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Top Frame, Hard to Weld

RAC68

Darth Vader
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Hi All,

A good friend in our Healey group had acquired a 1966 Phase 2 BJ8 and is in the process of restoring much that the previous owner left undone. Recently, he redid the full interior and was in the process of refinishing the top frame before installing a new top and was having trouble re-aligning and installing the top frame. Thinking the cut and welded "S" section was original, he made many failed attempts to fit the frame for proper operation and window positioning and, in frustration, decided to recut and fit the joints.

After inspecting my original non-cut "S" frame section and realizing his welded unit was cut to compensate for new frame attachment platform position changes, he decided to recut the welded "S" section on the passenger side and re-weld to a position that would allow proper frame positioning. After establishing and securing the "S" section for good frame fit, the units was quick tacked and the frame removed for final welding.

This is where everything seemed to have gone wrong. Using a 120V MIG welder outputting 85 amps (20% duty cycle) set on its highest setting and slowest wire speed, every attempt resulted in a non-flowing buildup with slight or no real penetration of the frame metals. I understand the top frame is, and needs to be, constructed of strong steel and my MIG may not have the power to melt this metal. Having only used this unit on sheet metal and Home Depot angle iron, could my speculation be correct? Would a 120V Lincoln industrial MIG with an output of 140 amps be better suited for the task? Is there something I am missing?

Any suggestions would be appreciated.
Ray(64BJ8P1)
 
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re: "... Using a 120V MIG welder outputting 85 amps (20% duty cycle) set on its highest setting and slowest wire speed, every attempt resulted in a non-flowing buildup with slight or no real penetration of the frame metals. ..."

I hope we have some 'real' welders on here who can answer, but here's my amateur's take:

This is counter to my experience; i.e. when you turn up the power you have to increase the wire feed speed to keep a good bead going (the greater heat burns the wire away faster). I too, have an under-powered MIG rig, and I've found that the wire must be as close to the metal as possible, without grounding out, to get the best penetration. I had trouble doing this as I'm nearsighted and wear contact lenses to get decent distance vision but, even with a magnifying lens in my welding helmet I couldn't see well enough to keep the wire close to the 'target.' Now, I don't put my contacts in if I'm going to be welding, and I can see the arc much better. I also lightened the shade of the helmet so I can see the arc and nearby metal; if the lens is too dark all you see is a bright white spot in a dark background. Of course, the sound of the process tells you a lot: sizzling bacon good, popcorn bad.

I haven't worked on any top frames, but I'm guessing it's tubular with 1/8" or less wall thickness; even a low-powered rig should be able to get a decent bead and penetration on this. My BJ8's emergency brake bracket has been broken for a long as I can remember; with the gearbox and OD out I took the opportunity to try to fix it by welding it back together. I was able to get a good, but short bead going and I think I got good penetration, and this is, I think, 1/8" plate welded to a chassis rail. I also did a rather poor repair on a cracked front suspension mount, but it's held for many years and miles. Not sure the exact nature of your repair, but if you're butt-welding tubing--or plate, for that matter--you should bevel both sides to get proper penetration. Also, you can preheat the area--a propane torch should do it--to get better penetration (this is why you 'stitch weld' on sheet metal, lest the preheating burn the metal away). 'Rhythm,' for lack of a better word, matters as well. Hold the arc in one spot too long and you get burn-through (sheet metal), or 'gobbing up' (thicker stuff) and if you go too fast you don't get enough penetration. Also, for a small, somewhat delicate repair like this a TIG rig would likely work better.

Side note: I've been interested in welding for quite a while, and I'm moving to a town with a community college with a welding program. I'm thinking seriously about enrolling once I get settled.
 

John Turney

Yoda
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...

Side note: I've been interested in welding for quite a while, and I'm moving to a town with a community college with a welding program. I'm thinking seriously about enrolling once I get settled.
I highly recommend it. I took a couple of community college classes on welding and it really helped.
 
OP
RAC68

RAC68

Darth Vader
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Hi Bob an thanks for your response.

The "S" section of the top frame is a flat 1" wide by 1/4" thick piece of flat metal. It extends from the frame base mechanism up to the main section and supports the wood and weather stripping at the back of the window. As I understood, running slow wire allows the greatest amount of heat to be transferred where as running fast would transfer less heat. On metal panel welding, I would run at a medium setting with faster wire and brake the bead line frequently so as not to risk warping the panel.

