I need about 67 rpm on a shaft.
An 1800 motor with a 40 to 1 gearbox = 45
An 1800 motor with a 20 to 1 gearbox = 90
Of course, Automation Direct doesn't have a 30 to 1 box and I want to use
them as a supplier.
The output of the gearbox will have a belt to drive the shaft but should I
use the 40 and step up the speed to the shaft with the appropriate sheaves
or step down the speed from the 20? Or, does it not make any difference?

Torque doesn't factor into this, I'm upgrading from 1/10hp single phase to
1/3hp 3-phase...and it's CHEAPER!!!

"Tom Gardner" wrote in message
...
I need about 67 rpm on a shaft.
An 1800 motor with a 40 to 1 gearbox = 45
An 1800 motor with a 20 to 1 gearbox = 90
Of course, Automation Direct doesn't have a 30 to 1 box and I want to use
them as a supplier.
The output of the gearbox will have a belt to drive the shaft but should I
use the 40 and step up the speed to the shaft with the appropriate sheaves
or step down the speed from the 20? Or, does it not make any difference?

Torque doesn't factor into this, I'm upgrading from 1/10hp single phase to
1/3hp 3-phase...and it's CHEAPER!!!

For no particular reason I seem to believe that two reductions are better
than one reduction and one increase. Just for fun, you might calculate it
both ways to see if one is easier with stock pulleys. Even if you use an
adjustable pulley, you might find one way easier or cheaper to implement.

Don Young

Why not use a VFD to control the speed of the 3ph motor? Then you can have
any reasonable rpm you want. That size would be rather inexpensive, also.
Respectfully,
Ron Moore

"Tom Gardner" wrote in message
...
I need about 67 rpm on a shaft.
An 1800 motor with a 40 to 1 gearbox = 45
An 1800 motor with a 20 to 1 gearbox = 90
Of course, Automation Direct doesn't have a 30 to 1 box and I want to use
them as a supplier.
The output of the gearbox will have a belt to drive the shaft but should I
use the 40 and step up the speed to the shaft with the appropriate sheaves
or step down the speed from the 20? Or, does it not make any difference?

Torque doesn't factor into this, I'm upgrading from 1/10hp single phase to
1/3hp 3-phase...and it's CHEAPER!!!

On Sep 6, 6:57 pm, "Tom Gardner" wrote:
I need about 67 rpm on a shaft.
An 1800 motor with a 40 to 1 gearbox = 45
An 1800 motor with a 20 to 1 gearbox = 90
Of course, Automation Direct doesn't have a 30 to 1 box and I want to use
them as a supplier.
The output of the gearbox will have a belt to drive the shaft but should I
use the 40 and step up the speed to the shaft with the appropriate sheaves
or step down the speed from the 20? Or, does it not make any difference?

Torque doesn't factor into this, I'm upgrading from 1/10hp single phase to
1/3hp 3-phase...and it's CHEAPER!!!

If I recall correctly ( and since I was mostly an electrical engineer
it is a big if ) the smaller pulley limits the power that a belt can
deliver. So for the same size pulley on the driven shaft, you would
have a bigger pulley on the gearbox if you used a 40:1 gear box and
stepped up the speed.

Dan

This may not be the right answer, but I bet it prompts some comments.

Tom Gardner wrote:
I need about 67 rpm on a shaft.
An 1800 motor with a 40 to 1 gearbox = 45
An 1800 motor with a 20 to 1 gearbox = 90

What Ron Moore said.

Will the budget stretch to $160 for a 1 HP VFD?
http://www.vfds.com/inventory.html#drives_0.125

Use the 20:1 gearbox and set the VFD to 74.44%?
Perhaps use a heatsink on the motor to compensate
for less 'fan effect'?

--Winston

On Sat, 6 Sep 2008 21:57:02 -0400, "Tom Gardner"
wrote:

I need about 67 rpm on a shaft.
An 1800 motor with a 40 to 1 gearbox = 45
An 1800 motor with a 20 to 1 gearbox = 90
Of course, Automation Direct doesn't have a 30 to 1 box and I want to use
them as a supplier.
The output of the gearbox will have a belt to drive the shaft but should I
use the 40 and step up the speed to the shaft with the appropriate sheaves
or step down the speed from the 20? Or, does it not make any difference?

Torque doesn't factor into this, I'm upgrading from 1/10hp single phase to
1/3hp 3-phase...and it's CHEAPER!!!

I would step down from the 20.

If you step down to below load speed and then step back up, the max
torque in the system is greater than load torque. Not that it matters
in this case but I thought I'd mention it.

"Ron Moore" wrote in message
...
Why not use a VFD to control the speed of the 3ph motor? Then you can
have any reasonable rpm you want. That size would be rather inexpensive,
also.
Respectfully,
Ron Moore

Out of the budget and somebody would dick with it.

"Winston" wrote in message
news:mSIwk.741$Wd.59@trnddc01...
Tom Gardner wrote:
I need about 67 rpm on a shaft.
An 1800 motor with a 40 to 1 gearbox = 45
An 1800 motor with a 20 to 1 gearbox = 90

What Ron Moore said.

Will the budget stretch to $160 for a 1 HP VFD?
http://www.vfds.com/inventory.html#drives_0.125

Use the 20:1 gearbox and set the VFD to 74.44%?
Perhaps use a heatsink on the motor to compensate
for less 'fan effect'?

--Winston

I have to make twelve units and the one speed will do just fine.

