I think it usually requires a variable speed motor and a controller. A better solution but too much $.
Gear motor for drill press
- Thread starter MillWeld
- Start date
I think it usually requires a variable speed motor and a controller. A better solution but too much $.
Shield Arc
Super Member
Variable Frequency Drive is what I was thinking about. 
Variable Frequency Drive Inverter VFD 7 5KW 380V 19A YA2 | eBay
Variable Frequency Drive Inverter VFD 7 5KW 380V 19A YA2 | eBay
BukitCase
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See their instructions here
http://www.surpluscenter.com/Instruct/I5-1647.pdf
On the starting relay - the motor appears to have a centrifugal switch (as most do) that connects L1 to the RED wire til the motor is up to speed - This lets the 120 volts energise the starting relay, pulling in the relay contacts (above the relay coil in the drawing) -
That puts both capacitors in parallel, increasing the total capacitance for starting.
When the motor comes up to speed, the centrifugal switch in the motor drops out, taking the START capacitor out of the circuit leaving the RUN capacitor.
They claim that motor draws nearly 10 amps, but uses only 440 watts - only way I see that happening is if the amperage is STARTING amps. Otherwise, 10 amps at 120 volts would be 1200 watts. (volts X amps)
Based on that, I think that a 10 amp, 120 volt AC relay would work - one I've used thousands of times (retired instrument/electrician) is the Potter/Brumfield KRP11-AN - it has TWO 10-amp sets of contacts, so if I were doing this I would wire BOTH sets of contacts in parallel. That way you would have some reserve capacity on the contacts, and they should last a LONG time.
BTW, if this motor REALLY only draws 440 watts, it would be rated at a maximum of 440/746, or .59 horsepower - still over half horse, and the slower speed should make your press act more like it had a 3/4 horse motor.
Still seeing no prob with this, as long as you have access to a way to (1) bore out your existing motor step pulley, and (2) fab a bracket that would bolt to the end plate of the new motor and match up to your existing motor mount plate (the one you move back and forth with the tension lever when you change speeds) - I'm thinking this would basically be a large "L" bracket, with a hole for the motor shaft, holes to match the motor end plate, and more holes in the other leg of the "L" to line up with the tension adjuster carriage.
Whew - as far as I can tell, I left out any more "brain farts" - HTH... Steve
http://www.surpluscenter.com/Instruct/I5-1647.pdf
On the starting relay - the motor appears to have a centrifugal switch (as most do) that connects L1 to the RED wire til the motor is up to speed - This lets the 120 volts energise the starting relay, pulling in the relay contacts (above the relay coil in the drawing) -
That puts both capacitors in parallel, increasing the total capacitance for starting.
When the motor comes up to speed, the centrifugal switch in the motor drops out, taking the START capacitor out of the circuit leaving the RUN capacitor.
They claim that motor draws nearly 10 amps, but uses only 440 watts - only way I see that happening is if the amperage is STARTING amps. Otherwise, 10 amps at 120 volts would be 1200 watts. (volts X amps)
Based on that, I think that a 10 amp, 120 volt AC relay would work - one I've used thousands of times (retired instrument/electrician) is the Potter/Brumfield KRP11-AN - it has TWO 10-amp sets of contacts, so if I were doing this I would wire BOTH sets of contacts in parallel. That way you would have some reserve capacity on the contacts, and they should last a LONG time.
BTW, if this motor REALLY only draws 440 watts, it would be rated at a maximum of 440/746, or .59 horsepower - still over half horse, and the slower speed should make your press act more like it had a 3/4 horse motor.
Still seeing no prob with this, as long as you have access to a way to (1) bore out your existing motor step pulley, and (2) fab a bracket that would bolt to the end plate of the new motor and match up to your existing motor mount plate (the one you move back and forth with the tension lever when you change speeds) - I'm thinking this would basically be a large "L" bracket, with a hole for the motor shaft, holes to match the motor end plate, and more holes in the other leg of the "L" to line up with the tension adjuster carriage.
Whew - as far as I can tell, I left out any more "brain farts" - HTH... Steve
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bigdeano
Platinum Member
I don't see that the motor has an internal switch. Starting relays are used on refrigeration compressors and other motors that don't have centrifigul switches. Getting the right one might take some research. I've bought them from Grainger before, but I don't remember how to find the right one.
npalen
Elite Member
AC Drives Overview
The VFD's (VariableFrequencyDrive) have come down in price as I see the single phase GS1 model shown here starts at $99 but only go up to 1/2 HP on 120 volt SINGLE phase. The VFD's are normally used with 3 phase motors but use solid state electronics to convert 220 volt single phase to 3 phase which drives the motor to give variable speed and reversing.
My only concern with slowing down your drill press with the GS1 drive is whether there will be enough torque left at lower speeds to run the 3" holesaw. You might visit with the folks at AutomationDirect to get their opinion.
The VFD's (VariableFrequencyDrive) have come down in price as I see the single phase GS1 model shown here starts at $99 but only go up to 1/2 HP on 120 volt SINGLE phase. The VFD's are normally used with 3 phase motors but use solid state electronics to convert 220 volt single phase to 3 phase which drives the motor to give variable speed and reversing.
My only concern with slowing down your drill press with the GS1 drive is whether there will be enough torque left at lower speeds to run the 3" holesaw. You might visit with the folks at AutomationDirect to get their opinion.
BukitCase
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Went on Bodine's site looking for a motor that matches this one - no luck so far. Did find a table of torque values on AC motors, and 44 inch pounds is typical for a 1/2 horse. If I get time tomorrow I'll check further - then at least we'll know if the motor has an internal switch or not. If not, you can get a "generic" starting relay on amazon for about $15, but I've not found concrete hookup specs on that yet either.
It would sure help if Surplus Center would print actual mfr #'s, I've been thru this a few times on hydraulic valves too... Steve
It would sure help if Surplus Center would print actual mfr #'s, I've been thru this a few times on hydraulic valves too... Steve
mjncad
Super Member
You can do it at that RPM; but you'll still have to baby the saw to get decent cutting and acceptable chatter. Use oil to cool the saw while cutting. I've done 3" or 3-1/2" diameter holes in 1/4" steel on my 17" Jet drill press at 230RPM; but it's a slow noisy slog.
I have written SC asking if the motor has a cent. switch. I'll have to wait until next week for a reply but I have found them to be very responsive. I also wrote Bodine.
Whether or not the motor has a centrifugal switch, according to the instructions, it looks straightforward to wire in a relay. The red from the motor and the hot from the line go to the relay input. The output goes to the caps. as shown. I guess there is still the question if it is a time delay relay.
Bob
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jwmorris
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Get a used HandyAuto torch. Cost about the same as a new gear motor and will cut perfect holes a lot faster than a hole saw.