VFD and 3-phase motor on drill press

rattle_snake · May 7, 2026

Looking to convert my Hitachi floor standing drill press to variable speed motor. Anyone done this?

Currently has a single phase 110V 1 hp motor, and typical twin belt 12 speed pulley setup. It is always set for the slowest speed, which is I believe is 210 RPM. Goal is to turn even slower, and also have some range of speed without belt change.

I bought a 2 hp 3-phase, 1800 RPM induction motor cheap, and can get a VFD for under $100. Plan to stick with the pulley system, in it's lowest ratio (8.3:1). Running VFD from 20 Hz to 120 Hz yields chuck speeds of 70 to 400 RPM.

Rick_Br · May 8, 2026

rattle_snake said:
Looking to convert my Hitachi floor standing drill press to variable speed motor. Anyone done this?

Currently has a single phase 110V 1 hp motor, and typical twin belt 12 speed pulley setup. It is always set for the slowest speed, which is I believe is 210 RPM. Goal is to turn even slower, and also have some range of speed without belt change.

I bought a 2 hp 3-phase, 1800 RPM induction motor cheap, and can get a VFD for under $100. Plan to stick with the pulley system, in it's lowest ratio (8.3:1). Running VFD from 20 Hz to 120 Hz yields chuck speeds of 70 to 400 RPM.

I've done that a few times and it is a good solution. Just be aware that depending on the VFD you may lose torque at lower frequency settings.

svtride · May 8, 2026

rattle_snake said:
Looking to convert my Hitachi floor standing drill press to variable speed motor. Anyone done this?

Currently has a single phase 110V 1 hp motor, and typical twin belt 12 speed pulley setup. It is always set for the slowest speed, which is I believe is 210 RPM. Goal is to turn even slower, and also have some range of speed without belt change.

I bought a 2 hp 3-phase, 1800 RPM induction motor cheap, and can get a VFD for under $100. Plan to stick with the pulley system, in it's lowest ratio (8.3:1). Running VFD from 20 Hz to 120 Hz yields chuck speeds of 70 to 400 RPM.

Yup, did a couple drill presses and a Bridgeport…works well. GFCI outlets in shop did not like VFD so had to replace outlet with standard outlet.

Firebrick43 · May 8, 2026

I have 5 machines on vfd and the drill press is probably the most useful.

On my drill press I used a KBAC-24D drive. It simple to operate and with no programming, just a few pots to adjust and more importantly is nema 4.

Nema 1 vfd are not ment to be installed outside of a cabinet or enclosure as someone can stick their fingers easily where they can be shocked or metal chips and dust can get into the drives openings shorting it out

stinkity stoink · May 8, 2026

I have never done it , but I will be following along if you do . You always do some interesting things.

tool_scrounge · May 8, 2026

Firebrick43 said:
Nema 1 vfd are not ment to be installed outside of a cabinet or enclosure as someone can stick their fingers easily where they can be shocked or metal chips and dust can get into the drives openings shorting it out

^ this. If NEMA 1, put it in a box but note the ventilation requirements.

I Usually buy NOS or lightly used brand name speed controls off of EBay vs. no-name stuff off of Amazon

jcarapet · May 8, 2026

This has been on my interest list for a while for my Shop Fox. The thing that has thrown me off so far is finding a motor with the right mount and spindle. Highly interested in this for tapping and just easier control.

Firebrick43 · May 8, 2026

jcarapet said:
This has been on my interest list for a while for my Shop Fox. The thing that has thrown me off so far is finding a motor with the right mount and spindle. Highly interested in this for tapping and just easier control.

What NEMA size and shaft diameter is your Shop Fox currently have?

whateg01 · May 8, 2026

I have a 6 pole motor on each of my main drill presses. The 1100 runs at about 60 rpm most of the time. The craftsman runs around 400 most of the time. Gobs of torque on both of them.

rattle_snake · May 8, 2026

Thanks for the info on the enclosure type I had not considered that.

