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Arc welding/frame shortening question

FMJ

FMJ

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Duluth, MN
I'm wondeirng if anyone can tell me what settings to use on my arc welder for 7018 rods. I've been trying different things but nothing comes out looking very good. I'm thinking that is my best choice for welding my frame back together after I take about 2 feet out of it. I've been told I have a knack for welding, but i'm completley in the dark about what settings to use. And about the frame, I read the post about frame modifications but all the tapper and stagger just confused the hell out of me. So, what I got out of it is that I should grind down the edges so they fit together like a V and then weld them starting from the middle and working outwards? And then should I box the whole frame after that? thanks for any help.
 
Don't cut your frame in a straight line, it will have problems afterwards.

I'd use a MIG welder....stick sucks. Just my personal opinion, although this is one place where stick will work ok if done correctly.
 
the settings on awelder are mostly determened by the thick ness of the rod.

3/32 takes less then 1/8 less then 5/32. and you also have to take into consideretion the tickness of materal.

and every welder is different, mine is not your is not his...

get some scrap the same thickness and start laying it down untill it works right. 7018 is a good strong rod, remember to weld up if you want a strong frame...
 
Generally 7018 is a DC rod. There some AC versions of it, but they don't work as well as the DC. So be sure that your machine is DC capable and if it is, that you have DC selected.

And stick doesn't suck Tim. It's just harder (for you) to use. 7018 will make a stronger weld than regular hard/solid wire MIG. 70k lbs tensile strength vs 60k lbs.
 
why dont you just move the spring hangers forward and bolt them back on with some grade 8's?, i did this with my old truck, i think that would be much stronger than cutting the frame and welding it back together
 
I've been using DC with about 135volts and the welds just dont look right to me. I can't see the puddle very well so it's hard to tell how i'm doing. If I can't figure it out and get it perfect, i'm just going to have someone better do it. Also, I've found that my arc welder using 6018 rods is just as easy as mig welding, and I trust the arc welder a lot more.
 
KidJethro said:
And stick doesn't suck Tim. It's just harder (for you) to use. 7018 will make a stronger weld than regular hard/solid wire MIG. 70k lbs tensile strength vs 60k lbs.
Click to expand...

I understand that. I do know how to stick weld. Just ever since I learned to use a MIG, I've shyed away from it. MIG is just too clean/easy/fast to deny its usefullness for nearly anything for me anymore.
 
86chevybanshee said:
why dont you just move the spring hangers forward and bolt them back on with some grade 8's?, i did this with my old truck, i think that would be much stronger than cutting the frame and welding it back together
Click to expand...

thats a good sugestion. would eliminate the worry and a little work of cutting and welding. But it sounds to me like he's already cut the frame...
 
sorry I confused you with the taper and stagger language...

basically it goes this way...
1)I measured many times crosschecking my measurements to make sure they were in equal places on both sides of the frame
2) I made my initial cuts like a Z through the frame .... then I cleaned everything up to fresh clean metal a couple of inches past each cut. I also beveled ALL the edges
2) I put the frame back together with honking c clamps and braces and again remeasured everything to make sure it was equal and the frame was square... this is the most difficult part of the whole job and where you need to take care
3) I made my reinforcement braces.... although my article specd 1/4 inch 3/16 is more than sufficient... the reinforcement extends 8 inches beyond each side of the cut... and in my case a little longer on the front side so I didnt end up under a stress point... in my case the rear cab crossmember
the side reinforcement was measured first.. ... this way when i cut it I could have the correct width to intersect with the top and bottom pieces so all would then have a nice spacing to make the first root weld and catch the frame as well... then it was mocked up and all the factory holes needed were drilled (the frame crossmember in my case)
The side plates have a fishmouth )_____( at the ends... a little more then dipicted... the bottom and top braces go straight across the frame (remember my initial cut was a z so they dont go over the same area as the initial cuts)... you NEVER weld straight across the top or bottom fo the frame... if you do this will be a stress point and where the frame will crack first... most likely on the bottom..

