DIY Tig Pedal - Part 2

today we're talking TIG amp control and in particular foot controllers in one of my earlier videos I did essentially a show-and-tell short clip of this foot controller it was maybe 10 seconds long and I didn't say a word at the time I had built this I was upgrading from this economy DIY pedal since then I've gotten a heck of a lot of questions comments emails asking for more details on this foot controller and I thought what the hey good enough reason I sort of break out all of my teak control history and chat through it hopefully this will answer some of those questions and for anybody who's just getting into foot control or maybe trying to build their own I highly recommend it it's a whole new dimension to TIG welding to be honest I couldn't imagine how I could get along without one of these these days so let's talk about what an amperage controller does we'll break into these and take a look at how they work this is the torch that came with the machine at least I think it is it's been a while you see this one hasn't gotten too much use they're very uncomfortable and rigid but this is I think is a bin Zell I'm not sure if I'm saying that right sometimes they seem called euro style torches and this one only has you know sort of a start/stop switch no amperage control whatsoever I have a few torches but the one that gets the most use is the CK worldwide with the flex cable I'm not sure what number this is but this is also a number 17 whether it is CKD 150 r8 r9c the torch has no controls on it just because I've slowly moved over to exclusively working with a foot controller but I do have a push button for it and this I can just sort of throw on with some electrical tape or some zip ties you know if you're in a situation where you can't use a foot controller if you're working on something big and you need to walk around it or your climate under a car or up a ladder I try to avoid all of the above and it's been a while since this has actually been all on the torch but it's good to have in case you need it and it's just a simple push-button it could be anything this is out of an old torch but like I say it's it's just a simple switch it could be a doorbell off the front of your house for all the TIG machine really cares since the first controller I ever started with and it's actually a volume control pedal for keyboard I just picked it up at a Music Center I think it cost me all of fifteen or eighteen dollars it certainly has its limitations it's all plastic it's very light the range wasn't perfect but it was a good way to to get started we'll break this down and take a look at what the insides look like after this I moved up to a homemade version I say I didn't like the feel of this and it was trimming off the top end and the low end of my amperage range and that got frustrating enough that I sort of built my own and this is what was shown in the earlier video if you haven't seen that again maybe take a look this is halfway gutted I disassembled it and we'll be rebuilding it quote-unquote for for the rest of the video just explaining how the parts work I did make a somewhat of a dumb move and I used the switch just out of my junk box this is the switch that initiates the high-frequency start this thing gave up the ghost on me I don't know a few months into using this foot controller and I wasn't able to find a replacement switch at least not something that was easily swappable as I was looking for this a friend of mine came across this foot controller I'm not even sure what brand this is there is SSC anyway it ended up having the exact resistor value potentiometer in here that I needed for my machine it didn't have the right connector but it was easy enough to to cut that off reverse-engineer what this thing was doing and adapted to my machine The Price is Right and I've been working with this foot controller though to be honest I was a lot happier with how the homemade unit worked I mean first of all it's a lot heavier you know it stays where you leave it it's a lot tighter well I mean when it had the spring in it it was a lot tighter in terms of control there's a bit more resistance this one's a little bit I don't know loose works fine I think I do lose a little bit of a low-end on this I get all the way up to the high end but you know you can sort of pulse it quickly and cheat your way out of that before we dig into the actual foot controllers I thought it might be useful to just talk about what the machine is actually expecting I think these are pretty much all the same I mean unless you have state-of-the-art new maybe all digital or Wireless foot controller you mean check your manual but your machine more or less will work this same way the only thing that might change or that's almost certain to change is this resistor value the potentiometer value in my particular case it my machine is looking for a 10k ohm range so here's basically this this is the heart of what's in the foot controller everything else outside the circle is more or less specific to my machine and my connector though there are a couple of details you want to keep an eye out for your machine here for example there's a small jumper without this jumper the the machine doesn't know there was a foot controller attached and also we do is start and stop the arc and up here in the detail you can see a small note if there is no potentiometer if there is no foot controller it only needs those two wires F and G from the from the push-button switch now I apologize if this kind of stuff is gone you know stating the obvious or gone too far back to the basics but based on some of the feedback I got it it became obvious that I have a quite a varied audience in terms of experience level so what's what's happening in the foot controller is we have a switch and a potentiometer and this is also true for you know torch mounted amperage controls the little slider buttons they're just different types of potentiometers obviously when the switch is open the machine isn't doing a thing as soon as the switch closes the machine is looking at this resistor value and outputting some amperage to your torch so in my case when the switch closes as you're depressing the pedal the Machine starts to read you know the resistor value when the fit switch first closes I think it's given me I start off at the top end at the 10k ohm and that's giving me the minimum which is five