Help with Drill Press conversion

[Foss]

Hello all,
I recently got tired of changing the belts all the time to change spindle speed  on my  40 year old 16 speed Taiwanese drill press so I decided to change to a 3 phase motor and added a VFD thinking that I could just vary the spindle speed with the VFD and no longer have to change belts. Then I realized that there were issues with the torque at different speeds. So............

I would like to mount a step pulley on the new motor to better control the torque at the spindle. I have been searching on line for step pulleys,
but all of the pulleys that I am finding have v grooves that are wider than the original step pulley on my motor (they are made to accept different sized belts .....3L,4L,A for example), and the step pulley that is on the spindle is made for 3L belts only. Therefore the two pulleys wont line up correctly.

I would rather not have to change both pulleys, so does anyone know where to find the narrower step pulleys. Also, what I am finding in step pulleys are consecutive numbers (like 3", 4", 5" in a step pulley) but I would really like something like a 2",4",6" ????

[daddo]

I had the same problem with my old drill press when the pulley broke. I found one here; https://electricmotorwarehouse.com/step-pulleys/  The 3L (3/8") belts are small and a pain to deal with. If you could, changing to a 4L wouldn't be a bad idea if you used the grooved belts which run smoother.

[Foss]

I had the same problem with my old drill press when the pulley broke. I found one here; https://electricmotorwarehouse.com/step-pulleys/  The 3L (3/8") belts are small and a pain to deal with. If you could, changing to a 4L wouldn't be a bad idea if you used the grooved belts which run smoother.

I went on that website and all of the step pulleys that I could find were for 4L or A belts.

[daddo]

You're right- their gone.

Can you switch to 4L?

[gregbois]

There is an excellent discussion here of the issue of torque and motor speed.  The right kind of VFD will deliver all the necessary torque at a given spindle speed, provided the motor is large enough.  And, 3 phase is the only way to go.

https://sawmillcreek.org/showthread.php?...lt-changes

Greg

[JDuke]

I have VFD and 3 phase on a couple tools but for my drill press where torque at low RPM is needed a DC treadmill motor and control works better.

And if you find it on Craigslist it will be almost free
Just look for older treadmill

[SceneryMaker]

I found a treadmill on the curb but the controller was missing so I salvaged only the motor. I found a lot of videos on making a CD controller but none of them measure and control speed. They only control voltage so speed changes inversely with torque. Does anybody know of a good speed controller for a 90 volt motor?

[JDuke]

Every time I’ve looked for a DC motor control I priced them then went back to looking for a used treadmill.

There are at least 2 near me for less than $100 that I’d be all over if I needed a variable speed motor, but I have a vfd and 3ph motor on a lathe, treadmill motor on a belt grinder, another on a drill press and one in reserve so I don’t need 2 more taking up space.

Duke

[KyleD]

It should be noted that not all VFDs are created equal. If it has vector-less torque control it will do a fairly good job of keeping torque up at lower RPMs I have both types on different machines in my workshop and will probably just get vector-less in the future if i find need another. My metal lathe has a vector-less VFD with torque control. Through the pulleys, I keep it geared to turn between 50 and 2000 RPM varying the motor up to 90 hertz. At 90 rpm under a sudden load such as threading shafts, it will slightly bog for a half second or so until the torque control kicks in.  This in a 10" metal lathe with a 1 kilo watt (almost 1.5 hp) three phase.