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Thread: DIY TIG Pedal

  1. #61
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    Aug 2010
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    Quote Originally Posted by BaronJ View Post
    Hi Joe, J&H, Guys,

    I've made the assumption that the internal pot causes the welder output to be maximum amps when the slider is at the VCC end.

    Based on your diagram (Joe) setting the internal pot at a lower value, say half way, would give the finer control of the output from the foot pedal that is wanted by Joe.

    This works because the resistances in parallel provides a lower value resistance with less voltage across it. Effectively a voltage divider supplied by a voltage divider. Which is essentially the circuit drawn by J&H.
    Your assumption is correct: 5V is max current and 0V is min.
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  2. #62
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    Quote Originally Posted by BaronJ View Post
    Hi J&H,

    Having the foot pedal connected and not in use should mean that the internal pot has very little ability to change the current output from the welder. It only starts to have an effect once the foot pedal is used to increase the output, because then the internal pot is supplying the external one and it is this that is now providing the control voltage.
    ....
    When the pedal is not depressed, the welder is 'Off'. There is a microswitch which turn it on as soon as you depress the pedal a fraction....
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  3. #63
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    Sep 2009
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    Sydney
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    Happy to report my pedal works as expected. Haven’t welded with it yet but I have since added rubber feet to the bottom to stop it sliding around on the garage floor.

    Looking forward to using it soon.

  4. #64
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    Default DIY TIG Pedal

    I have been using my pedal but I got the pivot backwards, so it really doesn’t work. I’ve been playing around with ways to make it work the correct way around but I’m really struggling with getting the return spring working.

    I’m contemplating scrapping what I have and starting again.

    I googled DIY TIG pedal and came across this, possibly the most elegant solution I have found to date and fixes the issue with the start switch and not taking up the lowest part of the potentiometer travel.

    I’m going to try and reverse engineer this instead. My plan is to build as much adjustment as I can in to it. You know that they say, if you can’t make it precisely, make it adjustable!

    https://youtu.be/f2ta08h3q5E

  5. #65
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    Sep 2009
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    Today I took a trip to Bunnings and bought a load of parts for my TIG pedal v2.0 build. 600x600x1.6mm steel sheet, small roller bearings, nuts and bolts and some L brackets.

    I also decided to take some measurements off the video above and actually write down some dimensions and sketch the part. Not something I did last time.

    I ended up with some cut sheet metal plus I also make some Aluminium bearing blocks that will trap the bearings against the inside box:



    I didn’t think 1.6mm was going to be sturdy enough but quickly discovered that was NOT true when I got it in my metal brake:



    Luckily it just coped and I like the slight radius it puts on the edges. Once I had the box bodies done I cut the end panels and bent them to shape. Careful fettling with the angle grinder and I had them ready to weld.

    I’m not the best welder but I love TIG welding and this virgin steel was a joy to weld. HF start and DC pulse is also a game changer for me. I wanted to have the welds plump on the edge so I can grind it back and not have to weld any pits:



    The bearing blocks are located and the 2 halves are welded. Just need to grind the welds back.

    It’s looking very promising already. A fantastic action and the perfect size.





    I’m going to do my best to mount the arm on the same pivot centre as the pedal to keep it a smooth action together but also plan on putting a small bearing on the end to make it slide nicely too.

    Lots more to do but I feel it’s going in a much better direction than my first attempt.

  6. #66
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    Peering over the crowd to see

    Sent from my SM-T580 using Tapatalk

  7. #67
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    Default DIY TIG Pedal

    Some progress today. First step was to grind back the welds and start with a nice clear chassis.

    Next I took some right angle brackets and made some Delrin bushes for them. These are going to hold the arm that controls the potentiometer. I rounded the tops not only because it looks nice but I also needed some clearance above for the potentiometer return spring:



    Next up I made the arm. 5mm steel plate with a steel rod welded on each side and drilled 8mm for a bolt. It won’t see a lot of rotation so I’ll lightly grease it once it goes together.

    I also welded on an arm at the top with a groove to take the loop of string that controls the potentiometer.



    On the back side of the arm I mounted the switch. It has a wheel which is a nice touch as I hope I allows the upper pedal to ride nice and smooth. The wheel is pretty solid so I hope it will be ok to manage the pressure of the main spring once I get that done.



    I couldn’t find any button headed bolts at Bunnings so I bought some M10 stainless ones and set about turning the heads off, putting an 8mm shoulder on for the bearings and an M6 thread to mount them. I don’t know why I punish myself by buying 316 stainless bolts as they’re a bit of a pig to machine. I’m generally ok with all the operations except threading. That’s tough going! But I tend to run the diameter a little undersized and the dies seem to just about cope.

    What didn’t cope however was my silting saw. I got the slots cut but my wider saw is now toast. I haven’t done a lot of slitting and I mustn’t have done it right as I was getting too hot and I burnt up the cutter unfortunately.



