MIG welding problem, adivce needed.

[ollypenrice]

Hi, I have the smallest of the Machine Mart hobby welders, doubtless the Tasco of MIG machines! However, over the last ten years I've built dozens of things with it, including four observatories, none of which has ever broken, despite my lousy welding. But here's my problem;

I get an increasingly strong impression that the first few joints I do work well, with a nice weld pool that pours along smoothly and penetrates well for such a small machine. But as the work goes on the machine seems to be less powerful, it struggles to produce a pool and sputters somewhat. Penetration is then awful. If I leave it and come back it seems to recover somewhat but it really seems to like an overnight rest. This seems ridiculous to me -- surely an hour should see it cool down? - but it does seem to be like this.

I'm welding one inch square steel tubing of a kind it has always handled. And it still does handle it for the first few joints.

Any idea what's going on? The wire feed and CO2 supply seem fine and I keep the nozzle clean.

Cheers,

Olly

PS I'm slightly off topic since I'm making a large fixed sunshade for the summer kitchen, but the sun is a star so I feel I can ask on here! 

[crashtestdummy]

Maybe the current is heating something up inside and causing it to be inneficient?

[ollypenrice]

Maybe the current is heating something up inside and causing it to be inneficient?

Yes, this seems reasonable.

Olly

[davefrance]

It's been a long time since I did any welding but I wonder if for some reason the amperage is falling off during use so that your are not getting a hot enough weld.

[Davey-T]

I have a quite large MIG welder that has a cooling fan so presumably they can overheat, does it smell of burning electrics ? probably time for a new one

Dave

[Toymaster]

I think the problem is that when it gets hot the output will drop due to increased resistance of the windings.

I had a small arc welder that suffered the same and after several minutes you had to increase the output.

Many times the thermal trip cut in and I had to wait for ages for it to cool down due to the large thermal mass and so it was not that good for bigger jobs.

Adrian

[twintin]

I have the same welder and it suffers the same symptoms. I had a small gas leak from the pipe to the bottle, it may be coincidence but once that was fixed it was ok for a while, although using it the other week to weld the van up it was doing it again.? Might be worth checking though?

[ollypenrice]

Thanks guys. Good to know that the problem has been seen before. I think it is time for a newer and bigger one - and with a fan this time. I'm sure the lack of a fan on this entry level machine will have something to do with it. I keep saying I've made my last fabricated objet but I've been saying that for over five years so I guess I probably haven't. 

Olly

[libraryman]

He he, I can see another tec cold finger and fan project coming off!! Who says you can't modify a welder???

Ray

[Zakalwe]

I spent 10 years in welding and fabrication. The probable cause is the coils overheating, which is common-place in cheap welders. You could stick a small desktop fan near the vents and that might help a bit.

it could also be that the wire feed is starting to play up. The feed motor could be overheating too and an inconsistent wire feed will cause sputtering. I'd put my money on the coils overheating though.

[keithatrochdale]

Could you add a cooling fan to it? 

[Tinker1947]

Thanks guys. Good to know that the problem has been seen before. I think it is time for a newer and bigger one - and with a fan this time. I'm sure the lack of a fan on this entry level machine will have something to do with it. I keep saying I've made my last fabricated objet but I've been saying that for over five years so I guess I probably haven't. 

Olly

All you were really after was for somebody to say you need a new one bigger and better....well you do go for it....

http://www.machinemart.co.uk/shop/search/filter/diy-mig-welders/type/any/module/shopcategory/page/1

[Toymaster]

I modified mine...

Stood it on bricks to give a space under it having removed part of the bottom and then positioned a fan next to it   

Adrian

[crashtestdummy]

As above,add your own cooling

[jetstream]

I am wondering if you have a dirty gun cable liner?After a bit of time crud builds up and can cause issues,also how is your contact tip?My MIG is used with 75AR/25CO2 and copper coated wire-the liner is blown out with compressed air at every spool change.

[Tinker1947]

If you do decide on a new one check the duty cycles the expense of one that run 100% (24/7)might just be a welder to far...

[Davey-T]

If you do decide on a new one check the duty cycles the expense of one that run 100% (24/7)might just be a welder to far...

Yes, you could go from the Tasco of welders to the Tak of welders, you know you want to.

I keep doing jobs and thinking I should buy a Dremel then think I'll never use it again and then a couple of months later ----------

Dave

[Phil Fargaze]

A shot in the dark because the most likely problems are covered above but have you got a good earth connection.

Sometimes the wire to the earth clamp can fray and heat can build up which in turn might increase resistance to the returning current.

[jetstream]

A shot in the dark because the most likely problems are covered above but have you got a good earth connection.

Sometimes the wire to the earth clamp can fray and heat can build up which in turn might increase resistance to the returning current.

Phil,great thought,MIGS need a really good ground

[ollypenrice]

More thanks guys. After a bit of testing I can be certain it is just temperature. After a good long rest it came bouncing back on great form so keeping it cool will be the trick and building in cooldown time. I do have a hefty fan so I'll use that. It is only a real cheapo tool but, honestly, the stuff I've made with it makes a long list.

The brilliant thing about fabricating here is that you can go and use the radial arm cutting grinder yourself at the builder's yard. (Fat chance in the UK.) I take a cutting list and come back with a project already in kit form. Six lengths at 1.7M, four at 1.2M ten at 17cm etc etc. All cut nice and square, too. Trezzini really is the prince of builders' merchants. The guys are all great fun, they'll spend ages helping, advising on materials, telling you not to buy this and that from them because it's cheaper ant so and so's...  It's one of the best things about living here. The other is Monique's cooking, which is now calling for me! 

Olly

PS They love it when England lose at something as well. Makes their day!

[ian_bird]

Monique's cooking. Monique's cooking. Sob!

Right! - Time for another trip to Les Granges!

How's Cachou?

Cheers

Ian

PS - A good MIG tip is to get one of those large CO2 cylinders from your friendly neighbourhood bar. You can get an adapter so you can use the flow valve with it. Saves a fortune on those tiny throwaway CO2 bottles. Another good tip if you haven't already got one is a self darkening welding mask.

[faulksy]

i no you have been using it for a while olly, but using co2 is a bad idea, you need a mix gas cougar 5 or similar, if you use co2 you would have to have the power set a lot higher than if you used a better gas. i use a argon co2 mix which is great.

[jetstream]

i no you have been using it for a while olly, but using co2 is a bad idea, you need a mix gas cougar 5 or similar, if you use co2 you would have to have the power set a lot higher than if you used a better gas. i use a argon co2 mix which is great.

CO2= spatter spatter spatter.75% Argon/25%CO2 mix is the best for short arc MIG (short arc is a mode of MIG transfer,other used is spray).Mike,sounds like we use the the same shielding gas-very smooth arc

[gary1968]

You could try moving away from C02, use a argon blend, something like Coogar 5 or Argo Shield. Using C02 will cool the weld pool, the other gases I mentioned require less powerful welders.

Hth, Gaz

Sent from my HUAWEI U8815 using Tapatalk

[Zakalwe]

I used to use Argoshield, which gives a "wetter" pool, but to be honest, the difference is pretty slight. Pure CO2 isn't nice to weld with at all...the pool is "lumpy" and you end up scraping spatter off everything. And it clogs the nozzle and tip up like no-one's business.