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Thread: AK74 Flat Bending Problems

  1. #1
    Gunco Member Uranium238's Avatar
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    Default AK74 Flat Bending Problems

    It took me almost 3 hours last night to get my AK74 flat bent using this cheap *** jig. I had to take a rubber mallot and straighten the walls out of the flat! First off, the damn thing went through crooked and I had to back it off and readjust it! Next thing you know, the carriage bolts provided with this kit stretched and gave way. Not to mention, there wasn't a recess cut into the steel to keep the squared off area below the head secured in the steel plate. This caused the flat to literally "walk" while I was tightening the bolts in sequence! Sequence...yes that's a next one on the list, why is sequence left to right? Why not inside out? It appeared to straighten out better when when I tightened inside out the second go around after the adjustment! In the end i was hammering that got it close and level enough to actually call it a receiver. It's hard to tell how straight it really is though and I don't know if I should trust it as being perfect for the build. I am going to buy some grade 8 hex bolts, nuts and washers to reassemble the tool to see if I can bend a Krink flat tonight.

    No pictures were taken last night as I was about ready to go ape s**t after the way the thing practically destroyed my flat!

  2. #2
    Gunco Member Uranium238's Avatar
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    Here are pictures of the flat bending jig I used. It was purchased off gunbroker. It also wasn't set right out of the box for 1mm receivers like the instructions said. I had to do that myself!

    The pictures are not mine of course since it makes it look really easy, otherwise I wouldn't be posting this now would I?
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    Gunco Member Uranium238's Avatar
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    Further research pointed out that this is a derivative of the Grasshopper jig.

    Instead of using carriage bolts to tighten the steel bars against the flat, I have opted for four 3" 5/16 x 18 full thread bolts supported by nuts. I couldn't find grade 8 in Ace, but will be using the same grade two as the carriage bolts. The flaw before was since there were no recesses cut for the carriage bolts' squares to be supported in, I believe this caused the tilting of the flat in the jig and several broken carriage bolts. Literally, none survived! I'll give it another go tonight with these 3" full threads on a Krink I'm working on for my Father in Law. If I do it right, looks like it won't be a shotgun (err AK) wedding.

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    Gunco Member Uranium238's Avatar
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    Question regarding the receiver cover, or dust cover:

    after seating the newly bent receiver into the trunion, I tried to test fit the dust cover and it's loose. It doesn't seem to want to fit into the groove in the rear sight block. Is this because the receiver may be bent crooked?

  5. #5
    Gunco Veteran muttman's Avatar
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    That can be one of the problems that you have. The side pices at 90, bowed out sides just to start with. Your best bet is to think of first flat as a test run and go from their.
    Muttman. Keep up dating on progress.

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    No Hope For Me Coils's Avatar
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    If you can, post a pic(s) of your bent flat, try to get a good clear one of the end so we can see the corners.
    Also a pic will help with the top cover issue, we can say a few things to check without seeing it, but a pic should get you one answer.
    "Government is not the solution to our problem, government is the problem" Ronald Reagan

  7. #7
    Gunco Member Uranium238's Avatar
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    I FIXED IT!!!!!

    The sucker is straight! The bottom areas are nice and tight now when they were bowed before!!! Pics to follow tomorrow.

    I am really trying to find a good article on how to repaint the plum handguards and stock. It's hard to find a color match for Bulgarian furniture.


    Pictures of straightening out the receiver. After running it through the grasshopper again, things tightened up a bit. The instructions on some forums tell you to 'snug the bolts' sandwiching the flat between the steel bars. This is incorrect. You do want to torque them down, but no more than about 26-30 ft/lbs (or until you feel them a little tight). This prevents bowing and will even straighten a bowed receiver to some extent.

    I used wheel bearing grease this time around versus WD40 and ran the flat through, tightening the nuts securing another plate underneath it. Wheel bearing grease is incredibly slippery. You can see the end result is a nice and straight receiver. I did take a mallot to it again to bang it out and ensure the corners were nice and tight. I dropped the barrel assembly, bolt and dust cover on to ensure a proper fit. Sure as hell did!
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    No Hope For Me Coils's Avatar
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    That looks like it came out nice, glad to see you got it.
    Yeah you want to use a grease or a heavy oil when pressing a flat, mainly on the areas that will be the lower part of the sides.
    "Government is not the solution to our problem, government is the problem" Ronald Reagan

  9. #9
    Gunco Member Uranium238's Avatar
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    I goofed on a hole for a rear trunnion last night. It looks like I may have to use JB weld to fill in the extra material I took out of the receiver, then sand smooth prior to paint. I don't think this will be too much of an issue. The hole is just too big and oversized in area by about 2mm. Kind of looks like an egg.
    Last edited by Uranium238; 03-15-2012 at 01:53 PM.

  10. #10
    Gunco Rookie rob-cubed's Avatar
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    Did you already rivet it together? If it's a rear rivet hole that's only slightly egged out, it's OK... when you taper the receiver and set the rivet, the egging won't matter.

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