[Stuff-Builder]

Hi all,

I got my grandfather's old Tig welder - it's a Montgomery Wards setup with a AC base, DC converter, and high-frequency unit. It works great and I've done lots of steel welding, and played around with aluminum a little.

I'm wondering if it would be possible to get some sort of amperage control unit for this welder? All the components and torches plugs in using some round connectors - about 1/2" od x 2" long.

Thanks,
Scott

[mxtras]

Your best bet would be to visit http://www.shopfloortalk.com/ or http://www.hobartwelders.com/mboard

I seem to recall this issue coming up before on one of those boards. Although I could be wrong, I seem to recall it being less than economical to do what you are trying to do but since this is a DIY type forum that you are obviously a participant of, you might be able to make it happen.

Scott

[tadream]

Hi all,

I got my grandfather's old Tig welder - it's a Montgomery Wards setup with a AC base, DC converter, and high-frequency unit. It works great and I've done lots of steel welding, and played around with aluminum a little.

I'm wondering if it would be possible to get some sort of amperage control unit for this welder? All the components and torches plugs in using some round connectors - about 1/2" od x 2" long.

Thanks,
Scott

It's gonna depend on how the unit's output is controlled. How do you adjust the amperage? If is uses a rheostat, it's doable, but if it's got some kind of crank handle, then you're SOL.

[NC Cams]

Been there, tried that, not readily doable.

The "foot pedal" is merely a simple rheostat type of device that actually controls a rather sophisticated voltage/current regulator scheme on welders so equipped.

To vary the output of a welder, you have to either vary the turns ratio of the transformer - just as you would to regulate voltage on any transformer

or

like whats done of V/F drives, vary the frequency and thus the voltage therefore the output current potential of the welder.

Unless you have the regulator built into or add onable to the output power control section of the welder, there is not anyplace you can plug the "foot pedal" into in order to have it affect output power regulation.

After looking into what it takes to ADD that feature to a welder, it ultimately is cheaper and easier to sell your welder and buy one that already has the feature you want.

Naturally the new one won't have the sentimental value of the one you got from your grandfather but it may be time to simply evolve to new technology instead of trying to update the old.

Ultimately, even if you you could find a way to put lipstick on a pig, it just doesn't pay to do so....

[Stuff-Builder]

Hey folks,

Thanks for the replies. That's about the info I was expecting. The voltage adjustment on this machine is made by sliding a big lever, not a rheostat, so I think I'm probably out of luck.

I'm just going to use this unit as much as possible and become the best I can with the fixed voltage.

It does a beautiful job on steel. Where I really run into trouble is when I've played with aluminum. The whole tube or plate heats up so much that the puddle just falls away. One of the guys at work recommended preheating the workpiece and then using less voltage out of the welder. I'll have to try that. Also, I wasn't paying much attention to cleanliness and he gave me some tips there.

Scott

[DSL PWR]

One thing you could try on the cheap is mount an actuator (think power window) on the adjustment stick and run it with a momentary switche (up and down). I know it's not the same as having a true foot pedal, but it would give you some local control, and I think once you got on to it you probably would like it. You could put some positive stops on the unit to give yourself a min and max setting.

I have no idea how well this would work, but it could be done very cheaply.

[greg b]

You will find that if you master tig welding all the materials you can without the use of a foot control you will be a much better welder for it.Not all jobs can be set up on a bench where you can sit down, infact you will find you may have to do all positions with the tig and in that case the foot controll becomes a bit useless.Keep plugging away with what you have, quite often those older welders will eat some of these new welders on the market unless your willing to spend descent money.Regards greg

[mxtras]

....the foot controll becomes a bit useless.

That's when a thumbwheel is used.

Scott

[mixdenny]

Hey folks,

Thanks for the replies. That's about the info I was expecting. The voltage adjustment on this machine is made by sliding a big lever, not a rheostat, so I think I'm probably out of luck.
Scott

I have a Sears AC welder with a high frequency tig attachment. It works pretty well and I upgraded to a water cooled torch. The original welder has an amperage control with a pointer that pivots through an arc. The thought I had about adding a foot control was to use a push-pull control cable (like a boat throttle cable) running from the pointer to a suitable foot pedal. One thing I note is that the amperage pointer is locked in position with a stout over-center clamp, so I wondered if the amperage control would try and pull towards one end or the other if it was unlocked and drawing power. I never tried it but there must be some reason for the clamp.

Now I did add a foot pedal to the Harbor Freight inverter TIG that they frequently have on sale for $199. I picked up a used guitar foot pedal on eBay for less then $20 and switched out the pot to the correct value. The amperage control uses both side of the pot, i.e., one increasing and one decreasing at the same time so you need to measure things carefully. And the pot I used was a 270 degree range, while the foot pedal was just shy of that, so you could have it go all the way down or all the way up in amperage, but not both.

I got that tig for some light gauge sheet metal welding and it didn't work out as well as I wanted since the amperage doesn't go real low, 30 amps as I recall, and the control was very sensitive at the low end to boot. I guess a pot with a different taper might have helped. I ended up selling it, but it did work fine within the range it had, and you can end up with a foot pedal TIG for well under $250.

I have read some good reports about Grizzly's pulsed DC TIG on sale for $510 right now. It goes down to 5 amps and with the pulse can do some really light work. The user who tested it had previously used a Harbor Freight TIG and found the Grizzly was superior in starting and with a much quieter, more stable arc. I emailed to their tech department to see if they had any thoughts about using the foot pedal from their more expensive welder and they just replied that it wasn't a direct fit. Perhaps it is just a simple pot control as well.

Dennis

[tadream]

Perhaps it is just a simple pot control as well.

Dennis

Yep. Every one that I've ever seen is just that. Most of them, however, are set up with the controls in series, so that they act in a master/slave configuration. The panel-mounted one still sets the max output, while the foot control one will vary the output from minimum up to wherever the panel control is set. For very light work, set the panel control fairly low, and you will have more precise, less sensitive control with the pedal. Also make sure that the pot you use is linear taper, not audio taper.