Trying to rejuvenate an old MIG welder

Thread Starter

Paul Pfeiffer

Joined Oct 16, 2020
9
It's a MAC WS1110. (I have no schematic!) The gas valve is in the business end of the stinger. No gas solenoid. A fine wire is energized by the same trigger, and goes back to a small circuit board that has the wire speed pot on it. But the only current I know of in the block of brass is the weld current! How can this be? More to the point, how can I add a gas solenoid and make this work? I have heard that the transformer type of mig welders are (often) worth fixing up. Maybe it isn't worth it. As far as I know, this welder was not originally set up to be "convertable" to a solenoid.
 

shortbus

Joined Sep 30, 2009
7,940
Sounds like you have a flux core Mig welder. The wire controlling the wire feed *could* be made to trigger a solenoid valve, but you would also need then to put a delay in the wire feed. The gas has to be present at the tip before welding starts to get a good bead. The delay would only need to be long enough for the gas to flow before wire movement so not a long time, but have no idea how long.

You didn't say how old it is so before spending too much time or money I'd make sure replacement stingers and tips are still available.
 

MisterBill2

Joined Jan 23, 2018
7,021
If you can put the solenoid gas valve at the weld gun that will reduce the delay a lot. And have a check valve right at the gun so that the gas line stays filled between each weld time.
 
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MisterBill2

Joined Jan 23, 2018
7,021
Adding a timer to the control system is certainly possible, it is determined only by how much cost and effort the TS is willing to invest. Probably a small PLC could be used to implement all of the various improvements.
 

Thread Starter

Paul Pfeiffer

Joined Oct 16, 2020
9
Sounds like you have a flux core Mig welder. The wire controlling the wire feed *could* be made to trigger a solenoid valve, but you would also need then to put a delay in the wire feed. The gas has to be present at the tip before welding starts to get a good bead. The delay would only need to be long enough for the gas to flow before wire movement so not a long time, but have no idea how long.

You didn't say how old it is so before spending too much time or money I'd make sure replacement stingers and tips are still available.
It was NOT a flux core welder. made around 1980 to 1990.
 

Thread Starter

Paul Pfeiffer

Joined Oct 16, 2020
9
Let me be more specific about the questions. Could I take a "signal" from the hot weld block in the stinger, triggered by the switch in the stinger, directly back to open a solenoid to flow the gas? What kind of circuit would I need?

If I match the voltage of the signal to the solenoid it should work, right?
 
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MisterBill2

Joined Jan 23, 2018
7,021
Certainly that could be done. Possibly there might be a need to provide some isolation of the different sections, but that is simple. And the delay between gas flow and wire feed would be simple to add as well. Probably the major effort would be finding places to mount the additional control components and the gas valve. Mechanical considerations often take the greatest effort, since you want the package to be durable and reliable.
 

Thread Starter

Paul Pfeiffer

Joined Oct 16, 2020
9
Certainly that could be done. Possibly there might be a need to provide some isolation of the different sections, but that is simple. And the delay between gas flow and wire feed would be simple to add as well. Probably the major effort would be finding places to mount the additional control components and the gas valve. Mechanical considerations often take the greatest effort, since you want the package to be durable and reliable.
...some isolation...but that is simple. are you talking about ...???...not getting your wires crossed?
 

Thread Starter

Paul Pfeiffer

Joined Oct 16, 2020
9
Can you have post flow with the solenoid at the gun, that would be nice. A cap to discharge with a post flow.
so the cap would "charge" when energized in the line to the solenoid, and drain for a few seconds to maintain the flow a little longer.(?) I just might be getting on to this electronics stuff. I've been wanting to learn some of it for a long time.
And most of the MIG welders I've investigated lately have the solenoid in the case. The gas tub is small. (i.d.=0.125") So the gas left in the line doesn't go very far when turned off. And the pressures are low. 1-2 lbs/sq.in.
 

Wolframore

Joined Jan 21, 2019
1,796
Separate power from a low voltage transformer is generally how the solenoids are powered along with the wire feed mechanism, you would want the cap energizing circuit on this mechanically switched off the same trigger for the welder. For a few reasons, the voltage and current from the welder has too much delta and you don’t want to take power away from your weld tip. By the time my welder gets to 100 Amps it drops the voltage down quite low.
 

MisterBill2

Joined Jan 23, 2018
7,021
...some isolation...but that is simple. are you talking about ...???...not getting your wires crossed?
Actually, the isolation would be to keep the solenoid valve circuit separate from the welding voltage circuit. I am thinking that part is important. So pushing the button on the gun would first start the gas flow, then switch on the power and start the wire feed. But I am not completely sure that the welding power needs to switch on and off all the time. It has been about 30 years since I used a wire feed welder.
 

Wolframore

Joined Jan 21, 2019
1,796
A steady DC voltage is what’s required for MIG, there are a few different machines that offer pulsing and various power profiles that help with welding. I’m not a big fan of old welders. The new machines are so much nicer, lighter and packed with features.
Nothing wrong with flux core for use where gas is not effective (outdoors) and where you have substantial thickness material.
 

Thread Starter

Paul Pfeiffer

Joined Oct 16, 2020
9
If it is a wire feed and no gas it is by definition a flux core welder. Why do you think 1980's or 1990's didn't have flux core? It has been used since the 1950's before Mig came about. https://en.wikipedia.org/wiki/Flux-cored_arc_welding
it was originally a with gas MIG welder. But there was no solenoid. gas was controlled by a valve in the whip handle. the original gas valve id dead. I am trying to make it into a good welder again.
 
That comment about the gas valve was in the first post also.
The problem with a flux core welder is the price of the wire. Expensive and not available everywhere.
And just because new welders are more fun is no reason to abandon reclaiming an older one that is probably much better built. And some folks really enjoy the challenge of reclaiming stuff like that. Including me.
 
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