aweekes1
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 posted on 27/8/05 at 05:10 PM |
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Capacitirs in a hobby MIG
Hi All,
I've just been playing with my SIP 150 MIG thing. I now have a nice bottle of Argoshield light and all the gubbins. Not cheap this weekend but
should work out a lot cheaper than the poo bottles even in the medium term playing at welding up scraps!
The other change was to throw in a some hefty capacitors. This had an amazing effect. It was like using a 3 phase machine, it just blasted out
fantastic looking welds on the thick stuff but even on min it blew through the thin stuff!
The only problem was that the SIP welder with its infamous wire feed uses the voltage across the +/- terminals as a signal to the motor control
circuit so as the caps were charged I would get a massive run on and end up with six inches of feed after each weld! I'll have to look into this
in more detail and try fewer capacitors?
Has anyone done anything similar with good results?
Cheers All.
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wilkingj
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| posted on 27/8/05 at 07:24 PM |
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What size (uF) / voltage Caps did you use, and which ones did you change in the machine?.
I have a SIP 150.
I suspect that you have got better smoothing on the wire feed circuit giving you better welds, and as the voltage is more stable (better caps / less
ripple) its causung the run on with the wire that you are experiencing.
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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aweekes1
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| posted on 27/8/05 at 09:01 PM |
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I think the total was around 72,000 all rated around the 60v mark. The welder typically throws out 34V or there abouts.
I didn't change any though, there isn't any capacitor smoothing on the standard machine at all. My thoughs on the capacitors was to smooth
out the power delivery rather than the wire feed but it did both. I'll try some experiments with around 15,000 uF later to see if it helps
smooth without the massive wire run on. Failing that it'll be big diode time or perhaps some modification of the motor control to shut off
properly when the trigger is released.
How do you find the machine? I had horrible problems but could jump on an industrial mig and knock out a respecable weld every time. I finally did
some welds today (without the capacitors) which looked "perfect". I guess the gas has a huge effect?
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wilkingj
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| posted on 28/8/05 at 09:29 AM |
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My defining moment was when a mate (local garage mechanic) said, If you have to squint at the weld when you flip up your mask then its OK. ie the wels
is still bright red/orange with the heat.
My main problem was fear of turning up the juice,
Now I run it flat out and adjust the wire speed, till it welds OK an a bit of same size scrap. Then adjust the travel speed (movement of the torch) to
stop blowing holes.
Seems to work much better that way.
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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MikeR
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| posted on 29/8/05 at 01:19 PM |
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does anyone know how true it is that ...... welds give out lots of radiation when they are glowing? I've heard that they give out lots of UV and
infra red radiation and you should keep your mask down till its not really glowing anymore to protect your eyes.
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JoelP
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| posted on 29/8/05 at 01:22 PM |
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infrared radiation is just heat, so techincally harmless. Read up on blackbody radiation if you're interested, explains a few things that i find
interesting. As for UV, id be suprised if any significant amount was relased - it would have to be stored from the welding.
Having said that, i am often suprised 
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lexi
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| posted on 31/8/05 at 10:08 PM |
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Anybody know who makes those SIP mig welders. I think they`re Italian aint they.
SIP just put their name on stuff don`t they? Could it be Cebora. I got a little 130 but have plans to get a good one. Had a shot of my mates big
Murex.......Wow!
Alex
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NS Dev
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| posted on 1/9/05 at 10:45 AM |
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quote:
Originally posted by MikeR
does anyone know how true it is that ...... welds give out lots of radiation when they are glowing? I've heard that they give out lots of UV and
infra red radiation and you should keep your mask down till its not really glowing anymore to protect your eyes.
what you have heard re. keeping the mask down is true, but not because of UV.
You should keep it down for a few secs because (usually with MIG) if there is some contamination in the weld, it can suddenly boil out and the weld
can "do a sparkler" on you and fire sparks into your eyes just as you lift the mask. I know a rally driver who lost sight in one eye from
this happening.
With arc (mma) welds, ALWAYS protect your eyes for a few secs after welding and when chipping.
I have a scar on my eyelid as the legacy of learning this the hard but very lucky way. I finished an upside-down weld on a large machine frame, I was
laying on my back to do it, and flipped the mask up, when a piece of the slag pinged off into my eye. By sheer chance I blinked at the same time and
it stuck to and burnt into my eyelid.
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MikeR
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| posted on 1/9/05 at 06:19 PM |
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ouch - thankgod i normally wait till the glow disappears in my mask before lifting the visor!
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A3rd.Zero
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| posted on 19/9/05 at 06:00 AM |
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Be careful when cranking a MIG machine up. It may look like a smoother weld but you have a much greater chance of creating a severe heat affected
zone. You will always create a heat affected zone of course but if the weld is too hot, it's as bad as if it were too cold. Try welding some
box into a "T" with the machine cranked and then bash it a bit with a hammer and a vice. If you tear the box at a distance from the weld
and the box looks grainy and brittle that is because you threw too much heat.
Milo
 Good weld vs Bad Weld
 May not be as pretty but likely a good weld
 This is "MIG spray" which is a process that hobby
MIG welders will not do. If your hobby welder makes a weld like this on box tube you are riding the edge of using too much heat. Any flatter and
smoother and you have a problem.
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