Foot Switch for VFD?

DustinY

DustinY

Knifemaker / Craftsman / Service Provider
Joined
Dec 29, 2016
Messages
750
Okay, so I bought a swag table & it came with a foot switch for the bandsaw. Works like a charm. I know for sure that I want something for my disk grinder when it comes - but can you use it with a piece of equipment that has a VFD? Is there a special pedal? Please advise :)
 
Are you wanting a variable speed footpedal like a household sewingmachine ? Deadman switch ? push on, push-off ?
Typically VFD has on-off terminals to connect a remote switch to.
Some VFDs can be programmed for momentary or maintained condition to turn on-off.
 
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Yes, any ON-OFF step switch will work. You can re-wire one of the cheap ones like The Count showed or use any of the others you find online. You should wire the foot switch in series with the existing switch as a safety feature.

I build them as a low current low voltage device from an SSR and use 9 volts DC as the switched power. Again, any ON-OFF step switch will work.

Here is an old tread with several ideas:
https://www.bladeforums.com/threads/best-footswitch-see-posts-10-13-14-19-29-45-51-52.822263/page-3
 
Stacy E. Apelt - Bladesmith said:
Yes, any ON-OFF step switch will work. You can re-wire one of the cheap ones like The Count showed or use any of the others you find online. You should wire the foot switch in series with the existing switch as a safety feature.

I build them as a low current low voltage device from an SSR and use 9 volts DC as the switched power. Again, any ON-OFF step switch will work.

Here is an old tread with several ideas:
https://www.bladeforums.com/threads/best-footswitch-see-posts-10-13-14-19-29-45-51-52.822263/page-3
Click to expand...

So they have to be wired in? They aren't plug and play like the band saw?
 
My KBAC does not start when you plug it in and the start switch always goes back to neutral. I doubt you could make it turn on and off with a switched outlet unless you pull the switch up permanently like you do with the portaband trigger. And that might not even work on the KBAC. Might be different for other VFDs. I have a foot switch on my portaband, but I don't really like it. Maybe it is because it is a dead man switch. I keep meaning to replace the foot switch on the portaband with a regular wall mounted switch, but it has not bothered me enough yet, I guess. I recommend you run the disk grinder for a month or two and see if you still want the foot switch. The only reason I went with the foot switch on the portaband is because it does not have an on-off switch and I had to put a clamp on the trigger.
 
Correct, you want it to work as a latching NC/NO switch, not a Power-ON/Power-OFF switch. It is simply putting a floor switch in series with the RUN/Stop switch on the VFD. A guitar or other latching switch might also work. I believe the RUN/STOP switch does not carry much current, but would have to see the schematic to be sure.

https://www.ebay.com/itm/Satco-80-1...323984?hash=item44397dd510:g:-s4AAOSwFzNcjAqg

https://www.ebay.com/itm/Guitar-Cha...897402?hash=item469fee2dfa:g:A14AAOSw6FhdrlO1
 
FORGET WHAT I SAID ABOUT A LATCHING SWITCH.
see page 9 - https://www.kbelectronics.com/manuals/kbac.pdf
This is the schematic for the power circuit. It is a SPDT momentary contact switch with center return from what I can see.

I think this footswitch will work.
https://www.ebay.com/itm/HEAVY-DUTY...798198?hash=item56bdb2c936:g:~eEAAOSwjolcJYlD

Wire one pedal as the RUN and the other as the STOP by putting the red wire on the RUN terminal, the blue wire on the STOP terminal, and the yellow and green on the COM terminal. Paint the bar above one pedal GREEN for run and the other RED for stop.

If you are clueless with a multimeter, you need to have someone who can check out the switch to assure it is momentary contact and not latching. The description says it is, but that isn't always right. You want a switch that only makes contact when you press the pedal and breaks the contact when you release it.

Anyone with basic wiring ability can build a simple run/stop foot switch from two of these:
https://www.ebay.com/itm/5Pcs-2-Pin...136975?hash=item521c101f8f:g:BMYAAOSwpaZbg5oT
 
I wrote this up yesterday and thought it was posted, but this morning I see it never got posted, guess I forgot to click the "Post Reply" button.

This is for Chinese VFD: For the footswitch on a VFD drive you wire the footswitch into the normal FORWARD/REVERSE terminals on the VFD. The the terminals are normally wired & programmed for an OPEN contact to be STOP, and CLOSED contact to be RUN FORWARD or RUN REVERSE. You could put the footswitch in the "GND" wire so the footswitch would be series with the FORWARD/REVERSE terminals. That would allow you to put the selector switch in either FORWARD or REVERSE position and control the RUN function with the footswitch.

I "THINK" KBAC drives can be wired for Automatic Restart per section 7.6, page 17 of manual (A40206) – Rev. J00 – 7/26/2018) so two switches are not required. I "THINK" wiring for Auto Restart would allow a NO switch to be wired in place of the COM-RUN jumper to allow RUN-STOP operation. You'll need to do some testing with the drive to confirm how this will work. Read section 7.6 closely. The Chinese drives are MUCH simpler {g}.

I've thought about doing this, but haven't really felt the need since I'm using running the disk in fairly slow speeds, 600 RPM to 800 RPM, and sometimes a good bit less. VERY seldom (if ever?) do I run the full 1800 rpm motor speed.

I did just place an order for this switch (https://www.amazon.com/dp/B07C17ZTL9) to test the footswitch idea and see how I like it. I use Chinese drives due to low cost and simple programming and wiring. With filters over the air inlets of the NEMA 1 enclosures make the drives last a long time.

