Question regarding old bandsaws

Hi, looking for some opinions, I recently bought a used, 17" very old cast iron meat bandsaw from a guy who used to use it for woodwork. It uses a 3 phase motor, not sure what the size is but the guy seemed to think that it was several horsepower, judging by the size of it I would think that would be about right. Anyway I fired it up today and cut some 200mm thick timber and also did some speed measurements, the motor revs at 1460RPM and the the band wheels spin at 552 RPM unloaded, with the 17" diameter wheels I estimate that the blade is moving approximately 1083 ft/min if my calcs are correct. This appears to be at least 2000 ft/min slower than ideal for a wood saw band travel speed.

So my options are in order of least expensive to most:

1) Just leave it as is and put up with the slower band speed.
2) Change the main pulley from the current 100mm with a larger 200mm pulley and matching length belts.
3) Get a larger motor (3-4HP) with a 2850 RPM and possibly a 150mm pulley.

So my main concerns are, I am wondering if I go for option 2, would the motor be underpowered. It does cut the timber and uses a 133" x 1/2" band with 4 TPI but it doesn't do it real fast or accurately, might have to get a wider band blade, but at this stage I am more concerned about whether the motor will handle the larger pulley and also if that will effect any bearings inside the wheels. Not sure what type of bearings are in it either!

Any ideas or opinions?

Cheers

Ed.

My calcs say 2456 ft/min blade speed:
17" * pi = 53.4 inches circumference (ie 53.4" per revolution)
53.4" * 552 RPM = 29,476.8" per minute
Divide by 12 to get 2456.4 ft/min

Thanks Elanjacobs, your right, I just rechecked my calcs and came up with the same answer as you, I must have pressed a wrong digit when working it out. Even at 2457.7ft/min it seems still slow as from what I have read about bandsawing timber it should be about 3500-4000 Ft/min or have I misinterpreted something that I have read?

Regards

Ed.

Quote:

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Originally Posted by Ed..

Thanks Elanjacobs, your right, I just rechecked my calcs and came up with the same answer as you, I must have pressed a wrong digit when working it out. Even at 2457.7ft/min it seems still slow as from what I have read about bandsawing timber it should be about 3500-4000 Ft/min or have I misinterpreted something that I have read?

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I did a quick and dirty survey of the speeds of the bandsaws on the H&F site.
the low speeds are typically 1500 while the higher speeds are typically 3200 Ft/min. and yours is more or less in the middle of the two.

Before you invest any further in this it would be useful to see the blade guides, some meat cutting saws have very rudimentary guides that need to be replaced to accurately cut wood.

Thanks for that info, I did suspect the guides and did a repair on one, this one is like a slit in a metal bar with some sort of padding material on the insides which go on either side of the blade, it looked like it was a bit worn, and instead of the pads being parallel to the blade, the mouth of it had opened up, I unscrewed it and clamped the ends closer and the pads are now straight to the blade with only a tiny bit of clearance between the internal pads and the blade. I am asssuming that the pads keep the blade from going side to side and force it straight during a cut, there is another guide behind it which is unlike any I have seen before, it is actually a piece of flat metal which the back of the blade runs/rubs against to keep the blade from bowing backwards when pushed against the wood. I would have thought that a ball bearing type would have been better as used in my metal cutting bandsaw. I will most likely replace that when I get time. I don't think that there are any lower guides which I would have thought that there should be. Might have to make one up.

So it looks like overall the speed is ok, if it is in the ball park then there is no point trying to increase it, I will look at the issue with the other guide and see if any improvement can be made.

Thanks for your help.

Cheers

Ed.

Might also be worth having a hunt for the plate on the motor that lists power, revs, etc. Older motors are usually a fair bit bigger than newer ones of the same power, so physical size probably won't give you a true indication of how much power you actually have.