Wah pedals

[Mark Williams]

I need to come up with a foot pedal 0 - 10 K ohm as an input to a VFD. Maybe a sewing machine pedal. Any ideas Guys?

 

[peter nap]

I don't know how much resistance a sewing machine pedal has but I would guess it work fine.
If nothing else, get a Radio Shack Pot and attach an arm, spring load it and mount it in a piece of angle iron.

 

[trespasser]

Go to mudhole custom tackle. They sell rod lathe parts, including foot pedals. The stock number from their catalog is pwp3. Not sure about suitability for your project, they can give you specifics. or call 1 407 447 7637. I do weird stuff all the time, they've never given me any flak. Levi

 

[RARanney]

Harbor Freight has foot pedals; not certain if they'd work for your application.

 

[Lynn]

Peter,
A search of Radio Shack site came up with:
http://www.radioshack.com/search.as...h&image1.x=26&image1.y=35&image1=submit&SRC=1
and nothing over 3 amp. I'm intrested because I want a foot switch for my 9" disk sander. Any suggestions?
Thanks, Lynn

I don't know how much resistance a sewing machine pedal has but I would guess it work fine.
If nothing else, get a Radio Shack Pot and attach an arm, spring load it and mount it in a piece of angle iron.

 

[Ripper]

Mark,
Don's suggestion to roll your own has a lot of merit: for a couple of ideas on how to go about it see the "POTBOX THROTTLES" about midway down this page.
Regards,
Greg

 

[Matt Shade]

Not a foot pedal, but would something like this work?
http://www.woodcraft.com/family.aspx?familyid=3957&refcode=05INFROO&PRID=Frgl3957

Its at least got decent amperage on it

Oops, I guess if your looking for one that you can hook to a VFD, guess that might not do it.
Well I'll leave the link in case someone else is interested in a speed controller. Looks good for the price.

 

[rfrink]

My Tig welder has a pot in the foot pedal It's a heavy duty pedal assembly. I bought it as optional "remote foot control" package. Maybe check with a local welding supply shop...get the assembly, then swap out the pot for the correct resistance if needed.

-Rob

 

[Mark Williams]

Thanks Guys, looks like roll your own would be a snap. That's a neat website Greg. It's in my bookmarks now

 

[peter nap]

If you need amperage, go to home depot and get a dimmer....I guess you can still get the turn-the-knob type. It will handle all the amperage you will put on it.

Remember to not take the ratings as the Scripture.
If a dimmer is rated at 5 amps and 120 volts, it will handle 600 watts.
V*A=W

if you are putting 12 volts at 10 amps you are pulling 120 watts so you are still safe by huge margins.

 

[pso]

There is a difference between controlling the motor directly and through a VFD as Mark is suggesting.

If the foot pedal is to be connected to the input of a VFD, then the current rating (amperage) and power rating requirements are very low. Virtually anything with a resistance value appropriate for that particular VFD would be OK. This is what the guy with the "Pot Throttles" is doing. You may want to set it up so that the foot pedal only controls the speed from 50% to 100%, say, since it may be too touchy otherwise.

Controlling the motor directly may not work very well since your resistor may have to be able to handle the full motor current at some operating point. Such potentiometers can be purchased but would usually be very large and expensive, probably more than what it would cost to get a VFD.

If I recall correctly, other people have found that dimmers and the Woodcraft router speed control will really only work on small, single-phase AC motors. They apparently don't work very well, if at all, on a motor connected to a grinder.

Phil