We are going to take a short break from the lower receiver and do some work on the upper rear top cover. This piece is what holds the ejector in place and covers the rear of the upper receiver.  In the original rifle it also contained the fire control mechanism. Due to the changes that we made to the fire control system it is now installed in the lower receiver.

In the first model reproduction this piece was made with only a single rib.

However in this model we are going back to the 7 rib design as in the original. I just think it looks better and more like the original.This is the story of making that pressing.

Pressing is an interesting art and science. While we do everything in solid works their sheet metal program is not actually designed for this type of work. A lot of steps were taken to get to the design that we wanted.

In this first picture is the basic sheet steel cut out that we started with to test the new stamping dies that we made for the pressing of the ribs.

This is a far way from what the actual design will be when we stamp for the top cover.

Here are a few pictures of the top cover rib stamping dies.

This what the stamping will look like just out of the die.

Nothing ever turns out as it suppose to during the first pressing. We had are share of up sets.

With the rib design correct and the overall shape correct it was time to test out the next step. This is to bend it into the correct shape for the rear top cover.

This next series of pictures is the actual bending of the top cover. This series was to test the actual die out and before it was installed in a set of die plates.

These two pictures deal with setting up the flats in the press dies by correctly placing it to bend it.

Once correctly located the pressing continues.

As a quick side not. The press used in this operation was a 20 ton from Harbor Freight.

Once through this operation the flat will come out with a rounded shape.

But the work does not stop there. Even though it has a basic shape it still needs to sharply defined. This next set of steps shows that being done.

You will notice that several hits are done during this stage. This is to insure that the lower flange is pressed square for the entire stamping.

Now that it is pressed tight it is taken out of the die and its support and this is what we have. Still a great deal of work to be done to it. In addition it is not quite the correct overall design.

The next post will deal with more on the upper rear top cover. I hope you enjoyed this presentation so far.

Now that you have seen the concept models it is time to get into the nuts and bolts of making this. So the first step is cutting the 16 gauge sheet metal to the proper size. This is no easy task as we do not know what the starting size is. So we cut the flat to the basic die size. These are cut in lots of 10 pieces on a friend’s shear.  Then we press them.  The first set of pressings will give us a basic idea how to proceed.

About now you ask why sets of 10. There is a certain amount of movement of the sheet metal on the die as no stops have been placed in yet. Using ten stampings allows us to verify the how the stamping looks. Once this initial set is completed we now adjust the size of the flat to give us the overage required we need for overlap.  So there is another 10 pressings for the scrap bin. Now we look at the stamping to see where we can remove metal and if any cuts need to be made in the blank to give us the correct and proper looking final product. A master is made to work from.

At this point a flat sheet of 16 gauge is taken to the water jet people and cut for the proper shape. Again all we do is 10. Once cut they are all pressed.  Now we should be very close to what we need.  If the pressings are correct we then cut up the complete sheet and press the complete run. Now, as for what we do with all the extra pressings. They are used for a variety of items. Some are used for testing the amp and time settings on the spot welder.

Some are used for doing tig welding. The rest are made into art , if you want to call it that.

Now on to the pressing. The dies are set up in the four poster press that we rebuilt – this is it prior to rebuilding.

Now onto some pictures of press operations…

This shows the properly sized and cut sheet in the dies and ready for pressing.

This is a side view of the same set up.

Starting of the pressing cycle.

Pressing completed.

As removed from the die.

A few pictures of the pressing die:

Now with both halves of the receiver pressed it is time to do the touch up work.  The receivers are placed in a mandrel and all the angles tightened up and prepped for spot welding. Each set of receiver halves is clamped together with this mandrel inside to ensure that all the corners are nice and square and the angles completely formed.That is it for today. The next post will be adding the side support pieces and setting up for the first milling operation.