[ScottD]

Im a week into my semi BREN build. My entire tool shop consists of a dremel, a Ryobi 12" drill press and a Harbor Freight gasless MIG welder.......

After SEVERAL attempts at the receiver (weld, crap, its warped, cut and re-do...crap, warped again...) I managed to get it all put back together. Let me tell you the fits I had on that center section......I used words I didnt even remeber......

Either way, I started to grind out the welds tonight. My beads are crappy, and my penetration goes about 1/2 way thru...(anything more and she melts/warps) but I built it myself dangnabbit ! Sure, I gotta tack it again in several places cause my penetration wasnt complete, and Ive had to re-do several other spots, but for a guy with minimal gear, Im pretty proud of myself.

Now, as far as the safety issue....all the bang happens in the chamber, the rest is just reciprocating parts. I guess I just wanted to say I love this hobby, especially when something finally comes together.....

 

[Z06]

Bren

we want photo's

 

[AK Addict]

we want photo's

Are you sure about that

 

[Orion Arms]

i have always said that a guy who is a bad welder is a great grinder

 

[ScottD]

I take that as a compliment.

 

[blackrifles]

i have always said that a guy who is a bad welder is a great grinder

No sh*t!! I think I wore out a case of grinding disks that week, next week I was welding like a pro, been doing it for almost 2 decades.

 

[Cactus]

As a certified welder id be concerned about not having full penetration. Did you make sure to weave the multen metal as to sew the pieces back together? a backing plate will help with heat distribution as well as elevating the work piece off the table so air can be drawn to the back of the weld. Also know flux core can have real problems with perosity; if your not care full witch will weaken the weld. If memory serves me correctly I dont think .030 flux core has that high of tencil strength as it is. Also grinding removes tencil strength with the more metal that is removed.
Just out of curiosity did you use that alluminum jig with the brass backing plates? I was thinking of doing this myself as I though this would help heat distribution as well as make it easier. Im not trying to slam your work my hat off to you for attempting something like this. I am just concerned and want to make sure no gets hurt. Good luck and if you were here in Sacramento id be happy to do this for you.

 

[Orion Arms]

I take that as a compliment.

it takes one to know one

 

[sdk1968]

i have always said that a guy who is a bad welder is a great grinder

yep that fits me as well....


Scott did you go about tacking a bunch of places and welding a little at a time?

im a CRAPPY welder. and with that: a jig and not welding too much in any one spot at a time is the key to not warping stuff up.

BLackrifles & PIrate are constantly giving me helpful tips on improving my welding.....

going slow and moving around to the other sides instead of welding all of one side has always been the best help to me..

oh and i did switch to ARGON on my mig welder instead of the flux core wire. that alone made a HUGE improvement in my welding and the "cleanliness" of my welds.

sdk

 

[glockhead]

iagree with cactus

you need deep penetrating welds. need to go slow too. we warped the first one we did also. pirate has the right idea. taking pieces from another receiver and using them as filler.

not sure i want my face next a receiver with crappy welds. it still pisses me off to think these bastards cut these up. what a waste

 

[ScottD]

I used copper backing plates that I got from onlinemetals.com. (shameless plug for a great and affordable site)

Yes I 'weave' my molten pools, up down or left right depending on the area. I did build up the sections somewhat before I put them together which really reduced how much fill welding I had to do. My biggest problem was that center cut. No matter WHAT I did, she would shrink up and cause the bolt carrier to bind. (No, I dont have a jig....saving that money for Pirate to hurry up and release his semi parts!!!!) I wound up using a shim between the parts to keep them the right distance. Hard to explain but it worked. I really cant believe the tolerance these things were manufactured too. When I grind it all down I look for inconsistincies in the bead, often I will drill or grind spots down and reshoot them. Unfortunatly this causes real rough spots and small pockets and I can never get a smooth, seamless weld.

For a guy with no training and a 120 dollar gasless welding machine, I do pretty well for myself. Sure, you will be able to tell I welded it myself and ground it all down. There will be plenty of surface flaws, but hell, thats the joy of saying "yeah, I built this myself...."

 

[sdk1968]

Scott,

when your finished welding it, if you get enough there and grind it back down.... yes you can tell it was welded (especially the good welders here) but it will be really hard to tell for anyone else who doesnt know what they are looking at.

9 times out of 10 the people who would critisize you couldnt do any better themselves... its always easy to knock someone else's hardwork and effort.

but for the most part the guys who can weld (like Pirate & Blackrifles) have always been the most supportive and said the best thing to do is stay welding and keep practicing.

it makes a big difference if your a rookie welder like me.

my pipefitter and boilermaker friends who have done it for many years can just walk up and do it every time and they laugh at my pathetic attempts of "gobstoppering" but give me the same advice: just do more of it.

sdk

 

[blackrifles]

Scott,

I'm seriously worried about the flux core wire, the welds holding up, based on very limited experience with flux core (and some FUGLY-looking welds...LOL!) can't say I trust this stuff, esp if my head was next to that receiver. Can you tell me what kind/brand of wire you're using? Might help with advice from those more experienced in flux-core. If the receiver fails, in all probability it will be in the center (locking shoulder) area, that takes the brunt of the stress.


