New Toy - Migatronic KME 550

Collected a new welder this weekend, an auction find coming from a shipyard with no warranty and assumed to need some repair work, but still an absolute steal for the price.

Whilst I won't be able to run it at the full 550A off my RPC, there's quite a few nice features which make it a major upgrade over my current machine:

• Latching trigger for reduced fatigue during long runs.
• Fully programmable pulse welding for sheet metal and aluminium.
• Pre-set "synergistic" modes for most gas mixes and filler wires.
• Compatibility with push-pull guns for aluminium, stainless and other awkward wire types.
• 4-roll feeder suitable for running flux/metal-core and dual shield.
• Water cooled gun (not strictly necessary for most of what I do, but is a nice to have even at lower power settings).

The first challenge was how to safely lower a 340kg item from the back ofy pickup, I briefly considered taking the top off and using my neighbor's gantry, but settled on using a ramp and a climbing belay plate in "guide mode".

All in all, it went pretty smoothly, although partway through it locked up sufficiently tightly that my erstwhile long suffering partner wasn't quite strong enough to release the auto-block and we had to trade places with her guiding it down the ramp and me operating the belay plate.

My ramp cobbled together from two layers of 2½" by 11" timbers salvaged from a neighbour's roof renovation performed like a champ, at one point holding 340kg of MIG welder and 120kg of foolhardy human with minimal bending.

Once in the workshop I assembled the feed unit on top using a length of broomstick as I had no steel bars the right diameter and the original spigot being long gone (the shipyard having put it on wheels and long leads to extend the range from power unit to weld), and snapped a pic with the missus for a sense of scale (She's 5'4”, the welder is 5" tall).

I'm planning to document the process of cajoling it back to life, fault finding, and fettling it up here, for general interest and as encouragment to others who might be tempted to buy welding equipment to match the other "big old iron" many (but not all) forumites are fond of.

Of course, it might be just fine making for a really boring thread... But after 15 years in a shipyard and 5 years in mothballs before being auctioned off, it's safe to assume it will have some faults (it's missing one of its four earth-lead lugs for one thing).

Edited By Jelly on 06/02/2023 21:26:40

Been there ! Got a Sureweld 375 for £25 ! It was like new but 3Ph. Built 20Kw diesel genny to drive it. Wonderful machine ! Would drive 1 and 1.2mm wire, made stick welding look old fashioned but put .8mm on and turn it down it would do bodywork repairs. The separate wire feeder(on wheels) made it good for BIG jobs as the transformer comes near and then you drag the feeder close to the work.

Your unit may need 25Kw 3Ph to drive it, not sure a RPC will be very happy with it ?

Good Luck, Noel.

The advice I have had from Transwave on running welding equipment was that as long as the demand from the welder does not exceed the rated kVA output of the RPC all is well, but that I should definitely have an appropriately rated MCB with a B trip curve (not the C or D one would usually use for a welder) between the RPC and the welder to prevent it creating an accidental overload causing damage.

In theory this does rather hobble it, as at full power it will draw an eye-watering 34 kVA, but for most of my normal uses, running around 2-6kVA which is well within the capacity of the converter will do fine.

I'm curious about your generator build though, where did you source the alternator, and did you include any voltage and/or frequency regulation feedback mechanism to the throttle or just set it up for manual control?

Peugeot 1905cc diesel, almost new Stamford alternators 20Kva built/ bought for the winter of discontent at a farm auction £110, 5 belt drive to let engine run at 2000rpm. Speed set manually using a frequency meter, injector pump rebuilt to run at constant speed. I also have a 25Kva PTO unit as well. Built a 12 ton electric/ hydraulic log splitter with 11Kw motor(motor and switch gear, a bottle of whiskey) to also run off this unit.. I live in a village with only 2 phases ! Noel.

I do keep looking out for alternators or motor-generators on eBay etc, although they don't seem to:

1. come up very often,
2. be well described when they do.

As it would be useful to have a decent gen-set and they're a fortune to buy even second hand, high hours and absolutely ragged.

The additional challenge today would be getting a sufficiently uncomplicated engine that I don't have to reverse engineer the ECU of a car into the bargain... good condition mechanically controlled diesel lumps are getting increasingly rare on the ground.

If i'm ever successful finding an alternator I may have to pick your brains on how you went about setting up the rest of the genny.

So transwave were ultimately unable to help me, as the design of RPC I have is one which their parent company acted as distributor for until they went bust, at which point the began manufacturing in house.

They did go to a lot of trouble trying to help, but alas it was not that simple.

I have however now made some progress towards getting this running again...