or six amps on my machine as I continue to push the pedal that resistance value is dropping to zero K or just zero I suppose and that's giving me my max 150 160 amps in my case so note number one make sure you connect your resistor correctly otherwise when you first push the pedal you're going to get 100 and you're going to get your max and then as you depress it it's going to start slowly drop so the operation of your pedal would be backwards and that quite frankly is the stuff of nightmares another important point and the most difficult part I think of making a foot controller is the timing between these two pieces so all's you have in your foot controller if you make a classic foot controller is a rotation so as you push the pedal you only really have one motion that's controlling two separate parts so as you push it and this switch closes you've also been moving your potentiometer so when that switch closes you might be at I don't know 9 K in this case instead of 10 K and so you've just chopped off 10% of your amperage range so that was a long-winded way of saying we need some way to control the timing that switch in relation to that potentiometer and make sure just you know darn foot pedal feels good and is consistent let's have a look at how this foot the volume control foot pedal is doing its thing the top plate of the pedal and I added this aluminum tread plate on here is just hinge through the side it's got a plastic peg that comes through a hole and this is the spring that's you know returns the pedal to the up position as that comes through the hole there's a spring that goes to a micro switch and I think the spring is that just because I couldn't get the exact range perfect I don't remember if that was original I don't think that little solder mark looks very factory so as I push the pedal down you can you can hear the switch activate almost immediately I continue to push that down it's changing the potentiometer value and as I let off switches off I don't know if you can see how screwed up that potentiometer shaft is in there but this took quite a fair amount of tweaking to get the position of this on the shaft and the in the right orientation so that when that switched on that switch was in the right resistance range or you know at one end of its range so I hope that's pretty straightforward this little circuit board is part of the volume control I think I didn't even use those wires I just left it in there I did at one point have another potentiometer that came in through the top that allowed me to fine tune the range of this potentiometer because I think as I recall I was having some trouble getting the timing and the whole range out correctly so here's where we run into what essentially was my first problem was the range of motion see his volume controller really only has I don't know 15 to 20 degrees of motion so that means my entire amperage range zero to 150 amps is controlled within this 15 or 20 degrees that's not a heck of a lot of let's call it a resolution for an amperage control so you know you might move it in eighth of an inch and increase your welding by 50 amps so the first thing to do is to add a little bit more range that pedal and here I think I'm in the at about forty degree range that's spitballing and call it almost double the problem with that now is I can't use the same type of pedal return mechanism that compression spring that's in the inside without having to make this pedal very thick so your foot would be I know six to eight inches off the ground and just probably wouldn't be very comfortable also the hinge is moved back again it's more of a comfort thing so as you actuate this your heel doesn't come up as much as it does in this volume controller see here the heel comes up almost as far as your toe goes down so what I decided to do instead of go with a compression spring I decided to use a you know spring in intention an extension spring and this is the spring ended up settling on this is more or less trial and error it depends how heavy your pedal is how much resistance you like the easiest place to put this instead of the front or the compression spring rent would be in the back so when you push the pedal down it would pull it back up but as you can see there's not really space back there for spring this size so I had to lay it down on the inside it's connected to that pin that pin just goes through the foot pedal on this side there's a small cable and wire cable tie and the other end of this cable is tied inside of the foot pedal exactly where you would expect and expend an extension spring to attach if it were to fit what I'm going to do is just sketch out what this part of the foot pedal looked like so here's my foot pedal and aside view and that's the hinge that the pedal is rotating about and that's just a like a quarter-inch countersink bolt and there's some nuts welded to the inside so we said the Yamaha or I think it was Yamaha volume controller just had his coil spring up in here and it was pushing the pedal back up I decided to go with the extension spring but it's too big to fit in the back to pull down on this side so I put a pin in the foot controller one that we just saw happens to be this one it goes you know from one side to the other put the spin put the spring on that to which I tied the cable that I just showed you and that goes around a pulley which is this one in the base of the foot pedal wraps are on that pulley and is tied to the underside of the moving part of the foot controller now here I had that small wire clamp and the wires looped around there with a small set screw and what I could do is pull this and increase the tension in that spring and that set the feel of the foot controller so laying the spring down allowed me to get it into a smaller package and get that spring force down behind that pivot point so now that big spring is pulling down here and pulling that pedal back up so I took the hinge bolts out of here if I take the foot part top part off the controller we look inside this is the pulley I just sort of installed it here the spring is connected just to a fixed shaft it happens to be a shaft that contains another free spinning pulley but we'll get to that in a second and the cable just comes over that hook around that pulley and up into the bottom of the pedal the cable just goes to a hole and has a like a little cable lug so that's the first part