John Crighton
New Member
- Messages
- 3
Hello,
I just found this forum yesterday and read it with great interest. I find I am not the only person having problems using a SIP mig welder. I read about the liners, plastic and metal, this is an area that I haven't touched but now that I have a few clues from this forum I will check and clean mine.
The wire speed control or lack of it annoyed me. I made a
separate motor speed controller in a small external box. The box contains a power transformer and regulated 12 Volt supply. Good for a couple of amps. The regulated output voltage can be adjusted easily, 10V to 15V for experimenting. To make the motor run at various speeds I used the PWM (Pulse Width Modulation) method. This is the circuit I used.
http://www.solorb.com/elect/pwm/pwm1/
This motor speed controller was built in a separate box for experimenting only but I now like having the box next to where I am welding so that I can fine tune the speed with my left hand while welding to try and get that fried egg crackling sound. The output of the PWM motor controller is via a double pole double throw relay. When the relay is on the motor runs when the relay is off the motor gets shorted out via the other relay contacts. This makes the motor stop quicker.
I added a small 24V couple of amp unregulated DC power supply inside the rear of the welder for general use. The gas solenoid now uses this power supply via a relay that I fitted. I fitted a button on the torch handle to make gas flow before I pressed the trigger. This didn't make much difference to weld quality. Just a little at the start.
My SIP Migmate cannot weld 1/8 inch angle iron. Maybe other SIP Migmates can but mine cannot. I experimented with the Choke and found that it would saturate at roughly 45 amps. I passed 45 amps AC current through the choke
on its own with a 100 amp meter shunt in series with it. An oscilloscope waveform taken across the meter shunt started to distorted around 45 amps. Below 45 amps OK.
I expected this choke to be good while passing 100 Amps.
I am not an electrical engineer just a hobbyist at technician level but to me this choke is dodgy. To me this SIP Migmate 100 is really a 45 amp welder! I then decided this welder of mine would be for car body sheet metal only.
I found a bank of seven large electrolytic capacitors and connected them to the DC output terminals. The previous owner had fitted two DC output terminal so that he could reverse the polarity for flux core wire. With my bank of capacitors (seven caps, 9000 Mfd 75V each) fitted I now had a choke input power supply. The loaded output voltage is now quite low but it is now far stiffer than before, voltage regulation wise, that is the beauty of a choke input filter type of power supply. The now lower and stiffer output voltage is plenty high enough for car body sheet metal. Not high enough for much heavier than that.
I had to find another choke to go between the output power terminals and gun. Far too expensive to buy as a spare part here in Sydney so I made my own with help from
a local transformer repair shop. I bought a bundle of laminations 10 inches by 2 inches and stacked them to a thickness of 3inches. I put about 35 turns of heavy wire round the bundle with a few taps. Now when welding, I can achieve that fried bacon ZZZZZ sound where before it was just a soft hissing sound. The weld beads on thin 40 thou. sheet look better too, not globbing through to the other side as readily as before. Experimenting with tapping points on my home made choke didn't make a lot of difference that I could detect. It works.
The 240V mains relay gave up with all the experimenting I was doing. I have used up more wire running test welds than real on the job welds. I read where other people had
relay trouble also. I have now fitted a larger relay than the original.
Future mods will be fitting a fan and finding capacitors that are physically smaller so that they can be mounted somewhere instead of my present lash up all hanging outside the welder with case sides off. Finding a smaller choke also.
Regards,
John Crighton
Sydney
I just found this forum yesterday and read it with great interest. I find I am not the only person having problems using a SIP mig welder. I read about the liners, plastic and metal, this is an area that I haven't touched but now that I have a few clues from this forum I will check and clean mine.
The wire speed control or lack of it annoyed me. I made a
separate motor speed controller in a small external box. The box contains a power transformer and regulated 12 Volt supply. Good for a couple of amps. The regulated output voltage can be adjusted easily, 10V to 15V for experimenting. To make the motor run at various speeds I used the PWM (Pulse Width Modulation) method. This is the circuit I used.
http://www.solorb.com/elect/pwm/pwm1/
This motor speed controller was built in a separate box for experimenting only but I now like having the box next to where I am welding so that I can fine tune the speed with my left hand while welding to try and get that fried egg crackling sound. The output of the PWM motor controller is via a double pole double throw relay. When the relay is on the motor runs when the relay is off the motor gets shorted out via the other relay contacts. This makes the motor stop quicker.
I added a small 24V couple of amp unregulated DC power supply inside the rear of the welder for general use. The gas solenoid now uses this power supply via a relay that I fitted. I fitted a button on the torch handle to make gas flow before I pressed the trigger. This didn't make much difference to weld quality. Just a little at the start.
My SIP Migmate cannot weld 1/8 inch angle iron. Maybe other SIP Migmates can but mine cannot. I experimented with the Choke and found that it would saturate at roughly 45 amps. I passed 45 amps AC current through the choke
on its own with a 100 amp meter shunt in series with it. An oscilloscope waveform taken across the meter shunt started to distorted around 45 amps. Below 45 amps OK.
I expected this choke to be good while passing 100 Amps.
I am not an electrical engineer just a hobbyist at technician level but to me this choke is dodgy. To me this SIP Migmate 100 is really a 45 amp welder! I then decided this welder of mine would be for car body sheet metal only.
I found a bank of seven large electrolytic capacitors and connected them to the DC output terminals. The previous owner had fitted two DC output terminal so that he could reverse the polarity for flux core wire. With my bank of capacitors (seven caps, 9000 Mfd 75V each) fitted I now had a choke input power supply. The loaded output voltage is now quite low but it is now far stiffer than before, voltage regulation wise, that is the beauty of a choke input filter type of power supply. The now lower and stiffer output voltage is plenty high enough for car body sheet metal. Not high enough for much heavier than that.
I had to find another choke to go between the output power terminals and gun. Far too expensive to buy as a spare part here in Sydney so I made my own with help from
a local transformer repair shop. I bought a bundle of laminations 10 inches by 2 inches and stacked them to a thickness of 3inches. I put about 35 turns of heavy wire round the bundle with a few taps. Now when welding, I can achieve that fried bacon ZZZZZ sound where before it was just a soft hissing sound. The weld beads on thin 40 thou. sheet look better too, not globbing through to the other side as readily as before. Experimenting with tapping points on my home made choke didn't make a lot of difference that I could detect. It works.
The 240V mains relay gave up with all the experimenting I was doing. I have used up more wire running test welds than real on the job welds. I read where other people had
relay trouble also. I have now fitted a larger relay than the original.
Future mods will be fitting a fan and finding capacitors that are physically smaller so that they can be mounted somewhere instead of my present lash up all hanging outside the welder with case sides off. Finding a smaller choke also.
Regards,
John Crighton
Sydney
