bad weld wakeup call

[emzdogz]

Today I welded some big coped bungs to the tail section of my bike, to mount the bottom end of my rear fender support to. Got both bungs on although not along the bottom as I have no access that far down. My whole plan is to get it mocked up and then upon dissassembly, with stripped frame that I can position different ways, "re-do" the welds. Grind them down if there is any doubt as to penetration and re-do if necc.

So I wind a bolt in on the right side, tighten it way tight. It's bottoming out against the frame rail tube and it holds fast. I do the same thing on the left and whoaaaaaaaaa.... the damn thing, when I really honked down on that bolt, SEPERATED and pried up from the frame rail - the end of the bolt against the rail behind the bung PRYING it off as I turned the bolt.

So I re-did it. Same deal. re-did it again. Same damn deal.

SO now last time I redid it, even honking that bolt pretty hard, the bung stuck like it should and didn't seperate. I mean I could have put a pipe on it and REALLY cranked on it, but now i believe it will be ok especially once I do the tear-down and can weld it all the way around.

Makes me nervous though. I'd whacked both bungs with a hammer and they stayed put. I've heard it said that that's no real test, but I think the thing today really brought that point home for me.

If I ever weld coped bungs, especially big ones again, I think I am going to make several diamond shaped "notches" in the sides of them where they contact the tubing, so as to provide natural places for several good tacks.

Funny thing is, as I was doing the welds I was getting that really great "mad bee" sound the whole time. Still not sure what the prob was.
Anyway, just thought I'd share.

 

[hotdog]

so no penetration..?? what are you welding with mig, tig or stick..??

 

[Travis]

Em,

You got a 110 MIG right? If so, you pretty much need to have it maxed out when welding anything thicker than sheet metal. What range of setting does it have and what are you using? You're now using gas right?

 

[emzdogz]

yep 110 MIG with gas. Lincoln "weldpak". Come to think of it, the thickness of one of those bungs (these are ones that use a 3/8 bolt) is a lot for this welder to handle. The tubing is maybe 1/8 inch thick? so that's within reason for penetration. But the bung, I would imagine there's good 3/16 between the outside edge and the bore.

I can tell when it does penetrate, because it colors the metal blueish there. So a few places it did actually get decent depth of weld. Those places "held" and had that discoloration at first.

I did have it turned up to "11"...err, I mean "D".


Anyway this is why (one reason) I didn't do the hardtailing or neck rake myself. Even though this fender won't be used for a passenger, I don't want it breaking, either. I think I will grind it down and create like a little "ditch" with dremel right where the join should be and run more beads, right "in" that little ditch.

thx guys!

 

[650Skull]

If one peice you are welding to is thicker than the other you have to hold a bit longer on the thick side, very important to have an even gap all the way aroud and cutting notches is not a good idea.

keep it up, its soooo satifying when you know you have done a good weld

 

[emzdogz]

thanks again, Skull, and all... am attaching 2 pics - one is a shot of the "good" bung the one that doesn't separate itself from the frame when a bolt is wound in and then torqued so the end of it pushes against the frame tube. The bottom half, btw, is not welded yet at all.

The next pic is a diagram on a photo of a tab I'm considering "harvesting" off an old hunk of Triumph abominable home made old hardtail I have hanging around. It was made out of the swingarm. Anyway, I figure that tab is attached to the tubing hella strong ala, Triumph factory 1968 or so. So if I cut a section out, I can lay it right on my tubing - and if the diameters match somewhat, have an easier piece to try and weld to my frame tube. The bottom of the fender brace would mount just as well to this as to a threaded bung.

Will require quite a bit of cutting though to get that off the hunk - times 2, as I'd need both. But it might be worth it. That semi-section of Triumph tube I delineated would lay nice and flat on my bike's tubing I bet, and make for a weld more appropriate to my welder's capability. (And mine too)

 

[kvanderploeg]

Take a torch (propane) and preheat the pieces to be welded. Sure helped me with my little 110V get some of those prettier welds when sticking some tabs directly to the frame. Thanks for sharing, Emz!

Kent

 

[scabber]

Being a welder is more than just striking an arc if you can't see it, penetration while you are welding you are not getting it. Where I use to work lots of so called welders apply for jobs around 2 out of 25 could pass a simple bend test before the X RAY test then the odds got greater 1 out of 100. Glad you posted this learn before you burn. I just read you have a 110v welder no wonder no penetration.

