Sealey Mighty Mig 100 Mk2 (not gasless)

[catceefer]

Jan,

I am not sure how I could have cut it in the wrong place and caused this effect as the torch and motor feed share the same cable. Either way, I have now sorted out a fresh feed to the controller without needing to use a toggle switch.

Regards,

James.

 

[Jan]

I don't have any pics of my mod at the moment but a word description should suffice. I disconnected the positive lead at the point where it was bolted to the feed to the torch lead. This was then connected to the Dinse socket. I then connected length of heavy duty flex to the now empty bolt and attached the dinse plug to the other end and looped it out of the machine. The negative lead was simpler in that I merely cut it and attached the socket & plug to either side of the cut. This means that I have not gone anywhere near the feed to the motor so its power connections are unaffected.
If the feeds to the motor in your machine are taken from the torch leads inside the box they should be left where they are, you should cut the leads 'downstream' of them and only the torch polarity will have been reversed.

 

[catceefer]

How many light-weight wires are in the SIP torch, feeding the operating switch, in addition to the heavy power feed?

 

[Jan]

Two: One is a light current/voltage feed and the other goes back to the primary of a relay inside the machine. Neither of these need to be touched when altering the polarity. The relay also controls the gas valve which is purely on or off. The current and wire speed controls are deeper inside the machine and also should not be touched.

 

[catceefer]

Jan,

That explains it. Mine has just one light weight wire in the torch, which runs back to the motor controller. The switch for the motor is really crude, being just a bent strip of metal that shorts this wire to the feed wire to the torch. As soon as the feed polarity to the torch is reversed, it automatically reverses the feed to the motor controller. The gas valve is purely mechanical.

Regards,

James.

 

[Jan]

It sounds like the design of your welder is older then me. That's OOOLLLDDD, man! Sorry, but without a full circuit diagram I can't give you any more info on how to convert it to gasless.

 

[catceefer]

Jan,

I may not have been clear in my posts, but I have now made the conversion and it is all working well. I was just puzzled how you had effected the conversion without rewiring the motor feed power.

I am not sure of the age either, but 1991 rings a bell.

Thank you for your help.

James.

 

[Jan]

As long as it works then 'All's well that ends well' as The Bard put it. Congrats. Now get that thing fired up and learn how to use it by practice, practice, practice!

 

[catceefer]

It works! I have just tried the machine out properly for the first time with the fluxed wire and am happier with the results than I expected. Using a scrap of the same sheet that I am using to repair my son's BMW, and setting the machine to its highest power and a high wire feed speed, I neatly burnt a long line through the sheet. Turning the power down to the lowest setting, setting the wire feed to about 3/10 and using a weaving motion, I managed to get weld down that penetrated without burning through. A lot more practice needed yet, but I am greatly encouraged.

Regards,

James.

 

[Jan]

Don't forget that welding flat on the bench is completely different to welding on the car. In the former scenario the worktop will soak up a lot of the heat, but having fresh air on both sides will allow the weld puddle to heat up a lot more. Eg. Using my SIP MigMate 130 on its lowest setting on the bench I can do a butt weld on mild down to 0.5mm, but a on a right angle joint the vertical metal will just evaporate. Someone with more talent/experience might be able to do this kind of stitching, but I'm a long way short of either yet.

 

[catceefer]

Time will tell, although, as I have a wooden workbench, the metal was up in the air, not flat on a surface. I still need a lot of practice, though, before using it on a car. Until then, I shall carry on using the proessional MIG welder up at the workshop where the car is currently stored.

Regards,

James.

 

[Jan]

You lucky sod! I live in a small OAP/disabled ghetto where I have more tools than the rest of the estate put together, but even so I'm seriously short on a lot of the more specialist machines that I would love to have:
Pillar drill
Lathe
Oxy/fuel burning/cutting/welding gear
Car lift/inspection pit
Sliding mitre saw
Etc, etc.
However if I won the lottery ... *Thinks* Must buy the occasional ticket!

 

[catceefer]

Jan,

Yes: I am very lucky. The real advantage is that I can work on the car at any time of the day or night and make as much noise as I like, without annoying the neighbours. Ready access to a wide range of tools is another bonus. I have most "normal" tools, but many, I have discovered, have worn out. Doing this car, I have so far found that damp in the garage has ruined a good pair of wire strippers, my angle grinder had lost all power, my battery drill has lost its speed control and is set to minimum and the battery charger appears to have run out of charge. There are also other specialised units around the estate, one of which has folding brakes that my friend can use to form the rather convoluted inner cill repair piece that is needed.

The fly in the ointment is that the place is a forty minute drive away.

Regards,

James.

 

[justvinnie]

I tried to use the machine yesterday and ran into an obvious, but unexpected, problem. With the polarity of the earth and torch leads reversed , the wire feed motor no longer works. The switch in the torch simply loops the original positive feed back to the motor controller, but revsersing it results in two negative feeds to the controller. I am currently installing an additional switch to reverse the power feed as well.

Regards,

James.

hi how did you sort the wire feed out as having the same trouble any help would be great

 

[justvinnie]

before and after

 

[Jan]

Just a guess, but ...

I think you've interrupted the Pos/Neg lines too far back in the circuitry. When I changed my SIP to give the possibility of switching polarity I did it at the front panel, so the motor doesn't have a clue what's happening out in the real world.