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Author Topic: Build methods  (Read 23196 times)

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LESchwartz

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Build methods
« on: November 11, 2007, 10:30:20 PM »
U-Drives

  • Pros:  Fast and easy.  No need to remove the barrel if the headspace is already correct.  No need for special tools.
  • Cons:  Reports of catastrophic failures.
  • Conclusion:  NOT RECOMENDED.

Screw

  • Pros:  No need to remove the barrel if the headspace is already correct.  No need for special tools.
  • Cons:  Screws can loosen (use good permanent lock-tite).  Screws can strip out.  And finally, there are reports of lateral movement receiver and trunnions, causing the trunnion holes to egg.
  • Conclusion:  YMMV.  Inspect frequently for movement, loose screws, etc.

Weld

  • Pros:  No need to remove the barrel if the headspace is already correct.
  • Cons:  Welder required.  Results are highly dependent on the skill of the person doing the welding.  There are numerous reports of cracked welds.  And finally, the heat of welding can cause the receiver to warp or the trunion to lose its temper.
  • Conclusion:  YMMV.  Inspect frequently for stress cracks in welds.

Rivet (basic)

  • Pros:  Rivets "flow" to to fill minor imperfections providing a solid fit that does not allow for movement.
  • Cons:  Bolt cutter style riveter is required to crush the rivets (or Plinker's jig and shop press).  A barrel press is required to press the barrel in & out.  Rivet crushers cost about $35 and up.  Plinker's jigs run about $150 and up.  A barrel press can cost from around $70 and up (less if you use the "big hammer" or "all thread" methods).
  • Conclusion:  Many professional builders consider this the minimum acceptable method to build a semi-auto AK.  If you already have the tools or have to adjust the headspace, you might as well rivet it.

Rivet (countersink)

  • Pros:  The receiver is pressed into the countersinks on the trunnions, providing an even more solid connection.  Besides, this is how they do it at the factory.
  • Cons:  In addition to the tools needed from the basic rivet method above, a Plinker's jig is required to dimple the receiver.
  • Conclusion:  Many professional builders consider this the minimum acceptable method to build a full-auto AK. 
« Last Edit: December 29, 2007, 01:54:10 PM by LESchwartz »
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LESchwartz

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Re: Build methods
« Reply #1 on: November 11, 2007, 10:33:32 PM »
The purpose of this thread is to facilitate a technical  discussion of the various methods for building an AK.  Please feel free to add links or comments of a technical nature.  Once the subject has been properly vetted, I'll update the original post and sticky the thread.

Larry
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LESchwartz

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Re: Build methods
« Reply #2 on: November 11, 2007, 10:41:46 PM »
Thread on the catastrophic failure of U-drives:  http://www.surplusrifleforum.com/viewtopic.php?f=40&t=32658&sid=2bbfb49886c0986cf2db518d9d12d0ec.

Thread on failure of screw builds:  http://www.sksboards.com/smf/index.php?topic=34255.0

Vector Arms sells a professionally weld built AK.  Click here for a photo (1600X624 image)

Scary weld build photos:

 

« Last Edit: December 20, 2007, 05:18:07 PM by LESchwartz »
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jkeen579

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Re: Build methods
« Reply #3 on: November 11, 2007, 11:13:14 PM »
I have done three screw builds so far with the NODAK SPUD reciever and went together without a flaw.  Used temporary loctite on the screws and all is well with that.  To me, this is the best way to go without putting out more money than what the gun is worth.  I did use 6mmx1 screws in the front and rear trunions.  Just wanted the extra stability.
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Fragger

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Re: Build methods
« Reply #4 on: November 14, 2007, 04:10:08 PM »
Understand what you are doing and YOUR limitations.
Build smart and stay healthy.
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vomSpeerhaus

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Re: Build methods
« Reply #5 on: November 14, 2007, 06:48:35 PM »
 LESchwartz ,
I must agree...that is the worst welding I've ever seen. DANGEROUSLY...pinholes, non fills, and cold welds (no fussion).
My first AK kit (a Rommy) will be here tomorrow. I have machinist background and still do my own machining. I plan to do a screw build as I've no experience with any rivet assembling. I'm still researching screw build. I want to do it safely!
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BillyBang

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Re: Build methods
« Reply #6 on: November 14, 2007, 06:54:36 PM »

Quote
Problems usually start with the loose screw behind the trigger,
and not those holding the front trunnion and rear tank to the receiver.

Sounds like a good signature line. ;)

BB
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LESchwartz

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Re: Build methods
« Reply #7 on: November 14, 2007, 07:42:25 PM »
Quote from: Fragger on November 14, 2007, 04:10:08 PM


Hey, I've seen that photo before!  If so, that was a factory built rifle.  IIRC the final conclusion on it was failure due to the bolt slap split the trunnion (headspace related).  But that diagnosis was from the photos, and not from an inspection (the owner de-milled it before sending it off to anyone for analysis).

Larry
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7.62x39

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Re: Build methods
« Reply #8 on: December 20, 2007, 09:43:51 AM »
The thread that some of those weld pics came from.
http://www.homegunsmith.com/cgi-bin/ib3/ikonboard.cgi?act=ST;f=24;t=8374
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LESchwartz

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Re: Build methods
« Reply #9 on: December 29, 2007, 01:58:15 PM »
Several folks have asked me what a "plinkers jig" is.  Here's a link with some info:  http://pookieweb.dyndns.org:61129/ak/rivet/rivets.htm.  Below is a photo of the jig set up to do countersinking.

Larry

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BROSkeeper

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Re: Build methods
« Reply #10 on: January 27, 2008, 09:26:37 PM »
I have done two screw builds. One Romy off a receiver I bent with a jig I made myself :shock: The magwell was a little tight on it. Fixed it with a file and shoots great. 5 or 600rds good to go. My frist build was a Yugo m70ab2 It was non matching. I got it to play with. I used a blank rec. for this one. I had a cheap drill press, spot welder, and a dremel. These were stepping stones for me. I only do rivet builds now. If you do an screw build you should be able to rivet it later if you didn't drill too big :(
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Messiah Jones

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Re: Build methods
« Reply #11 on: February 10, 2008, 03:49:21 AM »


 What do they mean that "Problems usually start with the loose screw behind the trigger"? That scares me because I'm too cheap to buy the trigger guard rivet jig and I thought it wasn't that important, hence I could use screws there.

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Fragger

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Re: Build methods
« Reply #12 on: February 10, 2008, 11:34:51 AM »
Ummm the loose screw behind the trigger as in the individual pulling the trigger.  :lol:
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LESchwartz

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Re: Build methods
« Reply #13 on: February 10, 2008, 12:13:22 PM »
Quote from: Fragger on February 10, 2008, 11:34:51 AM
Ummm the loose screw behind the trigger as in the individual pulling the trigger.  :lol:

 :lol:
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Messiah Jones

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Re: Build methods
« Reply #14 on: February 10, 2008, 05:07:33 PM »
Quote
Ummm the loose screw behind the trigger as in the individual pulling the trigger. 


 :oops: OMG, why did it have to be me?  :oops: LOL
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