I am also thinking of taking a Community College course to learn how to apply Cloisonné to restore my from badge. Having it done would cost around $300 and the course is less then $100 with an instructor helping me do it on my badge.
'

Thanks again,
Ray(64BJ8P1)
 

CLEAH

Jedi Warrior
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Ray, I think that is too small a welder to work with 1/4 inch plate. My 180 amp welder runs at 220 and has 10 wire speeds and 6 current settings. To weld 1/4 inch plate, my welder requires the wire speed to be set at 10 (max) and the current at 5 (next to max), as well as .035 wire. I don't think your friend's welder is up to this job.
 
OP
RAC68

RAC68

Darth Vader
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Hugh,

First, thanks foryour response.

I totally agree that my MIG is probably under powered to handle 1/4" plate steel and without the power, no penetration.

To get max welding amperage to the metal, with corresponding penetration, I may have had my MIG wire speed set too slow. Since I had the wire speed set to a low number, I was not getting the maximum my MIG was able to deliver and overheating the feed wire splashing it.

Thanks again,
Ray(64BJ8P1)
 
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Bob Hughes

Luke Skywalker
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We cut my soft top frame and re-welded it, the joint was Veed and a TIG welder was used.

I can get away with using my SIP 150 MIG welder just about on 1/4 metal, but the joint must be Veed and a bottom run put in first and then I weave in the rest, so far I have only used this method on my engine frame on wheels and a chassis support frame, I have not tried it out on the car.

:cheers:

Bob
 

Brinkerhoff

Jedi Knight
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Typically you would increase the speed of the wire along with the amperage as you weld thicker steel. Too slow a wire speed and the wire can't transfer enough heat .
 
OP
RAC68

RAC68

Darth Vader
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Bob/Brinkerhoff,

Thanks for your responses.

Bob, I like the idea of cutting a "V" to assist the penetration grab of the weld.

Brinkerhoff, Although I think my MIG and 35 wire used was too weak, I also believe I further aggravated the situation by having the feed set too slow causing the wire to flash and burn and not flow ... even for a tack.

Thanks all, when you do this so infrequently, I find I am always relearning until I get the feel again.
Ray(64BJ8P1)
 

Bob Hughes

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Ray

Forgot to add, I always try a sample weld on scrap first to iron :playful: out the wrinkles. I have also used MIG on my brackets for the spot lights, just slightly under a 1/4 inch.

:cheers:

Bob
 
OP
RAC68

RAC68

Darth Vader
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Thanks Bob,

I have welded 1/4" with my MIG a while back so I thought this would be the same. The Top Frame metal seems quite a bit harder then the Driving light brace I installed under the front pan that is braced on the bumper brackets. I had no welding that metal.

When you don't know what you don't know, you don't even know what to ask.

Thanks again,
Ray(64BJ8P1)
 

Keoke

Great Pumpkin
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Why not just take it to a welding shop and get it done????
 
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I am sure that the top frame, bumper brackets and all the like on a Healey is all be classified as mild steel, and therefore no extreme measures required. You just need to fine-tune your settings.

My first MIG welder (a Silver Beauty, Italian produced machine__doubt it cost much more than $100.00 in 1986) was very limited in horsepower, and for a lot of the stuff I wanted to weld, I preheated it with my o/a torch; the metal flowed beautifully after that! It was just by dumb luck that I was also producing reduced stress weld as the result of pre/post heating, lol. I've made three (^3) upgrades since then, and as long as nothing seriously breaks on it, I expect my Millermatic 252 to be the last one I buy (it shares chores with a Miller Dynasty 200 TIG affair, and a Lenco Twin-Spot; also have a couple of devices for joining/welding plastics too).
 
OP
RAC68

RAC68

Darth Vader
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Hi Randy,

You hit it on the Head. The MIG I am still using for most all I really need to weld is a Silver Beauty 90085 purchased in 1987 and used extensively. My first build was a Rotisserie and then addressed the rebuild of my Healey. It has performed well over the years and only gave me problems now. Maybe its old age that is hitting both of us (me and the welder).

Ray(64BJ8P1)
 
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