Motor choice and set up

cross thread

cross thread

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I want to power a small mill , I have zero knowledge of how to make/set up a PWM or SCR . I would like to buy off the shelf , motor and controller . I'm not even sure a DC motor is a good idea , also I'm not against a counter shaft but if it is not necessary that would be nice . I do want to be able to control speed by a dial . Please let me know your thoughts ., links will be helpful
What do you think about this ?
www.galco.com

15DVE

Drive, DC, 2A, 120/240VAC,
www.galco.com www.galco.com
Thanks , Mark .
 
cross thread said:
I want to power a small mill , I have zero knowledge of how to make/set up a PWM or SCR . I would like to buy off the shelf , motor and controller . I'm not even sure a DC motor is a good idea , also I'm not against a counter shaft but if it is not necessary that would be nice . I do want to be able to control speed by a dial . Please let me know your thoughts ., links will be helpful
What do you think about this ?
www.galco.com

15DVE

Drive, DC, 2A, 120/240VAC,
www.galco.com www.galco.com
Thanks , Mark .
Click to expand...
The motor is way too small for any meaningful work. 2.6 in-oz. of torque is less than 1/4 lb-ft.. And that is at rated rpm. When you slow the rpm, the torque will drop even further.
 
There is a serious mismatch between your motor selection and the controller. You need to match voltages. A permanent magnet brush motor doesn't use a field winding so the controller doesn't need that feature.
 
I was hoping you would read this RJ , well like I said (think Sargent Shultz) . Suggestions ?
 
What size mill? That makes a big difference. My RF30 clone has a 2 hp. motor and geared down to the lowest pulley speed, has probably 75 lb-ft. of torque at the spindle. My Tormach has a 3 phase 1 hp. motor. It has a VFD and on the low speed belt configuration and at the lowest speed of 150 rpm, the available torque is virtually unusable. I can't even countersink a hole with it. It's OK at higher speeds but I can't say it's overpowered.
 
My mill ? it's a Pratt & Whitney 3c horizontal . The table is about 4"X19" . At the moment and for the foreseeable future it will be in the horizontal mode , unless some one out there has a vert. head for sale . Please tell me what motor AC or DC and what controller of course I need low end torque . I have only 110v to power . I live in a town home the homeowners association will not permit modifications like making 220v.
Thanks , Mark .
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I am not familiar with that machine but a search shows that @DiscoDan has or had one.
 
RJSakowski said:
What size mill? That makes a big difference. My RF30 clone has a 2 hp. motor and geared down to the lowest pulley speed, has probably 75 lb-ft. of torque at the spindle. My Tormach has a 3 phase 1 hp. motor. It has a VFD and on the low speed belt configuration and at the lowest speed of 150 rpm, the available torque is virtually unusable. I can't even countersink a hole with it. It's OK at higher speeds but I can't say it's overpowered.
Click to expand...
Given that I know you have a very complete understanding, and expertise when it comes to making motors turn (ref: your great other thread "Reconfiguring an AC Induction Motor", you manage to put me in confusion about low torque at low speeds.

Of course, one can get "VFDs" that are hardly worth the name, and I suppose one can still get all kinds out there. In practice, I think a modern "VFD" is actually a pulse-width modulated servo-style switched motor drive with current vector feedback sensing that can produce large controlled torques, even on a motor running slowly, with massive slip. [ Torque x (Nearly zero) Revs = (Nearly Zero) Power ]

Regardless how good or bad the VFD may be at delivering torque, the Tormach would surely have a designed belt speed configuration choice to be able to "go slower", say a reasonable 150 rpm at the spindle, while the motor would be spinning at near it's designed loaded speed.

Running the motor with a VFD to still produce 150 rpm via the belt mechanical advantage should not involve a feeble torque. I am pretty sure I am misunderstanding something.
 
graham-xrf said:
Given that I know you have a very complete understanding, and expertise when it comes to making motors turn (ref: your great other thread "Reconfiguring an AC Induction Motor", you manage to put me in confusion about low torque at low speeds.

Of course, one can get "VFDs" that are hardly worth the name, and I suppose one can still get all kinds out there. In practice, I think a modern "VFD" is actually a pulse-width modulated servo-style switched motor drive with current vector feedback sensing that can produce large controlled torques, even on a motor running slowly, with massive slip. [ Torque x (Nearly zero) Revs = (Nearly Zero) Power ]

Regardless how good or bad the VFD may be at delivering torque, the Tormach would surely have a designed belt speed configuration choice to be able to "go slower", say a reasonable 150 rpm at the spindle, while the motor would be spinning at near it's designed loaded speed.

Running the motor with a VFD to still produce 150 rpm via the belt mechanical advantage should not involve a feeble torque. I am pretty sure I am misunderstanding something.
Click to expand...
My Tormach has two speed ranges via belt positions. The low speed range is 175 -3,250 rpm and 525 - 10,200 rpm. The motor is 1 hp, 1.5 hp peak, 3360 rpm. The low speed pulley ratio is 1:2.25 and the high speed ratio is 1.4:1. In the low speed configuration, the motor is running 394 rpm or 12% of its plate rating at its lowest setting.

The VFD is am Emerson Commander SK model. At the lowest speed setting, the motor frequency is 5.6 hz and I can literally stop the spindle by grabbing the 1/2" keyless chuck with my hand. I have never played around with the Tormach factory parameter settings.

Yes, Tormach probably made a bad choice for pulley ratios. There is large overlap between the two ranges. I suspect that the cabinet size governed their choice rather than performance. The spindle diameter determines the minimum driven pulley diameter for the low speed range while the cabinet determines the maximum diameter. Add to that, the constraint that the belt is used for both low and high speed and required pulley diameters to deliver appropriate torque and the design is fairly well fixed.
 
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