20 replies to this topic

[Possemhunter]

Hello all

Haven't been around for a while. Nerfing had been largely forgotten by me for a while. I got into machining, metal casting and other fun "big people" things.

But then I was given a Make magazine and saw their homemade launcher and decided to see if I could combine nerf and my new tools.

The result was a nice single shot pistol.





In the next one, you can sort of see the catch. I don't know if this type of catch has caught on yet or not, but a while ago, everyone still used clothespin catches. This catch is simple and dead reliable. A metal plate is just pulled inwards towards the plunger rod by the small spring. Pulling the trigger drives a wedge between the frame and the boot of the catch, pushing it out of the notch in the plunger rod.


Here is the plunger head and rod. Both were machined by me of course, along with everything else. The plunger is 3/8 steel. The rod is rather heavy, but I used a nice spring and the ranges are great anyway. I have made aluminum rods before, but the catch notch rounds over and becomes unreliable.



Here is the plunger assembly. The spring rest on the rear later had a shoulder machined into it to center the spring. The mounts for the catch and catch spring are drilled and tapped into the rear of that piece.


This is the barrel assembly. The forward center is recessed for the cpvc, so on one side I drilled it 17/64 for a dart, and on the other, 5/8 for the cpvc.





This is the rear center. It has one diameter turned that fits tightly into the 1" outer sheath, providing an airtight seal for the plunger tube to the rear. It was drilled through for the 5/8 cpvc, so that it could be coated with sealer and stay secure.



The barrel and the plunger all fit into 1" pvc, which for the purposes of explanation, I will call the upper receiver. This 1" PVC acts as the plunger tube and barrel sheath. It also provides the mounting points for the pieces.

The lower receiver...


Not much to look at. The grip is screwed on. I replaced those pictures screws with flatheads for the trigger plate to pass over.

Trigger and trigger plate. In this picture, the original mounting rivet was falling out. I re-drilled and tapped the hole for a small machine screw.


The business end. From dead on, you don't see the cpvc.


Other notes

All the centering pieces were drilled and tapped to mount to the 1" PVC. You can see all the screws along the top and bottom of the upper receiver.

The "sight" at the rear is held on by one of the same bolts that goes into the spring rest.

If you look at this picture again, you see the lug about midway, just where the lower receiver starts. This is 2 pieces of PVC solvent welded on. It gives a good spot for the lower receiver to attach.


If anyone wants more detail, please ask. I didn't make this a real writeup as you need a lathe to make most of the parts. From all the draconian measures that I see going on around here, I assume many of the users are about 12, and don't have lathes. But once again, if you would like more info, just ask.


Ranges haven't been officially measured. Shooting level, it breaks 50 feet easy with a good snug dart.

I will hopefully have some videos of the range test and construction up within a few days. Bandwidth permitting.


Questions, comments, concerns?

Edited by Possemhunter, 23 July 2012 - 07:14 PM.

[Daniel Beaver]

Ranges haven't been officially measured. Shooting level, it breaks 50 feet easy with a good snug dart.

Low, considering the effort involved. Lighten up the plunger rod, make sure the seal in the plunger head is good, reduce the friction as much as you can, and you'll double the ranges. And use a cross-bar instead of a keyring for priming - your fingers will thank you. (I'm harsh because I care)

Could you show us some more pictures of the catch? I can't quite visualize how it works.

[Possemhunter]

Like I said, it breaks 50 feet because its passing an object I know to be 50 feet away. It is going much further.

Oh, another note, all of my stefans have been eaten by the lawnmower...

My plan for the plunger is to thread it and and turn a nice, easy-to-grip knob. Maybe I will knurl it. The possibilities are endless.

The catch:



Why its sideways, I know not.





Instead of the vertical motion of a conventional catch, this one pivots out of the way to the side.



Hope that helps.

Edited by Possemhunter, 23 July 2012 - 07:42 PM.

[Daniel Beaver]

I see what you did there, I like that.

SOMEONE MAKE THAT, BUT WITH MATERIALS FROM WALMART.

[roboman]

You could easily replace most of that steel plunger rod with aluminum, particularly if you turned it so two aluminum pieces threaded into a steel catch piece.