Beerhippie · May 8, 2026

svtride said:
GFCI outlets in shop did not like VFD

You need a longer delay on the GFCI. I think we used 100mS. You won't find these at the hardware/big box store.

jcarapet · May 8, 2026

Firebrick43 said:
What NEMA size and shaft diameter is your Shop Fox currently have?

The motor plate is unfortunately pretty bare. I've measured the spacing on the plate and unfortunately it doesn't quite line up with anything exactly in the charts. I need to spend a little more time on the google machine for it. Maybe a 56c?

svtride · May 8, 2026

Beerhippie said:
You need a longer delay on the GFCI. I think we used 100mS. You won't find these at the hardware/big box store.

Thank you for this GFCI information. I did not realize that GFCI outlets came with differing delays.

Beerhippie · May 8, 2026

svtride said:
Thank you for this GFCI information. I did not realize that GFCI outlets came with differing delays.

I didn't either--until a new piece of equipment kept popping my GFCI breaker. Our local sparky got us straightened out and explained the delay problem with VFDs.

senlow · May 8, 2026

Beerhippie said:
You need a longer delay on the GFCI. I think we used 100mS. You won't find these at the hardware/big box store.

Hot damn!!! I learned something new. I will file that away in my little pea brain.

u3b3rg33k · May 8, 2026

rattle_snake said:
Thanks for the info on the enclosure type I had not considered that.

I really like the invertek drives for this. their native sensorless vector works great:

if you want really low RPM performance, look at a purpose built motor, like one of these:

you can find them for much less than list, but they have rated torque down to 0 RPM, and are TENV.

TurnipTruck · May 8, 2026

Beerhippie said:
I didn't either--until a new piece of equipment kept popping my GFCI breaker. Our local sparky got us straightened out and explained the delay problem with VFDs.

The VFD that I just put on my bandsaw has different jumper settings to better coexist with gfci receptacles.

svtride · May 9, 2026

senlow said:
Hot damn!!! I learned something new. I will file that away in my little pea brain.

In researching this more after the “delay" tidbit, I found this on GFCI classification definitions...
https://portablepowerguides.com/gfci-class-a-b-c-d-e-meaning-with-its-trip-level/
So far I couldn't find anything related with delay, just leakage amount..

Mike007 · May 9, 2026

This is my 3 ph Delta I converted a long time ago.

Beerhippie · May 10, 2026

svtride said:
In researching this more after the “delay" tidbit, I found this on GFCI classification definitions...
https://portablepowerguides.com/gfci-class-a-b-c-d-e-meaning-with-its-trip-level/
So far I couldn't find anything related with delay, just leakage amount..

I'll ask the electrician next time I'm over that way. It was a decade or so back, so I obviously don't recall 100%.

rattle_snake · May 11, 2026

Mike007 said:
This is my 3 ph Delta I converted a long time ago.

I like how you put the VFD control panel on the head. That is slick.

rattle_snake · May 11, 2026

Got the conversion done on this old drill press. Starting point:

PFabL09wKmX6dvkHfPDEA=w683-h911-s-no-gm?authuser=1.jpg

I had converted it to a hybrid long ago, never ran right, eventually lost the air filter.

nmBpbR76kw1d48I39ExRA=w683-h911-s-no-gm?authuser=1.jpg

Left 12 speed pulley system intact in lowest ratio. Low ratio is /7 or 250 RPM from 1750 motor.

BoJQ3TTf1KS5K-hQjgTaA=w683-h911-s-no-gm?authuser=1.jpg

Found a new, 3 phase, 2 hp, 1750 RPM motor for $100 on fbmp. 56C mount, 5/8 shaft same as the single phase, 1 hp motor it replaces.

nhx-1wJEBT5Rlq1dxWdA=w1215-h911-s-no-gm?authuser=1.jpg

Mount bracket for VFD and controls.