4) Once the frame is all jigged back together do your preheat of the welding area to 125 to 175 degrees,,,,
then tack properly and weld.... reheat to slow the cooling process... and regain some temper...
grind exterior welds flat
Place all reinforcements in place and clamp... stitch weld them all together and to frame... remember dont weld ACROSS the frame... so the ends of the bottom and top reinforcements are not welded
The whole welded area is painted and if you want (and I would suggest,,, use some of the gm/3m seam sealer on all the seams... that way corrosion wont start behind all of your hard work)

5) I love mig... BUT this is one case where stick welding is actually a better process (according to the "experts" I have interviewed at Lincoln/ESAB)... 7018 rod is the specd one for this application... 3/16"....DC is an excellent choice....You want to make it hot enough to melt everything together and not hotter... I would think starting at 125 amps and testing that first on your cut out material
It was explained in AWS literature that the 7018 is one of the purest rods when utilized properly... we could go into a long discussion on metalurgy but suffice to say its probably your best choice.... with proper beveling and welding and no concave weldment you could actually do NO reinforcement and have a frame be as strong as the original... I reinforced mine because its a dually and a work truck... and if welds start to crack i want some safety time to figure out what i did wrong

I hope this helps you... Ill be welding mine this weeked after a setup day yesterday and today (IF the weather doesnt piss on me)

cam
 
FMJ said:
I've been using DC with about 135volts and the welds just dont look right to me. I can't see the puddle very well so it's hard to tell how i'm doing. If I can't figure it out and get it perfect, i'm just going to have someone better do it. Also, I've found that my arc welder using 6018 rods is just as easy as mig welding, and I trust the arc welder a lot more.
Click to expand...


135 amps is a little high IMO.
A 1/8 7018 should run110-120 amps depending on the machine you are using
BTW for the strongest weld , allways weld up hill and put some type of plates at the splice but don't weld the vertical sides ,only the horizontal sides of the plates
 
84_Chevy_K10 said:
Don't cut your frame in a straight line, it will have problems afterwards.

I'd use a MIG welder....stick sucks. Just my personal opinion, although this is one place where stick will work ok if done correctly.
Click to expand...

There are plenty of guys out there who are artists with a stick welder. I know one who can weld sheetmetal and bridges (literally) with his stick welder. Don't condem the process b/c of the operator.


The strength of a frame is in the top and bottom flanges, not in the web. Someone recently posted the results of their research on this topic, try a search.
 
Damn...You guys are way over thinking the welding part of this.

In this application, 7018 is overkill. That coupled with it's difficulty of use for the average guy, make it a hard choice to reccomend. A MIG welder with sufficent oomph (200 amps+) is perfect for this kinda work. A frame is no more than like 3/16's. The steel is not hardened or heat treated in any special way. It's just mild steel. No need for a low hydrogen rod like 7018. If we were discussing the proper way to weld a large 1" thick lug for a shackle mount for a recovery point, then 7018 would be alittle more appropriate. Of course, 7018 isn't gonna hurt things in anyway and if ya feel confident with it, by all means have at it. If I had a DC stick welder, I would probabaly use 7018 on alot of stuff just to break the monotony of pulling the mig gun trigger. No need for post or pre heat. Just clean it up, set it up, and weld it up. It's not nuclear physics.
 
In reply to "and put some type of plates at the splice but don't weld the vertical sides ,only the horizontal sides of the plates". Square plates concentrate stress at the point where they end (verticle seam) due to loss of flexibility at the plate and cause cracking at that point (they shift the stress point- but do nothing to distribute it). If you make a long diamound shaped plate and weld all sides, you will distriube this stress over a very large area (horisontally and vertically) and drastically reduce the chance of cracking.
 
My Bad , I just typed the answer like I was dealing with a co worker that would understand what I meant:doah:

I have to be more clear next time ....
Also it has been my exp.that welding any vertical ends on fish plates causes more faliures than leaving them un-welded
Most of the time will weld past the plate (diamond with squared off ends)and hook the bead to relieve the stress point of the weld ending
 
fisheye ends or diamond... they are both good... stitch weld... not continuous weld... continuous is not needed and puts stress into the frame... As noted the top and bottom take the stress..usually with the bottom failure being the most common....


I dont consider myself an expert by any means... I have only done a handful of frames in my life... everyone has their tricks they subscribe to...
safe to say
taper and stagger, stagger and taper

I got my frame jigged together and welded today... tomorrow... some appropriate reinforcement... it will never break at or near the splice...

cam
 
I havn't cut yet. I was practicing today a lot more with 7018 rods and I havn't made much progress... I definetly trust my welds with 6013 rods, and the MIG welder I have is a Millermatic 135. 3/16 is the maximum it can weld and it just seems like it doesn't hold as good.

