shredder review

[Jitterbugdude]

Bob, That formula for torque applies to an electric motor. The torque produced BY the motor. You cannot transfer that formula over to a non electric pulley. Open the link below. It shows % torque as it relates to % speed. You will note that at 100% rpm (1750 rpm in this case) the torque is 100% (3 ft-lbs typical for a 1hp motor). Now using our shredder, the shredder pulley is spinning at 200 rpm, or about 10% of the motor. So, looking at the chart we see the torque at the shredder pulley is about 10% or about .3 hp.

The transmission analogy only holds water if we are talking about geared systems but in this case we are talking pulley/belted systems.

http://docs.engineeringtoolbox.com/documents/1503/electric_motor_speed_vs_torque_power.png

I think I'm about ready to go back to talking about tobacco. Anyone else care to join me?

 

[riverstone]

http://ourpastimes.com/calculate-pulley-belt-ratio-6196301.html

If you can open it, this explains it it very simple terms. I may be playing with words here but reading back on the posts I can see that the wrong assumption being made. You do not increase the torgue of the motor shaft by pulleys but you do increase the torgue on the driven shaft.

 

[deluxestogie]

I think I'm about ready to go back to talking about tobacco. Anyone else care to join me?

Excellent suggestion. There are many websites on various aspects of mechanics that explore these issues in simple or complex ways. Happy hunting.

Bob

 

[riverstone]

^+1

 

[burge]

My attitude is as long as it works

 

[MichaelSanders]

I know this is an old post but you could use a dimmer switch to slow it down maybe.

 

[Jitterbugdude]

Not running an ac motor at the proper voltage and frequency will shorten its lifespan. DC motors will work.

 

[BigBonner]

If you have a drill press , look at the pulleys on there . You should see three sets with multiple belt groves . They are for speed up or speed down .

Another speed control may be one of the older riding mower transmissions . Some are small enough to apply to the shredder and you could have three choices of forward speed and a reverse .

 

[larryccf]

I had thought about cannabalising one of the spare drill presses (got two older ones sitting in a corner in the shop) but the slowest speeds - slowest speed any of them offered (and they were all 5 speed drill presses) was 700 rpm. To make it down to 200 rpm i'd have had to cannabalise 3 of the pulleys, basically putting both of those drill presses out of business, and murphy's law sez i would need one the day after cannabalising it. I've already built the 2nd stage pulley set, just have to get around to mounting it on the stand's top and measuring for the 2nd belt. Total cost on the 2nd stage set was approx $35 for the two pulleys and 2 bearings.

 

[Brown Thumb]

There is a idea for Jtb. If you got a drill press laying around.
Chuck it in there an fasten to base then lay it on its side and see how the polish head cuts.
I wish I had a head laying around.

 

[ZigZagZeppelin]

Just wanted to thank Don for carrying a good manual shredder. His HD shredder is compact, heavy and fairly robust. Easy to crank. Well worth the money.

 

[burge]

Glad you got that one Zig they are way better than the elcheapo's. Its kind of like the first time trying ryo If you don't have the proper shredder you will get frustrated quickly.