Upgrading a SIP Migmate 130 Turbo welder – Part 2, The 6m Dollar Welder

So after it had been left abandoned in a cupboard for a couple years I was recently contacted by the guy who actually owns the old SIP Migmate welder saying he had a couple projects to do that would be good for a MIG but aware we’d previously done it serious damage to the torch he’d found a wire feed unit with a euro torch connector on ebay and could we make it fit. Well of course we could, what could possibly go wrong! Before I knew it he’d ordered it to ship to me so I guess we were modding the welder again. We can rebuild it better than it was before!

Upgraded Wire Feed

Wire feeder
The new wire feed motor

So this is what turned up – clearly a different beast entirely to the original plastic rubbish. Don’t be mistaken, it’s a top quality Chinese unit but it is significantly better built than the original – one being mostly metal it doesn’t deflect under load. Add to that the motor is rated at 40W which is probably four times more than the original one it should be able to drive wire through longer torch leads with no problem.

Wire feed drive comparison

You can clearly see the significant difference in the units in this picture. But that isn’t going to stop us!

First off we need to remove the existing feed unit. These are held on with four pop rivets which are quickest removed with a power drill. To extract the drive unit the torch must also be unbolted from it with the one retaining nut.

Migmate 130 of feed removal

So at this point you should be left with this :

At this stage you’re probably wondering how this will work, and if (however unlikely) you’re attached to this welder you probably want to stop reading, this will not be pretty!

If you’re you’re not attached to the welder I suggest finding an angle grinder and getting busy!

The key thing to note here is because the new drive is for a euro torch it is energised by the main supply so no conductive part of the feed drive can be in contact with the casing. Add to this the new unit has an adjustment on the top which needs clearance under the case the feed motor cut out needs to continue much lower down.

Due to the feed mechanism being physically wider the connector for the euro torch connector will sit further out than the original torch outlet. In an ideal world I’d have relocated the the wire feed to the bottom of the welder but the outlet inductor is behind the panel and I didn’t want to go trying to move that enough for that idea to be viable.

First cut for wire feed

The first cut doesn’t look too serious, then hack the front out :

Front first cut

Hmm, yes I’ll work out how to cover that up later!

Next up we make a plate to hold the euro connector. This is to prevent any movement on the euro connector causing it to hit the case which could end very badly. I found a random bit of polycarbonate I had lying about drilled a clearance hole in it then worked out where it needed to sit. The horizontal position here is less critical as we can adjust it on the mounting later. The plate needs mounting holes to fix it to the front plate so drill and bolt this. A trial fit then also identified that when the new feeder was fully forward in position more clearance was required in the internal plate so this needed a little more butchery.

New mounting for replacement wire feeder

The blue wire dangled through the divider in the picture is actually the trigger wire for the welder something we’ll need to sort out later to actually make it work.

Wire feeder trial fit

So here’s the trial fit, nothing touching the case where it shouldn’t and all seeming to fit well. around this time I wanted to get a matching torch for the upgraded welder so I went to my favourite welding shop (Noz-Alls in Cheltenham) to pick one up and while there I explained what I was up to with the welder and he helped me out with some more bits he had. Specifically I wanted to upgrade the welder from using 0.7kg wire spools to 5kg spools so I needed a new mount for the reel and not only did he have something he also mentioned that I’d suitable gas valve (the welder originally had a mechanical one in the torch but I hadn’t even thought about the fact euro torches don’t have this. Again he had just the thing available for a few pounds so I got that as well.

New feed roller

Now that looks more like a proper setup, this new mount just bolts through the divider plate. Next up we need to mount the drive motor itself, it is critical to remember the black plate under the drive must remain to insulate it from the mounting bracket. I originally intended to mount it with a section of angle but in the end I came up with another alternative. I had a short offcut of 40x40mm aluminium profile with a couple angle fixings which by luck was perfectly sized so I decided to use that up.

Mounted new wire feeder

Something I should probably note here is using either durloc or nyloc nuts on everything I can and make sure everything is good and tight. The owner of this welder can be hard on equipment and I want to be sure that when I hand it back it won’t just fall apart!

Fully fitted wire feed and reel holder

That’s the wire feed and 5 kg reel setup all installed. So now back to the problem I mentioned earlier with the gas valve. The black hose coming off the back of the euro connector is the gas line, I need to connect this to a valve. I decided to mount the valve on the electrical side of the welder because my plan was to drill out the original hole the gas hose entered through to take a more standard 3/8″ BSP threaded fitting.

