Proper sequence when bending a AK flat?

[SVT-40]

Since the hammer, trigger and center support pin holes are not drilled to full size on a AK builder flat. What is the proper sequence when building from a flat?

Is it best to drill the hammer and trigger holes to their proper sizes before bending? or leave them until after bending?

If after bending, before or after heat treating?

Same with the center support rivet holes before of after bending? Or after you have installed the rails?

[4thSBCT]

both are done after bending and after rails are installed and before heat treating

[Roccobro]

After bending. They are left undersized as the holes elongate druing the bending process.

You must also weld the rails in before reaming, or you'll be doing that step twice.

Justin

[SVT-40]

Thanks!

[7,62x39]

I always drill the holes after bending and before installing the rails, and then drill through the rails after they are welded in. I've had some bad experiences (more than once) with drilling both at the same time. The metal coming off from drilling the receiver was pushing itself between the welded rail and receiver, bending the rail out, not drilling through, and absolutely COOKING drill bits. The result was a ruined receiver, several ruined drill bits, and lots of wasted time.
I haven't had that problem, (or any) since ive been doing what i do now.

[69Mach1]

Since the hammer, trigger and center support pin holes are not drilled to full size on a AK builder flat. What is the proper sequence when building from a flat?

Is it best to drill the hammer and trigger holes to their proper sizes before bending? or leave them until after bending?

If after bending, before or after heat treating?

Same with the center support rivet holes before of after bending? Or after you have installed the rails?

Wow! You're finally building on a flat. Yay.

As chronological as I can get.

http://www.calguns.net/calgunforum/showthread.php?t=292985

[SVT-40]

Wow! You're finally building on a flat. Yay.

As chronological as I can get.
http://www.calguns.net/calgunforum/s...d.php?t=292985

Finally going native!!!

[DEF23]

I know that this won't make a difference to you guys who use an AK builder jig set-up:

But I install my rails BEFORE I bend my flats.

I don't have a spot welder (nor does anyone else nearby to me), so I do mine with a MIG welder while they are still flat.

I then modified my bending jig (home built also) to be able to fold them that way.

Then I do all of my drilling and reaming afterwards.

Never had a problem with one of my AK's yet.

But then again I have screw, rivet, thru bolt and weld built (that's welded sheet metal & not re-welded) AK's in my closet...........LOL !!!

So, I am not prejudiced against any strangely built AK's

[Roccobro]

I know that this won't make a difference to you guys who use an AK builder jig set-up:

But I install my rails BEFORE I bend my flats.

I don't have a spot welder (nor does anyone else nearby to me), so I do mine with a MIG welder while they are still flat.

I then modified my bending jig (home built also) to be able to fold them that way.

Then I do all of my drilling and reaming afterwards.

Never had a problem with one of my AK's yet.

But then again I have screw, rivet, thru bolt and weld built (that's welded sheet metal & not re-welded) AK's in my closet...........LOL !!!

So, I am not prejudiced against any strangely built AK's

There is always more than one way to skin a cat.

Justin

[CSACANNONEER]

BEFORE bending, you can use your rear trunion as a jig to drill the rear truion holes on flats which are not predrilled. If you don't do this, you end up needing to either eyeball it or use an expensive jig.

[Roccobro]

BEFORE bending, you can use your rear trunion as a jig to drill the rear truion holes on flats which are not predrilled. If you don't do this, you end up needing to either eyeball it or use an expensive jig.

I just use a piece of angle iron. Not expensive, but the decent $45 jig from Gunthings.com is made from the same stuff.

Justin

[69Mach1]

BEFORE bending, you can use your rear trunion as a jig to drill the rear truion holes on flats which are not predrilled. If you don't do this, you end up needing to either eyeball it or use an expensive jig.

I made my own jig to locate the holes after bending. Used in combination with the trunnion hole locating pliers from Slamfire51.

[Roccobro]

I made my own jig to locate the holes after bending. Used in combination with the trunnion hole locating pliers from Slamfire51.

I just came across a hammered (literally) rear trunion this morning. I think it will live again like yours!

Justin

[SVT-40]

There is a much easier, and basically free "tool" you can easily make which allows exact location of rear trunnion holes for drilling, and which will hold the trunnion and receiver during drilling. You only need two small scraps of steel, a 1/4" bolt and a washer.

Additionally not all trunnions are the same. I have noticed some minute differences in each one. This tool uses the trunnion which you will build with so there can be no drilling errors.

Of course you do need a drill press and a drill press table cross vice.

The "tool".
The angled side is for the Romanian pattern with the slanted inside milled curve on the top tail of the rear trunnion. To use it on the Romanian you just turn the jig over and mate the curved side inside the trunnion instead of outside.


Mounted on the trunnion.



Align it like this and put it in your cross vice.


In the vice. (Ignore the mess )



Move the vice until the hole in the trunnion is aligned with the drill bit.



Continued on next post!!

[SVT-40]

Continued!

Slide the receiver on the trunnion, clamp it in place and drill away. Piss right on every time!!! If your press table is real level and perpendicular you can drill both sides all in one shot. For the next set of holes just remove the receiver from the trunnion and relocate the bit to the next hole. I usually place a unused rivet into the previously drilled hole to keep everything aligned, then clamp and drill as before.


Works every time!!

I also use a block of wood under the receiver (not shown) just to be sure nothing moves as I drill the holes.


The jig is basically free, and although mine uses a bolt to hold everything together. You can actually get along without it because the vice clamps everything together so tightly that nothing really moves. The bolt just makes it easier to hold everything before you get it in the vice.


I mocked up a unused receiver and trunnion for the photos above, that's why you do not see me actually drilling the holes as well as the finished product.