foot control pedal....

[tufty113]

nice work...wish i was that cleaver to make one.....

 

[RichardM]

Nice job, I can see what I'll be making after a new welding trolley.

 

[philpullan]

this is really interesting ive been looking at pedals for my machine and dont seem to be able to find one its a really old philips machine not inverter type big transformer type . is it easy to work out what pot value id need to make a pedal ? having never used a pedal do they switch when pressed eliminateing the torch switch or are they simply used as a current controler ?
i think i could knock one of these up easyly if i knew what pot values the machine needed

phil

 

[shenion]

See if you can read what the internal pot is. Most use the same for an external.

Most have a switch to turn on the current.

 

[SirDick Diodenob esquire]

Phil , Have a look on the back of the pot , the rating in k ohms is normally marked on it and if its an older welder then its a wire wound linear pot 5 or 10k ohm probably but if I were you I would just remove the current control pot from your machine and put it inside a homemade footcontroller similar to the ones shown in the previous posts and run three wires to it , dosnt matter about the switching unless you want it , in which case you could add a micro switch . Even though one of them is using string this is just as valid a way of doing it and may be just as reliable as a commercial unit , remember for a period of at least 50 years valve radios used a peice of string threaded around pulleys and a variable capacitor to tune in to radio 4 long wave and it worked very well .

 

[philpullan]

cheers for the replys . i see exactly how it works now admitadly i hadnt thought about it im basically making a foot control that does the same as the dial on the front of my machine
SirDick Diodenob esquire
nice idea with using the pot from my machine but its a big sliding copper connector around a ring about 8inch circular so would make for a huge pedal or boxing to fit it in il see what i can find out hopefully it has its specs on it if it does il post up my progress with knocking one up
truely brilliant website this everyones so helpfull glad i found it

phil

 

[shenion]

Sounds like it is similar to my Airco and the Dialarcs. The wirewound pot (rheostat) controls the saturation current of the inductors.

These are 25 to 300 ohm and anywhere form 15 to 200 watts (mine is 150 ohm/150 watt.) You will not likely find them except on ebay. Usually the only option is the OEM pedal.

More modern ones add an amplifier so they can use a lower-wattage pot.

 

[philpullan]

this is what my dial looks like thats bulit into the machine

im thinking about making a stepper motor controled via a foot pedal move the dial leaving everything as is on my machine just adding whatevers needed for the motor fitment and wiring for its control to the inside of my machine

any opinions on that ?

phil

 

[shenion]

I would use a DC gearmotor.

I was thinking of ding similar on my MIG. It has a big wheel you turn to set voltage (about 100 turns). Would be nice if I could set it from the wire feeder.

 

[philpullan]

I would use a DC gearmotor.

for my set up you think one of those would be better than a stepper ? my dial only turns about 350degrees from stop to stop . know what you mean about your mig ive used one like that would be nice to adjust them by pushing a button

phil

 

[shenion]

A stepper motor requires a controller and may need a gearbox to get enough torque. A DC motor would just need a power supply.

 

[philpullan]

may be easyer than the stepper then , so itl go forward and backwards without a controller , for a dc motor wouldnt that mean id have to swap the polarity for the forward/backwards ? not sure how id manage to build that into a foot pedal

 

[citizen kane]

Correct, dc motor will require a gearbox and a servo controller, probably easier than a stepper though.

 

[Luke]

If you just want to run a geared motor one way or the other, you don't need a servo controller, simple change-over switches will give you direction control.

 

[citizen kane]

So, you press the pedal down, the motor runs one way, when does it stop? It needs some kind of feed back, the motor needs to drive the current control to mimick the pedal movement.

 

[Luke]

Why mimic the traditional foot pedal?

two foot buttons, drive one way, drive the other, simples?

 

[pedrobedro]

A pedal that rocks in the middle and drives each way ? The response might not be very quick but it would do the job, sounds complicated compared to a potentiometer though. Is the set up in that welder a rheostat ?

 

[citizen kane]

Why mimic the traditional foot pedal?

two foot buttons, drive one way, drive the other, simples?

I cant think of a good reason for not mimicking a traditional foot pedal.

 

[hotrodder]

Foot remote is analagous to a throttle pedal in a car- if a pedals stiff, notchy or erractic driving smoothly becomes much harder. Easy enough to adjust to pedals with varying amounts of travel but too long or short can make life less comfortable or harder... a pedal that's too 'short' makes driving smoothly more difficult because the resolution is poor i.e. tiny foot movement = large changes to throttle/amps. Long travel pedals improve resolution but go too far and they become uncomfortable to use- i forget the brand but i've used one welder where (unless sat at a bench) the pedal required some really unnatural ankle movements. That last point is where the SSC is miles ahead of some

A stepper motor/DC motor to move the machines pot... effictively similar to the 'fly by wire' throttles in modern cars?

Only improvement that could made to a traditional style pedal is to make 'em cordless imo (one less cable to trip over)

 

[Luke]

I cant think of a good reason for not mimicking a traditional foot pedal.

apart from needing to close the position loop, as you've stated.

it's a lot simpler to just run a motor in open loop speed control. I'm not saying its the best solution, it's not, but it is easy, and cheap.