I also strongly suggest you try 4568T14 as a barrel material. The tolerances are much tighter, it's hard anodized (pretty), and 6063 is actually really nice to turn, if you have carbide tooling to break the anodized layer. The hole is also held concentric to the OD, unlike CPVC or the other common aluminum barrel material from McMaster. I use 6" of each on my aluminum barrels, press-fit together, and it works like a charm.

You could also invest a little in some Mother's aluminum polish and spin your parts up to 1500-2000 RPM on a lathe, then hold a piece of a paper towel with polish on it against the part, as you would with emery cloth. It gives an almost mirror finish. Automotive wax will protect that finish and prevent oxidation.

[KoRnEd]

Holy crap, that catch is ingenious! The only problem I see is a strong enough extension spring, which of course can be solved fairly easily. I look forward to some higher-powered blaster to utilize this.

[Possemhunter]

You could easily replace most of that steel plunger rod with aluminum, particularly if you turned it so two aluminum pieces threaded into a steel catch piece.

I also strongly suggest you try 4568T14 as a barrel material. The tolerances are much tighter, it's hard anodized (pretty), and 6063 is actually really nice to turn, if you have carbide tooling to break the anodized layer. The hole is also held concentric to the OD, unlike CPVC or the other common aluminum barrel material from McMaster. I use 6" of each on my aluminum barrels, press-fit together, and it works like a charm.

You could also invest a little in some Mother's aluminum polish and spin your parts up to 1500-2000 RPM on a lathe, then hold a piece of a paper towel with polish on it against the part, as you would with emery cloth. It gives an almost mirror finish. Automotive wax will protect that finish and prevent oxidation.

That is and idea, to thread a steel piece in. I will try to suck every bit of efficiency else where first, but I'll remember this. Heavy plunger rods never help.

I am only using HSS bits. I have heard that if you get under the layer in one pass, any bit will work. Is this true?



The catch does work extremely well. It takes up very little space and isn't prone to breaking at all. Since the catch lays flat against the spring rest, that takes all the force from both sides, which makes for a VERY sturdy build. Spring pushes against one side and catch against the other.

[roboman]

That is and idea, to thread a steel piece in. I will try to suck every bit of efficiency else where first, but I'll remember this. Heavy plunger rods never help.

I am only using HSS bits. I have heard that if you get under the layer in one pass, any bit will work. Is this true?



The catch does work extremely well. It takes up very little space and isn't prone to breaking at all. Since the catch lays flat against the spring rest, that takes all the force from both sides, which makes for a VERY sturdy build. Spring pushes against one side and catch against the other.

I would actually look into lightening the plunger rod first, as you'll see a huge performance jump if you do.

Yeah, you can do that, and the layer is only about .003" thick. 6063 is a little gummier than 6061, particularly since it's not T6-51 or T6-511. You really should look into a small set of indexable carbide tools, they're available for $50 or so, and worth every penny.

[Draconis]

As pointed out by both Robo and Beaver, plunger mass will make a huge difference in performance. There are many reasons that the majority of us continue to use primarily plastics in our modifications and homemades. I suggest acetal/delrin for the rod and priming handle.
As for the machinations within this infernal device.... Some of you may remember that I run the office of an auto shop, and have for ten years now. This has made clear, simply through observation, which engineering designs make sense and which don't. Aluminum is an excellent material for construction, but not when in moving contact with other materials. It may take a while, and I may be overreacting because of that, but those parts will wear upon each other over time.

[roboman]

As pointed out by both Robo and Beaver, plunger mass will make a huge difference in performance. There are many reasons that the majority of us continue to use primarily plastics in our modifications and homemades. I suggest acetal/delrin for the rod and priming handle.
As for the machinations within this infernal device.... Some of you may remember that I run the office of an auto shop, and have for ten years now. This has made clear, simply through observation, which engineering designs make sense and which don't. Aluminum is an excellent material for construction, but not when in moving contact with other materials. It may take a while, and I may be overreacting because of that, but those parts will wear upon each other over time.

