Better pics: bending an AK flat, step by step

[TNToy]

Screwups included.

I went over to Dab Dibbles house tonight and used his press for a couple of minutes. Had to hustle, since he had to go to work at 7PM, and I didn't get there until 5:20. Damn traffic.

1. Packaged Tapco flat and rails as it arrived from Copes.

2. Press with jig positioned.

3. Male & female halves of the jig, with the flat ready to be bent.

4. This jig has two very handy locating pins that can be inserted into the bottom. They ensure the flat is centered and correctly positioned front-to-rear, for an even bend. Theoretically. Just stick them in, tighten down the 4 1/2" bolts, and grease both the flat and the jig. I used a green, synthetic wheel bearing grease. It's messy, but I've got cases of carb cleaner lying around, I knew it would work, and it was handy when I was on my way out the door this morning.

5. Starting the bend. With a little practice, you can spot the jig in the press so that it bends evenly all the way across, on both sides. I got the hang of this on about the third flat. Of course, I only had 3 to bend. Go figure. Getting and equal, even bend is pretty important. I'll get to that in a minute.

[TNToy]

6. Once the bend is started, it gets to this point very quickly. (This is a mockup after I removed the bent flat, as you can tell because most of the grease has been wiped off.)

7. Then you just push it in until it's flush, pull it out of the press, flip it over, and use a brass drift to drive the flat out of the jig. Unbolt the flat, stand the flat on it's end in the jig, and tap the center portion of the jig out the end of your shiny new receiver.

8. 3 receivers, ready to be ruined as I figure out what the hell I'm doing.

9 & 10. Like I said, be sure you bend evenly. I suspect that was the problem here. See how that rails aren't equal in height?

The really bad one (about 1/16" off) was my first one, and is pictured around the jig in picture #9. The pretty much perfect one was my last one, and I was extremely careful with it. In the last picture below, it's the one on the right. The 'bad' one is the center one. I think I'd prefer flats without a pre-bent lip on the top, like the AKBuilder flats. This would have been a non-issue, as you form the rail yourself and trim the excess.

Experienced guys: What's your advice here? I'm probably going to clamp the cockeyed receivers back around the male jig in a vice, and use a deadblow or brass hammer to reshape the rails to the correct profile. Also, even the one with perfectly-aligned rails ended up about 1/16" above the corner of the jig: That gap you see was simply equally spread between the two sides. Is that a problem?

[Napoleon047]

I prefer the flats with the preformed rails because they are easier to do with my simpler bending jig. I dont rely on pins and holes in my jig, so I always use some layout blue and a scribe to accurately place the male die.

[rockmup]

TAPCO's with pre bent rails- trouble with most of them....20 or so

AK Builders flats-0 problems......80 or so

All using the same jig as you. The only thing different is we press in from the other side. I can't see that it would make any difference though.

Your second to last pic looks to me like the holes might be off in the flat. Looks like you came up a little short on one side and long on the other

[NEWMANS OWN]

just another jig pic. not all jigs are created equally. lol yours has ivory in it

Good post, pics allways help. What type of grease are you using?
thanks
J

[JEEPRZ]

The Tapco prebents always end up with the rail just a bit too high. Also, dont trust the hole position on the lower rails when intslling them. Align the rails with the trunnion, mark where the holes need to be slotted, slot holes, then install the lower rails.

As far as the crooked ones go, it looks like there was either a problem with the alignment pins, or the hole position on the flat. Are the pin holes in the center of the receiver floor now?

[animator]

We've always bent Tapco flats, but not the "pre-bent" rail versions.

With that jig, there's a long bar with two tube handles that looks like it's had the shit beat out of it--that's what we used to draw over the rails.

For the first run of flats (30 or so) the center pins were used, and every flat came out perfect.

For the last run of flats (20 or so) the center pins were not used, and each one came about 1mm offset. The trigger axis pin holes still line up on them, and so far, there haven't been any problems with building on them.

I've never seen one as off as that one, but that's not saying a whole lot. Were the flats identical, as far as measurements go? Or was one kinda wonky? I know Tapco occasionally sells "blemished" receiver flats, but I do not know what qualifies for a "blemish".

