jimmythefly

I was just looking at what other seals are available that might reduce friction/increase performance. McMaster doesn't show anything for the 1.375" ID, however there is this teflon version for 1.5".

https://www.mcmaster...526n16/=1c76sfl

I wonder if it would boost performance at all, or if it relies on a smoother more perfect bore than what we might get from the usual tubing sources. 

In trying to figure this stuff out, I found this design guide, which is just full of information.  I haven't been all the way through it yet but figured you guys might be interested.

http://www.applerubb...esign-guide.pdf

You've probably thought of these but I didn't see them mentioned:

- Make it so the magazine IS the grip. i.e. when you remove the magazine the blaster has no grip at all left. Obvious problem is that now the method used to secure the mag/grip needs to be very robust.

- Or really hog out the grip so that it is just a backstrap and front, and maybe a large base plate. But no scales at all, and the magazine itself becomes the scales once it is inserted. 

You mentioned on Facebook that you tried a 788 + K31, correct? And that it was still pretty hot, but lower effort to prime than the [k26] alone? Please confirm I'm not sure I have that correct and I'm not clear on the source of the 788 springs. 

Slightly related:

I'm thinking about ways to adjust or change the dart velocity, other than swapping around springs or O-rings. 

Is it possible to guess approximately how much internal pressure is generated by the typical [k26] set up? 

I am thinking if a small adjustable blow-off valve could be added, a person could then adjust on the fly.

https://www.acklands...ALVE/p/WWG4ZK10

Or perhaps ports drilled in the barrel, that could be covered or uncovered by rotating the barrel a bit, or rotating a sleeve that covers it. 

Looking good! What's the tube spec for the clear plunger tube? I assume it is a different material or thickness than the stock spacer tube, correct?

 

2) Use a captured hex nut recession for one of the threaded rod's fasteners 

 

 

The hard part about any of this is that you need a way to keep the threaded rod from rotating during assembly. It's not the easiest thing to do, I'm considering adding a set screw or two where possible to help lock the rod in place. 

 

By securing one nut per rod, you gain the bonus of not needing two wrenches. If you can keep the threaded rod from rotating when you tighten the blaster up, you'd be able to disassemble & reassemble everything with just a Leatherman - to me that's a big added value.

 

If you use a distorted-thread lock nut on one end, and a nylock on the other that would work fine. 

In my experience the distorted-thread type require more torque to install, which means that they will stay put and keep the threaded rod from rotating while you wrench the nylock nuts on and off. 

So you'd first install the threaded rod into the distorted-thread nut with both parts loose. Grip the rod near the middle with pliers or whatever so you don't booger up the threads anywhere important. Then slide the whole thing into place with the nut nesting inside the hex recess you have created in the 3d printed part. 

And you could always use some loctite red if you really want them to stay put. 

I have done this sort of thing before on other projects. It will be worth it to make a test part with hex recesses printed at .2mm size increments to see what size gives the best fit for the nuts you are using. 

FAIR WARNING: I have not actually built a Caliburn yet so please double check to be sure you can assemble it the way I think you can.