VS treadmill motor swap question..

[Firefyter-emt]

Can anyone suggest a good place to start on the pulley size for the motor? I can run on any of the lathe pulleys, but I need to buy a pulley for the motor. I was thinking about 2.5" any thoughts?? I have to mill this for a .671 center hole from .625 so I don't want to order the wrong one.

 

[rgundersen]

Silly idea maybe, what about taking the shaft size down the 2 hundredths?

 

[Firefyter-emt]

I could, but I would have to take to motor apart to chuck it in a lathe to do so, plus if something goes wrong I can easily buy a new pulley, no so with the motor shaft. Pulley is an alloy, shaft may be hardened...

 

[dfurlano]

I just opened the hole on the old pulley and mounted on the new motor.

 

[Firefyter-emt]

Right, but the center hole is just a procedure.. What I really need to get an idea on is what size pulley size to get, not the shaft diameter.

 

[Tea Clipper]

What speed range do you want out of this? Let's do some math! []

Spindle RPM = lower pulley diameter divided by upper pulley diameter times the RPM of the motor.

So now all you have to do is juggle some numbers around to see what dia. size to get, that will meet your target speed range.

Is this what you'd like to know?

 

[dfurlano]

I just used a 1:1 ratio. The motor pulley is the same diameter as the drive shaft pulley. The pulley I modified was a step pulley so I could increase speed or torque depending on need but so far I have left it alone.

 

[Firefyter-emt]

Great, that is around where I was thinking for the speed range. I plan to use a single pulley so I can eaisly jump up or down one step at the lathe. But I was wondering what the sweet spot was. I know the DC motors have less torque at low speed, and was thinking maybe it would be better to "speed it up" at the motor by slowing it at the headstock. However, I might max out too slow at the high end. I will give it a shot at 1 to 1. I plan to run on the 3rd largest pulley step at the lathe so I can go up one to slow it down and down two to speed it up if I have to. I am keeping the old wood top on the lathe untill I get this figured out. Then after I know for sure what step to run in I can figure out the exact placement of the motor.