 

[jetero41]

Emz, another trick to better welds is to grind a bevel on to the piece to be welded and then build up with multiple passes. I agree completely with preheating and suggest only welding bright shiny (clean) metal.
Good luck, you can do it.

 

[gggGary]

1. I am not a certified welder but did do industrial mig welding
2. It takes a book to get through all the angles of proper welding.
3. don't use the welded triumph bung thing that is just WRONG.
4 grind a fillet (45 angle) around the base of the bungs before you weld.
5. There is way too much wire being fed in for the temp you are welding at.
6. Preheating the bung will help penetration.

Just a guess here the Weldpak looks like a mono control set up? Wire speed varies WITH the amperage knob? If so my guess is that you need to reread your manual. I'm thinking that when changing from flux core wire to solid core wire on a set up like this you will need to use a SMALLER size wire with solid wire because each foot of wire contains much more steel compared to flux core wire which is half flux or more?

The strength of the weld does not come from adding filler it comes from melting the base metal on both sides. The filler just helps bridge the gap. Your welds appear to show a lack of understanding of this. A weld bead that is near the right combination of heat and feed should have more of a concave look. A smooth downward radius, not that heavy hump of metal in the middle of the weld area that I see on your welds.
My suggestion is that you use that old POS triumph frame to practice practice practice. My mig welding usually involves a weave or figure 8 pattern that gets the arc out on the base metal on both sides of the crack widening the heat zone to improve penetration. You did not say WHICH weldpac you have. The smallest ones may not have a enough oomph for those solid bungs. The suggestion to preheat the bung sounds like a good idea to me.
So preheat. grind an angle on the base of the bung, reduce wire speed or size relative to amperage, and practice. Good luck and let us know how it goes.

 

[emzdogz]

thanks again guys.
gggGary, I think you may be right about the too much wire thing. I kept thinking it was not the case though, because towards the end of a bead the wire would start "bumping" the metal. But now I think it's because by that time I had lost penetration and so the wire wasn't melting as it should - not because my feed speed was too great.

My welder (weldpak 100) does have wire speed control, even when used with the gas bottle and unshielded wire.

Given an easily accessible (right in front of my face on a table) flat-on-flat workpiece, I can make really nice welds. But the position I'm trying to work in just kills it. 1 foot or so above the floor with stuff crowded all around us. No room to move around.

I think I can do these welds much better, but it's going to have to wait til the teardown to get them right. So I can have a bare frame that I can move into easier positions to work on.
For now, I'm just considering these things sort of heavily "tacked" on - and won't count on them holding up under real use conditions. I just need to get things positioned how I want them, check out the ergos of the bike and then in a couple months when it cools down and dries out a bit, go ahead and do the tear-down and finalize these welds then.

Might go give it another stab later with less wire speed just for the heck of it....but I might not. It's a steam bath out there and we had a major thunder storm last night, so everything's really wet back there. PLus I knocked my left hand against something yesterday and it hurts like heck today (even typing! lol...)

So I think I'm going to let it go for today.

Thanks again, everyone.

btw, one of the reasons I do post these things, even tho they make me seem kind of dumb, is that I bet for every one of my "gahhh, this is sooo hard" whining posts, there are several inexperienced young guys who are too proud to ask about the same thing. Maybe, maybe not! I just hope me posting my dumbassery will prevent someone elses dumbassery from putting them in danger on the road.

 

[kvanderploeg]

I have plenty of "dubmassery" moments. Doubt I'll quit that anytime soon either!

Kent

 

[scabber]

Dog I think you could be a very good welder with the right machine. The 110V just don't have enough power to do what you are trying to do. They will barely do light gauge sheet metal.

 

[1974jh5]

I have the same 110V Weldpak and I use the flux core wire. It splatters etc but it gets hotter. Heat is the key! BUT! I run it on a 20 amp circuit (12 gauge wire) and do my damndest not to use an extension cord. Extension cords etc run on a 15 amp circuit (14 gauge wire) will cut down on the welder's output. I have welded all kinds of stuff ranging from 3/8" plate (tractor steering box bracket, I beveled both sides and made multiple passes) to 1 3/4" x .095 wall roll cage tubing to 20 ga. sheet steel all with no problems. My buddy has a real nice Miller 240V welder with gas etc, the welds are strong but ropy looking, much like what you have on the bung.

I'd say go back and bevel the bung, clean the metal thoroughly (use lacquer thinner to wipe everything down, dont use brake cleaner! That stuff can create phosgene gas!), make sure the bung is clamped TIGHT (that's also the key to sheet metal welding), crank up the power and slow down the wire speed.