GunLab (KnownHost) » Sheet metal pressings

Building the semi auto MP-44 part 5

Chuck — Thu, 09 Jun 2016 08:00:34 +0000

This is another update on Pete’s project of making a semi auto MP-44.

In this post Pete goes over making the replacement pieces for the lower receiver area.

As with everything in the making of this rifle there is a great deal of trial and error.

It is interesting to see the tooling that Pete make to do the work necessary to complete the task.

There is a great deal of hand fitting and filing in this project.

It is looking better and better.

Pete is a master metal smith. I am impressed with the quality of the work that he has done on this project.

Building the semi auto MP-44 part 4

Chuck — Tue, 03 May 2016 08:00:19 +0000

This post deals with just one of the small stampings that goes into making a MP-44. he part being make for this post is the sheet metal reinforcement for the back of the magazine well. This simple part closes the rear of the magazine well, strengthens the rear of the magazine well, addes extra support for the magazine catch area and provides a guide for the magazine.

This is what the part looked like after being removed from a torch cut receiver. There is not much there that is useful, however with a little work a new part can be made.

The first step is to measure out the part and then design a female stamping die that will meet the contours of the part.

Once verified it is time to move onto the next part

In this case the next part is the male die. As this process is being accomplished a number of stampings are done.Generally nothing happens correctly the first time.

Now the die is added to. The complexity of the die either requires a cnc machine to make it or a fabricated die has to be made. Due to the lack of cnc yhe die was pieced together to form the required shape.

After the stamping dies are completed then it is time to work out through trial and error the proper shape of the blank.

Not comes the moment of truth. If everything works properly then a good part will be made.

It took a great deal of work to design and make the press tools that were necessary to make just one simple part.

Building an MP-44 semi part 2

Chuck — Mon, 21 Mar 2016 08:00:35 +0000

This is the second in a series of post of Pete, a friend of gun lab, building his semi-auto MP-44. From our previous post you could see the absolutely dismal condition of the cut up receiver pieces that Pete had to work with.

You can see from these pictures that there was no back section. So the only answer for Pete was to design the tooling and make a new rear section. This is that post.

In this photo you can see the style of the female die with the cuts for the ribs to be pressed in.

As with all stamping work to obtain the best possible product you must have a flat that is the same and you must have a method of properly locating that flat.

This male stamping die is much more complicated to make then most people think. All this tooling was made on a manual vertical mill.

With any press tool you have to have guide and alignment pins to obtain a quality product.

Pete does all his pressing on a simple shop press.

To fabricate the rear pieces it take multiply set up’s.

Some real nice tooling to make his rear section.

This is not a simple process to make the rear sections.

You can see for this final photo the quality of work that Pete produces.

If anyone is interested in a replacement section drop me a comment and I will forward it to Pete. He has a few of these left.

Building a MP-44 semi part 1

Chuck — Mon, 14 Mar 2016 08:00:29 +0000

In previous post we showed the process of machining out a MP-44 trunnion. To test that our trunnions are correct Pete, a friend of gun lab and owner of the trunnions, has started a project of rebuilding a badly torched cut receiver.

It must be stated up front that Pete is licensed to manufacture weapons up to and including machine guns. This rifle however is being made as a semi auto only and not a machine gun.

This article is a number of posts as the work required to rebuild this rifle is extensive. You can see from the Photo’s just how badly it was destroyed.

By most peoples standard this would be just junk.

However, to a master metal man this is just a challenge.

A great deal of fitting and fixturing is required to assemble this receiver.

A fixture is made for everything

In the next installment we will discuss making the new back piece.

Another sheet metal pistol

Chuck — Wed, 13 Jan 2016 08:00:50 +0000

After my post on Axel’s home made sheet metal pistol I came across another one made by Clinton Westwood. In the following videos produced My Clinton he goes over the process that he went through to make a 25acp pistol from this set of plans.

Part 1 This deals with making the magazine.

Part 2 deals with making the frame

Part 3 is making the fire control group

Part4 Is making the rails and slide

Part 5 deals with making the frame web and trigger guard

Part 6 is making the barrel

Clinton has put together a nice set of videos describing his journey and he has made a very nice pistol.

Lower receiver support pressing for VG1-5

Chuck — Fri, 13 Nov 2015 13:26:20 +0000

In this video we are pressing the lower receiver strengthening piece. This piece effectively increases the support metal around the front barrel support from 1/16 of an inch on both sides to 1/8 of an inch.

Here are a couple of close up pictures of the drilling fixture.

All the front supports pressed and drilled.

