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Mike8623

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#1
Guys, I've one of those cheaper belt sanders with the side sander on it. The motor is 1/3 hp and the motor just doesn't get it done. It bogs down real quick.

My question is do I need a motor with more horsepower or one that has a higher rpm rate.

Can anyone out there school me a bit in electricity and the relationship between hp nad rpm when it comes to power on belt sanders and how to get more power.
 

Hawkeye

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#2
The first consideration is what you want to do with the sander. If you're sanding wood or plastics, you don't want to run it any faster. If you want to grind steel, more speed is useful, but there will be times you want to slow down for finish work without overheating the metal. In either case, more HP will help, but with the ability to change speeds. The easiest way to do that is to use step pulleys on the motor and sander shafts.

For any motor driven sander, a critical factor is how hard you are pushing on the work. A light touch will allow any sander to keep moving.
 

Silverbullet

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#3
For your question speed or hp? Speed doesn't mean more torque or strength. Hp will make the difference , your bench sander is not going to be strong enough to take much pressure to stop it . If it were a large upright or commercial model you almost can't stop them ever but there hp is probably 2 to 5 hp three phase motors. They also have dual belt drive . You can had a larger hp motor and it will help tremendously .
 

Superburban

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#4
More HP, or more RPM's? Don't think of them as replacing each other. I have a little battery powered motor that spins around 5000 RPM, it will never even budge your sander.

You likely do not want to turn your sander faster, so the more RPM's is still not what you want.

Electricity has nothing to do with your question. You want more power (HP). In simplistic terms, horse power is a factor of torque, and RPM's. By changing pulleys around, you can change the final RPM. Lower the final RPM, you increase the torque, Raise the RPM, you decrease the torque.

A 1HP 1725 RPM motor, and a 1HP 3450 RPM motor both geared to the same final RPM, will be close to the same capability (not wanting to get into parasitic and other loses).
 

Tozguy

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#5
Sometimes just replacing the belts and discs with fresh ones will require less power to get the job done. Vary the grit to suit the job and keep belts and discs clean (with crepe rubber stick).
Don't know the history of your sander but if you need more HP I would get a new machine rather than just a new motor. With the machine you have now more patience might be more appropriate than more HP (don't mean it in a bad way :))
 

RJSakowski

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#6
It's not hp you need but more torque. You can get more torque by reducing the ratio of the drive pulley diameter to the driven pulley diameter. The sander will turn slower but not be as likely to bog down. Other than that, you would need to increase motor size.

Another consideration; when you say "bogs down" do you mean the motor stalls or does just the belt stop? If the motor is still running, the belt may just need to be tightened.
 

chips&more

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#7
Sorry, but if you buy cheap, you get what you pay for. Imports like to exaggerate the HP rating, use plastic instead of metal and I can go on and on. Maybe take it as lesson learned and go buy a real belt sander…Good Luck, Dave.
 
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