Undervolting a bandsaw to get lower speed.

[Joopie]

For 9" bandsaws that don't have variable speeds, is it okay to undervolt them to get a lower speed? In particular, I have a Ryobi BS901.

 

[Hubert S.]

It looks like the saw has an induction motor with a start capacitor, so it will not work.

 

[Stacy E. Apelt - Bladesmith]

Lowering voltage may lower power, but it won't lower speed. It will also heat up the motor severly. DON'T do it.

I had one of those saws for trimming scales and handle blocks. They are pretty weak saws. I never did it, but planned on changing the weak 1/3HP motor out for a 1/2HP 3phase motor and VFD. This would have required some changes in order to mount the motor (mainly drilling new mounting holes). I gave the motor to a friend starting making knives before I ever got around to modifying it.

 

[john april]

even if you could get it to work, the lower the voltage , the torque will get lower as well as the speed. the saw will slow down easily. a vfd seems to give full torque even at the lowest speed.

 

[Joopie]

So, bad idea... What are some other ways to reduce speed? I've seen larger pulleys. What else is out there?

 

[Nathan the Machinist]

It has already been said, but I will add to it, induction motors, which are locked to the line frequency, are not slowed by reducing voltage, they are slowed by reducing the line frequency which requires a variable frequency drive. In this application a step pulley reduction would probably be the best bet.

 

[Joopie]

It has already been said, but I will add to it, induction motors, which are locked to the line frequency, are not slowed by reducing voltage, they are slowed by reducing the line frequency which requires a variable frequency drive. In this application a step pulley reduction would probably be the best bet.

Someone is selling a larger pulley specifically for 9" bandsaws for $75 plus shipping, but my model is not mentioned. I suppose I'll look at adapting a step pulley as you suggest. Another thing I noticed is that used gear reducers can be had for around $40.

 

[Hubert S.]

So, bad idea... What are some other ways to reduce speed? I've seen larger pulleys. What else is out there?

Do you want to slow down the saw to cut metal? I don't want to discourage you from trying to make that work with the saw you have, but the Harbor Freight Variable Speed bandsaw is not terribly expensive ($129) and you can probably find a coupon for 20% off.

Wood is normally cut an order of magnitude faster than metal, meaning you would have to slow down your saw by an order of magnitude if you want to convert it to metal cutting. Looking at the back of your saw, I do not think this will be possible by simply changing one or two of the pulleys, because the motor is mounted fairly close to the center of the wheel. I think there are probably two timing belt type pulleys in there that provide a reduction of 1:3 or 1:4 with very little room between the pulleys. Of course, you can come up with a way to have pulleys outside of the saw housing, or a gearbox, but at that point, the Harbor Freight saw starts looking more and more attractive...

 

[12345678910]

So, bad idea... What are some other ways to reduce speed? I've seen larger pulleys. What else is out there?

What's the point of all this ?

I had a bandsaw of that type.

I consider it ok for kydex cutting for sheaths.

Silk purse/sow's ear

The wheels are plastic
It has half the blade guides it needs and those are weak.
The whole thing is made of cheese, no rigidity
You won't get any metal cutting blades for it.

I would not spend a single dollar on trying to get it to do anything else.


I agree with the above, get the HF portaband.
Get the bi-metal blades for it, not the carbon.
You can get Milwalkee blade in any Home Depot
If you order online 25x at a time, you can get them for $6.50 each.


It will cut steel

10 Amp Deep Cut Variable-Speed Band Saw

Amazing deals on this 10Amp Deep Cut Variable Speed Band Saw at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Many folks have these instead.

1 HP 4 in. x 6 in. Horizontal/Vertical Metal Cutting Band Saw

Amazing deals on this 4In X 6In Hor/Vert Metal Cutting Band Saw at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

I had two, paid full price for both and couldn't keep a blade on despite fiddling and adjusting


If you're on low $, I'd do my first 100 knives with a hacksaw and files, maybe add an angle grinder in there.
But if you try mods on that bandsaw you would be pissing away good money.

 

[Joopie]

What's the point of all this ?

I had a bandsaw of that type.

I consider it ok for kydex cutting for sheaths.

Silk purse/sow's ear

The wheels are plastic
It has half the blade guides it needs and those are weak.
The whole thing is made of cheese, no rigidity
You won't get any metal cutting blades for it.

I would not spend a single dollar on trying to get it to do anything else.


I agree with the above, get the HF portaband.
Get the bi-metal blades for it, not the carbon.
You can get Milwalkee blade in any Home Depot
If you order online 25x at a time, you can get them for $6.50 each.


It will cut steel

10 Amp Deep Cut Variable-Speed Band Saw

Amazing deals on this 10Amp Deep Cut Variable Speed Band Saw at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Many folks have these instead.

1 HP 4 in. x 6 in. Horizontal/Vertical Metal Cutting Band Saw

Amazing deals on this 4In X 6In Hor/Vert Metal Cutting Band Saw at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

I had two, paid full price for both and couldn't keep a blade on despite fiddling and adjusting


If you're on low $, I'd do my first 100 knives with a hacksaw and files, maybe add an angle grinder in there.
But if you try mods on that bandsaw you would be pissing away good money.

I'm investigating mods for the Ryobi BS901 because I inherited one. It needs several repairs due to being left to sit for several years: new tires, plastic knobs cracked, etc. My intent for this was to make cutting 1/8" steel quicker and easier. EZ Lock disks in my Dremel will work, but it takes a long time and is rather error prone. So I cut out something significantly larger than it needs to be and then I file it to shape. Given that I also want to use this bandsaw for cutting wood and the complications people have warned me about monkeying too much with this thing, I'll reserve it for wood use. I have been eyeing an angle grinder for doing things other than making knives, so that's on the table.

I'm having trouble telling which saw was the one that gave you trouble.

 

[12345678910]

I'm investigating mods for the Ryobi BS901 because I inherited one. It needs several repairs due to being left to sit for several years: new tires, plastic knobs cracked, etc. My intent for this was to make cutting 1/8" steel quicker and easier. EZ Lock disks in my Dremel will work, but it takes a long time and is rather error prone. So I cut out something significantly larger than it needs to be and then I file it to shape. Given that I also want to use this bandsaw for cutting wood and the complications people have warned me about monkeying too much with this thing, I'll reserve it for wood use. I have been eyeing an angle grinder for doing things other than making knives, so that's on the table.

I'm having trouble telling which saw was the one that gave you trouble.

get the portable