Pressing the rear cap for the VG1-5 rear housing

Chuck — Tue, 13 Oct 2015 08:00:18 +0000

This post deals with pressing the cap for the upper housing. We start with a laser cut blank that has been de-bured.

And using the pressing tool.

We end up making the cup that going into the rear upper housing to be welded in.

This is the video of that process.

VG1-5 update

Chuck — Mon, 07 Sep 2015 08:00:44 +0000

This last 2 weeks has been spent working on the lower receiver of the VG1-5. This weapon was originally design by the Germans to use the most basic of materials and machined tools. There was a very large amount of hand fitting during the process of making this rifle. All the sheet metal that was stamped was done with basic tooling and each rifle was individually fitted. This is the video that shows the first in a series of steps to assemble the VG1-5.

With this phase completed it is on to the next step.

AR-180b upper receiver

Chuck — Wed, 19 Aug 2015 08:00:41 +0000

Here At Gun Lab we actually have a number of projects going on. While we are waiting for our heat treating to come back for the VG1-5 and AR-180b parts we started on the AR-180B upper receiver. This receiver is design to fit on the Nodak-Spud lower as well as the AR-180B lower and the original AR-180.

The project was started July 20th when a friend sent me a original flat for the AR-180. That evening I sat down and started the solid model drawing for the upper receiver. It was not a priority project here and was put on the back burner until the projects on the mill were completed. However, by July 30th I had completed the solid model and had completed the first set of basic modelling for the stamping die.

This first picture is of an original AR-18 flat that has had ribs pressed in.

This picture shows what it would look like after the next stamping. The basic shape is cut out.

The next step that was performed was to bend the bottom tabs.

The next step was then to punch out the ejector port and cocking handle opening.

With the advent of technology we have made a few changes to the process in which this part will be made.

In looking at an original AR-180b upper you can see a few of the manufacturing changes. Looking at these pictures and at the actual part you can see that a laser cutter was used versus stamping them out. The cost difference is huge.

What we have done is drawn up the receiver then changed it into a flat design then had that laser cut out of the proper material and thickness of sheet metal

Next we started working on the stamping design.

Once the basic design is completed we start working on each component of the design and changing the parts and assembly as we go along. Finally we come up with a working model.

Then every part and component is accurately located and attached.

Down to the pins and screws.

Once this is done we start making each of the individual pieces. Starting with the basic stock.

To the final products.

The next step and post will be the assembly then off to testing.

This is were we stand now on 8-17 and starting from 7-20. Less then 30 days from concept through design and modeling to programming and machining.

Not bad.

MP-44 trunnions update

Chuck — Tue, 18 Aug 2015 08:00:12 +0000

We finished the first 6 test sample MP-44 trunnions to the buyer. This is an update report on the product. At the time we made these we had no flats to test them against so certain measurements could not be verified against an actual matching part. This lead to a couple of minor dimensions that would have big effects.

The first in the button hole that is one of the points that a sheet metal pressing sets into the trunnion properly. The hole dimension was correct, however its position was off by a very slight amount.

A .5mm in one direction and a 1mm direction in another. Small but important. Now with the solid models changed this will no be a problem in the production run.

The second problem was one of our radius was off. This radius allowed the flat to set next to the trunnion.

As you can see in the picture the radius is incorrect and not allowing the flat to set properly to the trunnion. Most likely this was a file and fit part of the original manufacturing process.

This is what it should look like.

The remaining test pieces will be corrected and sent to Pete to test prior to making the final production run.

Some of the differences that we have come across that need to be addressed when reverse engineer a part. What are the tolerances that we have to deal with. An example of this is the trunnions that we are working on. We just receiver a second cut original cut trunnion and have found the following differences. First with the original trunnion that we received there is .010 difference in parallelism between the two sides. the width difference between the first trunnion and the second one is .015 measured over the complete part in both cases. Now between our part and the first one that we started with we found our parallelism to be .003 and the difference between the two parts .003. So now the question is what is the max width. Are we over because the first part we tested was at max or are we in spec. The next step is to put the part in a receiver and check it out.

Reverse engineering is a great deal of work. Here at Gun Lab we do a large amount of it ranging from simple to almost impossible projects. In fact we currently have one our plate that has taken 2 years to get to basic drawings, now comes the hard part of checking it against every other component. Just to grasp the project not every minute has been spent on it and lucky the owner of that project is not driving me crazy and understand the complexity of the task he is asking. However it will be perfect when it is done. Everything has to checked, re-checked and then checked again, not an easy task and sometimes very frustrating but in the long run worth it.