Swapping MIG for MMA

[cheesegas]

I've had an elderly (no digital, just 4 current settings and wire speed!) 200 amp MIG set for a while, it's been great for welding car chassis but for bits on the boat it's a right pain to drag it and the gas bottle down the path. And the wire feed motor is starting to complain again so it's time to replace it.

 

Thanks to an advert on Facebook, I've been tempted by this MMA set as it's tiny and the inverter can be dialled back to run off my 2500w generator. Best thing is no gas bottle to lug around and get changed!

 

Anyone have any experience with these, and arc welding? Reviews seem to be positive. I've never used an arc/MMA set before though! It'll mainly be used for 3-6mm steel.

[dmr]

On thicker steel like boats arc welding is good. Its reputed to be a bit more difficult than MIG but I don't find this (but originally I was taught to gas weld which probably helps).

Its big problem is that it makes a mess with weld spatter, and also needs the slag chipping off afterwards. There are anti-spatter sprays available but they only help a bit.

The lack of gas bottle hassle is replaced with consuming a lot of sticks.

 

................Dave 

[BEngo]

MMA is much better for outside work if it is breezy.  Slag does not blow away from the job before it has cooled.?

 

I would be looking to see that the welder current when dialled back for a  2500W genny is big enough for the jobs you want to do..

 

It is also worth looking at the welder duty cycle at the sort of output you will need.  Having to stop for a cool down is OK if you are doing bitty jobs with short runs and lots of dodging about.  PITA if you are doing a substantial overplate.

 

Inverter welders tend to be ideal for small jobs. Light weight, small size so easily moved around, and  not in the way on a boat.  MMA cables also tend to be easier to drag around than a MIG gas/wire feed tube, marginally.

 

  As Dave says, you will use a lot of sticks, and need something to carry them around the job in and somewhere warm and dry to keep them when they are not being melted.  They are no use at all if they get damp.

N

[cheesegas]

Thanks both. In terms of weight, I think I'd rather carry a bag of sticks than lug the MIG's bloody gas bottle and then wheel the machine down an uneven towpath though! Noted about it being more difficult though, I'll have a good play before using it on the boat. On the sticks, I didn't know they were so affected by moisture, Looks like you can buy small packs for a little more money though which should keep them fresh as I'll be using the machine only occasionally.

 

This wouldn't be used for any big jobs - bitty stuff like enlarging the gas locker, covering up some unused skin fittings etc so a short duty cycle is fine. 50% is probably ok, although on my big MIG set I'm used to 80%....

 

On the power usage, I do have access to a 6kva set as well, but that's even more unpleasant to wheel around than the MIG + bottle combo! My genny copes with 2500w sustained loads fine, but there's no mention in the literature about the output current when the input is below 13a.

 

Edit - forgot to put the machine in the original post!

https://www.r-techwelding.co.uk/arc-welder-r-tech-pro-arc135/

 

Edited March 31, 2021 by cheesegas

[Canal321]

I have a little parweld inverter welder. It's smaller than a toaster but will still run 3.2 rods easily. Rods are available on eBay, 20kg for around £45. That's a lot of welding. Remember with stick you pull towards you, not push away ;). 

[BEngo]

I keep my rods at home in the airing cupboard, next to and on top of the oil boiler.  They don't  seem to come to any harm there.   The really old style containers from the days when rods came in tins are worth looking out for.  Very handy for moving a selection of  rods to the boat and keeping them dry.   Otherwise look at tupperware spaghetti box  type stuff.

 

The spec recommends a 6 kVA genny.  I expect this is to cope with the initial arc striking surge, cos 16 A in for full output is only 4kW.  A 2500W genny , which is probably only about 2KVA in reality, may struggle, particularly at high currents and the poor power factor of a welder. Any chance you can borrow or rent a similar inverter welder to prove it is happy on your genny before splashing the cash?

N

[cheesegas]

I've had a 2500w resistive load on the generator for hours and it's happy with that, rated at 3100w peak for 2 seconds so it should cope with striking the arc at less than full output I reckon, despite the pf <0. It's never struggled with the MIG on full current, but that pulls considerably less current.

 

I'll try and borrow an inverter welder and see how it copes. Thanks for the advice on storage too!