Good news:

• Tested it on three phase at a mate's unit, and it powers up and runs still, and the damage appears to be cosmetic.
• Managed to source a generator, 25kVA silenced diesel which was being used to power a similar welder by another boat repair firm until recently when they moved premises, let go at a very reasonable price.
• The genset is small enough to fit through the rear door of my workshop, allowing me to put it inside my fenced garden where it won't be at the mercy of diesel or copper thieves.

Bad News:

• The cooling system has algae
• One of the DINSE sockets (Earth 2 which covers 80-200A) is not as I initially thought just pushed in but in fact totaled, and accessing the inside of the panel it mounts to in order to mount another looks like it's going to be a huge pain.
• The generator whilst electrically and mechanically sound, has some significant structural rust, so as soon as I get the welder running I'm going to need to patch the frame and enclosure.
• Moving the generator through the workshop will require me to cross two steps and involve moving two milling machines, the workbench, and a substantial amount of stuff on racking to clear a path.

Unknowns:

• Only had a brief opportunity to test, so it's not clear if the synergistic programmes still run correctly, I may yet need to take it for a professional service and calibration if I want that to work.
• The 15M umbilical for the separate Wire Feed is a pain in the neck and I'd dearly like to split them down into a 1m and 14m section with connectors in the middle for when I do need that, but the required screened female connector for the control lead is eluding me at present.
• Genset is only rated at 25kVA continuous, in principle it's standby rating  means it can deliver the full 33kVA for 550A @ 60V for around 200hours per year,  it remains to be seen how well it operates with the welder set to above 420A... Which could be a limiting factor if I want to do any thicker aluminium welding.

Edited By Jelly on 14/06/2023 23:18:26

Not sounding too bad.. but like me (and most others here I expect) you now need a bigger workshop..!!

Be interesting to see how she goes..

Tell me about it, I swear workshop equipment is a hitherto undiscovered type of gas, expanding to fil the space available.

An extension is something that I have been working on plans for (there's an additional 4m×3.2m of space I can claim going backwards towards the house before it negatively effects the garden)...

But to justify the expense, it will really need to accommodate a dedicated office space as well so I can have my guest room back.

Edited By Jelly on 14/06/2023 23:25:04

..200 tdi L-R lump.. ..still around, still being re-manufactured, good supply of spares..

That photo makes it look almost as big as the workshop

Always extra-satisfying to use a machine to mend itself!

Dave

That's an interesting find. Never seen a Migatronic welder in anything other than dull green -my 1980's 180A set- or slightly brighter green, their newer stuff. If you are going to be welding Aluminium, are you going to hope that you don't get a birds nest with the 4 roller setup, or are you going to use a spool gun? I converted my welder for such.

The first owner was clearly HSS Hire (it's been blacked out in some places but not well) and it's in HSS's corporate shade of blue, so presumably if you order enough welders at once, Migatronic will paint them a custom colour from the factory...

I'm wondering if it's a unit that was on-hire for so long that when the time came to return it at the end of a contract, HSS just sold it to the customer for whatever the remaining book value was to avoid having to deal with collecting and servicing something they no longer wanted on the books... Which would explain how it ended up in storage and being sold for peanuts to me.

.

For the Alu Welding I'm hoping to be able to get set up with a water-cooled push-pull gun, a friend of a friend has one going spare so I need to go over and see them about it at some point.

If that doesn't work out a spool gun like your setup is my fall-back, but I'd have to make a bypass loop for the coolant circuit and use manual settings rather than the synergic mode to avoid the power-source unexpectedly frying the gun with more current than it's rated for.

Depending how long it takes, I might get a small spool of Alu wire to give it a go through the wire-feeder, but I'm not holding out hope that it will cope well, with the torch lead itself being 4m and all.

Yeah it is!

Although I'm not sure quite what the implications are in this case, I suspect that I probably don't want to put the generator enclosure and chassis into the welding circuit of a machine which is protectively earthed to that self-same chassis... My gut feeling is that it could go badly wrong.

A lot of the patching is on panels which I can lift off and do in my booth with the MIG (Halleluja!), but some of the bits of the chassis proper, I may need to do with the stick welder instead.

For ali it all depends on the wire thickness as to what type of torch you use. I used 1.2mm with a teflon liner, I think 3m torch. Thinner wire may well need a short feeder or gun feeder. For ali I would go for TIG, unless heavy section. Good luck. Noel.

If it's too thin to MIG I'd probably OA weld it, TIG is a skill I have consistently failed to master... And I'm well aware that to most people it sounds crazy to find gas welding aluminium easier, but my fine motor control isn't up to holding a consistent arc length without dipping the tungsten or moving so slowly I blow through.