What sort of motor do I need?

[Richard]

Hi

Me and the old man are making a bench saw from chopping logs on the farm. The blade is approx 700mm wide (pretty big as they go i think).

In your opinion, what would be the best sort of single phase motor to attach to drive this blade? and what sort of power? I'm guessing it would need to be pretty torque'y? but not sure exactly what type!

Thanks in advance!

(and before anyone asks H&S is more than adequtally catered for!)

 

[Marvo]

From limited experience of saws I think they rely on the speed and momentum of the blade as much as raw torque. The large saws I'v seen use a standard induction motor. You're going to be limited by the single phase supply, usually single phase motors are around 3Kw max. Even at that size you're talking about a large supply to accommodate the start current. Maybe consider using a soft starter to reduce the start current. The type of motor would usually be dictated by the blade itself which should have a recommended running speed stamped on it somewhere. This would dictate if a 2-pole or 4-pole motor is used.

 

[oldtimer]

Forget what motor to drive the blade just buy a fit for purpose table saw that has everything on it ie ovload protection, safety guards etc then all you need to do
is get a supply put in for it.
Remember Heath Robertson died years ago this is a whole new ball game years ago we used to read stories about farmers losing arms and legs on machinary like this so if you think I am having a pop at you then think about this if one of you is injured with this and you think a well I am insured then think again because you have just handed the insurance company the biggest "I dont need to pay card" because you did not follow the rules with regards to using machinary "fit for purpose"

 

[Amp David]

Is he related to Heath Robinson by any chance? HA HA

 

[Richard]

From limited experience of saws I think they rely on the speed and momentum of the blade as much as raw torque. The large saws I'v seen use a standard induction motor. You're going to be limited by the single phase supply, usually single phase motors are around 3Kw max. Even at that size you're talking about a large supply to accommodate the start current. Maybe consider using a soft starter to reduce the start current. The type of motor would usually be dictated by the blade itself which should have a recommended running speed stamped on it somewhere. This would dictate if a 2-pole or 4-pole motor is used.

Thanks, thats very useful.

 

[antimatter]

Ditto, not worth taking a chance, us humans have evolved enough by now to know danger ahead when certain situations arise, and this is one of them.

 

[nickblake]

who needs a motor

[video=youtube;2_ZisaAd7bo]http:/[/video][video=youtube;2_ZisaAd7bo] 0:50

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Circular saw blade throw cuts 2x4 lumber stud /www.youtube.com/watch?v=2_ZisaAd7bo[/video]

 

[Marvo]

I disagree with some of the skepticism above, large saws don't have to be unsafe. There are various systems around that can stop and retract saw blades safely on contact with a finger or any other appendage you might get caught up.
Here's one such system;
Safer 10-inch Table Saws - Video Clearinghouse - SawStop

Here's how it works;
Safer 10-inch Table Saws ? How it works ? SawStop

 

[Guest123]

Now thats impressive Nick!

 

[oldtimer]

Just be happy you dont live in the states if you ever watched Micheal Moores Sicko then their for the grace of God go I . A guy got his fingers taken of with a table saw and he did not have enough money to sew all of them back on again

 

[bugsy]

this should do the trick, not sure about the drive train though!