    The L brackets and potentiometer bracket are attached to the chassis with countersunk bolts. I think they look neat.



    I reused the old potentiometer mount but cut the top off (to make it easier to tighten the nut).



    It took a lot of fiddling but I now have a almost working lower section:



    I have some music wire on the way to make my own torsion spring, once that is done the arm with return on its own and the lower section (bar wiring) should be done.

    Still loads to do but is slowly getting there.

  8. #68
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    I wanted a strong stop on the pedal motion so that I don’t run the risk of breaking the potentiometer. Some scrap steel and an M4 nut and bolt:





    It works perfectly and really easy to adjust and lock in place. I have the pedal lock set to horizontal for now.



    I also drilled the rear panel for the switch and max amperage potentiometer. I though I was going to have to cut a notch out of the upper pedal but the clearance I have is just enough I have them clear with some minor modifications. So I’ll trim the switch and have them hide up inside the upper pedal.

  9. #69
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    Sep 2012
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    Hi Neevo,

    Very nice work !

    Just a caution, put a piece of plastic insulation behind the pot terminals, then there is no risk of them being shorted together by touching the metal work behind them.
    Best Regards:
    Baron J.

  10. #70
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    Default DIY TIG Pedal

    Good idea. I’m thinking of hard wiring his pedal vs having a removable connector so I’ll make sure I solder and heat shrink each connection. Wide open pedal in the middle of a weld would not be fun :O

  11. #71
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    Thanks Neevo,

    I don't like heat shrink over lead free soldered joints ! Over time the solder crystallises and becomes high resistance before becoming open circuit. I use only 60/40 rosin cored solder for all electrical joints.

    Heat shrink can hide a bad joint ! Often an ohmmeter doesn’t see these crystallised joints because they don't put enough current through them to show them up. I have an ohmmeter that passes 1 Amp through a suspect joint, often forcing it to go completely open circuit.
    Best Regards:
    Baron J.

  12. #72
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    I’m the same. Still use rosin core 60/40. Can’t get the lead free stuff to work as nice as the leaded.

  13. #73
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    Mr postman arrived today with my new ER32 Collet Chuck for he lathe (that’s another project) and my music/piano wire. I couldn’t find the appropriate spring I wanted so in the end thought I’d have a go at making my own.

    I ordered 2.5mm and 1.5mm wire so I could gauge which would work best. In the end I decided on the 2.5mm and I am lucky I did as I failed to realise I was ordering 1.5mm Brass rod! Not ideal for a torsion spring :O

    I watched a few videos and set about making something to safely bend the wire around.



    The end was bent 90 degrees and a hole was drilled in the square tube to lock the end in place. The clamp was just there to stop it popping off.

    I did 4 rotations and just felt the tension to get it right. The coils were not perfectly straight and have a tendency to open up a bit but I’m confident they will be ok when wedged in between the l shaped brackets.

    I pulled the arm out and installed the spring. Then once the bolt was in I tensioned the spring by locking the upper section in against the arm (there is a 180 degree bend on the end to stop it popping off the arm).



    I’m amazed to say it works absolutely perfectly! I’ve even surprised myself!!!

    I was keen to get the top pedal on and give it a test run but I’ve unfortunately welded up one of the holes as I got the alignment wrong and I’m not really going to crack out the angle grinder at 8pm. That will have to wait for another day.

  14. #74
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    Hi Neevo,

    That is one thumping great spring ! Nice
    Best Regards:
    Baron J.

  15. #75
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    Default DIY TIG Pedal

    So after a few extra bits this weekend I am very close to giving it a test run. Just a couple of things to fix.

    I made the brackets to accept the pivot bolts. Originally I made them from 5mm plate but accidentally tapped them M8 not the M6 on the end of the bolts. So I had to remake them from 10mm. A bit overkill but in the end I had a happy benefit which was these act as a stop to not allow the pedal to lift up too much.



    Now that I have the top section working properly I could test the arm movement. Turns out I had 12mm extra lift I could use so I set about milling that off the back of the arm base. I went too far unfortunately but this gave me the option of making it adjustable too:






    In the end this is a much better option as it really gives me full control to dial the pedal in.

    I also removed the old switch as it fouled the upper pedal. I went to Jaycar and bought a latching square switch:



    It works much better and you can dial the pedal in with minimal effort:



    I now also have the wiring in to the chassis. I still need to drip out the clearance channel on the top pedal but my plan is to have this hard wired to the pedal and then have a connector block inside:






    So I have a mechanically sound pedal right now:






    So I still have one final mechanical challenge to solve. I need a way to make sure the pedal is lifted off the switch in the resting stage. Another torsion spring would be ideal but 2.5mm is way too thick. I may have to buy some 1mm and make another. This needs to be mounted on the lower chassis so it doesn’t impact the arm action.

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