Actually, the wear can be massively reduced if the parts are polished, waxed and lubricated. That's exactly what I'm doing to my aluminum xbow catches, to prevent excessive wear on plastic parts.

[zx532]

Some of you may remember that I run the office of an auto shop, and have for ten years now. This has made clear, simply through observation, which engineering designs make sense and which don't. Aluminum is an excellent material for construction, but not when in moving contact with other materials. It may take a while, and I may be overreacting because of that, but those parts will wear upon each other over time.

I would venture to say that the wear probably isn't too bad on nerf guns (as long as the surfaces are somewhat smooth of course)
recently my car hit an overly large bump, and the (what appeared to be) aluminum power steering line came loose and began rubbing on the axle, It still took 50 miles (at least), and more than half of which were at highway speeds, before the axle rubbed through the line. There is no way that the nerf guns will be doing anything similar

Also, Awesome pistol. Love the catch

Edited by zx532, 24 July 2012 - 02:20 AM.

[Possemhunter]

I got out my tape measures and took some test shots after lubing the gun. I lubed to plunger of course as well as the spring rest where the plunger rod is guided.

Taggers that fit a bit loose were going about 53 feet.

My very poorly made stefans from years ago were going 55 feet.

The best darts I have right now (just getting back into nerf) are cut down streamlines. They are 2.5 inches long and fit very snugly. I ramrodded those down the barrel. Shots were consistently hitting and passing 83 feet. These streamlines do not have the obnoxiously large hole in them for some reason ( just a pinprick that was loaded facing upwards), so they were quite accurate. There was no erratic flight path. I think I could easily hit someone that far away.

I'm very happy with 83 feet from this pistol. A better plunger rod would no doubt get me into the 90's.

To give some more specs I will say that the draw is 2.25 inches. The spring is a replacement from Joseph Fazzio's, the most amazing hardware store/ steel depot/ industrial supplier ever. I might have the package somewhere for a part number.

[Draconis]

I would venture to say that the wear probably isn't too bad on nerf guns (as long as the surfaces are somewhat smooth of course)
recently my car hit an overly large bump, and the (what appeared to be) aluminum power steering line came loose and began rubbing on the axle, It still took 50 miles (at least), and more than half of which were at highway speeds, before the axle rubbed through the line. There is no way that the nerf guns will be doing anything similar

1. A power steering line would be made of steel, not aluminum. The pressures involved in that system would be too high to be able to trust thin aluminum.
2. Plastic is softer than aluminum versus steel and would lose out much earlier.
3. Vehicle speed would make no difference in how fast the pipe wore through, as the axle rotates a given number of times for distance, regardless of speed.
4. Yes Roboman, we are all very impressed that you have machines at your disposal which allow you to expend four times the work to make an inferior material perform mostly okay. Good for you. If you were using acetal or nylon in place of aluminum and thus could cut out the polishing, waxing, and lubrication steps... How many more catches could you make in a given period? How much less would those plastic catches wear on ancient crossbow shells?

I don't want to be a dick here, because I really do think you make some great stuff. I just want people to stop using the wrong materials. This community of homemade builders has matured a lot in the last couple of years. Collaboration has become the norm, and we are coming up with some awesome stuff because of it. But use of metals makes homemade shift toward paintball and airsoft, rather than nerf. They have their place, specifically in pressurized applications, but otherwise are overkill.

[hamoidar]

I see what you did there, I like that.

SOMEONE MAKE THAT, BUT WITH MATERIALS FROM WALMART.

I did: http://nerfhaven.com...howtopic=22547' class='bbc_url' title='External link' rel='nofollow external'>catch
Although most, not all, people thought it was useless.

Holy crap, that catch is ingenious! The only problem I see is a strong enough extension spring, which of course can be solved fairly easily. I look forward to some higher-powered blaster to utilize this.

Heres your gun: http://nerfhaven.com...howtopic=22560' class='bbc_url' title='External link' rel='nofollow external'>gun
The extension spring actually can be rather weak, as that's what I used, and it can easily hold a [k26].

On topic: I'm glad someone got around to making on of these.(no pun intended) I bet you could hopper-it with such a large plunger tube. Good job!