Gas Valve

New gas valve

The valve I bought is a direct fit to the 5mm ID hose off the euro connector. The valve inlet is an 8mm barb so I bought an 8mm to 3/8″ BSP female hose barb and screwed it into the back of an 3/8″ BSP bulkhead fitting. The bit of hose is a section of 8mm fuel hose I had lying about. The valve actually has a nut on one side to allow it to be mounted to a panel, in this case I mounted it to a section of aluminium angle. These valve are available in a range of voltages; usually 6/12/24VDC in welders but others are available. Since the feed motor is 24 VDC and we need this to open when the feed is on it makes sense to use the same then we only need one trigger switched supply for both.

Earth lead

So with the addition of a detachable torch I thought a detachable earth lead might be a good idea. I bought a 10-25 dinse connector off ebay, this comes as a plug and socket pair where the socket fits through a hole in the panel and the plug is bolted onto the end of the cable. To mount the socket I undid the clamp inside the welder where the cable was fixed to the supply transformer. The cable is held in by a plastic clamp so just undo that and pull the cable clear and remove the clamp from the panel. As it turns out the panel hole was fitted with a dinse connector in a different model and so they actually fit the panel perfectly with the anti-rotation key even fitting. Again for the power connection to the socket I used a 10mm re-usable cable lug but had to fold the solid core from the transformer back on itself so the clamp would tighten onto it solidly.

Dinse connector
Make sure it’s all tight; you don’t want this coming loose!

Wire Feed Controller

I decided in the end rather than bothering to improve the existing speed controller which is well documented to have issues I’d simply replace it with a modern PWM DC motor controller. PWM controllers generally allow a very wide range of adjustment and because they apply full voltage the motor retains excellent torque even at low speeds. So I bought another quality Chinese board off ebay and after a couple weeks I had one of these:

These go for about £2.50 and from my initial tests with a 19 VDC laptop supply and the new 40W motor it worked perfectly and it gave very smooth control up through the full range. The only thing that might need adjustment later is that full speed seems excessively fast for a welder but this is something to assess when the motor is loaded. With the smoothness of the range this wouldn’t be a problem but if we don’t need it later it would be better to add a resistor to make the controller only go up say 75% full speed when the dial is at maximum. But we’ll worry about that later.

The next problem is the nut on the potentiometer which would normally hold it in place fits right through the original hole in the panel. So I found a large penny washer which it would tighten up on and drilled two holes in it. This washer was then pop riveted to the front panel. With the knob back on you cant even see the rivets.

New motor controller
Rear view of the new controller
And the front view – you can see the other additions as well

Now, you may notice I’ve taken out the original PCB. This is partly because we needed the spot for the new speed controller but also because that makes about half the PCB redundant. The only other things on the PCB are a small 12V PSU (to drive the main supply relay), a couple line filter capacitors and a 16A relay which switches the main supply. My plan is to replace the relay with a 24V coil one and run all the control off the separate 24 VDC supply.

More to follow in the next update!

5 thoughts on “Upgrading a SIP Migmate 130 Turbo welder – Part 2, The 6m Dollar Welder”

  1. Thankyou so much for putting this up,

    I have the little brother to this welder, a migmate 105… bought from halfords in an emergency when fitting a turbo diesel engine in my VW LT camper,
    Sunday afternoon and i found the turbo sat exactly where the right hand engine mount was welded on the chassis.

    I’ve always had issues with varying welds due to what i now know is the crappy wire feed motor set up… mine’s had a nyloc nut jammed under the adjuster screw, with the screw right down to put enough tension on the rollers to get it to feed the larger spool i use, i can imagine my motor mount is distorted to hell now.

    I was looking at beefing the plastic feed motor mounts up, but i’ll need a new torch soon too and could do with it being a few feet longer,
    i am still running the 1997 vintage plastic liner it came with too (poked the wire out the side of it a few times as well)
    I guess i just got used to having to position the welder so the umbilical was as straight as possible to get it to feed at all.

    Now i think i will do what you are doing, go for a euro torch set up, separate psu for the wire feed motor, PWM motor control etc.

    Do you have part numbers for the bits you have added?

    i’d like to do away with the 3 rocker switches for power selection too, and have a rotary switch that works in a logical ‘next click is higher or lower power than the last’

    i have some industrial rotary switches, they can be set for how many clicks you want upto 9 i think, the contact blocks can be stacked etc,
    i’d just need to figure out which contacts to make and break as the knob is rotated and that should be an easy mod that would make these welders nicer to use.

    Only other mod i could think of is a temperature regulated cooling fan, maybe one with more air flow than the cheap jangely thing fitted atm, and perhaps some attempt at directing the air flow over the hottest parts inside the welder.

    1. No problem, the point of this blog was always more about listing that one odd bit of info someone might need at some point rather than any sort of mass appeal so it’s really good to know it’s actually helping people out there!