0q-sni_PCi_LvA5GSyTg=w1215-h911-s-no-gm?authuser=1.jpg

Bought a $80 VFD, 3 hp, 220V, Nema 1. Wires protrude out the bottom. Need an on/off switch in the system so I decided to get a $20 junction box to mount the stuff and wiring in. I could have rewired and used the existing on/off switch on the head of the press. Switch in J-box consolidates the wiring. The enclosure needs to be ventilated for heat dissipation. I drilled a few holes top and bottom. Not going to run it for long or at full torque so not going all in on thermal transfer. The one mount flat head screw contacts the VFD base heat sink and bolts to metal mount so it might do something.

2ls96jhPoGkSJTOv7MiKQ=w683-h911-s-no-gm?authuser=1.jpg

The control panel can be remote mounted with a ribbon cable so I did that. The box was barely deep enough and the panel had to go in a specific location to clear the rest. Retained the light feature on the press but had to rewire it for 220v and use a 220V rated bulb.

Nt3Jbzy46u8-a90kCHxLg=w683-h911-s-no-gm?authuser=1.jpg

Added an on/off switch at the box so the power wiring is simplified. Removed the on/off switch on the head and put in a block off.

f8Q4coEt5xt_yMp0UaPXw=w683-h911-s-no-gm?authuser=1.jpg

Bought a 25' 'welder extension cable' that is a 6-50P plug with 12 gauge wire (instead of #6 wire for 50 A). Used the molded male plug and made a whip about 8' long. Motor bolted right up no mods needed.

6YWJnnoekDHA4FF0wRmPQ=w683-h911-s-no-gm?authuser=1.jpg

In general the speed lower limit is around 20 Hz, and upper limit of 120 Hz. This yields a speed range of 6x. 60 Hz corresponds to 250 RPM, so RPM range becomes 83 to 500 without belt change. The VFD has a boost feature available. To test I ran the motor below 20 Hz with a 1" twist drill and exerted as much pressure as I could. It just ate so no concern of lack of power at the lower limit. Total cost was $250

7O_6BpyFO75wEkfnxAaKw=w683-h911-s-no-gm?authuser=1.jpg

Beerhippie · May 11, 2026

rattle_snake said:
Retained the light feature on the press but had to rewire it for 220v and use a 220V rated bulb.

If you run a 4-conductor whip and use 4-pole plug (appliance cord and plug), you can use any leg of the 220V to neutral for a 110V circuit.

rattle_snake · May 11, 2026

My 220v wiring and receptacles do not have a common wire so not a viable option. light bulb is cheap.

It is possible to get a 110V VFD, but finding a used/cheap 110V 3-phase motor is difficult.

tool_scrounge · May 11, 2026

Plenty of 120v in to 240vac out VFDs, but due to current limitations in most applications, they only go up to 1hp.

rattle_snake · May 11, 2026

I didn't see a 110 in 220v out in the cheap **** on amazon, but now I see they do exist. Probably shoulda done that. but 220V cuts all the currents in half, smaller wiring, and the receptacle was already there.

whateg01 · May 11, 2026

rattle_snake said:
My 220v wiring and receptacles do not have a common wire so not a viable option. light bulb is cheap.

It is possible to get a 110V VFD, but finding a used/cheap 110V 3-phase motor is difficult.

you mean a neutral?

aquinob · May 11, 2026

Nice install. Just to confirm, you wired the VFD directly to the motor and the switch controls the power to the VFD?

u3b3rg33k · May 11, 2026

tool_scrounge said:
Plenty of 120v in to 240vac out VFDs, but due to current limitations in most applications, they only go up to 1hp.

the one I posted above is 120V voltage doubler, 1.5hp.

mm08822 · May 12, 2026

svtride said:
In researching this more after the “delay" tidbit, I found this on GFCI classification definitions...
https://portablepowerguides.com/gfci-class-a-b-c-d-e-meaning-with-its-trip-level/
So far I couldn't find anything related with delay, just leakage amount..

I had this exact same suspicion about it actually being trip level vs a time delay. UL 483 (IIRC) only specs a max time that devices must trip. Most devices do actually trip much, much faster than the requirement.