that's the pedal return and the force you feel under your foot the next part then is the potentiometer now this gets a little bit tricky in my particular case there wasn't that much space to work in it's not difficult it's just a little bit finicky instead of building this into the bottom of the foot controller I decided to put it on its own little frame and it looks like it's just a piece of one and a half inch square tubing with some windows and some holes drilled in it the idea here is that we have a small pulley with some very strong string wrapped around it if I can get this on the pulley it lets you adjust the potentiometer position by pulling on both sides now the string is tied to the pulley there's just a little through-hole there maybe you'd see that better it's just a single loop through a hole in the pulley so that the relative position of the string can't slip so let's call that the pulley we just saw that the string is looped on get a turn or so string it's tied to the pulley here on this end I have a smaller spring tied to the frame of the foot pedal and in my case it's this spring here it's just enough to get the potentiometer to turn this side so this is fixed to the foot pedal and I'll show that to you in the in the actual pedal it goes around another just idler pulley and it gets tied to the bottom side of the actual foot pedal so what happens when you push the pedal down you essentially put slack in the string and this spring can retract turning the potentiometer when you let the pedal go the pedal had that much larger spring that we saw just earlier when you let the pedal go it pulls this back up overpowers this small spring it turns the potentiometer back that way now there's probably a dozen ways you could do this and I faintly recall looking into things like rack and pinions or linkages but this seemed like the most compact package since all of these parts could essentially be in the same plane but anyway let's get back to this pulley there's one important dimension here that is key to getting your pedal to work correctly so this whole potentiometer sub-assembly and again it's just the potentiometer with its nut on the inside the shaft comes through and there's a little Teflon bushing here just fit in here there were screws in from the other side that kept that in place one end of this had the spring tied to it I was attached here on the other side of the frame there's just a little loop welded there and this is where the spring attached I've got it temporarily tied here that would be bolted down so the spring is in the back as I pull this string it turns the potentiometer and stretches the spring I'm missing a loop of string on that pulley but I think you get the idea the other side of the string goes over this pulley that's just a fixed shaft and this is just an idler piece of plastic it wraps over that and exits the top of the base so here it is coming in out through the top and I can pull this that adjusts the potentiometer and when I let it go the spring that we saw pulls it back and this bit it's tied to the underside of the pedal once you have the foot controller together you'll be able to measure what the effective throw is so from full up pull down this particular pedal has about it's called three inches so in that three inches of linear motion I've got to turn this potentiometer through its whole range so I just took that three inches and you know sort of worked backwards figure out what diameter this little pulley needed to be the circumference of this is some multiple of three inches it's looking at it it's probably half so as I push this down just you know the not on this walker on there two times ish once you have that dimension worked out and this is installed you know you let everything go the large spring will pop the pedal up I pull the string through the inside here made sure my potentiometer you know was at one end of its throw and tied that knot so that means my potentiometer was starting you know at one end of its range and as I push this down the small spring would take it all the way through the rest of its range to the other side so that takes us to the last piece of the puzzle which is the switch that starts and stops the whole amp control cycle now the switch might look a little odd because the entire top part has broken off the only thing to be aware of when you're putting a switch in is how much throw you have at that switch position so this had a top case with just a little nub that came off the top now you're probably not going to find a switch with a 3-inch throw if you did you could just put it up here at the front so you're going to have to put the switch somewhere near the pivot point I found it easier to release a switch to start the cycle instead of press a switch some on the backside of the pivot when I push the pedal it lets go the switch and that starts the cycle so you'll just have to check which one of the three or the normal is closed and normally opened and use the appropriate one to fine tune the switch timing the top of the foot pedal has essentially a big set screw on it I can adjust this from the top there's a little split in there and it's got a little plastic no the intention was to keep from doing damage to the switch but I guess that didn't work and then once you know from the top I like the timing I could go in with a small wrench and use this nut as a jam nut to stop the stop that adjustment for moving so I think that covers it so this is the one I'm actually using now I plan to open this up and see what this looked like inside I started expected to find some kind of access panel on the bottom but it looks like there's just a long pin that goes through it they headed each side to keep it from coming apart now usually I have quite a bit of trouble with leaving well enough alone but in this case that would require I think drilling these things out I don't know I might leave well enough alone here but I think you get the idea anyway I hope that answered some of the questions from the first video and as always I hope you found that interesting

Channel: This Old Tony

Views: 213,045

Rating: 4.9375176 out of 5

Keywords: TIG, TIG pedal, TIG foot controller, amp control, amperage controller, TIG amp control, TIG welding, DIY, homemade, Gas Tungsten Arc Welding (Literature Subject)

Id: -P6w-tj8_Tk

Length: 24min 27sec (1467 seconds)

Published: Thu May 21 2015