I always use ER70S-6 with MIG, it's what we use in automotive work, I would think it would more than handle the abuse in firearm apps, because there are a LOT of rewelded semi-auto receivers around here, and they're doing just fine yrs later.

SDK, I promise when I make it up there, you'll learn to weld blind-folded within the hr, that dirt-dobber sh*t will be a thing of the past, maybe we need to teach you after a few drinks, calm you down, LOL!

 

[Cactus]

Most flux core if done properly has a 6000lbs tenscil strength minimum, if done properly. The holes that you are talking about are perosity. Perosity happens when there are contaminates in the welding process ( mostly slag ). I know its allot of extra work but flux core requires extreme cleaning when doing this kind of delicate work. Also I can not stress enough the importance of preping the work piece. The cuts on the reciever should be ground dowm and a notch or v ground in them. Also there should be a gap in the work piece ( A welder is never afraid to fill a gap that what they always use to tell me.) That way you have a clean surface for welding and more room for penitration and welding surface. Also small welds then extensive cleaning will help with the heat problem. A needler was a god send whe I use to work structural steel but a whire wheel will work on this. When you think its clean shine a flashlite on the piece and I bet you will find something. Flux core is strong and easy to use in the flat position. you could also put metal in the work piece to act as a heat exchange. Allot of times I work small section to small section kind of like tightning lug nuts to help with warping from heat. Also alow to air cool never try to rush things by quelching. That jig seems like a great invention and ive been talking to a great machienist I know to try and make one.

 

[ScottD]

I bead blasted the surfaces, then I ground down the edges to about a 45 degree angle. All seams had a small gap between them. Like I said, I may have a cheap ass welder, but Ive learned how to work it.

My MG42 hasnt blown up yet, and I had to fill weld sections up to a 1/4 inch on that sucker!

 

[bullseye]

I have not done a reweld before but I have had the opinion that if you took the pieces seperately and built up the area where the cut was made giving extra material so that you could grind it down to fit perfectly then just bevel the outside and reweld geting full penetration and not warping or shrinking because most of that would happen before it was put together for the final weld

 

[sdk1968]

BLackrifles: im very much looking forward to that and im sure that as hyper as i am that a "sedative" probably wouldnt hurt... ony problem there is im a whiskey drinker and if i didnt stop after the first few im probably just gonna burn my feet again. LMAO

Cactus:

i was wondering when that Preocity word would come out.... i hear this all the time from my welder buddy's when they are getting their x rays done.. its the thing they all try to avoid.

all i know is that its supposed to be damn near impossible to use a flux core wire and not get a lot of it.. its the reason i went to gas and it made a huge difference on my rookie a$$.

 

[Cactus]

Mig welding is the way to go that shielding gas makes everything clean and its super easy. Flux core burns flux inside the wire to create a shielding gas. When I took my Flux core cert test we had to pay extra special attention to slag removal so we didnt get perosity or worm holes. Flux core can be ultra strong, hell its what I used to weld up buildings and anything over an inch in diamiter it just takes more time to master. I literaly taught my brother to mig weld in a afternoon. I hope you guys dont think im knocking you around this is just my area of expertice and I would like to help if I can. I am certified in 22 positions for mig and flux core welding, I think I have 24 for 7018 and 60 series arc welding, and god only knows how many I have for pipe now. I am a journey man welder and as a apprentice I worked under a ex-submarine welder from Maire Island. I also have a degree in metalurgy. I paid for school by welding and now its just my hobby. I hope to be tackling this same thing in the next few months my self. I think its great people on this board take on things like this and it something my son loves to work on with me. What are the tolerances like you guys were talking of earlier? Are they tight or like an AK and the more slop the better?
Also any tips you have id appreciate. Thanks

 

[Roc Rat]

I had several gun kits hanging fire till I got a Mig,,,, FINALLY last week I became the proud owner of a Lincoln Power Mig 140c. I have it set up for gas welding,,,, I'm like a kid at Christmas!!!
I second on BIG blocks of copper. Onlinemetals and McMaster-Carr

 

[Commander47]

I am not an expert by any means and there is a ton of great advice on here.


I have been flux core mig welding for years now and have a couple tips for you.

Porocity is is the solidness of the weld. With gas welding the amount of carbon slag is generally reduced. With a mig weld. work slower and stop and wire brush the weld often to remove the carbon bubbles in the weld.

You will have a great deal of trouble preventing warping and getting a deep weld if you don't back up the receiver. You really need to clamp the pieces to something. Lining up the pieces and clamping them to a sandwich of some lengths of steel and copper from home depot would help you greatly and be cheap.