pulley ratio / replacement motor question
 

In article ,
"mark" wrote:

Two questions in one night! I have a crappy 1hp (yeah, right!) 14" bandsaw,
and I have a replacement motor. The only issue is the motor (a 1.5 horse
out of a delta contractor saw) runs at 3450 and the bandsaw motor runs at
1725. Can I just decrease the size of the motor pulley to get a safe speed?
I think the motor pulley is about a 3" or so. Is this safe to do?

It should work fine. What you need to do is get a motor pulley that's
half the size of what you have now, or a driven pulley that's twice the
size of the current one, or some combination of the two that results in
a driving:driven size ratio being half of what it is now.

The only thing to think about is that if you make the driving (i.e.
motor) pulley too small, you'll be bending the belt over a very small
radius and giving it very little contact area with the pulley, which
could result in slipping.

What are you going to do with the 1 HP motor you're taking off it? I've
got a 1/3 HP motor on my old Craftsman 12" saw that could use upgrading,
and I would be happy to dispose of your old motor for you to save you
the trouble and expense of getting rid of it yourself :-)

mark wrote:

Two questions in one night! I have a crappy 1hp (yeah, right!) 14" bandsaw,
and I have a replacement motor. The only issue is the motor (a 1.5 horse
out of a delta contractor saw) runs at 3450 and the bandsaw motor runs at
1725. Can I just decrease the size of the motor pulley to get a safe speed?
I think the motor pulley is about a 3" or so. Is this safe to do?

Yes and yes.

--
Jack Novak
Buffalo, NY - USA
(Remove "SPAM" from email address to reply)

"Roy Smith" wrote in message
...
In article ,
"mark" wrote:
The only thing to think about is that if you make the driving (i.e.
motor) pulley too small, you'll be bending the belt over a very small
radius and giving it very little contact area with the pulley, which
could result in slipping.

What are you going to do with the 1 HP motor you're taking off it? I've
got a 1/3 HP motor on my old Craftsman 12" saw that could use upgrading,
and I would be happy to dispose of your old motor for you to save you
the trouble and expense of getting rid of it yourself :-)

Good point about the belt radius. I'll look at the top pulley and see if I
have room to change that one instead. Whereabouts are you located?

"mark" writes:

Two questions in one night! I have a crappy 1hp (yeah, right!) 14"
bandsaw,
and I have a replacement motor. The only issue is the motor (a 1.5 horse
out of a delta contractor saw) runs at 3450 and the bandsaw motor runs at
1725. Can I just decrease the size of the motor pulley to get a safe
speed?

Absolutely, but do it right.

About the smallest sheave you want to use with an "A" section belt (FHP
motor belt) is 2"-2.5" which will have a pitch dia of 1.75"-2.25".

Take your existing sheaves from the 1725 RPM installation, measure them and
subtract about 1/4" which will get you close to the actual pitch diameter.

The ratio of the pitch diameters is the actual sheave ratio.
Since this will give you the existing sheave ratio, it is a straight forward
math problem to arrive at the correct solution for the new sheaves.

HTH

Lew

In article ,
"mark" wrote:

"Roy Smith" wrote in message
...
In article ,
"mark" wrote:
The only thing to think about is that if you make the driving (i.e.
motor) pulley too small, you'll be bending the belt over a very small
radius and giving it very little contact area with the pulley, which
could result in slipping.

What are you going to do with the 1 HP motor you're taking off it? I've
got a 1/3 HP motor on my old Craftsman 12" saw that could use upgrading,
and I would be happy to dispose of your old motor for you to save you
the trouble and expense of getting rid of it yourself :-)

Good point about the belt radius. I'll look at the top pulley and see if I
have room to change that one instead. Whereabouts are you located?

The Bronx, New York.

On Tue, 14 Dec 2004 02:23:23 GMT, "mark" wrote:

Two questions in one night! I have a crappy 1hp (yeah, right!) 14" bandsaw,
and I have a replacement motor. The only issue is the motor (a 1.5 horse
out of a delta contractor saw) runs at 3450 and the bandsaw motor runs at
1725. Can I just decrease the size of the motor pulley to get a safe speed?
I think the motor pulley is about a 3" or so. Is this safe to do?


It might depend on your driven wheel size to fit the space you have.
You might reduce the one by half, but if not feasible to do that or
increase the other, you can have an intermediate double-wheel,
something like A .....B..C.....D with B,C on the same pulley. A
drives B and C drives D. The intermediate system can be placed
anywhere suitable, not necessarily directly in between.

I'm about to set up a motor slash pulley affair, thanks to a leftover
Delta motor and a mandrel from Woodcraft. Question, please. The setup is
for soft felt wheels for polishing; I'm somewhat fearful of using this
setup because of its tendency to take control of say the chisel you're
sharpening. I plan to reduce the 3450 to 1725. Would it make sense to go
even lower? Remarks? Thanks in advance.


In article . net,
says...

"mark" writes:

Two questions in one night! I have a crappy 1hp (yeah, right!) 14"
bandsaw,
and I have a replacement motor. The only issue is the motor (a 1.5 horse
out of a delta contractor saw) runs at 3450 and the bandsaw motor runs at
1725. Can I just decrease the size of the motor pulley to get a safe
speed?

Absolutely, but do it right.

About the smallest sheave you want to use with an "A" section belt (FHP
motor belt) is 2"-2.5" which will have a pitch dia of 1.75"-2.25".

Take your existing sheaves from the 1725 RPM installation, measure them and
subtract about 1/4" which will get you close to the actual pitch diameter.

The ratio of the pitch diameters is the actual sheave ratio.
Since this will give you the existing sheave ratio, it is a straight forward
math problem to arrive at the correct solution for the new sheaves.

HTH

Lew