Anyway, I never took a 2nd look into it. Class D gfci devices do trip at ~20mA as compared to Class A tripping at 4-6mA, however.

u3b3rg33k · May 12, 2026

mm08822 said:
I had this exact same suspicion about it actually being trip level vs a time delay. UL 483 (IIRC) only specs a max time that devices must trip. Most devices do actually trip much, much faster than the requirement.

Anyway, I never took a 2nd look into it. Class D gfci devices do trip at ~20mA as compared to Class A tripping at 4-6mA, however.

i don't think you can get a class D gfci in 5-15 format though. something about how 20mA isn't sufficient to protect life.

mm08822 · May 12, 2026

He never stated format. Class D is intended for equipment protection but still follows UL 483 if a listed component is used..

loganb · May 12, 2026

I did this to a Powermatic DP and documented it starting about the post below, I wander "a bit" on projects so will probably have to go a bit to get to the end but 2-ish years later and 0 issues with the setup so far.

3rd time's a charm with a 3 car workshop

The farm I live on has electric power to the pivot, but the well has an old 504 NA Case diesel power unit on it. It is kind of silly, but it is also kind of nice. With no generator on the power unit, we can run it at whatever RPM we want to, go get the water flow we like (old well, it is...

www.garagejournal.com

rattle_snake · May 12, 2026

whateg01 said:
you mean a neutral?

yes, transformer center tap connected to dirt.

aquinob said:
Nice install. Just to confirm, you wired the VFD directly to the motor and the switch controls the power to the VFD?

Yes. The on/off gates power to everything. Big red button when bit hooks the workpiece and spins it.

I didn't see a way to 'turn off' the VFD, but maybe there is a way or sleep mode.

I would bet that if I change to a 110v input VFD that it would trip my GCFI, because murphy's law.
Amazon has a turd for $30 more that is rated for 2 hp.

rattle_snake · May 12, 2026

svtride said:
Yup, did a couple drill presses and a Bridgeport…works well. GFCI outlets in shop did not like VFD so had to replace outlet with standard outlet.

Damn you for posting such a **** drill press. Makes me feel inadequate about the aesthetics of mine. The pulley lid is just so cool.

rattle_snake · May 14, 2026

On another forum a control idea for power tapping was shared. Use two digital inputs on the VFD for a push buttons. One to go forward slow and another to go in reverse slow.

whateg01 · May 14, 2026

rattle_snake said:
On another forum a control idea for power tapping was shared. Use two digital inputs on the VFD for a push buttons. One to go forward slow and another to go in reverse slow.

For power tapping on a vfd machine, just wire it to run in reverse with a toggle switch and have a push button to override that and run forward for the actual tapping itself as soon as you release the button to go forward the machine will reverse on its own

rattle_snake · May 14, 2026

auto reverse, so

1) flip sw to reverse rotation (motor not running)
2) press button to tap in FWD.
3) release button to get REV.
(repeat 2/3 as needed by just press/release)
4) push stop button
(flip switch back to do other stuff)

opposed to:
1) press button to tap in FWD.
<auto stop>
2) press other button to get REV.
<auto stop>
(repeat 1/2 as needed)

mm08822 · May 15, 2026

This may have been the solution to the gfci recept tripping issue mentioned earlier in this thread.

High Frequency GFI's…….. Some good information for you contractors.

This is the information for high frequency GFI's….….. Get educated and ready for a new product. https://www.ul.com/thecodeauthority/knowledge/high-frequency-ground-fault-circuit-interrupters

www.garagejournal.com

u3b3rg33k · May 15, 2026

mm08822 said:
This may have been the solution to the gfci recept tripping issue mentioned earlier in this thread.

High Frequency GFI's…….. Some good information for you contractors.

This is the information for high frequency GFI's….….. Get educated and ready for a new product. https://www.ul.com/thecodeauthority/knowledge/high-frequency-ground-fault-circuit-interrupters

www.garagejournal.com

sounds like this is new old news:

https://www.se.com/us/en/faqs/FA104476/

that said I'm all for breakers that don't annoy me.

VFD and 3-phase motor on drill press

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Attachments

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Attachments

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

ALLIANCE MEMBER

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member