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dskippy

Member Since 06 Feb 2013
Offline Last Active Nov 07 2017 10:29 AM

Posts I've Made

In Topic: Caliburn: Mag-fed Pump-action Springer

30 March 2017 - 09:23 AM

It's going to stick out if you've got a square - it'd need to interface with the catch throughout the whole cycle, and the catch is basically also the stock buttplate here. It needs to be an omni-catch because it's also a floating catch, and it's tough to make a floating square PR. Even if you did, you might still need to omni-catch as you can't control the PR rotating in the cylinder if it's floating.

 

Oh right I forgot that the whole plunger is free to rotate.


In Topic: Caliburn: Mag-fed Pump-action Springer

30 March 2017 - 12:15 AM

An omni-directional floating plunger rod cannot be made from square stock because rotation would prevent it from fitting through a square hole. And you don't need a machine lathe for the plunger rod (but you do for the ramrod and bolt core), you just need to cut the ends squarely.

 

Yes an omni-directional floating plunger rod cannot be made from square stock... but if your plunger rod is square, and thus unable to rotate, it doesn't need to be omni directional, right?


In Topic: Caliburn: Mag-fed Pump-action Springer

29 March 2017 - 04:02 PM

This is amazing, CaptainSlug. Well done. I've been wanting to build a mag-fed, pump-action blaster for a while. Thanks for the great write up. I might try to implement this.

 

I have a question about the plunger rod. I notice you're goal is to reduce inner cuts with the scroll saw. Effectively reducing the difficulty in making the blaster. Inner cuts can definitely be pretty annoying to accomplish. But the rod plunger rod is also tricky because you need access to a machine lathe. I like to use square plunger rods because they're easier to make. They can be cut with a scroll saw and they don't rotate so they only need a notch on one side. I wonder if you've ever considered a reuleaux triangle drill bit. They allow you to drill square holes. Since the plunger rod is only one size, you'd only need one special reuleaux bit for the whole project. This might enable you to use a square rod and eliminate the machine lathe process.

 

I ask this mostly because I am considering doing just just if I duplicate your design. Not necessarily to try to sway you toward square rods yourself. I'm wondering if you have thought of this and think there's some reason to go with the round rod anyway or was it just not considered?

 

The reuleaux bit is a really nice solution that I think should be more well known in the NerfHaven community. There's a lot of square holes out there being cut with scroll saws. In general, most plunger rods are the same size too, so most nerfers would only need one bit total in their shop. I actually use an X-Carve CNC for my templated cuts so square is really not a big deal for me anyway.

 

Well thanks for the great write up! Looking forward to seeing any tweaks you make to it.


In Topic: Air cylinder for pushing darts through clips.

15 December 2015 - 12:13 AM

Hey guys,

 

I made some progress this weekend. Here's the printed out mag well.

 

magwell_zpsa9cxjqnb.png

 

The printed part came out alright, though it definitely needs some adjustments. The space for the magazine's directional tab is too small and the holes for the bolts too big. It will do just fine for the first round though.

 

I've also gotten the air cylinder, QEV, and DCV in the mail. Here's the basic setup for the first test.

 

setup_zps2ibwd65w.png

 

I need to make the inside of the chamber (the PVC tee joint) as laid out in this thread. I also need to machine the ram rod that I just got in the mail today. It's 9/16" Derlin rod that will go on the end of the air cylinder. Hopefully I'll have a video demonstration of the whole this working next weekend.


In Topic: Air cylinder for pushing darts through clips.

11 December 2015 - 06:04 PM

But, thinking about it more, friction takes over sometime before pressure equilibrium is reached let alone a vacuum is formed. Therefore, an ideal length barrel would never form a vacuum and opening/venting the chamber would do nothing.

 

Yes but in the context we were discussing this, we did not have an ideal barrel. We had a barrel that was too long and we were planning to put a measuring stick down the barrel to see how far it got. So the statement that a lack of a vacuum could potentially increase performance is valid. Though I definitely don't know how the lack of a vacuum vs. the friction would play out.

 

One thing I can do is find the ideal barrel length first by firmly sealing the back of the barrel and not allowing the ram to retract. After that is done, I could test performance in an ideal length barrel and see if performance is affected.