some tips on fully welding fishmouth joints

[gearwhine]

I'm getting some metal for a cage soon. Bending and notching are no problem. But FULLY welding a round tube comes very hard to me, even on smaller peices, like welding control arm joints on. I've been practicing and practiing, but can never do a nice job unless I stop and reposition 3-4 times at each joint. I can't really twist my hand, my body, and weave the wire back and forth all at the same time. Is it really that bad to stop an start again?

Do you guys have any techniques or did you just keep trying it until you got used to it? Like a slower wire speed and lower heat so you have more time to move around or anyhting like that? I'll be using a mig welder.

I will practice some more, bend up the cage and stuff (when I actually can get to it) and if I still can't do it, I'll have to pay someone to weld it for me, ehhhh. Thanks _nicko_

 

[CartsXJ]

In my experiance, starting and stopping is not a bad thing, although this was with a TIG welder on 4130. Another, trick that we did with building our frame was to drill a hole in the surface of the tube in the middle of the joint area. This lets the air escape when you are welding, as not to blow out your bead. Ask me how we figured this one out:twak:.

 

[AJsArmor]

Starting and stopping isn't bad at all, basically stitch welding. Be sure though to keep your concentration of heat in the joint itself of course. A really good way to practice on tube is to cut a chunk of 3-4' of it and then fishmouth a bunch of short stock, maybe 3-4" long. Weld them up, and look inside from the top, you should see signs of complete penetration of the material. Don't worry about starting and stopping as you work your way around. It's better to burn that sucker in nice and hot rather than use less heat.

 

[Redcbr007]

I took some welding classes and they used to say 'use the hottest setting the machine goes, it will burn a hole through, then turn it down a little and see if it burns through, keep going down untill it doesn't.' So basically run it as hot as the material will let you


my 2 cents

-Red

 

[Colorado_XJ]

Repositioning yourself is a must in a lot of situations. It will require a modicum of finesse to master your tie-in's (start/stop points), but it will come to you. I have been welding for years and run a structural steel shop here in Colo Spgs, and part of certain welding tests REQUIRES you to stop your weld midway, then count to 10 and begin again at your stop point. So if you can master it, there is no problem with it. If you are running MIG, you might try running less wire speed or more voltage to buy you a little time and decrease your weld size. If you are running a TIG, well, that's a heck of a lot easier.

CARTS has a good tip about the weep hole....nice tip for gas-shielded welding.

And I also agree with AJ about being better to go in hot than cold.

In general, just stick with it...it'll get a lot easier in time!

 

[TC]

Ditto the above, plus when you stop each weld don't just stop at the same speed you've been welding at. That will leave a rounded end to the bead and when you start your next one you may not get full penetration where the two meet. Try stopping each "stitch" (except the last one which will run into the first one) by SLIGHTLY whipping foward about a 1/4 inch. What you are trying to leave is a little oval "crater" ( for the lack of a better word). Then you start your next stitch at the far end of the crater and back weld that 1/4" while you get a good bead going again. This makes for a more continuous weld without 3 or 4 gaps in the root of the beads. It sounds more complicated than it is, we're only talking about 1/2 of a second at the end of each bead. Try it, you'll see what I mean. TC

 

[XJJPR]

2 tips:

Bevel your material, the fish mouth end, at least 1/2 the thickness of the material.

and

Flatten the points of the fish mouth. Meaning where the fish mouth comes to a point grind them perpendicular to the tube itself for a at least 1/2" across.


This all gives the weld some place to go without over flowing all over the place.

mark

 

[gearwhine]

Thanks a lot for the help. I understand what you're saying TC, and it makes sense. Colorado...about the stopping for some time...you think it's a good idea to stop and wait for a while before starting up again...or just stop reposition and go back at it until it's fully welded? Sorry for the basic questions, most of my welds are just straight filet welds, so I don't want to F up welding a roll cage that I'll be spending days working on.

I will give everything a shot once my tube comes in and see what happens. maybe post pictures so you guys can bash it all... _nicko_

 

[Lawn Cher']

Just remember that it'll never be as booty-fabbed as mine, which is why I never mention it.

 

[gearwhine]

Just remember that it'll never be as booty-fabbed as mine, which is why I never mention it.

haha, that's for sure...

 

[4ward]

Just remember that it'll never be as booty-fabbed as mine, which is why I never mention it.

You just did

I can usually get 1/2 the joint done in one shot, but that's on the easy to get to areas. I wouldn't worry about the wait time, it's actually easier the quicker you are as there is still a good amount of heat in the area that was just welded and you don't have the typical cold start problems. Just don't get in a rush and do a bunch of practice on spare chunks laying around. Practice in all the F'ed up positions you think you'll be putting yourself in too(upsidedown w/1 hand and 1 eye closed type situations)