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Old 06-03-2015, 06:05 AM
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JohnBoy JohnBoy is offline
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Default SIP Migmate Pro 170 DP

Picked up a new welder at the weeked.

It's a SIP, italian brand, closely related to the existing 130A unit I have.

It's better in that it has a removable torch and earth, is copper wound, can run gasless, has an extra 40 amps and a much better duty cycle.

it also has the same crappy motor speed control issues that the 130A machine had, and only has a half wave rectifier.

Still though it only cost €120 and I have buyers lining up for the 130A welder.


i'm going to apply the same principles of turd polishing as I did on the 130A machine here http://www.shopfloortalk.com/forums/...ad.php?t=43551 just hopefully tidier/better.



First job is to swap the capacitor and one of the cooling fans on the 130. I went overkill there, it runs too hot with the capacitor, melting the insulation on the earth lead and the inlet fan is completely un-nessecary with two powerful outlet fans pumping the air out.


I've a 24v power supply on order to run the feed motor independantly of the welder transformer instead of the laptop power supply I used on mk1.
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Old 06-03-2015, 06:21 AM
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The pix you posted sure agrees with the italian branding....
Looks like Antonio wired it after eating a large plate of spaghetti....

It is good that the 130 has buyers waiting.
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Old 06-03-2015, 06:07 PM
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all that spaghetti is very mod friendly though, lots of wire to play with.

threw it up on the bench tonight, the torch had seized into the socket, some gentle persuasion with a pipe wrench sorted that.

braced the crappy plastic wire feeder and reloaded the wire.

Rerouted the power cable in through the back, then I went and fitted the capacitor and resistor I'd had in the 130A machine and did a test.


Except it appears that 47000mF isnt enough capacitor for 170A I let the smoke out of it before the wire had fed all the way to the end of the gun.
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Old 06-03-2015, 07:44 PM
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Originally Posted by JohnBoy View Post

Except it appears that 47000mF isnt enough capacitor for 170A I let the smoke out of it before the wire had fed all the way to the end of the gun.
You can buy canned smoke on the Net, its handy for anything made by Smith and Lucas(the Inventors of Darkness). Might work on Italian electrics too.
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Old 06-03-2015, 10:02 PM
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You can buy canned smoke on the Net...
Not sure why you'd need that, Gerry, seems to me you're pretty good at makin' your own...
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Old 06-03-2015, 10:56 PM
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Not sure why you'd need that, Gerry, seems to me you're pretty good at makin' your own...
Oooh, that hurt.....go ahead and laugh, you fools, but this'll help John get that welder working
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Old 06-07-2015, 01:49 PM
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So I may owe my capacitor an apology.

In my haste to get it wired I may have inadvertantly blown it up by wiring it the wrong way round


To say that I am pissed at myself would be an understatement.

I did try some welds with the flux cored wire that's in the machine and it seems to burn wire anyway. serious overrun on the wire feed (over an inch after releasing the trigger!) but the seperate power supply should sort that out.

Two new caps en route from germany, the one I blew up came from greece. Continental europe seems to be second only to china for cheap capacitors.
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Old 06-07-2015, 04:57 PM
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I am always amazed when anybody can get a welder.. Sort through all the different wiring, then figure out what it needs..

somehow the welding stuff, especially the newer stuff just looks to complicated..

Nice sorting out.
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Old 06-10-2015, 09:13 AM
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somehow the welding stuff, especially the newer stuff just looks to complicated..
Lincoln 650 inverter on a robot...Rep couldn't get a good weld with it...
He was "designing his own waveform" and it wasn't working out.

It didn't sound like frying eggs, rather it was the worst arc I have ever heard.

Best I can describe, a kid walking thru a pile of leaves, and deliberately
draggin his feet for more noise.

He was telling me that you can "sit at a computer and design your own waveforms
for it, then download to the power supply"

Damn thing has more computing power than on the space shuttle....

So I said "basically it's a big audio amp ?"

He said "yes, a 650 amp audio amp"

So I said "Hook up a C.D. player to it, chuck in "freebird", and get to welding"

He wasn't amused....

Last edited by digger doug; 06-10-2015 at 09:53 AM.
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Old 06-16-2015, 06:42 AM
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Originally Posted by allessence View Post
I am always amazed when anybody can get a welder.. Sort through all the different wiring, then figure out what it needs..

somehow the welding stuff, especially the newer stuff just looks to complicated..

Nice sorting out.
A machine like this is actually pretty simple when you break it down. The wiring is a bit of a mess, I can only assume they use the same inner loom in a bunch of models so there's acres of slack to suit.


I've finished my work on it, here's a post I did by way of explanation on another forum.


When I did the sealey mig I said I'd post a proper description of the job I did on it. I'm no expert in this stuff, I just did some reading on migwelding.co.uk and weldingweb, people have been doing these mods for years.

The specific details of each welder will vary, but the principles of these basic migs are all pretty similar, as are the problems.

The problems stem from using cheaper components and circuitry, to an extent you get what you pay for. I wouldnt buy a new welder to do these mods to, but I'd buy a second hand one for sure.


