Mission: to make a 'Vitamins' kit for the Rainbow. By Vitamins, I mean the the catch, grip, and trigger. From the build writeups I have been reading, these seem to be the most kludged together bits while being vital to the operation of the blaster. I want to make these and release the plans under an opensource license so that anyone with the desire to do so should be able to reproduce it with the right tools.
Improvements over current offerings:
Material: must be inexpensive, durable, low friction and commonly available
Assembly: should not be 'Fiddly'. The assembly instructions should be easy to follow and quantifiable. i.e. they should not include words like 'tweak', 'fiddle', or 'play with it until it is right'
Longevity: Wearing parts are to be limited to Commercial off the shelf COTS items wherever possible. Ideally, 10,000+ cycles is the goal.
Installation: should be able to be done with only a drill, and hardware
To do this, I am going to break it into 4 development stages
1)the Catch
2)Grip and trigger
3)Assembly Jigs
4)Installation and servicing procedures
Part 1: The Catch
From what I can tell, this is one of the most important pieces and one of the hardest to remove and service if something goes wrong. For my first iteration, I am working with HDPE because it is cheap, strong, abrasion resistant and easy for me to work with. I like to work with it because I can cut it at quickly in my CNC router and if I run out or mess up my last piece of stock, I can just run over to Walmart and pick up a cutting board and get back to work.
Design criteria:
For a catch to function as a catch it has to at a minimum:
Catch the plunger every time
Hold the plunger (no accidental release)
Release the plunger easily when the trigger is pulled.
This is something that most designs out there do well. The goal of my design is to refine the basic design and make it more durable, reliable, and easier to service.
The most important change I am making to the basic design is to add Nylon bushings to allow the plunger rod to slide as friction-free as possible while reducing slop and binding. I am going to add MDS-Filled Nylon Bushings (Mcmaster Part# 6294K444) because it is inexpensive and have good wear resistance.
On to the design:
Since this is a minor change to an existing design and the parts themselves are rather simple I drew it up in Inkscape. After a bit of drawing,
I generated some tool paths and cut out some pieces on the router.
and with some thought, I figured out a nice assembly procedure which I will take pictures of and write it up soon.
The parts came out a bit smaller than I had hoped with and OD of 1.34" but that can be fixed easily enough, the ID on the other hand was almost exactly perfect for the bushings I plan to use at 5/8" (0.625")
I am considering adding a channel to keep the catch plate centered and retained in the assembly.
Edited by Aeromech, 23 November 2015 - 03:03 AM.
