SE Mesa LW Spec Design

 

LW Spec Front End

Coming in at 1.05kg (2.3lb), the original Mesa blaster isn't exactly a heavyweight, but it's no featherlight either, especially compared to other Nerf blasters. There are always benefits in lightness, so it makes sense to try and lighten the Mesa a bit. I'd be happy to get it under 2 pounds, or .91 kilograms.

Planned Modifications

Since most of the back half of the blaster is pretty buttoned up, there wasn't much I could do in the back to save weight. Thus most of my weight savings came from the front. Now this does affect the center of mass of the blaster to bias it a bit towards the rear, but that seemed like an acceptable change for a few reasons. For one, a lighter front made it a little more maneuverable, as there's less inertia when turning. Also, I wanted to add some side rails for more accessories, which would have cancelled out the weight savings in the front and biased the center of mass anyways. 

In the entire blaster, the 3D printed components actually don't weigh all that much. I think the grand total was just under 400g, with the rest of it the hardware components. Some things I couldn't lighten, such as the plunger tube, priming bars, and barrel, but I could definitely try to lighten the PVC barrel shroud and angle iron, which probably make up half of the weight. This is where I expect the most weight savings.

For the rail, I believe I can remove some material without impacting the structural rigidity of the piece. Simply by virtue of how things clamp onto it, it should be sufficient to have a few crossbars while leaving the rest of it hollow. In addition, I want to add some side rails, which actually add a considerable amount of weight, negating several of the savings in exchange for a much more flexible setup.

There's a few places where I can save some weight by thinning the components. The front end is fairly chunky, and I think I should be able to thin out some of it to save some material. It's not a particularly load bearing piece, so thinning it out should not affect performance. The paddle mag release, while not very heavy, could be made slightly shorter for a very small loss in weight. The plunger could potentially be made lighter and also improve performance by reducing inertia, although since it's load bearing I will have to experiment if I can optimize print layers to save some weight. I may be able to make the stock marginally lighter by cutting a channel down it, but it's already pretty thin and skeletal. 

There's also a few places where I am unable to save weight. The pump grip and ram components are load bearing, so I don't want to weaken them. The magwell and handle are pretty slim, so it is unlikely I will be able to make any changes to them. The plunger tube supports has already been optimized pretty heavily, so I don't think I will be able to make any meaningful changes there. 

Barrel Shroud

The barrel shroud is actually a significant amount of weight compared to the 3D printed parts, at almost a fifth of the weight of all other 3D printed parts. One way to reduce weight is to eliminate the shroud entirely, but I did not like that option because it would leave the brass susceptible to dents. I didn't want to switch to a thinner material like conduit piping either, since that would change the dimensions and be harder to source. Thus the only way to lighten it without changing the base component itself is to remove material. The easiest way to remove material is the tried and true method of drilling speed holes. It's not the prettiest solution, but it doesn't look completely out of place (barrel shrouds tended to have slots or holes for cooling ventilation) and can be done with just a drill. To that end, I put .5" holes every 1 inch along the length of the pipe, leaving about 1.5" for the parts where it is slid into the 3D printed parts. Since this part isn't structural, it wasn't a big deal to have larger holes, and it took off more weight.

To build it, I had to find a way to drill centered holes repeatably into the pipe. To do this, I built a jig that I could clamp into a drill press vise along with the pipe. That ended up working pretty well. One thing to be careful of when drilling like this is that it tends to jump a bit when it breaks through the other side, so make sure the vise is attached well onto the table, and to go slow with the feed. Otherwise you may end up with some chips off the edges of the holes, which I got for the first few.

Drilling in progress

With this procedure, I was able to cut the weight of this part by 23 grams, which is more than the weight of the muzzle piece of the blaster.

Barrel shroud before and after

Angle Irons

In the same fashion, the easiest way for me to reduce weight is to drill speed holes on the unused underside. While not as pretty as a trussed design or slots, it is the only machinable method I have at my disposal. Figuring out where to have the holes is the challenge. The only safe place is the underside of the front, where the slide is. Since the pump grip slides along that rail, no attachments will ever be screwed on that face, so it is fine to drill holes there. The side profiles of the rails are most likely no-gos. The midsection is where the magwell and handles are, and may intrude with comfort as they are high touch areas. This leaves just the bottom rear as the only other available place to drill. However, I'm not sure how I would like to make use of that region, and I may redesign some of the mounts in the Mark II version of Mesa to utilize the bottom side more for a cleaner side profile. Ultimately, I decided against doing this in the meantime, and left it as a complete rail.

Tactical Rails

This was a bit of a wash, as I wanted to remove weight from the existing rail, but also add rails on the side of the blaster, which added weight. It ends up being a net positive increase in weight, but I also gained another foot of rail space. Alternatively, I could cut the increase in half by using just two rail sections for half the space. 

The top rail was pretty easy. Since the majority of the rail will almost never be used for any optics, I could simply cut out the middle. Every fourth segment has a crossbar to maintain rigidity if something does get clamped on, so the strength isn't affected as much.

I decided to make the side rails removable, because 90% of the time, I don't have a reason to run them. Luckily, the entirety of the side of the angle iron is unused, so I decided the best way to make it usable was to have evenly spaced holes across the entire side. This way, I could attach the rail anywhere along the length, so that it won't affect the balance of the blaster. To prevent conflicts with the pump grip and handle, the rails are slightly canted inwards. They are attached with the same screws used on the rest of the blaster. I left enough space for two 3" rails on a single side, if anyone needed that much rail space.

Summary

The end result is fairly subtle, but makes some major quality of life improvements in the capabilities of the blaster. While it doesn't add any performance improvements, the slightly lighter weight and extra rails make it more maneuverable and adaptable to changing environments. As always, the blaster is always a work in progress, and there are many other places that can be improved upon. My next focus will likely be creating a lighter plunger head, as reducing that mass should net some serious performance and durability gains. Until then, this is enough to tide me over for a while. These upgrade parts can all be found on Thingiverse if you would like to upgrade your own Mesa.

LW Front, double side rails

LW blaster, single side rail