[Possemhunter]

I just want people to stop using the wrong materials. This community of homemade builders has matured a lot in the last couple of years. Collaboration has become the norm, and we are coming up with some awesome stuff because of it. But use of metals makes homemade shift toward paintball and airsoft, rather than nerf. They have their place, specifically in pressurized applications, but otherwise are overkill.

Why care what its made of? It still shoots foam and is never going to wear out or break on me. Plastics get brittle. Metal will not in this situation.
There is lots of pressure on these parts anyway. Maybe not air pressure, but a spring.

For me, this was a chance to test out new tools and materials. I think everyone should try to get the most out of their capabilities and tools. The material was also free. The aluminum came from scrap lawn mower engines that were poured into castings. The waste sprues became my stock for turning.

[Righteous Fondue]

I did: http://nerfhaven.com...howtopic=22547' class='bbc_url' title='External link' rel='nofollow external'>catch
Although most, not all, people thought it was useless.

I don't see any walmart available parts in that write-up, aside from the adhesives...
This blaster, and the blaster featured in MAKE: were both over-engineered. With the supplies, money, and time you spent on making such a blaster could be spent on a +bow, rainbow, or even a SNAP, and you'd get equal, or greater results. It's nice you're learning how to use your tools, and the catch design is interesting, it's just not very ground-breaking or as easy to make for a majority of modders, who usually don't have much more than a dremel.

Edited by Righteous_Fondue, 24 July 2012 - 11:32 AM.

[Draconis]

Why care what its made of? It still shoots foam and is never going to wear out or break on me.

Because there is something inherently non-nerfy about all metallic internal components. I thought that it was completely ridiculous of MAKE to feature such a ridiculously simple design, made with ridiculously complex tooling and materials as an example of this community. If you actually use it enough, it will wear out on you. And it will probably be the aluminum components wearing out the steel.

Plastics get brittle.

Usually only when exposed to UV. Which is relatively unlikely with internal components. And is REALLY unlikely with nylon or Delrin.

Metal will not in this situation.

Sure, because cast aluminum isn't known for breaking under pressure, ever.

There is lots of pressure on these parts anyway. Maybe not air pressure, but a spring.

Yeeeaaaahh... Not any more than a [k26] spring, or you wouldn't be able to prime it with a key ring. And [k26] springs have been shown time and again to be completely contained by polycarbonate and nylon.

For me, this was a chance to test out new tools and materials. I think everyone should try to get the most out of their capabilities and tools. The material was also free. The aluminum came from scrap lawn mower engines that were poured into castings. The waste sprues became my stock for turning.

The Earth thanks you for recycling.

[proplus]

I guess we have a new roboman in the forums.

[Meaker VI]

I see what you did there, I like that.

SOMEONE MAKE THAT, BUT WITH MATERIALS FROM WALMART.

I'd had an epiphany a few days ago, that these drywall anchors:


would probably make good catches. The wings have a nut in the center that accepts a bolt, and are spring-loaded to open as shown. They'll easily fold all the way over onto the bolt. I was planning on trying to use one as a shear-catch (mount the wings parallel to the plunger pull), but it might actually work well for this purpose (perpendicular to plunger pull). They're available just about everywhere - Mcmaster has them for as low as $0.13/ea (package of 50)- and in a large variety of sizes. I'm pretty sure I've seen smaller ones than 1 1/2" wingspan.

I really like the lower receiver on this - it looks good and sturdy and not like it's too much work. Pretty sure I can even get pre-drilled u-channel at Home Depot/Lowes. Overall a really clean build.

[Langley]

There's no need to turn this into a debate over what materials are best suited for replacement parts and homemade nerf blasters.

There's already been a thread about the article in MAKE and the original design that it's based on, and I don't think there's any debate over whether it's a little over-engineered for most of our needs. It's a cool hobby project, especially if you have some nice machine tools to play with, and Possemhunter has taken an interesting approach.

So I guess I can forgive him for not fixing his location info in his profile when he came back.....for now.

[Possemhunter]

Thank you Langley. I will attend to that location shortly as well.

If anyone has anything else constructive, please comment.