Making the Gerat 05

In the last post I showed you some of the parts that had been made for the 06, this time we will chat about the o5 and do a little more detail about the making of it.

The life of the 05 starts out like any other pressing as a water jet cut flat. The initial flat were made with my band saw and file until it is some what close to what I need. Then they were stamped and checked.

IMG_1008s

Then drawings are made up based upon our findings and 10 flats are water jetted out. They are pressed and cut to determine if the metal is moving properly in the die. The final pressings are checked and measured to see if it correct. Then the drawings are again changed and 10 more flats ordered and re-stamped and the process is started all over again. Some where between the 8th and 12th time we finally have a product that we want. Once we have the flats are correct and we feel that they are ready I determine the number that I am going to make. In the case of the 05 I want to make 50 complete rifles with the possibility of making 100 total if they sell. So I order 120 flats. In theory that should make 60 receivers. However, if truth be know I am hoping to get 50 complete rifles at of that number. With each step that we take, fixtures have to be made, milling has to completed, welding set ups need to be design and tested so by the time I get to the final product a certain number of them will be reduced to scrap.

IMG_1661sIn this picture you can see one of the test sets that we stamped a year ago. This isĀ  3 out of 4 receivers that we made. All of them have problems of one sort or another. On the center one the cut for the mag housing was to far back and the lower on has a similar problem but to close to the mag housing. There was also a tearing problem on them as well. the top of the mad well was not pressing correctly and we changed the design and dimensions of the front angle piece. At the end of this process we though we had a correct design, that was not to be correct.

IMG_1660sThese 5 receiver flat are the latest batch of test pieces that we made. This group came after doing a series of test pieces were we changed the flat design and the stamping dies. There are also major problems with every one of the flats. All but the last one tore and they all had problems with the upper corner of the magazine housing.

IMG_1675scThis picture shows the tearing.

IMG_1707scAnother problem was the design of the flat.

IMG_1731s

This one shows that the flat design was not correct and would have to be changed as it left to much metal up close to the barrel extension.

IMG_1709sIn addition to the visible problems we have to cut a few of them to check metal thickness after stamping.

IMG_1667csThe dies were changed again to insure the proper metal thickness.

IMG_1666s

A few more pictures of the same stampings before and after modifying the dies.

IMG_1669s

IMG_1668sSo now with the stampings checked and re-checked we are ready to stamp out the right side receiver. From start to finish the process has taken about a year and over 100 bad stampings have been made. The good news is with the right side completed we can now used that knowledge to reduce the number of bad stampings on the left side of the receiver. Until next time.

2 comments to Making the Gerat 05

  • John D.

    Surprised you were able to eliminate the receiver tear in a single draw. Automotive practice would be to stamp this receiver in two ‘hits’. The first hit would have formed the guide rail and the receiver ring, with some formation of the magazine well. The second hit would finish the magazine well and create the bottom of the receiver. This would have allowed the blank to ‘flow’ into the guide rail during the first hit and avoid tearing.

    You can see the severe flow striations on the receiver bottom surface in Photo 5, which also shows the receiver tear. Heavy lubrication of the blank in the striation area might make a single hit process feasible.

    For prototype automotive stamping on steel dies, molybdenum disulphide NLGI 2 grease would be ‘painted’ on the surface of the steel blank which becomes the receiver bottom. You might also be able to single hit this part with a compound die, but this is probably unduely complex for these short production runs.

    Kirksite offers much greater lubricity than steel in stamping dies. Kirksite dies are one of the secrets of the prototype stamping industry. You might try a Kirksite casting for your next complex stamping die.

    • Hello John. I enjoyed your comment and it has got me thinking about solutions for a few of our problems.
      I have heard about kirksite but have never seen it in use. It is something to look into, thanks for the heads up.
      To eliminate the tearing problem I had to change the die slightly to allow the metal to flow better. I also had to modify the flat. There was to much metal in a few spots that would not allow it to flow properly. We have also changed our lubricant over the last two years based on the recommendations of our supplier.

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