Gear motor for drill press

[Mendonsy]

I have an older Central Tractor (now Tractor Supply) 16 speed drill press that I modified for variable speed, reversible several years ago.
I replaced the original 1/2 hp capacitor start motor with a 3/4 hp 3 phase motor and added a TECO 1hp inverter drive that converts 115 volt single phase to 230 volt 3 phase. I also added a foot switch for hands free operation so that I can use it for drilling and tapping. I can run it as low as 16 rpm on the low speed setting.
FM50-101-C

 

[npalen]

There's a lot of 3 phase used equipment that can be had for a reasonable price as most folks don't have access to 3 phase power. The VFD (variable frequency drive) will run off of single phase and varies the frequency to control RPM. The frequency can also be INCREASED from the standard 50 or 60 cycles/second to increase the RPM and, for example, it can be doubled by dialing up 120 cycles/second. Common sense comes into play, however, as most motors and machinery are not intended to run at much higher speed. Another nice feature of the VFD's is soft start and stop which can be adjusted and, as Mendonsy mentions above, nice to be able to reverse for tapping threads.

 

[SPYDERLK]

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

if it has the centrifigal switch you will not need a relay for that small motors draw. If it does not have a cent switch a relay could control the capacitively phase shifted start winding. ... You could also do this manually with a single pole double throw switch having a center OFF position. You could also run the motor without the starter winding by just rope starting the press in the direction you want it to rotate. - O-ops. Actually above, no, after a look @ instructions. -You could however do it with DPDT or install a pushbutton momentary switch to be used in starting.
,,,,On 2nd thot after review of the instructions it looks as tho this motor does not have a start winding. The red lead presents no ability to carry real current because that current would be limited by the relay coil. The hookup merely doubles up the capacitors on the blue line during start. The 2nd switching options above could accomplish this. Rope starting w/o the start cap would work as well.
larry

 

[bigdeano]

On a drill press, which starts with practically no load, the motor may start ok with just the running capacitor. I have a small motor that uses a running capacitor and it starts fine without anything else.

 

[bigdeano]

On 2nd thot after review of the instructions it looks as tho this motor does not have a start winding. The red lead presents no ability to carry real current because that current would be limited by the relay coil. The hookup merely doubles up the capacitors on the blue line during start. The 2nd switching options above could accomplish this. Rope starting w/o the start cap would work as well.
larry

Just thought I would comment on this. The coil in the relay would have a low impedence so it can carry the full motor current. At high current, like when starting, the relay would pull in, putting the start cap in the circuit. As the speed increases the current would decrease letting the relay drop out.

I think what I would do is try it without the start relay and start cap. If it won't start I'd put a Hard Start kit on it. They put these on refrigerators and air conditioners to make them start easier. One side of the line would hook to the red wire.

I'd like to get one of these motors, but the shipping cost to WA almost doubles the price. I'll have to think about it for a while.

 

[travis potter]

At one time I had a old drillpres with a jack shft with a 5 sheeve pulley on it by combing the belts on the pullies it it would run real slow and could be built real cheap. hint use a cheep hf drill press for the jack shaft

 

[MillWeld]

The jack shaft idea has got my attention. I've seen examples on the web and I have pulleys from 2.5" to 10" dia so I may make my own; or would it be better to buy another step pulley? I'm trying to maintain my top rpm of 2800 and go down to ~100 or less rpm; that's a 28:1 ratio. Is that reasonable? I haven't analyzed the possible diameter ratios for what I have; it gets a little tricky because you can't utilize all the steps on the pulley. What do you think about allowing the jackshaft pulleys to slide along their shaft? Bad idea because it is a vertical shaft? Ideas are welcome.
Bob

 

[SPYDERLK]

Just thought I would comment on this. The coil in the relay would have a low impedence so it can carry the full motor current. At high current, like when starting, the relay would pull in, putting the start cap in the circuit. As the speed increases the current would decrease letting the relay drop out.

I think what I would do is try it without the start relay and start cap. If it won't start I'd put a Hard Start kit on it. They put these on refrigerators and air conditioners to make them start easier. One side of the line would hook to the red wire.

I'd like to get one of these motors, but the shipping cost to WA almost doubles the price. I'll have to think about it for a while.

Do you know this, or is it surmise? ... because I see counter issues; 1] Relays draw a lot more current to pull in than once in and holding, 2] it would be an unusual type of relay coil to put up with motor sized current continuously. More likely there is an internal centrifugal switch on the red line.
larry

 

[BukitCase]

From spyderlk - "More likely there is an internal centrifugal switch on the red line."

That's the main reason for my same conclusion on page 1 of this thread :=) Steve

 

[CNC Dan]

Do you know this, or is it surmise? ... because I see counter issues; 1] Relays draw a lot more current to pull in than once in and holding, 2] it would be an unusual type of relay coil to put up with motor sized current continuously. More likely there is an internal centrifugal switch on the red line.
larry

They are a special kind of relay. Called "current sensing" relay.
They have a few (10-20) turns of heavy wire for the coil. Used instead of the internal centripetal swich. The pull in and drop out current is different but they're made with that in mind.