Cam, if I could see some pictures of your frame when it is done, that would help me immensly. I'm still a little foggy on what the braces should look like and how they should be welded up. Also, what do you mean by "you NEVER weld straight across the top or bottom fo the frame... if you do this will be a stress point and where the frame will crack first... most likely on the bottom.."?

This is what I have from this right now:
1. Cut the frame at an angle
2. bevel and clean everything
3. measure like crazy
4. preheat before welding
5. don't weld the vertical seems
6. stich weld on braces on both sides
7. paint it
 
FMJ said:
I havn't cut yet. I was practicing today a lot more with 7018 rods and I havn't made much progress... I definetly trust my welds with 6013 rods, and the MIG welder I have is a Millermatic 135. 3/16 is the maximum it can weld and it just seems like it doesn't hold as good.

Cam, if I could see some pictures of your frame when it is done, that would help me immensly. I'm still a little foggy on what the braces should look like and how they should be welded up. Also, what do you mean by "you NEVER weld straight across the top or bottom fo the frame... if you do this will be a stress point and where the frame will crack first... most likely on the bottom.."?
What I meant was where your braces terminate... ie the ends.. dont weld them...

This is what I have from this right now:
1. Cut the frame at an angle ....I did a z,,, that way there was never a top and bottom joint that was in the same plane)
2. bevel and clean everything (bevel down to basically 3/16/// so if you laid a 3/16 rod in the bevel it would fill it)
3. measure like crazy (use KNOWN points.. in my case I found factory bolt holes which I checked before I cut to make sure they were equal
4. preheat before welding 125 to 175 degrees... your looking to slow the cooling process down when done and heating it up before starting... controls the weldment from cracking... doesnt eliminate it but controls it
5. don't weld the vertical seems (seams)
(you have to weld some on the vertical areas... but if you diamond<> the ends you wouldnt be welding vertically.... or if you fishmouth() the ends again wouldnt be vertical)
6. stitch weld on braces on both sides
7. paint it
Click to expand...
... if you cant finish paint what you have done... keeps the clean weldment from rusting which it can do overnight

Now... this is the way I did it... and some others have other opinions.... so pick and choose what works best for you ....
Ive been welding for 20 or so years with certs.. have done a handful of truck cuts.. another handful of big truck cuts... and a couple of street rods... no broken frames as of yet.. but again I DO not consider myself an expert

Im me your number... I can call you anywhere in the US for free with my service if you need me to answer more questions... now is the time to ask!!!

Pics.... ok,, I have to cut the braces tomorrow afternoon so pics may be a day away or so... the frame is already cleaned up and you cant tell its been cut or welded now.. so current frame pic wont help

cam
 
1- Cut in a z shape.
2- Definatley
3- Measure twice, cut once. :D
4- Not nesecary unless your welder doesn't have enough juice to do it unassisted. (irrelevant in this case)
5- Don't weld verticle seams? Err, Not sure exactly what that means, but if its meant to say not to weld the 'z' cut that you make, thats wrong. Bevel it, weld it, grind it smooth.
6- Yup
7- Yup

At the risk of sounding cocky...I can say that I qualify as an expert in this kinda ****. 2 years trade school. 11 years otj experience. And 13 years+ fabin my own ****. Held an AWS D1.1 cert. Unlimited thickness, all positions on plate with 7018. Let it go when I joined the Army though. All practical experience. Not a "web welder". Do it everyday 10 hours a day.

There is nothing wrong with most of the advice given here. Some just not needed and will cause more work. Alot of the times around here, anything concerning welding gets way way over thought. Turns into a confusing jumble of $hit that confuses the one asking the questions. Welding stuff on these trucks is not rocket science. A MIG welder and/or an AC only stick welder will do everything that our hobby requires. If ya wanna get into chromo TIG welding etc, thats a different story. Alot more intricate and complicated knowledge required to do correctly. All we're doing is welding mild steel. K.I.S.S applies.

And I'm not meaning to step on anyones toes...Just doing what I can to clear up some stuff. :D
 
Well first of all thanks for all the help. My frame has been at the sand blaster for a month and a half (blaster is broken) so as soon as I get that back i'm going to start this project. Between pictures and the help you have already given me I should be fine, but I also have free long distance so that might be a big help when i screw somthing up, I'm going to sign up right now so I can PM.
 
I'm also wondeirng if it is common practice to box the frame after somthing like this?
 
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