It sounds like you've got the basics there. Power = Torque x speed so you
can calculate one from the other two.
Your easiest option isn't to re-invent the wheel but to look at other
bandsaws that use a similar blade and note their motor power. Exceeding this
by one step is generally a good idea, especially if you're looking at real
budget machines.

John

"Terry G" wrote in message
news:2gkOc.12361$1o.9980@fed1read06...
Thanks for all the advice. I am pretty familiar with the ratios I need to
achieve, and the blade speeds, but I was just looking for an average
torque
so I can determine the size motor to get.

I am going to be installing a second motor, along with my current 1720
RPM
1HP that I currently use for wood. I have a 10 to 1 reduction at the
slowest speed using 3 pulleys and two belts. I will be installing an ac
gearmotor that will run around 150 to 250 rpm, and use the existing 10 to
1
reduction I have. This will bring my spindle RPM down to around 20, which
will make my blade speed around 80 FPM.

I am a little concerned about belt slippage, but I won't be doing to much
heavy duty cutting, and I am usually not in any rush. I can tighten the
belts up pretty well.

So my last bit of missing information is what power ac gearmotor do I buy.
Since I am going through another 10 : 1 reduction I should be able to
multiply the torque rating of the motor by 10 and get my final torque at
the blade.

Almost all the ac gearmotors I have looked at have a torque rating. I am
looking at a 1/3HP motor that turns 180 RPM with 100 in/lbs of torque. So
after I go through my pulley reduction, I should have about 65 FPM blade
speed with around 1000 in/lbs of torque. Does this sound like it would
work? I am not sure what type of steel, or exactly how thick I will be
cutting, therefore I am not sure what blade I will be buying. But I will
be
doing lighter duty stuff, probably no more than 1/2" steel, and very
little
of it.

I just want to make sure I buy a motor that will be sufficient enough
since
I really have no idea what type of motors, and gear reduction the average
lower cost metal band saws use.

Thanks.




"Randal O'Brian" wrote in message
...
You need about 3/4 HP minimum(more is better) for decent cutting speed.
The
blade speed should be between 100 and 150 ft/min for ferrous metals.
These two numbers along with the wheel diameter and the motor speed
determine your total reduction ratio and the torque required.

Belt drive is iffy for the final drive to the blade drive wheel because
of
slippage with reasonable size pulleys, say 6" or less. It can be done
if
you use a tight belt and keep it tight with an adjustable mount.
Bicycle
chain or cog belt drive is better. You need a constant hp drive( belts
and
pulleys or gears) which rules out a VFD if you are looking to get max.
performance of the saw and motor at any speed.

Commercial saws such as the Delta or Wilton wood/metal use a combination
of
belt and gear drive to get about 8 different speeds. You can get by
with
2500 ft/min for wood/plastic/brass/aluminum and 100 ft./min for ferrous
metals.

Randy


"Terry G" wrote in message
news:R6TNc.6015$1o.735@fed1read06...
I was wondering what the torque at the blade of a metal cutting
bandsaw
would be for a lighter duty machine. Or how powerful a motor do these
machines run, and what type of gear reduction do they use.

Thanks.