Problems
  1. Wire feed mechanism
  2. Torch liner
  3. Wire feed electronics
  4. Wire reel mounting
  5. Cooling
  6. Arc stability



1) Wire feed mechanism
Cheaper welders tend to use single drive wheel feed mechanism. The plastic flexes, requiring undue pressure to be put on the tensioner to get the system to feed. A brace from the tensioner pivot down to a lower screw on the unit means you can run with way less tension and still get a consistent feed. Cost €0.10

2) Torch Liner
Cheap welders have plastic torch liners, a metal liner will have far lower friction, giving a smoother feed and making it easier for the cheap wire feed mechaism to do it's job. I've read some people suggesting using net curtain wire, but a proper liner is cheap. Cost €10.00
http://www.ebay.co.uk/itm/SIP-Weldma...item23529850cf


3) Wire feed electronics
This is the big one. Cheap welders use the welder transformer as the power supply for the wire feed. They tend to also use cheap/basic circuitry to control the voltage to the motor. What happens is the arc voltage drops under load, slowing the motor, breaking the arc, causing the voltage to rise, ramming the wire forward, shorting the circuit, dropping the voltage, slowing the motor, breaking the arc and on and on. The fix is to power the motor independantly, and while at it, to use a better control circuit.

For power I used a 24v transformer and control a PWM circuit, both from ebay. PWM is a method of controlling motor speed that applies full power for moments at a time, increasing the duration of those moments up to a constant supply to give full power. It gives a very smooth control and is better for a motor long term than controlling it's speed with low voltage.

In both the welders I've done I removed the existing controller completely and rewired from scratch.

The 24v power supply is powered off the mains switch of the welder. 24v power goes into the PWM board all the time the welder is turned on. 24v+ also goes out to the torch trigger and comes back in to power two 24v relays when the trigger is squeezed. One relay switches on the mains input to the transformer, the second switches the output from the PWM circuit on.

The one variable between the two welders I've done is the thermal cut-out. On the sealey it was a thermostat that shut off mains input to the transformer, so I powered my 24v power supply from that. On the SIP is is a thermostat on the low voltage circuit feeding the gun trigger so I fed my 24v to the trigger through it.

Cost €22

http://www.ebay.co.uk/itm/2216538177...%3AMEBIDX%3AIT
http://www.ebay.co.uk/itm/3216368704...%3AMEBIDX%3AIT


4) Wire reel mounting
The springs used to tension some of these feeders can be too strong which can make it very tough on the weak feed mechanism, also some of these welders can unlock their feed screw. Cutting a ring or two off the tensioner spring can ease these issues. I'm also going to make a new reel mount to better carry 5kg reels in the SIP, which the Sealey didnt suffer at. Cost €0-€5


5) Cooling
These welders tend to have very cheap, simple fans which just kindof move air about, but dont really direct it anywhere. proper computer style case fans will do a much better job of pushing air in/out. I've removed the stock fan and mounted a 230v extractor fan outside the case as it frees up room inside to mount the power supply. Cost €18

http://www.ebay.co.uk/itm/2312604559...993%26_rdc%3D1

6) Arc stability
Bigger, quality arc welders use capacitors to smoothen the arc outputted by the rectifier in the welder. Cheap welders dont have these capacitors at all. The capacitor needs to be quite large, but you can use a few together to get capacity. I didnt find any hard and fast rules for capacitor sizing but I've gone with 50,000uF which has a noticeable effect. The capacitor needs a high current resistor across it's terminals to burn off residual charge when you release the trigger, otherwise the torch would remain live for some time after releasing the trigger. The capacitor will also increase the effective voltage of the welder, it will run hotter. On the sealey that was too much for it, the earth lead insulation started to melt under load!!

The capacitor is simply wired in across the output terminals of the rectifier, before the choke. The capacitor has to be wired in the same polarity as the rectifier output, unless you want to make a whole lot of smoke :blushing:
Cost €35.00
http://www.ebay.co.uk/itm/2815736214...%3AMEBIDX%3AIT




On the SIP I havent had to do the torch liner as it has a metal one already, it has cost €85 to upgrade a €120 second hand welder into what should be a pretty useful machine for the money. It could be done a whole lot cheaper by using some power supplies removed from other equipment and case fans removed from old PCs but I wanted to do this one more "properly", partly at least to find out what it would cost to do.






Some other mods to consider:
Relocate power in cable to the rear, dunno why, but it always annoyed me having the mains going in the front of the mig when both arc welders take it in the back, it also freed up an ideal spot in the front to install the capacitors.

Upgrade earth sockets. The sealy had a built in earth and the SIP has a short little one. I'm going to install a bigger Dinse socket to allow interchange of longer earth from other welders.

I would also be possible for a delay timer circuit to be installed to control the gas solenoid which would give post gas flow control. Its a common feature on higher end migs, but I wont claim to know what practical difference it makes. but it would be easy enough to implement with a delay timer circuit from ebay.

I dont have in progress pics, just one of the completed wiring job in the SIP.
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