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Can I fill a gap with/whilst welding?

24K views 71 replies 13 participants last post by  mi chael 
#1 ·
I'm fitting some small box sections to my chassis, but they don't fit very well

I've spent the day improving the fitment, but I've still got a gap down one side which requires welding

My question is how much gap if any is acceptable whilst mig welding?

The gap is around 2mm
Can I weld this, fill it another way, or will I need to do something more involving?

The edge in question doesn't need any strength

I'll post a picture in a second
 
#52 ·
They say that "cleanliness is next to goddlyness". Weld prep is very important. I clean everything I weld with the TIG. The Mig I used to be a bit relaxed with but it does work a lot better if the surface(s) are clean.

Although it is very time consuming, it is a vital part of the welding process.
 
#57 ·
ant_8u said:
Also, I've ground the bonnet hinge box off of the front crossmember so it can go on again correctly, but it's burnt through in a couple of places

Is this still good, or should I buy a new one?
They're pretty cheap, so I'll buy a new one if that's best, but I'd also like to keep all the original items where possible




I would use that piece to practice weld on and get a full thickness piece to install.

Your grinding looks like it has reduced the thickness of the material quite a bit.
When grinding you need to be aware of the thickness and try to maintain it or the strength is diminished.
 
#58 ·
ant_8u said:
This is the horizontal weld on the crossmember
I know it's not all that great, but I'm pleased with it




Now THIS on the other hand?!?
I know I should have stopped, but since I didn't know what to correct I decided i should finish the 'bead' so you guys have more to look at and tell me what went so badly wrong




I didn't change any settings on my welder, just went to a vertical face

Why did my weld start to 'hiss'
And why is it such a poor weld compared to my first one?

Thanks guys
Looks to me like you were trying to weld thru garbage and you do not have the skill yet to attempt to weld on a frame.

That whole mess needs to come off, nice shiny bare metal in the weld zone.
Get a puddle started on one side of the gap and let it melt into the base metals, more the puddle across the gap letting it fill and melt into the base metal on the other side.

move slightly uphill with the puddle and work back across to the first side.
Repeat till you are at the top.

IF it goes wrong STOP. It wont get better by splattering more bird turds on it , it will only require you to spend more time grinding.

the only place you should be spraying weld thru primer is where paint cannot be applied after welding, like a lap joint , or the inside of a box.

I think you should consider finding a person that welds that will come over and spend a hour with you and get you headed in the right direction on some scrap pieces.

It is nothing to weld a practice set up for hours on end, take a break, and go right back to practicing the same thing again. Repetition makes perfection.
 
#59 ·
Easy solution, Bob. DON'T CLICK!

Make sure your ground connection is clean and even grind a spot if there is doubt. Very important as a poor ground connection will eat up some of the voltage your wire needs to see. Be the same sort of clean with the weld area also. MIG has poor penetration properties anyway, having a CLEAN/SHINEY weld area will allow the metal to puddle with lower voltage and give you a better looking and penetrating weld. I personally can't see your feed speed being too slow if you are on 8 with a power setting of 1 or 2. Seems way too high to me. Is there a chance you are working outside or somewhere there is a draft? The symptom you discribe has happened to me when a draft or wind blows the gas away from the weld or the few times I had brain fade and started the weld before turning on the bottle. Just thinking. Classes are a great idea also. One hands on demo is worth a thousand posts. :)
 
#60 ·
i hate to suggest it, but i wouldn't ride in anything you welded ant.
i'd hate to even be on the same road that your driving down.
you really need to find someone else to weld it.

you need to get better at welding before you attempt any structural welding.
 
#61 ·
Another thing to consider is your wire size. Here, one can use; .023/.025" .030", .035" and .045" in a MIG for common sizes. That equates to about .5MM, .7MM, .8MM and 1.1MM. I have a 120V machine that has .023" for exhaust tubing, sheet metal, etc. and a 220V machine I've found that .030" wire works best for the automotive related welding I do. Wire size will make a huge difference in your power and wire feed settings. Experienced welders can cheat either way but a novice needs to get close on the wire size. Maybe that's why I have two machines....it makes me look better. :)
 
#62 ·
ogre said:
i hate to suggest it, but i wouldn't ride in anything you welded ant.
i'd hate to even be on the same road that your driving down.
you really need to find someone else to weld it.

you need to get better at welding before you attempt any structural welding.

