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Poor man's pin buster

7K views 16 replies 13 participants last post by  jkarlc 
#1 ·
Here's the score so far, Max's pin buster 8, Romy pins 0

Some of these Romy's are real bears to get out, I've read a lot of horror stories lately, with lots of folks having to resort to heat and/or drilling to pop these thing loose.

I think the major problem is getting the trunnion to remain flat and fully supported while pressing.

The pin area of the trunnion is relieved half way around by .118 and the remaining area of the trunnion is .040 low once the receiver stub is removed.
This leaves precious little flat surface to work with.

I found a 1/2" SAE washer .118 thick, and cut off 1/4 of it.
This fills the missing area around the pin perfectly.

I then took one side of a receiver stub and welded both pieces to a piece of 3/8 steel plate, drilling a hole for the pin to come through.

The upper rail engages the trunnion and locates it properly.

Between the washer and receiver stub, the trunnion is 100% supported and the pin remains perfectly perpendicular to the press.

Now the only rock and roll I have is on the radio
 

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#2 ·
Here is the other half of the equation.

I took a piece of 1-1/2" black iron pipe welded a steel plate to one end.
Then I took a 9/16" lag bolt and cut off the shank section, rifle drilled it and welded it to the steel plate.

I bought some 15/64" hardened drill rod, cut a short piece for busting them loose, then a longer piece to push it out.

I drilled and tapped two holes for set screws.
One holds the drill rod in, the other secures the pipe to the ram of the press.
 

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#7 ·
Vulcan,

I have one like that also, one of Plinker's.

I have used it on many builds with good success on most builds.
On some really tough ones, like a few of the AMD65's and a lot of these Romys, I had some trouble with the trunnion trying to roll.

No matter how well the rest is supported, the pin hole area it's self is still only supported on two sides.
The cut up washer is the key. I would use it even with your aluminum block
 
#16 ·
(disclaimer - I'm on the beginning portion of my very first AK build, on a Romy kit)

I saw the first pic in this thread the other week, but didn't read much of the rest of it (short attention span strikes again). Grabbed a washer of about the right size, and after filing a notch in it for the pin, gave it a test fit. I suppose I should have checked the thickness first :tongue:

Figured I needed a plate to keep the trunnion flat and steady, so a grabbed a small piece of aluminum plate. I machined a recess for the area around the pin, a hole for the pin to push through, and a divot for the handguard lever thingy:



I then planed the back side to the requisite thickness:


A wrap of masking tape held it in place while in the press (used the 50-ton at work). Last piece of the puzzle was what to use as a pin to press out the barrel pin. I figured out the hard way that a piece of plain stainless rod won't cut it (amazing to see the end just moosh over like play-dough), so I dug in the scrapped tool bucket and found a snapped off tap shank. Drilled a hole in a scrap of aluminum bar to accept the shank (drilled a few thou undersize), then drove in the shank with a whack from a BFH. Viola - a push pin in a holder:



I figured that securing the 'pin' in an aluminum base would keep the pin from tipping over when pressure was applied and very suddenly going *PING!* in my general direction. Worked beautifully! According to the gauge on the press, it finally broke free at around 6-7 tons, and pressed on through with increasing ease. Now to pull the barrel!
 
#17 ·
Great idea with the washer! I just finished popping the barrel pin using this method along with an old vise. Since I don't have a welder (on the tool list), I epoxied the washer pieces (used two different sizes to make thickness) to a piece of scrap steel and drilled the relief hole. I used a rounded bit driver along with a 16" pipe wrench cheater on the vise and it worked great.
Thank you, thank you, thank you...
Now, to figure out how to pop the FSB without marring the barrel.
I'm having way to much fun!
 
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