Build Pics/Information Thread
 Main Discussions   Started by MotoG5   2019-02-11 17:47:49 -06:00   Comments: 9    Viewed: 138

  1. MotoG5
    MotoG5 Member
    Thought it would be helpful to start a thread where build pics and information exchange could go. The pics below are of my current DPM project.


    MotoG5, 2019-02-11 17:47:49 -06:00
  2. Bryan
    Bryan Member Staff Member
    Looking good so far!
    Bryan, 2019-02-12 10:11:34 -06:00
  3. Aaron Kroll
    Aaron Kroll Member
    What are you using for a jig to reweld?
    Aaron Kroll, 2019-02-18 13:15:09 -06:00
  4. MotoG5
    MotoG5 Member

    I picked up one of the Cajun Country DPM jigs. The jig is not really as good as I had hoped and lets just say if I had it to do over I would have cobbeled up something. I cant say its of no use at all but its not really all its advertised to be. The biggest short coming with the CC unit is that it is not possible to set your gaps for proper over all finished length once the rec sections are set on the main bar. Its fine for doing the final welds once every thing is well tacked to establish the correct overall length. My present plan is to do the tacking (tig) using the lower rec to set up the rear weld gap along with the bolt carrier to maintain alingment. Then doing the front weld tacks using the bolt carrier for alignment and a cut barrel stub to set proper length. Then use the CC jig to do the finish welding.

    This pic below shows how the CC jig sets up. The rec pieces shown are not the ones I am using now. I found a rec on line that was only cut at the front shroud threads and at the rear so the middle section where the bolt locking flaps are located is not effected. So I will only have to do two welds and not worry about the critical center weld.

    MotoG5, 2019-02-18 17:27:52 -06:00
  5. Aaron Kroll
    Aaron Kroll Member

    I've got a similar setup in that I'll be using pieces from two different kits together and having only two welds. I plan to pick up a complete receiver from SMG to use for reference as well. I dont know how much shrinkage I can expect, but I'm wondering if I tack it setting headspace with a no-go guage, if it would shrink to acceptable levels during final welding?
    Aaron Kroll, 2019-02-18 19:05:36 -06:00
  6. MotoG5
    MotoG5 Member
    Couple of questions on your project. Are you planning on using the complete rec for your build? If so all you will have to worry about is headspacing on the new rec to complete things. Are you going to do another build on a rewelded rec made up from the left over parts from your kits?
    MotoG5, 2019-02-18 20:18:04 -06:00
  7. Aaron Kroll
    Aaron Kroll Member

    I intend to do two builds. I'll use a complete receiver for the first and a reweld for the second. I'm just concerned about shrinkage affecting the headspacing. A different alternative I've considered is shimming the locking flaps if possible. I could even weld spare receiver scrap together to determine the expected shrinkage and shim the flaps accordingly.
    Aaron Kroll, 2019-02-18 20:54:05 -06:00
  8. Bryan
    Bryan Member Staff Member

    If you are using TIG, you can expect about 10-15% of the weld gap width shrinkage.  I usually overclock the barrel stub the amount I expect it to shrink based on the gap, give it four heavy tacks, remove the stub and go to filling in the rest.   

    I also don't use "jigs" for any of our projects (DP's, Bren's, ZB's, etc)  I use the original parts for alignment and spacing.  I then fill the gap from one side "up-to" but not bonding to the adjacent piece.  I do this for all joints, then remove them all from the parts used for spacing and alignment.  At this point, I back fill the internal areas up to the same surface I created earlier when filling the gaps.  I usually add about 0.015" more than needed so that I can grind the surfaces to but up totally.  I then re-assemble all of the pieces back on the parts again and finish the weld up.  Remove the newly welded parts and once again back fill the insides, then remachine all the channels, and surfaces, add any semiauto features needed and we're pretty much done.  This method makes the DP's that have been cut through the locking area and the Bren's that have been cut at a heavy angle through the front mag catch re-buildable for us.

    Hope this helps guys.
    Bryan, 2019-02-18 21:19:45 -06:00
  9. MotoG5
    MotoG5 Member
    Thanks for sharing your process. It is indeed helpful. Really like the tip on clocking the barrel stub.
    MotoG5, 2019-02-19 16:20:58 -06:00
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