Again, allow me to emphasize I have NO experience with the KBAC drives and could well be mis-understanding the wiring of the KBAC drives, so take what I wrote above with a grain of salt and double check everything. If the above is totally wrong be SURE to correct my post. I'm more interested in having the right info, than I am in being right myself.
 
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I need someone who has a KBAC-24D to chime in. Does the switch return to the center after you flip it up or down?

If I read the KBAC info right, the switch isn't an ON/OFF type, but a momentary contact type. This triggers an electronic circuit, and does not actually switch any power.
 
Stacy E. Apelt - Bladesmith said:
If I read the KBAC info right, the switch isn't an ON/OFF type, but a momentary contact type. This triggers an electronic circuit, and does not actually switch any power.
Click to expand...
I read the "default" setup the same way. The manual shows the START/STOP switch will be a NO for RUN, with a choice of NO or NC for the stop function. From reading the manal the KBAC has a "latched" internal setup so a NO contact closure starts the system running, and will continue to run with contact open, and requires an input to the STOP terminal to stop.

That's why for the footswitch to work as we'd like I "think" the auto restart function has to be setup. That's why I emphasized reading the auto restart section.

As I'd envision the footswitch to operate would be with foot off of the footswitch the disk grinder would be stopped. Pressing on footswitch would cause the disk grinder to run, direction of disk spinning would depend on position of Forward/Reverse switch.

Is that how ya'll would expect the footswitch to operate?
 
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On the KBAC-27D, it returns to center when you flip it up (start), but it stays down (stop).
 
That confirms my thoughts. The foot switch should only make a momentary contact. The internal electronics of the drive does the latching. When you push the switch down to STOP, it breaks the latching circuit.

I stand by my earlier post:
see page 9 - https://www.kbelectronics.com/manuals/kbac.pdf
This is the schematic for the power circuit. It is a SPDT momentary contact switch with center return from what I can see.

I think this footswitch will work.
https://www.ebay.com/itm/HEAVY-DUTY...798198?hash=item56bdb2c936:g:~eEAAOSwjolcJYlD

Wire one pedal as the RUN and the other as the STOP by putting the red wire on the RUN terminal, the blue wire on the STOP terminal, and the yellow and green on the COM terminal. Paint the bar above one pedal GREEN for run and the other RED for stop.

If you are clueless with a multimeter, you need to have someone who can check out the switch to assure it is momentary contact and not latching. The description says it is, but that isn't always right. You want a switch that only makes contact when you press the pedal and breaks the contact when you release it.

Anyone with basic wiring ability can build a simple run/stop foot switch from two of these:
https://www.ebay.com/itm/5Pcs-2-Pin...136975?hash=item521c101f8f:g:BMYAAOSwpaZbg5oT
 
My disc has a KBMA-24D and I just plugged in the HF foot pedal and have been using it for months
 
AVigil said:
My disc has a KBMA-24D and I just plugged in the HF foot pedal and have been using it for months
Click to expand...


Which one? And does your switch return to middle once you START it? I have a KBAC-27D on my grinder and it returns, but the disk will have a KBAC-24D and im not home to inspect the package or VFD.
 
I flip on the VFD and use the foot peddle for on off.
We had a thread about this awhile back. I talked to several makers who just plug in their foot peddle.
 
Thanks Adam, good to know. I wasn't aware that you could switch the power on and off to that VFD and not loose the RUN status. I'll have to experiment with that.

I will say that there may be voltage spike issues with switching the main power on and off instead of the RUN/STOP circuit. I plan on putting foot switch capability on most of the equipment as I build it into the new shop, so I will post on that as I get to it.
Drill presses and bandsaws are simple and only require a HF type footswitch (ON/OFF power switch pedal). The bigger motors will have SSR switches or be triggered through the VFD RUN/STOP circuitry.
 
Adam, did you use the "Automatic Restart" function I mentioned above to get the drive to automatically start when power was applied? Something must have been changed from default setup since that method would have the drive starting when power was applied at beginning of day. Imagine your 2X72 grinder, or a bandsaw functioning that way.

I agree with Stacy, starting 'n stopping by switching the power is NOT the approved method and does have the dangers of voltage spikes.

While the use of two foot switches will certainly work, just seems a bit awkward compared to a single foot switch where you press foot down to run, lift foot to stop. Looking a bit further in the manual Stacy linked to above in section 5.8 starting page 15 then on page 16 there is a remote NO "enable" switch shown. That is one spot to put the NO foot switch. Reading a bit more it looks like a better place would be in the COM line of the forward/reverse switch. Leaving all wiring as it is, wire the NO footswitch in series with the COM wire of the Forward/Reverse switch. This would allow placing the Forward/Reverse switch in the forward position, motor won't run until the footswitch is pressed. Only problem with that method is the footswitch must be pressed for motor to run.
 
Just plugged it in. Got the info from other makers who have been using that way for a long time.

It works like a champ and I know several others doing the same, this is with the KBMA-24D.

I have been using it with a HF pedal for about a year and I use my disc a lot.
 
AVigil said:
Just plugged it in. Got the info from other makers who have been using that way for a long time.

It works like a champ and I know several others doing the same, this is with the KBMA-24D.

I have been using it with a HF pedal for about a year and I use my disc a lot.
Click to expand...
HF pedal .........I will use it on all my grinders ,not just on disk sander . It is like you have assistant while work ...........
 
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