Struggling to weld thin sheet

[jweaver]

I generally use my welder for 2-3mm steel.. I have done thin work, but never worried about finish. But today i decided to have a crack at cutting a hole in some 0.8mm sheet and then welding in a patch.

I cut the hole.. Made a patch.. And tacked it in place.. Then started welding it, using overlapping "spots" with 1 second pauses between welds.

The first 8 spots went well.. Very well.. But then i started blowing through.. My assumption was that the area was too hot, so i moved to the other side of the patch and blew holes in that too..

It was almost like my welder had incresed its current mid way through... I started to randomly try to work out what was wromg and before long i had run out of space...

Before i try again, does anyone have any idea what went wrong?

Jon

 

[Exuptoy]

What welder are you using?

 

[jweaver]

what welder are you using?

GYS Smartmig 162... I just popped out for another try and am not pleased.. I don't know whats changed.

I have attached a photo.. THe line of 'good' welds are marked with an arrow.. The rest are just awful as I was trying to get back in the grove..

I then moved on to a piece of thicker steel and I can weld that either.. The welds are too 'high' and they just don't seem right..

I wound up the power on the 2nd (Thicker) sheet, but the welds just got fatter....

I should point out that I am using 0.8mm wire.. I know I perhaps should have switched to 0.6, but I forgot.. But I can't work out why the first 8 or so "spots" were so clean.. And suddenly I am either blowing holes or creating mountains (OK.. Slight exaggeration.. Hills) of welds.


I hope someone has some ideas..

Jon

 

[Exuptoy]

Don't just use the guide from the welder, it is only a guide after all, you need to experiment by increasing the power etc and checking what happens. Maybe turn the power up to 2 then back off the wire speed a little. You need to know what your welder does in a given situation. That's the only way to learn.

If using 0.8, maybe try weaving and travelling a little quicker to see what happens, you'll maybe not blow through so much then.

 

[PhillipM]

More voltage, less wire feed when spotting or using the TSM technique.

 

[jweaver]

Don't just use the guide from the welder, it is only a guide after all, you need to experiment by increasing the power etc and checking what happens. Maybe turn the power up to 2 then back off the wire speed a little. You need to know what your welder does in a given situation. That's the only way to learn.

If using 0.8, maybe try weaving and travelling a little quicker to see what happens, you'll maybe not blow through so much then.

I get that.. But it started out fine and then turned to crap. And I didnt' change anything... And I never managed to get back to where I was.

Initially the spots were flat.. And they didnt' blow through.. But after that, they started to make holes and I never manged to get it neat again.

I will take a step back.. Cut another hole and start again.. Its a shame that the sheet I am using is galvanized and it takes a load of preparation to get it 'safe'.. Need to find some plain sheet I think.

Jon

 

[carlos420uk]

I had to weld some similar patches into a Honda which had 0.8mm metal.
I used 1mm material to make the patch's and cut them to be a very good fit.
For welding I found it best to start the arc on the 1mm piece and then flick the puddle over so it wicked onto the 0.8mm (Tack, Tack, Tack method). I only welded about 1" or so at a time and let the metal cool between welds.

The fact your using Galv. metal won't help, even if your cleaning it up first. If there is any still on there, when you weld over it it tends to "pop" and cause a blow through.
Aside from the patch metal, make sure that your base metal is clinically clean. Use a strip disc to clean it up instead of a flap or grinding wheel as it will leave the metal thickness in tact, whereas the latter will tend to thin it out.

Switching to 0.6mm wire would also make your life a little easier I think.

 

[jweaver]

I had to weld some similar patches into a Honda which had 0.8mm metal.
I used 1mm material to make the patch's and cut them to be a very good fit.
For welding I found it best to start the arc on the 1mm piece and then flick the puddle over so it wicked onto the 0.8mm (Tack, Tack, Tack method). I only welded about 1" or so at a time and let the metal cool between welds.

The fact your using Galv. metal won't help, even if your cleaning it up first. If there is any still on there, when you weld over it it tends to "pop" and cause a blow through.
Aside from the patch metal, make sure that your base metal is clinically clean. Use a strip disc to clean it up instead of a flap or grinding wheel as it will leave the metal thickness in tact, whereas the latter will tend to thin it out.

Switching to 0.6mm wire would also make your life a little easier I think.

THanks for your comments.. Some good tips there.. I went back and watched/read the tutorial page and wonder if I have found something.

When I cut my 'patch' I wasn't too careful about getting it to fit tight.. The original hole was perfectly square, but the patch wasn't.. THis mean that along the sides, there were gaps which got progressivly wider.. Nothing major, but there were certainly gaps.