"Don Foreman" wrote in message
...
On Sat, 6 Sep 2008 21:57:02 -0400, "Tom Gardner"
wrote:

I need about 67 rpm on a shaft.
An 1800 motor with a 40 to 1 gearbox = 45
An 1800 motor with a 20 to 1 gearbox = 90
Of course, Automation Direct doesn't have a 30 to 1 box and I want to use
them as a supplier.
The output of the gearbox will have a belt to drive the shaft but should I
use the 40 and step up the speed to the shaft with the appropriate sheaves
or step down the speed from the 20? Or, does it not make any difference?

Torque doesn't factor into this, I'm upgrading from 1/10hp single phase to
1/3hp 3-phase...and it's CHEAPER!!!

I would step down from the 20.

If you step down to below load speed and then step back up, the max
torque in the system is greater than load torque. Not that it matters
in this case but I thought I'd mention it.



It just seems natural to reduce to speed, I don't know why. Would the 20
box be more robust and run cooler, last longer, etc.?

On Sat, 6 Sep 2008 20:56:41 -0700 (PDT), "
wrote:

If I recall correctly ( and since I was mostly an electrical engineer
it is a big if ) the smaller pulley limits the power that a belt can
deliver. So for the same size pulley on the driven shaft, you would
have a bigger pulley on the gearbox if you used a 40:1 gear box and
stepped up the speed.

Dan

This may not be the right answer, but I bet it prompts some comments.

You remember correctly. Assuming everything is sized to the load, two
reductions will result in a more compact and cheaper drive.

--
Ned Simmons

On Sat, 6 Sep 2008 21:57:02 -0400, "Tom Gardner"
wrote:

I need about 67 rpm on a shaft.
An 1800 motor with a 40 to 1 gearbox = 45
An 1800 motor with a 20 to 1 gearbox = 90
Of course, Automation Direct doesn't have a 30 to 1 box and I want to use
them as a supplier.
The output of the gearbox will have a belt to drive the shaft but should I
use the 40 and step up the speed to the shaft with the appropriate sheaves
or step down the speed from the 20? Or, does it not make any difference?

Torque doesn't factor into this, I'm upgrading from 1/10hp single phase to
1/3hp 3-phase...and it's CHEAPER!!!


I'm a big fan of Automation Direct, but why are you stuck with them?
Oriental Motor makes small and smaller 3-phase gearmotors in just
about any power and ratio you could want. They stock the component
motors and gearheads to make just about anything they list. Figure
around $250 for a typical gear+motor.

http://catalog.orientalmotor.com/cat...rs-?&plpver=11

--
Ned Simmons

On Sun, 7 Sep 2008 02:45:31 -0400, "Tom Gardner"
wrote:


I would step down from the 20.

If you step down to below load speed and then step back up, the max
torque in the system is greater than load torque. Not that it matters
in this case but I thought I'd mention it.



It just seems natural to reduce to speed, I don't know why. Would the 20
box be more robust and run cooler, last longer, etc.?

If designed to the same specs for efficiency, lifetime and power
output the boxes should be quite similar. Gear volume generally
depends on power level (speed = diameter, torque = thickness, power
= torque * speed, power in = power out + losses).

I don't know what the case might be for the two particular examples
you have in mind.

Tom Gardner wrote:
"Don Foreman" wrote in message
...

On Sat, 6 Sep 2008 21:57:02 -0400, "Tom Gardner"
wrote:


I need about 67 rpm on a shaft.
An 1800 motor with a 40 to 1 gearbox = 45
An 1800 motor with a 20 to 1 gearbox = 90
Of course, Automation Direct doesn't have a 30 to 1 box and I want to use
them as a supplier.
The output of the gearbox will have a belt to drive the shaft but should I
use the 40 and step up the speed to the shaft with the appropriate sheaves
or step down the speed from the 20? Or, does it not make any difference?

Torque doesn't factor into this, I'm upgrading from 1/10hp single phase to
1/3hp 3-phase...and it's CHEAPER!!!

I would step down from the 20.

If you step down to below load speed and then step back up, the max
torque in the system is greater than load torque. Not that it matters
in this case but I thought I'd mention it.




It just seems natural to reduce to speed, I don't know why. Would the 20
box be more robust and run cooler, last longer, etc.?




You should get a 'Martin Gear' catalogue with all the specs. on pulley
size, HP rating and the rest of the info you need to design your system.
I think they have a website with the same info.


John

I would consider the Oriental Motor solution to be the most cost effective,
because of OM's quality and reliability.
Available in reversible, single or three phase models up to about 1/8 HP or
slightly higher, with the gear reduction providing higher torques at lower
speeds, such as the speeds Tom G was asking about.

The VFD solutions hardly seem worth consideration, since the only frequency
required (and highly dependable) is line frequency.

I've seen case lots of new Oriental Motor components on eBay in the past,
and I doubt that a better value is available anywhere.

They have numerous styles of gearheads in single-output-shaft, selectable
right or left side right angle shaft or dual RA shafts. I believe most of
them are entirely ball bearing gearheads, including ball bearing assemblies
on both ends of the internal gear shafts (also the motor shafts).
Additionally, there are models with electric brakes, clutches, (or both),
impedence protected, thermal protection, and tachometer output (and maybe a
couple of other features).
I've seen some models fitted with optical encoders as an add-on option from
OM.

WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Ned Simmons" wrote in message
...

I'm a big fan of Automation Direct, but why are you stuck with them?
Oriental Motor makes small and smaller 3-phase gearmotors in just
about any power and ratio you could want. They stock the component
motors and gearheads to make just about anything they list. Figure
around $250 for a typical gear+motor.

http://catalog.orientalmotor.com/cat...rs-?&plpver=11

--
Ned Simmons