      You’re absolutely right about hacking about the plastic feeder system to make it work and certainly the metal plate (or something else) across the outside to stop the rollers splaying apart makes a huge difference to the grip on the rollers make a significant difference and I used it like that for some time quite service-ably. If you haven’t done this mod I strongly recommend it! The other big difference is the standard tiny gas bottles lose pressure so quickly it’s almost impossible to get a consistent flow and the supplied regulators are rubbish. Changing to a proper sized bottle is well worth it if you can spare the cash and it’ll make a massive difference to the quality of the weld and it will run a constant gas flow for a very long time.

      Rocker switches – I looked at doing the same but in the end decided the cost of all the mods was already getting a bit out of hand for such an old welder and the switches were quite expensive to do the combinations needed properly. Switches need to be 16A type rather than the more common 10A ones as they’re on the supply side of the transformer. The best solution I found was a cam switch with the right profile which I found online but it was special order and about £60. The problem is on the transformer you don’t just have one wire at the end then variable tappings for the other side for the different voltages, the way it works here is the high/low switch selects one of two tappings at one end and then the max/mid and mid/min switches select one of three tappings the other so you need a double pole rotary switch that does the following pattern:

      1-1, 2-1
      1-2, 2-1
      1-3, 2-1
      1-1, 2-2
      1-2, 2-2
      1-3, 2-2

      A simpler (and cheaper!) alternative would be retain a normal switch for low/high then just use a basic 3 position switch (ideally a 3 way on type usually marked 1-2-3 with no 0 position) to replace the other two switches.

      For the other bits I don’t really have part numbers as such as some of it was scrounged from whatever I had lying about or bits my local welding shop had spare but I’m happy to try to guide you where I can.

      The feed system was this one .I’m not sure why its now listed at £310 but mine was about £40 unfortunately I’ve no idea what welder it was from.
      Similarly the larger spool mount and gas solenoid was from another welder the same company was parting out. The company is amazingly helpful and I’ve been in there several times for random spares for things I suggest giving them a call to see if they can help you out https://www.weldingdirect.co.uk/

      The PSU I used was firstly a waterproof CCTV psu off ebay but it proved inadequate and would fail when the motor started so I replaced it with a cheap laptop style black block PSU I had about which from what I remember was 19V @ 5A. Even then with the motor speed at full with the load of the wire against it stalls the PSU but the speed is excessively high to the extent you’d never weld that was at that anyway. 75% speed or less and it works fine. Eventually I plan to mod the motor controller so the 100% position gives 75% speed to give finer adjustment but that’s not a priority.

      3/8 BSP Brass pneumatic bulkhead fitting
      Dinse 10-25 earth cable cable & panel mount connector set
      Female 3/8 BSP – 8mm hose barb adapter to match gas solenoid
      3″ of 8mm ID fuel injection hose – again because that’s what I had to hand but any suitable pneumatic line would be fine.
      10mm Ring Re-usable welding cable lug to suit 25mm cable (used to connect the transformer cable to the back of the new dinse connector
      Finder 16A/250V base code 97.01, relay code 46.61, 24VDC coil + diode single pole change over. I used the 97-01 din rail bases because I had them and a bit of rail about, they also do a screw in panel mount adaptor code 46.05 which might be easier for you.
      Mini DC motor speed driver 3-35V (these are all over ebay for a couple quid) upgraded with IRLB8743PBF mosfet (through hole version of the normal surface mount component) and a TO-220 heatsink I had lying about because the even though these are advertised at 5A speed controllers they can’t do that without overheating almost immediately and the upgrade massively increases the cooling capacity.

      I think that’s all of it. Writing this reply had reminded me I never did write part two of it up and I thought I had! I’ll do that when I get a moment and hopefully it will be even clearer. The good news is I returned it to its original owner as his xmas present and it’s still working some months later!

  2. Thanks for this, I’ve the smaller gasless mig which uses the same motor drive and the info has given me a kick up the arse to get this sorry mig working.

    1. Hi,

      Glad to hear it might be useful to someone!

      I’m going to do an update to this project once I get the latest mods working – I recently heard the guy I modded it for was having problems with it tripping the circuit breaker in his barn so I’m working on an inrush current limiter for the main transformer to get round this. As it currently is it’ll be ok on a 16A C curve breaker but if you put it on max power it trips a 16A – B curve which is more common in domestic buildings. This might not be relevant to you since it’s the 130A version and only on max. I also took the opportunity and replaced the hacked about motor controller with a bigger 10A version for a few quid off eBay The 3A one with the added heatsink didn’t fail but I though it would be best for reliability. Although being larger it needs brackets to support it.

      What I can tell you is with all these upgrades it behaves like a totally different machine!

  3. My 105 amp version trips a 16 amp type B breaker on max power too, always done that since new,
    so i just got used to putting in a type C breaker in the garage consumer unit where the welder lived when i moved house.

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