15 replies to this topic

[CaptainSlug]

Okay, so drawing inspiration from Carrtoon's Tec 9 and seeing if I can make something with some leftover +Bow parts I've been tinkering in CAD the past few days. Far fewer parts would have to be machined to make this compared to the +Bow.

I now have this interesting configuration. Which I decided to name the Wob+ (The Backwards +Bow).


The operation is similar to Carrtoon's creation, but I'm avoiding using too many plumbing parts. I did have to switch to a different spring from the one used in the +Bow because it had to be a larger outer diameter and it had to have a lower compression load rating.

The plunger rod is SCH40 PVC pipe with a 12-inch thinwall PETG barrel nested inside of it.

Blaster length: 16" (when not primed)

Plunger Specs
Plunger Chamber ID: 1-3/8"
Draw: 6"
Spring load: 10 lbs

I need to figure out a better way to make the plunger head. Right now I would have to make it out of solid PVC rod lathed to size, but I'll start reading up on different options.
I'll make a prototype after I finish working on a much sillier project.

Edited by CaptainSlug, 26 February 2008 - 12:35 PM.

[jwasko]

I was actually just contemplating making something along these lines, except with readily available plumbing parts.

I need to figure out a better way to make the plunger head. Right now I would have to make it out of solid PVC rod lathed to size, but I'll start reading up on different options.

I'm not exactly sure what you mean by using a "solid PVC rod lathed to size," but I was thinking of something akin to Carbon's SNAP-5:

The front of the plunger chamber would be a 1.25" to 1/2" PVC bushing (assuming the plunger chamber is 1.25" PVC), with the 1/2" hole widened slightly to allow the barrel/plunger shaft to slide through easily.

On the rear end of the barrel/plunger rod, you would use a bushing to increase the diameter of the pipe to (if I remember the size Carbon uses correctly) 0.75" PVC, with a 0.75" end cap (with a hole in it) or coupler on that to act as the plunger head.

The problem would be the seal on the plunger head...you couldn't use a standard SNAP washer setup. There are alternatives, of course, but it would make things a little more complicated.

What I am most interested in, Slug, is what you plan to put on the back end of the plunger chamber. Carrtoon used an end cap, of course, but I'm not sure I like that...it's either too hard to take off, or might come off too easily (even flying back when you fire).

Edited by jwasko, 26 February 2008 - 12:56 PM.

[CaptainSlug]

The plunger head has to be PVC cemented to the outside of the SCH40 pipe plunger rod. Rather than try to get plumbing parts sanded down to fit for me it would just be easier to custom make solid pieces using the lathe at work.
I'm hoping to just use the same o-rings I used in the +Bow (1-3/8" OD, 1" ID).

The rear of the plunger chamber is capped with a 1/4" thick polycarbonate frame piece that is bolted to the 1/2" OD rods you see that are above and below the plunger chamber. This puts the impact stress on the frame piece and rods and not the plunger tube itself.
You load a dart into the back of the barrel before priming by hinging the trap door attached to the rear frame piece.

[Gyrvalcon]

The new design is rather nifty, but without the Crossbow form factor, I think it loses its original charm.

And what's all this about a much sillier project? Do Tell...

[CaptainSlug]

This design isn't really in direct competition with the +Bow. It probably won't be shooting as far either since the spring is slightly less than half as powerful.
I just wanted to try making a slightly simpler springer that isn't 3-feet long.

And the silly project is going to remain a secret until it's finished.

Edited by CaptainSlug, 26 February 2008 - 09:22 PM.

[General Cole]

I would make an adaptable version for the +bow brackets if I was you in this project.

[Green Riptide]

I love the look, but it seems terribly unwieldy. Maybe a stock with a hole drilled through for dart loading? You could also do some fun things with BBB-style cocking if you attached a foregrip to the barrel.

Edited by Green Riptide, 26 February 2008 - 09:46 PM.

[CaptainSlug]

When this gun fires the barrel is in the forward position and then will be moving backwards in order to fire the dart, so your free hand should be nowhere near it. A foregrip would have to be added to the grip pieces.

As for a stock, it would have to be really short.

Edited by CaptainSlug, 27 February 2008 - 12:41 AM.

[GBscientist]

Doesn't having the barrel move make it difficult to aim?

[Eboreg]

You seem to be leaning towards the "trigger on the front" design lately (Arr). Not that I don't like it. Who doesn't like dual-wielding assault/sharpshooter rifles? And given what's happened to b00m13, I am grateful for your well-being. Please don't get amnesia, that would be a big loss of talent and of a "life".

[CaptainSlug]

The functional issues I see being problematic with this design are due to the priming cycle which is as follows.

1. Load a dart into the barrel by opening the trap door at the rear of the plunger chamber.
2. Prime the plunger/barrel
3. Close trap door

You can't interchange steps 2 and 3 because if you close the trap door prior to priming the plunger the suction on the dart will pull it into the plunger chamber. This would be far less awkward of a cycle if the trap door were spring-loaded and controlled by a thumb switch of some kind.

I'll have to think about how to accomplish that in a simple way.

[Green Riptide]

Well, I had an idea involving a clip, but the barrel being surrounded on all sides by the plunger kind of makes things difficult.

On a side note, the first thing to come to mind every time i see this topic is Word of Blake.

[themilkman]

Well, I had an idea involving a clip, but the barrel being surrounded on all sides by the plunger kind of makes things difficult.

On a side note, the first thing to come to mind every time i see this topic is Word of Blake.

Every time I see it I think of "World of bitches"... but that's just me....

ANYWHOOO...... What if you tried a loader sort of like a bolt action rifle on the back of the gun?

[Spectre666]

On a side note, the first thing to come to mind every time i see this topic is Word of Blake.

Yay, someone else plays Mechassault 2.

On topic: That is a cool idea and all, but I thought you were working no the ARR. I'm still really eager to see that thing when it's done.

[CaptainSlug]

I've been revising the small details of the ARR CAD files before I start machining it. My supply of plastic is kind of low so I won't be making anything new out of polycarbonate until I can take another trip to buy more scrap.

I'm rarely working on one thing at a time. I have atleast 4 projects in-progress right now. Some secret, some not Nerf-related, and some I'm making some progress on but not posting about.

Edited by CaptainSlug, 02 March 2008 - 11:32 PM.