Bandsaw Blade Speed

[Rob Will]

In reading up on bandsaws I noticed that some large saws, particuarly the Tannewitz GHE have very high blade speeds (8400 sfm) while other saws have a blade speed more in the 5000 sfm range.

Does an individual (non-production) person really need a bandsaw going that fast? Where does that kind of speed help?

For resawing, does one need a slower blade speed?

Can I use a frequency drive on a 3ph direct drive bandsaw?

Just for comparison (ha) how fast is the blade speed on a 12" Craftsman bandsaw from the 1970's? How about a WoodMizer? (LT40).

Thanks,
Rob

[James Boster]

Rob, I have an older tannawitz 30" saw. I changed mine from 3 phase to belt drive single phase. When I done this I had to slow it down in order to get my 5hp (245 frame) motor to start it. Mine is currently running around 4800 fpm. Originaly it ran 6000 fpm. My homemade bandsaw mill (same as a woodmizer) runs around 4600 fpm.. I raised the speed of my sawmill up a few years ago after reading suffolk machinerys book on there timberwolf blades. I lost a tremendous amount of torque and slowed it back down to 46-4800 fpm. I don't do a lot of resawing on the tannawitz because I do have a bandmill. I am planning on putting the three phase direct drive motor back on the tannawitz now that I have upgrade to a 10hp rpc. I hope some of this rambling on helps. I will say there is absolutley no comparison between a 12 or 14" saw and a large cast iron machine. I love my tannawitz and it was one of the best things I ever bought.

[lou sansone]

hi rob..

good question that I continue to cover .. and will again. for belt driven band saws this is a non issue, but for direct drive saws it makes a big difference. as james has said the 5000 sfpm is the right range for resawing by hand. many 36 and 42 inch band saws are known as high speed saws and run in the 9000 to 12000 sfpm.. these are just too fast for regular hand resawing. look at all the best european saws for example and they are all running 5400 sfpm. how do they do it? belts and pullies

the problem becomes more difficult with direct drive saws. As I have said in the past it took me 2 years of constant searching before I found a saw with the super slow speed 575 rpm ( 5500 sfpm) motor. they are very expensive and rare.

so can you freq the motor ? your not supposed to use non-inverter duty motors for a couple of reasons ( any saw you will buy will be non inverter duty ). first is the cooling issue and second is the supposed insulation resistance to high frequency voltage spikes. hey maybe all that I have read in my books and industry pubs is bunk and there will be no problem.
its your money - personally I would look for an inverter duty motor or look for a slow speed saw. they are out there - you just have to look and ask questions..

best wishes and happy hunting
lou

[Rob Will]

many 36 and 42 inch band saws are known as high speed saws and run in the 9000 to 12000 sfpm..

12,000 sfpm blade speed = 136 mph!
So Lou, what is the advantage of having this kind of speed?:eek:
In industry where would this be applied?

It seems to me that things would get rather exciting if a blade breaks at that velocity.

Now I'm getting discouraged about a big direct-drive BS.....
(why is direct drive better than belts?)

Rob

[lou sansone]

12,000 sfpm blade speed = 136 mph!
So Lou, what is the advantage of having this kind of speed?:eek:
In industry where would this be applied?

It seems to me that things would get rather exciting if a blade breaks at that velocity.

Now I'm getting discouraged about a big direct-drive BS.....
(why is direct drive better than belts?)

Rob

that is why they are called high speed band saws.

my carter wheels are dynamically balanced to 180 mph! no kidding. the old iron spokey wheels had a limited speed to them from my understanding. high speeds would cause them to fly apart

I know a lot of guys rush out there and buy these iron beasts and they sit in storage in someone's barn for years. if you ask them how they cut, they say "cuts great" when in fact they dont have any real experience with them on a daily basis. my advise if to look for a saw with modern carter wheels and a slow speed motor. sure you can belt drive the thing and get it slower, but the whole reason for these saws is DIRECT DRIVE!

lou

[Dave Richards]

Rob, I expect you would find those high speed bandsaws in commercial resawing operations where the wood is being fed under power. If the blade is running faster, the feed rate can be higher than we'd normally see or care about. In industrial applications it's about the speed.

[Rob Will]

This little voice in my head keeps saying "The devil is in the details". I just have to ask the question: Exactly why is a direct drive bandsaw considered better?

As Lou mentioned, a 575 rpm motor is rare and expensive but with a 36" wheel diameter, that's what it takes to get the blade speed down to an acceptable level.

So from a saw performance and low noise point of view, what are the problems or limitations associated with belt driven bandsaws?

Thanks,
Rob

[lou sansone]

all drive trains have some type of inefficiencies to them as well as vibration and resonance. the direct drive removes most of them because there is nothing between the prime mover and the object. I guess one could also simply say " try them you will like them " and that works as well


so any one out there with direct drive machines that wish to say ... oh man those belt driven things are just the cat's meow!

lou

[tod evans]

so any one out there with direct drive machines that wish to say ... oh man those belt driven things are just the cat's meow!

lou

not i. but there is something to be said about the "weak link" some of us abuse our equipment and need such things as belt slippage to keep from toasting motors. :) .02 tod

[lou sansone]

not i. but there is something to be said about the "weak link" some of us abuse our equipment and need such things as belt slippage to keep from toasting motors. :) .02 tod

excellent point !
thanks tod
lou