Reading about 'gaps', it seems they are bad on thin metal.. And I have a feeling that I started in an area where the patch and hole were touching, but as I moved along, started filling a gap.

I have managed to find some sheet in our scrap pile from work.. Ranging from the skin of an old Microwave (0.8mm) up to some 3mm stuff from some blanking panels. They are painted, but its better than Glav.. Will take some effort to clean them up fully before welding this time.

I will try and do some more tests at the week and see how I get on.

Thanks for your help

Jon

 

[carlos420uk]

No worries, it can be frustrating when you first start out.

The gaps on metal that thin are going to make your life hard. If you have access to the back of the panel then why not hold some cardboard up against the hole and then draw out a little template on the card. Transfer that template onto the sheet and you should have a perfect fitting patch.
I also like to round the corners of my patches off instead of leaving them sharp and that seems to help stop them blowing through.

Another little tip is using some copper on the back side of the weld seam as you weld. It will act as a little heat sink and also act as a support for the weld metal where the gaps are (Although as mentioned your better without gaps).

Try this link for the strip disks I mentioned to remove the paint on the metal you acquired:-

http://www.weldequip.com/abrasives.htm (7th item down the page)

Good luck mate.

 

[Wendelspanswick]

Could be worth calling in at a local engineering or fab. company and asking if you can raid their scrap bins.
I managed to pull 3 almost complete 2m by 1m sheets out of a skip as they where out of tolerance in thickness, chucked a fiver into the tea kitty.

 

[jweaver]

No worries, it can be frustrating when you first start out.

The gaps on metal that thin are going to make your life hard. If you have access to the back of the panel then why not hold some cardboard up against the hole and then draw out a little template on the card. Transfer that template onto the sheet and you should have a perfect fitting patch.
I also like to round the corners of my patches off instead of leaving them sharp and that seems to help stop them blowing through.

Another little tip is using some copper on the back side of the weld seam as you weld. It will act as a little heat sink and also act as a support for the weld metal where the gaps are (Although as mentioned your better without gaps).

Try this link for the strip disks I mentioned to remove the paint on the metal you acquired:-

http://www.weldequip.com/abrasives.htm (7th item down the page)

Good luck mate.

Thanks Carlos.. In this case I could get behind the hole, so could have made a good template.. But I wanted to do it from the top, and to be honest, rushed it a bit.. If it was a 'real' job I would have made a patch which was a much tighter fit.

When I do my tests this weekend, I am going to take a lot more time cutting/shaping the patch so that its a better fit.

I already have a load of 'flapdisks' so will use them to clean the metal first.

As for the copper, I am on the hunt for somethign suitable to add to my growing collection of 'tools'.. I am looking around my office and speaking to the electrical guys to see if they have any "busbar" lying around.. But am also going to hunt around my garage for off cuts of copper pipe that I have.

Thanks again

Jon

 

[EDRA]

hi..i am new member here. i have same problem in welding to the wrought iron 1mm thick..its always through become a hole..for your info my welding brand is wim 210s. its malaysia/german brands weld machine.

 

[jweaver]

Just to give you an update... I think i cracked it.. Had another go welding some thin material and it started well, but then started to get messy. I question what i was changing and then realised that it was down to wire length.

For some reason i was moving the torch away allowing 10-20mm of wire to poke out.. Once i moved the torch close agai. It was MUCH better.. So i think i have cracked it.

 

[Flapdisk]

Are you welding with gas? because what you are describing here suggests you may not have a good gas supply and as you pull the torch away there isn't enough gas getting on the weld.?

 

[keeny]

the settings are easy to do, it all to do with
good hand speed when you doing mig welding, keep practicing
good look,,,

 

[Jan]

If the protruding wire length was as much as 20mm I would expect that the gas shield would have mostly been lost and you would be really struggling to maintain a constant weld. You need to aim for no more than 5mm so the gas cover is complete. 10litres/min should be adequate at that distance which will give you a decent amount of welding time before the cylinder runs out.

 

[Flapdisk]

I thought I had already said that

 

[BrokenBiker]

5mm? might be a bit hard to see what your doing at 5mm. I stick to around 10-12mm and have never had any gas coverage issues @8-10lpm. even with gasless I keep the same arc length and have no issues.

 

[Jan]

Just hold your head to the side of the nozzle.

 

[BrokenBiker]

Just hold your head to the side of the nozzle.

i do. ive never found any cause to hold the torch that close, even when welding cars and thin sheet using either co2 or 5% Ar mix