15 replies to this topic

[jackclancy]

Hi all. I was attempting to weld in a new rectangular patch to the Mini floor earlier. One side of the patch was totally fine, but when I switched to all the other sides - the car bodywork just kept melting and creating holes. I had to get a bit creative with it, managed to sort of botch it in the end, but I know there's probably a simple reason this is happening. I turned the welder down to its lowest power and it still happened. 

 

If anyone could help that would be great!

 

Thanks

[Avtovaz]

there could be loads of reasons with out sounding unhelpful! But posting a pic is always the best thing. 

 

It does sound a bit like the one side was on good metal , and the others had rust in them that made it thin maybe. Did you "dot" it or try to seam weld in in one go?

[jackclancy]

I sort of managed to do it by welding an absolute tonne (if that makes sense). Ended up with quite large lumps. I would try and weld the two bits together and then a hole would form, then I was having to sort of fill the holes in. I.e not just spots. But I was attempting to do spots yes!

 

The car body isn't rusty at that point!

 

Its all welded in now and dont have pics of it mid progress. I can get a pic tmrw!

[jackclancy]

I hasten to add this was my first time welding haha!

[sonikk4]

So was it a cut out and you welding in a repair patch  (butt welding) or just laying a patch over??

 

If it was the first, what was the gap like all around the patch you were welding in?? Too big a gap and it will be an utter nightmare unless you have a copper backing piece.

Too small and the weld will pucker up creating high spots. 1mm gap is a nice width.

 

Laying a patch over, ideally pulse welding will see you through nicely, however this is all dependant on your power setting and wire speed.

 

What were you welding with, MIG with gas or gasless?? Gasless takes time to master, gas is more forgiving but like anything correct metal thickness, cleanliness of the metal is paramount. And a very good earth as well for your earth clamp, shiney metal is your friend here.

 

And of course power level and wire speed.

[bikewiz]

As sonikk4 says using a copper backing plate will help with blow through.

 

Try practicing on some scrap to get your settings right before you go at the car.

Edited by bikewiz, 21 January 2025 - 10:07 PM.

[68+86auto]

Cheap welders have too high of a minimum voltage to easily do thin steel. My welder is designed specifically for welding car panels so has a very low minimum current.

[stuart bowes]

what size wire are you using? 0.8 or more is probably too much. 0.6 works well for me

blowing holes for ages was the main obstacle I had to overcome for quite a while

keep it to really short bursts literally just welding small dots at regular intervals letting it cool in between, then gradually build that up round the join until it's complete

if one blows leave it and move on to another blob, come back to it, half the problem is where you're welding at an edge there's nowhere for the heat to spread hence the heat sinking with copper backing would help by spreading the heat to the other side of the gap as well

while you're filling the inevitable holes again go slowly, short bursts, keep letting it cool before adding more. if you keep going while it's still red then the welding wire will keep poking into the hot weld pool and bursting it (or at least that feels like what's happening.. there might be a better technical explanation)

getting a comfortable resting position and using your off hand like you rest a snooker cue makes it easier to maintain the right torch angle and gap, vary those a bit until you find what works and then stick with it (should be something like 70-80 degress angle and about 10-12mm gap as a starting point)

and spend as much time as you can getting the patch really well fitted and aligned. if it's a bit off, don't be afraid to bin it and make a new one

this is the aim https://www.youtube....rts/eI3SiUs1hps

Edited by stuart bowes, 22 January 2025 - 01:43 PM.

[sonikk4]

No one has asked this yet but model of welder are you using?? And also within my reply I asked what type of welder ie MIG Gas or MIG gasless?? This is pertinent as this forms the basis of a lot of the answers you will need.

Also if you go into the Bodywork section and look at the pinned threads. You will see one from me ref What Tools Do You need. There are pointers on there as well for welding.

[68+86auto]

https://www.mig-weld.../thin-metal.htm

[jackclancy]

Ah so much good info on here thanks everyone!! I am using this welder: https://www.toolstat...lder-set/p48359

 

I have just bought some 0.6mm wire to try that. 

 

I was butt welding. From reading above some of the gaps were doubltess too big then! So will make it snug next time. I will also get a copper backing piece to help! I think I also need to let it cool for longer too as I was doing quite fast bursts.

 

Is that welder fit for doing a car?

[stuart bowes]

Ah so gasless is the relevant thing there as Sonik points out that does make a difference, you could do a bit of research specifically on that 

 

smaller wire (electrode) size should still help to bring the current and heat down though either way.  don't forget you'll need 0.6mm tips as well as the different wire, and check the roller in the feed has a groove for the 0.6mm size or it won't feed properly.  likely you just take the roller off and turn it round to the smaller size groove

Edited by stuart bowes, 22 January 2025 - 11:50 AM.

[sonikk4]

From my personal point of view this is not an ideal starter welder as welding with gasless wire is a bit of an art to be honest.

Yes I’m sure that once you have practised A LOT with this unit you will get an acceptable weld. So you need lots of .9mm and 1.2mm steel sheet. I cannot offer any more tips with welding with this sort of unit as I have never used a gasless MIG.

[bpirie1000]

Sometimes local college will offer evening classes in welding to give you some confidence and knowledge of working with a welder or your welder.

I would also say that practice is the key.

Always easier if you have someone show you to start with.

[68+86auto]

It's not impossible to use that welder but it's going to be difficult. Some argue whether it matters but the minimum current on that welder is specified as 50a which is way too much as far as I'm concerned. You want one that can go down to around 30a, my one goes to 20a. Because doing so requires more transformer windings (cost), cheap welders don't do it. Neither do big industrial welders as they are never intended to be used for thin steel.

 

You should be able to make it work but it will require careful adjustment, trigger operation and skill.