By the end of Part III, I had a working forward charging mechanism.... and realized I was doing it wrong. This post is all about the redesigning of the forward charging setup and handles. The main difference is that I am going to stack the linear guides vertically instead of side by side.
Let's get to the details.
The side-by-side setup I had working in Part III of the build didn't allow the right and left-side charging handles to move independently from each other. There was also more "slop" than I wanted in how the handles were moving. This slop felt like it would end up being points of failure down the road.
My new approach is to stack the linear slides on top of one another and then use angle iron to make handle mounts that rise from the slides to above the Grey Birch La Chassis M-LOK fore end. Below you can see the rails and slides stacked. I used a pair of nuts as spacers to give the bottom slide room to move freely.
And here is how the new setup sits inside the fore end. Notice that the black button head bolt on the front end of the slide (which is the M-LOK bolt) only catches the edge of the slide rail. I'll address that later on.
This shot shows the room under the Volquartsen's barrel and the approximate location of the steel tube that I'll use to transfer the motion from the forward charging handles to the bolt.
With the slide's vertical mounting set, I started working on the aluminum angle iron that'll become the mounts for the charging handles. I'll use one piece for each side's charging handle and a third to be the front attachment of the transfer rod shown above. This setup, which will make more sense in pictures/videos below, will allow each charging handle to move freely of the other.
The next two photos show all the main components in place, with and without the barrel. The left side charging handle rides on lower slide & track. The right side charging handle and the front mount for the transfer rod ride on the upper slide.
When the left side charging handle is pulled rearward, it presses against the lefthand size of the transfer rod angle iron. When the right side handle is pulled rearward, it presses against the whole of the transfer rod angle iron. Neither the right or left handle comes in contact with the other handle. They each move independently, but both move the transfer rod mount.
As described above, the left side charging handle was only coming in contact with the left toe of the transfer rod mount. I was concerned that this would pinch under tension, so I added a threaded rod to the bottom of the right side of the transfer rod mount.
I used my hand drill and a 6-32 tap to thread a hole in the bottom of the transfer rod mount....
And you can see below how the rod extends down to catch the "toe" of the left charging handle's angle iron. The left charging handle now contacts both the left toe of the transfer arm mount and this threaded rod on the right side.
If I've got you totally confused with the various angle iron pieces and sides, watch the video below. It's a wrap around of the whole setup that shows the touch points of each component. It also has a sneak peak of the cooly-colorful charging handles that will adorn this bad boy.