No offense taken buddy - Especially when I feel the same way

My practice welds were getting pretty good, but I now know only practicing one type of weld doesn't make me anywhere near ready

So it's back to practicing I guess - Only this time I'll practice various joints and corners and different gauge metals too

I don't plan on ever selling the car, so I want to take my time and do the job properly

You guys told me to cut everything off, and that's what I've done
I can see I need more practice, and so that's what I'll do


I've spoken with various shops previously about doing the work
They want around $15k for just the welding - that gave me the incentive to learn how to do the work myself

Thank you to everyone for your patience, and for taking time to reply to all my silly questions, your help is very much appreciated :cool:
 
#63 ·
Sorry, but I have had no time to post any pics of welds etc for you to look at. I have been very busy myself. I will try to post soon(maybe within the next week). The videos you have been looking at should be a ble to tell you a bit more than just a few pics anyway. Hope you are slowly making progress with your practicing.
 
#64 ·
ant_8u said:
You guys told me to cut everything off, and that's what I've done
I can see I need more practice, and so that's what I'll do
actually i said to grind everything out.
i wouldn't have cut them off, just grind out most of the weld so you can get back into base metal.
this will save you time next time and it will save you from grinding to far into the base metal :D
 
#66 · (Edited)
You had your settings pretty darn close when you ran this weld. Maybe a bit cold - turn up the wire speed a bit,you should be able to run uphill with those settings. It doesn't look like a lot of penetration, but you are almost there.


Most guys that run wire only set it once for all positions in most instances.
If it is getting a bit hot speed up a bit.
Just don't get cold lap like you did in your vert picture.

Remember clean everything, the ground clamp location, the weld zone, and ditch the weld thru primer .




I suggest you get some scrap pieces, set the machine how you had it in this picture, run a half dozen more beads in this flat position, then turn your test piece on end and start going vert up.
A bit of practice will make a world of difference.

All position welding with mild steel wire is a easy thing to learn, hang in there!

If the wire speed is to slow it will burn back to the contact tip,and pop, if it is to fast it will keep jabbing the metal which you should feel in your hand holding the gun.

Take a practice coupon , leave the temp where it is and turn the wire speed all the way up and try it, you will see what I am saying.
Then turn it way down and try it, you will see how it acts.
This will help you figure out the correct speed by knowing what wrong looks and feels like.
Now do the same thing with the temp, keep a constant wire speed and crnak the temp upand down, you can even crank it while you are welding or have a helper crank it as you request.
Play and practice, its all fun.
 
#67 ·
Do the practice welds as suggested. Come on now MIG welding is pretty easy. Just get some similar metal, put it on a bench and weld it together. By the look of your welds you are seriously under penetrating. So this is how I like to do things, over due it. Turn it up as hot as you can and melt the damn thing thru, blow a hole to two, get a feeling of what is TOO MUCH, then back it down and practice. Weld something together and then clamp it in a vice and with a big hammer beat the crap out of it to try to break your weld. This is a common "destructive test" and it should be done on anything being welded where there is any doubt. And Ant, you should have some serious doubts with those welds!

But all you need is some practice, don't touch that frame until you burn a few holes in test metal and beat it up with a hammer.

Brian
 
#69 ·
Thanks again everyone, I truly am so grateful that you're taking time out of your schedule to help me with my problems

I think the main issue I must have has was the fact that I blasted everything with a couple of coats of weld through primer before trying to weld it - I've learnt my lesson there now though

I won't be touching the chassis until you guys say I'm good to go

I'll post some pictures of my practice welds at the weekend and you can tell me how things are looking


FAO - OLDFOOL
Thanks for posting that edited picture with the text on it
That's really help too
I wouldn't have even noticed the difference between the cold weld and the good penetration part unless you'd pointed that bit out
It seems very similar until someone points it out, and then it's just down right obvious

Thanks again all :)
 
#72 ·
Ant 8

I have been unable to find time to post more pics on welding. I have been very busy with other work and am not going to be able to post any more pics. Hopefully you have had more success with your welding over the past couple of weeks. Best of luck with your welding (hopefully you have been able to get into a welding course at your local college).
 
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