Fixing the skewed one definitely doesn't sound easy, but hopefully it will be salvageable.

[TNToy]

If it's not, then I'm disappointed, but not SOL.

I bought 3 flats, and I've got 2 kits (one of which might not even be salvageable) to build. So I was going to have a spare reciever. Guess that might not happen.

I need to go look at the holes. Reforming the rails might be possible with enough beating. Moving the holes? That's tougher.

[Aces'n'8s]

Maybe your AKs can still shoot with just a little bit of cant to them?

[f0cker]

Originally Posted by Aces'n'8s

Maybe your AKs can still shoot with just a little bit of cant to them?

I see them being shot sideways on purpose on TV all the time, I figure a bit of accidental sidewaysness can't hurt.

[sinistertrucker]

My first Home built Ak with Home-made jig came out sideways...



The slight cant makes for a better cheek weld

[TNToy]

Originally Posted by animator

Fixing the skewed one definitely doesn't sound easy, but hopefully it will be salvageable.

It's toast.

I don't know why I hadn't thought to check earlier, but I just took a set of calipers to the flat. I was assuming that the rails were off, and that everything else was good. Clearly, I somehow I got the flat off-center in the jig pretty badly.

At the locating pins, I'm .061" offset at the rear, and .031" off at the front. That's a lot more than it sounds like. The pins would be all cockeyed going through it, the magwell and trigger would be offset toward the right side of the gun quite noticeably...

It's just not worth fixing. I'll use the prefect one for my Copes kit that was in good shape, and the slightly off one for the really rusty gun. This one's just going to be a conversation piece, or something...

[PONY_DRIVER]

That sucks, but at least you have enough receivers for your kits.

[proletariat]

Wimps. Nice "press". I bent my flat between a bottle jack and the transfer case skidplate on my truck.

[TNToy]

Originally Posted by rockmup

TAPCO's with pre bent rails- trouble with most of them....20 or so. All using the same jig as you.

Originally Posted by JEEPRZ

The Tapco prebents always end up with the rail just a bit too high.

Okay. So you guys who've had this issue, what did you do? Attempt to hammer them down lower (doesn't look like it'd work) or just build the gun with the rails up 1/16" higher than 'normal?' Did it run if built like this?

Advice? (My two good flats look like this. The rails are within a couple thousandths of being equal (ones .005" and ones .008"ish off), so they're going to be fine that way.

[JEEPRZ]

Just place the lower rails in the correct position, disregarding the predrilled holes in them.

AKs are not too picky...it'll run just fine with them a bit high, its just not 'right'.

[TNToy]

Hoped you'd say that.

This is a weld build. Clamp everything into place where it'll function, and burn it in. Right?

[JEEPRZ]

Heat treat
Screw trigger guard/ selector stop on, clamp front trunnion in and check mag fit.
Rivet/weld front trunnion when mag is right, check all the mags you have.
Set lower rails (.250 drill bit works perfectly 99% of the time), mark holes for slotting
Remove rails to slot holes
Reinstall/ weld lower rails
Reinstall barrel
Clamp rear trunnion, check cover fit, adjust trunnion as necessary
Rivet/ weld rear trunnion.
Notch upper rail for bolt install
Check headspace
Install FCG/ furniture
Start blastin

[animator]

Originally Posted by TNToy

Hoped you'd say that.

This is a weld build. Clamp everything into place where it'll function, and burn it in. Right?

You should be fine.


The last flat I bent with that jig has a .003" difference in height, and it's just fine. It is also .02" off center. I'd take a pic but my digi can seems to be taking a shit right now...

My Yugo pre-bent flat has a .008" difference, and it's fine also. You should be good to go.

[rockmup]

Originally Posted by TNToy

Okay. So you guys who've had this issue, what did you do? Attempt to hammer them down lower (doesn't look like it'd work) or just build the gun with the rails up 1/16" higher than 'normal?' Did it run if built like this?

Advice? (My two good flats look like this. The rails are within a couple thousandths of being equal (ones .005" and ones .008"ish off), so they're going to be fine that way.

They were not my flats ( i just bent them) but the guys all bent the upper rails flat and ran them. They just lived with it like that. It seems to not make much difference. not even when they are out of square some.
They all ran as is.