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Thread: Hk/Cetme flat bending and weldments

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    Hk/Cetme flat bending and weldments

    Well ive pretty much given up on finding a PTR91 receiver for a HK/Cetme project ive been sitting on, so now im looking at getting a flat and parts to make a receiver. Question is,can someone bend it for me and tell me were the receiver pieces get welded in? Roger.
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    Quote Originally Posted by Roger Davis View Post
    Well ive pretty much given up on finding a PTR91 receiver for a HK/Cetme project ive been sitting on, so now im looking at getting a flat and parts to make a receiver. Question is,can someone bend it for me and tell me were the receiver pieces get welded in? Roger.
    Only if they are an 07 FFL

    BATF says a flat becomes a receiver when it is bent. Once it is bent I believe you could take it to a shop that does TIG work and get the welding done, but you can't leave it there and come back later (that is considered a transfer).

    Have you contacted any HK builders about this? Doesn't seem like a completely off the wall service to offer really, at least not to me.

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    I was going to do the welding. I was understanding that once it was welded it became a receiver. I was trying not to have to buy a bending jig for one receiver. Ok, well can anyone tell me were exactly the weldment go into the receiver. Roger.
    Navy Chief (Retired)

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    Gotcha, I sure understand wanting to avoid buying a jig for just one flat (I'm in the same boat at the moment). I was thinking of building one since the concept is really pretty simple, something like this one, but with some guide rods that locate on those tabs the flats have now:
    2010-04-24_083146_Jig3-3.jpg

    As to locations, most of the build threads around here are pretty old, and we may have lost the pics at some point, but you can start here:
    http://www.militaryfirearm.com/Forum...tme-amp-HK-FAQ
    Its one of the stickied threads with useful links.
    You can also look for info on weaponsguild.com's forum, there are a number of builders from here who hang out there too.

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    holescreek's Avatar
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    There's a new home made bending jig idea that's been used a few times on WBZ that only requires a section of unistrut, 20mm bar, and some all thread. Maybe one of the fellows that's used it will chime in with pics. No need for fancy bending jigs anymore.

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    Quote Originally Posted by holescreek View Post
    There's a new home made bending jig idea that's been used a few times on WBZ that only requires a section of unistrut, 20mm bar, and some all thread. Maybe one of the fellows that's used it will chime in with pics. No need for fancy bending jigs anymore.
    Sounds great to me. What is WBZ? I don't see a thread about it on weaponsguild, but I've not looked around extensively yet.

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    Here you go. A little expensive, but cheaper than buying a flat, a jig and the time spent bending and welding it. In stock at the time of posting this.

    Edit: Make sure to check the Welded option.

    http://brethrenarms.com/product/ptr-...pped-receiver/

    ptr91receiver-8_867_detail-300x300.jpg
    Last edited by scottz63; 06-21-2016 at 11:11 AM.
    14EH AIT Instructor-PATRIOT Fire Control Enhanced Operator/Maintainer

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    Senior Veteran Mike928's Avatar
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    Quote Originally Posted by jdowney View Post
    Sounds great to me. What is WBZ? I don't see a thread about it on weaponsguild, but I've not looked around extensively yet.
    It will be kinda hard to see a thread about WBZ on weaponsguild since is a builders forum myself and Holescreek run and since the folks on WG love us so much! LOL!

    Anyways, I recently used the jig Mike mentioned and successfully did an MP5 flat. I will gather some pictures and give a bit more info shortly.
    Last edited by Mike928; 06-21-2016 at 08:51 PM.
    WBZ

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    Senior Veteran Mike928's Avatar
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    The original idea wasn't mine. Is basically using a unistrut as the jig with a 20mm rod to push the flat...

    I have been hesitant to try this because I could see all kinds of things that could go wrong with the idea..

    My main concerns was the flat forming a peak on top since you are not really pressing against a "female jig" that has the correct curvature, the other concern was the strut spreading apart. I also thought that tightening the nuts to bend the flat was going to be a bitch....

    None of those was an issue to my surprise! actually tightening the bolts takes very little effort.

    The strut is freaking perfect!

    Now, I had an "improved " design and I started building it but I just had to give it a try the simple way first and see if it worked...it doesn't! )

    When you start tightening the nuts the only thing you accomplish is to "bend", flex actually not permanently bend the 20mm rod,

    My "improved design" was gonna have two pieces of angle iron reinforcing the strut on the sides and I cut a shallow 3/8" channel on top of the rod with a plan to reinforce it with flat plate and use that to draw it down. I never got that far because i wanted to try it out but that channel was what made bending possible.

    I would put some tension in the nuts, cause the rod to bow and then smack the 3/8" flat bar with a hammer ...it worked perfectly.

    I guess if you have a press then hammering is not needed or if you can device a way to push it down with a C clamp (the clamp method could prove a pain in the ass to keep applying pressure straight down and is why I did not try it.

    Either way it works as a jig and if you have a press it would be no different than any of the fancy jigs out there.

    here is the carrier drop test.

    https://www.youtube.com/watch?v=yVN8qHIxvr4
    Attached Images Attached Images
    Last edited by Mike928; 06-21-2016 at 06:12 PM.
    WBZ

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    holescreek's Avatar
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    Dont forget to cut a clearance notch in the unistrut to clear the ejection port lip.

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