24" wheel grinder......well maybe

thats... emm big!!

cant wait to see that in action, Bruce

a youtube video would be good actually!!
 
PT Doc said:
Should be interesting. What size belt do you to jump up to?
Click to expand...

My grinder will accept 2" x 132" sanding belts. It use to take both 132"and 72" but now I,m not sure a 72" will fit any more, We shall see I guess. The idler wheel will slide down so I can still use the 132" belts.
 
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Hey, the machine shop got the hub made and the rubber turned down to 2" wide. I haven't seen it but my buddy sent me a picture of it. They made a stainless shaft too. I think its a "Manly" wheel.
Image1_zpsc456a48c.jpg
 
I have the wheel here now and am looking into a pulley for the shaft. Heres a math problem for ya:
I want the motor to run at full speed with the big wheel running at 800 rpm max. The motor is a 1700 rpm motor and has a 2" pulley. What size pulley do I need for the driven shaft?
 
Red neck math
2" pulley at 1700RPM going to a 4" pulley would give you 850RPM and a 5" pulley would be 680RPM. I think to be dead on (I don't know if you can get fractional pulleys) 4.25"

Disclaimer: Caution I run a power saw and kill trees for a living. Any math done here can and may be wrong.:)

http://www.blocklayer.com/pulley-belteng.aspx

Hopefully someone with more experience comes along
 
Do you really grind at that speed? that's over 5000 feet per minute, or 57MPH. If it flies off, you'll get a speeding ticket :les:.

Put another way, that speed would create about 220-g's of force - each pound of rubber on that rim would be pulling away from the center with about 220lbs of force.
 
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Roger T said:
Do you really grind at that speed? that's over 5000 feet per minute, or 57MPH. If it flies off, you'll get a speeding ticket :les:.

Put another way, that speed would create about 220-g's of force - each pound of rubber on that rim would be pulling away from the center with about 220lbs of force.
Click to expand...

Roger, I may be going about this wrong. Maybe I need to figure out the surface feet per minute with the 14" wheel and use the proper pulley for the same surface feet per minute with the 24" wheel.
 
The 14" wheel has a 3.66 ft circumference; the 24" wheel has a 6.28 ft circumference.

If presently you're driving that 14" wheel with a 1700 rpm motor using a 2" drive pulley and a 4" driven pulley, that works out to be 3111 ft/min.
1700 x 2/4 x 3.66 = 3111

Switching to the 24" wheel; if you change to a 6" driven pulley the speed would be 3559 ft/min. Moving to a 7" driven pulley, the speed would be 3052 ft/min.
1700 x 2/6 x 6.28 = 3559
1700 x 2/7 x 6.28 = 3052
 
I dont think there would be any shame in starting off at a slower speed.... :D

Thats gotta be a bit intimidating the first time its fired up!!
 
Bruce,
I too would go on the slower size to fire that thing up. Thats a lot of mass & energy to try at full bore the first time.

I would go say 1/3 of the speed you want for the maiden voyage and watch and listen for any vibration etc. You may want the slower pulley speed for finshing belts anyway. A step pulley with a top, middle and lower speed might work just right.
 
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This machine has a 1HP DC motor with a variable speed drive, so starting out slow will be easy. We're just trying to guess what the top speed should be.
 
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