not allow the door to close.
 

ARC-170

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I called an electric motor place near my house and he told me that the size I'm looking for is not common in a double groove pulley because two pulleys put too much stress on a 1/2" shaft. He said it would be fine with just one pulley when I explained what I was actually going to do with it. Now that I know the original pulley was close to 2" OD maybe I can buy one (or two) of the 2" OD ones and see how it goes.

No one commented about making one. I'd like to hear your thoughts and comments on that option.
 

CluelessNewB

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I can buy one (or two) of the 2" OD ones
The original pulley had 2 steps of different sizes, the smaller 1.93" OD and the larger 4.39" OD. If you get two pulleys the same size you will not have the same speed ranges as the original and swapping between them will be more of a problem.
 

ARC-170

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The original pulley had 2 steps of different sizes, the smaller 1.93" OD and the larger 4.39" OD. If you get two pulleys the same size you will not have the same speed ranges as the original and swapping between them will be more of a problem.
I know. I may just see about getting 2 different sizes now that I know what size to get. The plan is to have the two grooves on the motor shaft align with the 2 grooves on the driven wheel. That way, I can just have two belts; one for the small motor pulley/big pulley and one for the motor pulley/other big pulley. Changing belts is thus a matter of just taking one off and putting the other on, no need to move the motor.
 

wa5cab

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In the original setup using a 2-step motor pulley and a 2-step countershaft pulley, the same belt fit both positions. That's probably the reason for the rather odd diameters of the 9-428 1/2" bore) and the 10-428 (5/8" bore) pulleys. Clausing still carries the 10-428 with a reducing sleeve for the older 1/2" shaft diameter motors. The factory pulley is more expensive than the Chinese single groove ones but if you consider that the total cost of doing it with two different diameter pulleys and two different length belts (assuming that you buy decent quality belts) will be doubled, And the spindle RPM's probably won't match what it should be, you aren't saving much money over doing it the original and in my opinion right way.
 

ARC-170

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Clausing has them for about $100 shipped. Does this seem reasonable?

However, I have some hesitation. When I was measuring the speeds I currently have, it vibrated quite a bit at the higher RPM. The machine is bolted securely to the table and the table is sturdy. Is this normal? I haven't really needed the higher RPM's yet, so getting a pulley that allows for 2,000 RPM on a machine that vibrates gives me pause. Would it help to take some video so you can hear and see it?
 

CluelessNewB

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1) How old and crunchy is your belt? (very common problem)
2) Is your motor shaft straight? (bent shafts on 1/2" shaft motors are unfortunately common also)
3) How about your motor pulley? Is it a low budget unbalanced diecast part? (again not uncommon)

$100 seems like a lot but reproduction and used parts also go for big money on ePay. (It may be your best option)

Definitely check your motor shaft before you spend the money on a 1/2" bore pulley.
 

ARC-170

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1) How old and crunchy is your belt? (very common problem)
2) Is your motor shaft straight? (bent shafts on 1/2" shaft motors are unfortunately common also)
3) How about your motor pulley? Is it a low budget unbalanced diecast part? (again not uncommon)

$100 seems like a lot but reproduction and used parts also go for big money on ePay. (It may be your best option)

Definitely check your motor shaft before you spend the money on a 1/2" bore pulley.
1. It's a new link belt. Maybe it's too loose?
2. I put a dial indicator on it and it was perfectly straight.
3. Yes, it appears to be diecast.

Well, I looked at the set up again and it runs fine. I wonder if I had something out of place when I tried this before? I posted a video of the machine running:
 
Last edited:

mickri

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In my humble and not very knowledgeable opinion not having the exact same speeds as original won't make a bit of difference in the operation of your lathe. You are going to find speeds and feeds that work for you with whatever pulleys you have on your lathe. 2" and 4" pulleys are so close to original that you will never see any difference. The difference between a 1.93" pulley and a 2" pulley 3.5% faster. Your 15 rpm will now be 15.5 rpm The difference between a 4" pulley and a 4.39" pulley is 9% slower. The fast speed on my Craftsman 12x36 is 2072 rpm. With a 4" pulley it would be 1885 rpm. Still not enough difference to make any difference in the operation of your lathe.

You can find 2" and 4" pulleys with a 1/2" bore all over the place. You can probably find a 2"/4" step pulley too. Surplus Center has 1.75 and 4.45 1/2" bore pulleys. McMaster Carr and Grainger have them too.
 

ARC-170

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In my humble and not very knowledgeable opinion not having the exact same speeds as original won't make a bit of difference in the operation of your lathe. You are going to find speeds and feeds that work for you with whatever pulleys you have on your lathe. 2" and 4" pulleys are so close to original that you will never see any difference. The difference between a 1.93" pulley and a 2" pulley 3.5% faster. Your 15 rpm will now be 15.5 rpm The difference between a 4" pulley and a 4.39" pulley is 9% slower. The fast speed on my Craftsman 12x36 is 2072 rpm. With a 4" pulley it would be 1885 rpm. Still not enough difference to make any difference in the operation of your lathe.

You can find 2" and 4" pulleys with a 1/2" bore all over the place. You can probably find a 2"/4" step pulley too. Surplus Center has 1.75 and 4.45 1/2" bore pulleys. McMaster Carr and Grainger have them too.
Yeah, I figured the same thing. I don't need the exact speeds it originally came with, but it would be nice to have more than I do.

I looked at all 3 places and could not find the 2 groove pulley (2"/4") I needed. I was actually surprised. The issue with using 2, single-groove pulleys is there is not enough space on the motor shaft, and they would hit the cover. I'm hoping the stock pulley I just ordered will fit. The motor I have is not original, so there may be issues. We'll see!
 

mickri

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This thread got me interested in the possibility of making a pulley. Found an old article on how to machine a pulley. And this video on making one

 

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