Elec Motor spinning
 

From time to time it would be handy to have a small metal cutting bandsaw.
I was noticing that my wood bandsaw has the drive pulley exposed underneath
which conveniently is two speed so has an unused space for another belt. It
would be possible to rig up another motor with gearing to get the blade
speed into the proper range. So the question is - can I just rig up two
motors and apply power to the one for the speed needed or is free spinning
the other motor bad for it somehow? And I do realize that hot metal chips
in sawdust can be a bad thing and recognize the need to clean it out
thoroughly before switching over.

Thanks.
Steve.

Why bother with a second motor? Use an intermediate step pully and gear
the motor that is there down. Two benefits: 1) Cheaper, 2) Increased
torque for cutting tougher materials.

On Wed, 10 Aug 2005 15:06:39 GMT, "SteveF" wrote:

From time to time it would be handy to have a small metal cutting bandsaw.
I was noticing that my wood bandsaw has the drive pulley exposed underneath
which conveniently is two speed so has an unused space for another belt. It
would be possible to rig up another motor with gearing to get the blade
speed into the proper range. So the question is - can I just rig up two
motors and apply power to the one for the speed needed or is free spinning
the other motor bad for it somehow? And I do realize that hot metal chips
in sawdust can be a bad thing and recognize the need to clean it out
thoroughly before switching over.

Thanks.
Steve.


Or put on a 3 phase motor and a VFD.

Gunner

The two highest achievements of the human mind are the twin concepts of "loyalty" and "duty."
Whenever these twin concepts fall into disrepute -- get out of there fast! You may possibly
save yourself, but it is too late to save that society. It is doomed. " Lazarus Long

The slow speed motor would bne badly overrevved when using the high speed
motor.
You'd have to apply a one-way clutch to that motor to keep it from being a
grenade under there.

--
Why do penguins walk so far to get to their nesting grounds?

It will work fine as long as you don't overspeed the either motor more than
2X it's rated speed when the other is running.
This precaution is to prevent possible rotor damage. Spinning a unpowered
motor has no effect other than some additional bearing wear which should not
be an issue in your case.

Randy


"SteveF" wrote in message
.com...
From time to time it would be handy to have a small metal cutting bandsaw.
I was noticing that my wood bandsaw has the drive pulley exposed
underneath
which conveniently is two speed so has an unused space for another belt.
It
would be possible to rig up another motor with gearing to get the blade
speed into the proper range. So the question is - can I just rig up two
motors and apply power to the one for the speed needed or is free spinning
the other motor bad for it somehow? And I do realize that hot metal chips
in sawdust can be a bad thing and recognize the need to clean it out
thoroughly before switching over.

Thanks.
Steve.

Now that it's been pointed out I would be spinning one motor REALLY fast.
Thought about the VFD but would need to run it around 2-4 Hz to get things
slow enough. Found a parts diagram for the Delta metal/wood saw and they
just use two step pulleys with huge changes in diameters so I might see if
those could be retrofit to my saw.

Thanks all.
Steve.




"SteveF" wrote in message
.com...
From time to time it would be handy to have a small metal cutting bandsaw.
I was noticing that my wood bandsaw has the drive pulley exposed
underneath which conveniently is two speed so has an unused space for
another belt. It would be possible to rig up another motor with gearing
to get the blade speed into the proper range. So the question is - can I
just rig up two motors and apply power to the one for the speed needed or
is free spinning the other motor bad for it somehow? And I do realize
that hot metal chips in sawdust can be a bad thing and recognize the need
to clean it out thoroughly before switching over.

Thanks.
Steve.

do a google search on one-way clutch [I get 175k hits] you
only need one to keep the slow speed motor from being driven.
Most likely your local bearing supply has one in stock.

On Wed, 10 Aug 2005 21:06:55 GMT, "SteveF" wrote:


Now that it's been pointed out I would be spinning one motor REALLY fast.
Thought about the VFD but would need to run it around 2-4 Hz to get things
slow enough. Found a parts diagram for the Delta metal/wood saw and they
just use two step pulleys with huge changes in diameters so I might see if
those could be retrofit to my saw.

Thanks all.
Steve.




"SteveF" wrote in message
r.com...
From time to time it would be handy to have a small metal cutting bandsaw.
I was noticing that my wood bandsaw has the drive pulley exposed
underneath which conveniently is two speed so has an unused space for
another belt. It would be possible to rig up another motor with gearing
to get the blade speed into the proper range. So the question is - can I
just rig up two motors and apply power to the one for the speed needed or
is free spinning the other motor bad for it somehow? And I do realize
that hot metal chips in sawdust can be a bad thing and recognize the need
to clean it out thoroughly before switching over.

Thanks.
Steve.

SteveF wrote:
Now that it's been pointed out I would be spinning one motor REALLY fast.
Thought about the VFD but would need to run it around 2-4 Hz to get things
slow enough. Found a parts diagram for the Delta metal/wood saw and they
just use two step pulleys with huge changes in diameters so I might see if
those could be retrofit to my saw.

Thanks all.
Steve.


Don't know what Delta saw that is, but I've got a 14" Delta wood/metal
saw. It has a gearbox as well.

4-step pulleys on the motor and on the gearbox input shaft allow any of
four geared speeds for cutting steel, brass, etc. For wood (or
aluminum), a large pulley on the wheel shaft is driven by one of the
steps on the motor pulley.

To switch between wood and metal you change to a different belt and
then throw the gearbox engagement lever.

To get steel cutting speeds with pulleys, you'd probably need a
jackshaft to step it down twice. Plus, you need a lot of torque -
which might cause a belt to slip.

John Martin