AK Flat bend Strike One

[Rifleman1971]

I tried bending my first flat on the HF 18" brake type bender I assembled.. NFG..one side too long and uneven,, Not sure what I HAVE WRONG. I set it up with 5/8" from the center of the pins to the bend seam and also offset the top plate .040 for the thickness of the flat.. I also screwed up and drilled the hammer pin holes first so it distorted a bit.. Question for someone who has built this jig,,, How far from the pins should the bend edge be? I did reinforce the jig on both sides with welded plates to beef it up, I just need to get an idea where I F;d up.. Any input greatly appreciated,

[Loyal11475]

Wow, sorry to hear that you destroyed a flat like that? My opinion is that going cheap, that is failing to aquire the proper tools, or not buying a ready made receiver from a reputable company, will lead to more of what you experienced bending your flat and wasting your hard earned dollars......If you want to build something that you can bet your life on, that won't blow up in your face or that is aesthetically pleasing to those who may gaze upon it, then go get a Curtis; Jig, Flat, Rivets, Center Support at minimum......Oh and don't try to rush your build, drilling the Hammer, Trigger Pin Holes prior to bending, was not good. Building has a general order to it, like the 10 Ten Commandments, you can play with them here and there as builders do, but do it after step one (bending), or you will find yourself wandering through the AK Builder Desert for years to come........

[akma]

I made the HF bender but it needs reinforcing otherwise it will not make a tight clean bend. I trimmed the bending plate to 1-1/4" then center your flat on that. I scribe on both sides of the plate to make sure when I turn the flat around to do the other side I already have a reference line already there.

[Rifleman1971]

I did brace the two sides, I used a 3/16" piece of flat bar for my top clamp and it has a slight radius edge after closer inspection that may have had a negative effect.. I thought maybe it wasn;t tightened enough and it moved a bit causing the differences ... I have been going over it and will use a thicker top plate and double check all dimensions.I see where you went a tad further with the locating pin dimension then I did,, I went for .625 and I forgot to allow for the plate thickness(.040) ,,Thanks for the input and its back to the project,,,,,,,

[allesennogwat]

You need a few extra flats and practice. The big problem with bending flats is they are made of high strength alloy steel. They are not plain sheet steel. They are not designed to be bent on a fold over sheet metal brake. Normally the type of steel is bent on a press brake which looks like a sheet metal shear. The other proper way to form the type of steel is pressing it in a jig. The steel is too strong and too springy to use a regular sheet metal brake.

[bfgmovies]

I've bent a couple flats using something simalier to the grasshoppers jig, both of them came out simmilarily to yours, personally I've just been building on 100% receivers
If I ever get a jig I might build on flats, but I really like the fully heat treated nodac spuds

It's hard to get everything lined up with cheap jigs I guess

[ronin]

As alles said, this alloy needs more of a press brake than a folder because you need tight corners and need to avoid stretching the metal. It may work out for you - I've seen guys do it over the years with the thinner flats. I've not heard of anyone doing it with the thicker heavy duty flats. Not sure which thickness you are attempting. The old style are around 0.040" and then there are 1 mm and even 1.5 mm flats now. I don't think the latter could be bent by anything except a press brake/ flat-bending jig type setup with the correct ram to handle it.

For what it's worth, the AK-Builder flat bending jig works great. You can turn out real high quality receivers with it.

[Rifleman1971]

.040 is a millimeter and my flats are that thickness. Granted there are better ways to do everything, I am attempting to duplicate the bender that Black Market Arms sells using the HF brake as the base... I appreciate all the input from you guys and will consider it all ... I made some minor fabrication errors on it and am attempting to correct those. I have already gotten some good ideas to possibly save the tool... If it was easy everyone would do it as they say,, So I am heading back to the drawing board to see if I can salvage it.

[radkoch]

Are you taking into account the thickness of the metal when you are doing your set up. You will need to offset it a little to make up for the metal thickness.

Also as you stated you may have to make the center of the bending bar stronger as they tend to bend/bow in the middle

[Rifleman1971]

Gonna get a thicker bar for sure or double the existing one..Should I have offset the locating pins by 1 metal thickness??,, I did offset the edge of the bending bar by .040 to bring that edge in a small bit.

