Hello and help a newbie

[JRoque]

Hello everyone. This is my first post here and I've never welded anything so forgive the neo-questions.

I have to say that of all the welding sites I've seen so far, this is by far the best. This picture made all the difference to me in understanding welding and how it differs from soldering.

Ok then, my question is regarding a broken office chair base I want to repair. The picture below shows the fracture and how it needs to be welded back. The whole piece comes off and it's there for the pic opportunity. It is 1/8" (3.25mm) thick, mild steel.

So far, I've gathered I need to grind/clean both the center and the rest of the base surrounding it. I also guess I need to somehow ground the center piece and the outer base at the same time and start by tacking it on a few places.

I bought a Lincoln 3200 HD (25 - 135A) welder and it came with flux (gasless) and solid wires. I don't have a gas bottle yet to do MIG so will be trying my luck with the flux wire. Gulp. I know I need to practice elsewhere before trying on the real thing but, any tips on how to solder this type of stuff? Other than reviewing my health insurance policy?

Regards,
JR

PS: Yes, I spent $450 on welding stuff to fix a $100 chair. But don't worry, I have a 10lbs hammer that I'll be using to break more stuff in the future.

 

[madkayaker]

hello and welcome.

Firstly there is nothing wrong with spending $450 to repair a $100 chair.
Are you sure its steel as many are aluminium or cast steel

 

[Robotstar5]

Hi, and welcome

If you are going to weld as is you need to protect the fabric covering from sparks / heat or you will have to learn upholstery once you have mastered welding!

 

[peterd51]

Hi,

you'll usually not need to 'ground' both pieces unless the gap between them is getting towards 1/8" or so.

Clamp onto the bigger piece and start with your torch pointing slightly towards the edge of it then, as the arc strikes, the blob of weld will fill the gap and both pieces are at ground potential from then onwards.

Regards
Peter

 

[JRoque]

Thanks everyone for your kind welcome and comments.

On closer examination, the material appears to be cast steel of sorts. It holds a magnet and I can easily put a mark on it with a file. It also has 3 (really bad) spot/short welds on it which is probably why it failed in the first place.

The whole assembly comes off the chair with 4 bolts and I plan to take it out before welding. Point well taken as I didn't think of that until yesterday. I would have ended up with a nice weld on a charred chair...

Ok Peter that makes sense about grounding and it sure makes it easier for me.

What about the flux wire I plan to use? Should I try with that or should I instead buy a bottle to do MIG? I understand I will see a lot of smoke and splatter when using cored wire. But will that make the job so difficult that a newbie should even bother with it?

Thanks,
JR

 

[Paul.]

That looks exactly the same as the chair I'm sitting on now, except mine isn't cracked, its a steel pressing, the boss in the middle is mig welded in probably by a robot, the pressing operation and the loading of the chair has created stresses which have led to the cracking, It may crack again but there's nothing to lose by welding it, and the repair may well outlast the rest of the chair, clean off the paint before you start and if possible vee out the crack with a grinder to assist with penetration, or if you take the bracket off you can weld both sides.

 

[JRoque]

you can weld both sides.

hmmm I see. Glad you brought that up since it segues into my next question - unrelated to the chair project. So... can I cheat on how thick a metal I can weld if I weld it on both sides? For example, if my welder is specified for 6mm max, can I weld both sides and be able to work 12mm? Hey, worth the try.

Thanks,
JR

 

[shenion]

You can weld both sides if needed. you can also leave a small gap and/or v-groove the joint to allow better penetration.

Larger work you can do a V-groove then use several passes to fill the weld.

The gasless will work. It will be a bit messy with some spatter. Best to practice on some similar thickness metal until you can consistently do a good weld.

 

[jotto]

Hey JR, not to hijack your thread but in what thread did you find this picture?

Would be interested to read up on the differences between those welds.

 

[Paul.]

Its from one of Malcolm's tutorials, here,

 

[JRoque]

Yep, very powerful pic and certainly an eye opener for me.

Ok guys I "welded" today. Here's the account of the events:

At first it wouldn't weld at all. I started troubleshooting the problem and pinpointed it to the fact that the welder was still unassembled in the box. I took it out, put it together and things started working much better after that. Mine came with two nozzles. The first one looks like a piece of plastic in a cone shape. The second one is a larger bronze cone that I presume is for gas welding. I used the plastic one for the core welding I was doing.

I read about the possibility of lots of smoke while using core wire so I took the party outside. There's a 20 MPH wind today so it's rather brisk. I guess that helped clearing things up because I didn't have any problems watching the "puddle". As recommended, I used a "pull" drive which meant the gun blocked where I was going; only saw where I had been. I did find myself tilting the gun every which way to see what I was doing and that didn't seem to have too much of a bad effect.

The picture below shows the terrible results. Actually, it didn't look this bad the first time around but then I decided to "touch up" and really messed things up. For some reason, laying more material on the previous run caused lots of splatter and now it looks like it has the measles with tons of little metal balls around it.

For clothing and protection I wore a long sleeve pullover, jeans, boots, welding gloves and mask and a leather bib. I looked more like a scarecrow than a welder... But hey, I'm writing this now sitting comfortably on the repaired chair so it's mission accomplished for me. Looking forward to breaking something else that needs welding. Thanks much for your help and guidance.

Cheers,
JR

 

[malcolm]

Well done - that doesn't look half bad! For a first job it looks really impressive.

The flux cored wire coats the weld with a protective slag that you need to knock off with a slag hammer before welding over it. That could be where the spatter came from, though gasless does tend to be spattery by nature. When welding over existing welds it's best to grind the existing weld back to the level of the surrounding metal otherwise you'll heat up the previous weld rather than the surrounding metal.

Looking good though - wire speed looks about right and you've got a continuous weld going, so you'll likely have joined properly. If you have some scrap to practice on try a higher power setting or go a bit slower for even nicer results.

Pull is the thing to do for gasless so far as I'm aware. Arc welding is similar - it means you aren't trying to weld over your own slag.

Some people don't use a shroud at all for gasless welding. I've not come across a plastic one before. Doesn't it melt? Could you post a photo?

 

[zardoz]

Just be aware that it soon gets very hot on the surrounding area (unless you stitch weld and wait till it cools in between). Make sure you dont set it on fire.

 

[JRoque]

Hello. Thanks much for the words of encouragement.

It really amazes me that you can tell all that by just looking at a weld picture. Yes, power was low, as it turns out. I mistakenly set it one notch too low. And yes again, I did not clean the slag between passes. Wow, that was good.

Ok below is a picture of that "plastic" nozzle I was referring to earlier. It came factory mounted with the gun along with the tip you see there. There is nothing in the manual indicating which one I should use so I left it in there. If I mount the brass nozzle then the tip does not stick out at all - it's flush with the shroud. Is that how it's supposed to be?

Regards,
JR

 

[malcolm]

That's cunning - I'd not seen one of those before. Yes the tip is just inside the shroud when you use the shielding gas type (like the one in the logo on the top left of this page) - that's to help get a good coverage of shielding gas.

It's not needed for gasless, though can make it easier to position the torch without touching the contact tip against the work - the distance between the contact tip and the work ought to be about 5mm.

I guess the gasless shroud is there to stop you getting spatter on the mounting for the shielding gas shroud, but lets you see the work better.