What size pulley should I use with DC treadmill motor?

[mattthemuppet2]

I'd strongly recommend against running the treadmill motor direct to the spindle, they are waaaaay too fast. You'll be running the motor really slowly and have next to no power. I have a 1:4.5 reduction from motor to countershaft and haven't yet made the countershaft step pulley, so I'm using a single poly V pulley that gets me around a 1:1.5 reduction on the middle pulley. That's still too fast as the top speed is around 2000rpm, which is a bit much for a 1929 lathe When I get round to making the step pulley I'll aim for a top speed on the largest spindle pulley of around 1500rpm. Not that I intended using it for long at that speed, but for short spells it'll be fine.

 

[jdsantiagojr]

I can't see the entire gear train in the photo, but the general area appears to be for a "back gearing" mechanism. If so, there will be a shaft with a gear at either end and a latch mechanism to allow the cone pulley to rotate individually from the shaft. Please note that back gearing and the latch must never be engaged at the same time.

My machine is ~25-30 years newer and of different manufacture, so I am just guessing about most of what I'm saying. The only thing I am sure of is that back gearing and the spindle latch should no be used at the same time. As with most things, there will be exceptions. But for a novice, NEVER is a good rule until you have some idea about what you're doing.

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I was actually curious about the red and

I can't see the entire gear train in the photo, but the general area appears to be for a "back gearing" mechanism. If so, there will be a shaft with a gear at either end and a latch mechanism to allow the cone pulley to rotate individually from the shaft. Please note that back gearing and the latch must never be engaged at the same time.

My machine is ~25-30 years newer and of different manufacture, so I am just guessing about most of what I'm saying. The only thing I am sure of is that back gearing and the spindle latch should no be used at the same time. As with most things, there will be exceptions. But for a novice, NEVER is a good rule until you have some idea about what you're doing.

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the image was bad . I was actually curious about the two different pulley sizes on the counter shaft (purple). Both have belts to the 3” pulleys below. The ratios are different and was curious what the setup is called and why they’re setup like that .

 

[jdsantiagojr]

I may be wrong, but I think the south bend literature for that era quotes the countershaft speed (I seem to recall thats what I worked to, so I then use that speed, in the end my slowest non backgeared speed was about 600rpm at the spindle,

You're correct. Just checked and it mentions the speed in one of the lathe catalogs.

 

[Grendel]

thaanks, I just rechecked my speed and I am turning the countershaft way too fast (whoops) so I too need to recalculate and redo my latge pulley on the countershaft.

 

[Grendel]

further to mu comment above, I have calculated my countershaft is running about 900 rpm (whoops) so I have obtained a billet of aluminium to make a 12" driven v pulley on the countershaft to replace the 6" one I currently have, fortunately I found the necessary aluminium local to myself, on ebay, and managed to get 11 pieces 300mm dia and 30mm thick for just £100- thats less than scrap value

 

[Grendel]

this is it, its the bit cut out when they build roulette wheels = 12" diameter 1 1/4" thick

 

[aliva]

This may give you some insight

Pulleys and Belts - Inch

Visually calculate pulley size rpm belt length and speed wwith animated scaled diagrams - Inch

www.blocklayer.com

 

[Grendel]

well i didnt have a big enough chuck to hold the pulley blank, so using the two holes already in the plate, I bolted it to a 10"faceplate.
then I turned down that side to thickness, all except for the area of the bolts, drilled some new holes that would pass into the previously turned area and faced off the remainder, if you have a working lathe, you can make replacement parts, and new pulleys comes under that heading.
now I have the boss I can hold in the chuck to true up the other side, but first i think I may leave this on the faceplate to drill the hole and shape the v groove, and yes, there was a huge amount of aluminium swarf to clean up

 

[jdsantiagojr]

@Grendel, @Bi11Hudson
I ended up keeping the pulley arrangement the same and machined a small v-pulley for the motor. Welded some brackets, added new pillow blocks and swapped the belts. I also wired up the SCR motion controller to dial the motor speed to 2400 RPM / 220 RPM @ counter shaft. Still not at the 290 mark but a little worried about how hot the motor got after running continuously for 15min to 20min.

With this original arrangement I can always go back to AC motor that was originally used. If for some reason the DC motor fails or catches on fire. . . lmao.

@Grendel I did have question about the motor heating up. I noticed after running it for about >15min it did get hot to touch. Does your motor get hot ? How are you keeping it cool?

 

[Grendel]

once i complete this mod it will bring my countershaft speed down from 900 rpm to a more reasonable 450, not the 275 mine should be but better than over 3 times the speed, that should in turn raise the torque available.
I was originally planning to machine the V groove on the original setup, however my engine mount stops me getting a tool to the material in the correct orientation to do this, so I had to dismount it, turn it around and hold it by the boss, this of course allows the whole plate to sing to me while machining, slowing down to my current slowest speed using back gears does reduce this, but I am still getting chatter, never mind - its just a vee for a pulley, it doesnt have to be pretty too.