[6526]

some suggestions here

http://www.akfiles.com/forums/showthread.php?t=6572

[collector]

Sorry to say, this sounds like a very complicated method. Buying two angle irons from Home Depot and measuring the width with four bolts with three nuts on each would be easier. Two on the inner portion to hold width and one on outer surface to keep it from bending out; however, a shop press is needed for bend, even a small eight or five ton A frame that mounts on a work table would do it! Collector

[I.Oak47]

This is why I bout one from BMA, knowing me I'd of bent $100 worth of flats before building it correct. thus making it not worth building it byself

[Shocker47]

You can teach a monkey to use akbuilder flat bender in 5 minutes. That's how easy/idiot proof it is. That's why I ponyd up the bucks n bought one

[akma]

Originally Posted by collector

Sorry to say, this sounds like a very complicated method. Buying two angle irons from Home Depot and measuring the width with four bolts with three nuts on each would be easier. Two on the inner portion to hold width and one on outer surface to keep it from bending out; however, a shop press is needed for bend, even a small eight or five ton A frame that mounts on a work table would do it! Collector

Welcome to the forum! RyanSD has a nice jig for about $70. Do some poking around here and you will get a lot of insight into bending flats.

[scooterwrench]

Rifleman,I screwed up ten pounds of scrap .043" sheet metal trying to fold a receiver the way you're trying to do. Seemed I kept having the same problem with uneven rails or ripples in the sides. I finally spent two days building a press jig after seeing the AKB jig,nailed it on the first try. If you have access to the raw materials this is what you build,
http://www.akfiles.com/forums/showpo...37&postcount=3
This shot got missed on that post,
The thing is to keep your tolerances close. I allowed .0005 between the outside of my flat and the inside of my anvil. The flat is an AKB,best I've seen so far.

[Beryl]

Just get the Polish pre-bents and live the easy(er) life.

[RG Coburn]

...or buy one from Harlan and have a unit thats actually heat treated correctly.

[cd]

Looks like a lot of members on here haven't fully embraced the DIY's spirit. If it wasn't for people like rifleman1976 trying to push the envelope and take the road less traveled this hobby wouldn't be where it is today.

Rifleman if you ask BMA for a blueprint he just might give you one as long as you don't plan to sell the jig.

[Rudy]

Originally Posted by Shocker47

.... That's how easy/idiot proof it is. ...

Nothing is idiot proof as idiots are too ingenious.

I bent my first receiver out of some high strength sheet steel using a brake. It was a much bigger brake that could take 1/8" thickness by 48" wide.

[WTSGDYBBR]

Buy a AK-Builder jig you will not find noting better then that.

[ironbike]

i say right on !! a man in his garage , doing his thing ! thats what its all about ,,sure anyone can buy a tool ,,,and i have ! ,, but ive also ,,made/modified many/ many tools over the years ,,,so i say carry on !!! youll learn with each bend !

[2Munkeez]

I used the BMA Bender and mine turned out like shit. So out of spec u could not put a (underfolder) rear trunnion in the back. Ordered Curtis's jig (along with a new flat) and life is good seriously, his shit is worth every dime, buy his stuff, you'll be happy and we will know he's doing good enough to stick around.

[motorhead]

if you want to build a bending jig, build a 555 type out of angle. brake type benders have a long history of fail.
i've still got my 1st generation ak builder jig. bought it used here way back when.

[FloridaAKM]

+ 1000

Originally Posted by Shocker47

You can teach a monkey to use akbuilder flat bender in 5 minutes. That's how easy/idiot proof it is. That's why I ponyd up the bucks n bought one

[cd]

I once tried to build one of the bender jigs from a HF bender and later decided against it. My makeshift 555 jig works but I will be buying one of the AKB jigs for 1.5 fats.

The most economical way to go in my honest opinion is to purchase a ABK jig and about a dozen of his flats. Bend them all then proceed to resell the jig in the market place. I call dibs by the way

[jdindadell]

Originally Posted by cd

I once tried to build one of the bender jigs from a HF bender and later decided against it. My makeshift 555 jig works but I will be buying one of the AKB jigs for 1.5 fats.

The most economical way to go in my honest opinion is to purchase a ABK jig and about a dozen of his flats. Bend them all then proceed to resell the jig in the market place. I call dibs by the way

This. I see the old style bending jugs for for 140 plus all the time. So bend a few and resell taking a 30 dollar or so loss. Material to make your own jig (which will not be as good as the akb jig) will cost more than 30 bucks...

Or see if anyone in your area has a jig you can "borrow"...

[uzitiger]

Originally Posted by allesennogwat

You need a few extra flats and practice. The big problem with bending flats is they are made of high strength alloy steel. They are not plain sheet steel. They are not designed to be bent on a fold over sheet metal brake. Normally the type of steel is bent on a press brake which looks like a sheet metal shear. The other proper way to form the type of steel is pressing it in a jig. The steel is too strong and too springy to use a regular sheet metal brake.

I also destroyed a few flats myself. I tried to use a sheet metal brake and missed and I got a chance to borrow a bending jig and the first one didn't bend right because the locating pins were missing. After I realized what happened I finally got them right. I checked the Tapco flat on a metal analyzer at a scrap yard an it's 4140 chrome moly steel.

[vedackster]

i made my own press bending jig similar to AKBs. worked great. only .001 diff between the sides in height.