Sprocket for Fireworks Machine

[pyronaught]

This is a chain sprocket for a machine used to wrap fireworks shells with paper. This one piece part replaced about four separate parts previously used to fasten a commercial sprocket to this metric D shaft. Being able to make a perfect fitting D shaped bore built into any size sprocket I want is awesome

I eventually want to try and get many other parts converted over to printed ABS in a redesign that makes everything more adjustable. The metal version is very troublesome to adjust for different shell sizes. Not having to worry about the machineability of my designs really opens up some doors to what can be done here.

Here's a video showing what the machine does on a small shell (the size you can buy at fireworks stands). It can go all the way up to about 5" diameter, maybe even 6". Lucky for me, my neighbors love fireworks!

https://www.youtube.com/watch?v=bdkxFFg ... oXccpORKLA

If your curious how well the fireworks made on this machine perform, here's a video of three shells that are the same size as the one in the video:

https://www.youtube.com/watch?v=QwgKlcg ... A&index=16

sprocket1.jpg (293.61 KiB) Viewed 8226 times

sprocket2.jpg (380.92 KiB) Viewed 8226 times

[jimc]

damn...so you make fireworks too? so is that just a hobby or you do that professionally? think i might have seen a video on discovery or something of them making fireworks. looks like an extremely dirty job. almost as bad as autobody lol.

[pyronaught]

I started out making them as a hobby, then helped out on professional displays for a while, then got really good at making them and started winning a bunch of contests, then started a website teaching other people how to make them at passfire.com, then developed some realistic simulation software for prototyping fireworks displays and scripting them to music which is my main business currently (showsim.com). So I guess you could say I make professional grade fireworks as a hobby, but I'd never want to do it as a job because it is indeed dirty and repetitive and the danger goes up when you start dealing with larger quantities of them. I've pretty much just scaled back to using the machine above along with a few other machines that make the components and just put together a small 4th of july backyard show once a year.

I have a friend that runs an auto body shop out of his house too who also makes fireworks for a hobby. Not the fancy stuff like what you do, just basic paint jobs. A lot more people make fireworks as a hobby than most people think, and the accidents are few and far between. The bigger problem is usually getting into trouble with the law.

[jsc]

Out of curiosity, what software do you use to model? And is there a standard tooth profile for chain sprockets?

[pyronaught]

Out of curiosity, what software do you use to model? And is there a standard tooth profile for chain sprockets?

I use Rhino 3D for everything. There probably are some standard tooth profile dimensions on the internet somewhere, but I just took the dimensions off an existing sprocket that I had. Rhino has a Polar Array feature that makes it pretty easy to take a single tooth and duplicate it around a center point at a given radius.

Just make sure you use 100% infill for the gears like this or the hub will rip right off of it!

[jimc]

ahhhh another rhino user on the forum. i use that as well and have turned a few other users here onto it. so far everyone has given good feedback on it and really love it.

[pyronaught]

ahhhh another rhino user on the forum. i use that as well and have turned a few other users here onto it. so far everyone has given good feedback on it and really love it.

I'm a big fan of Rhino. I've been playing around with different 3D modelers since the mid 80s when the first ones started appearing for the Amiga computers and Rhino is my favorite one so far. I was using Caligari True Space prior to Rhino, which was pretty good for non-engineering applications like 3D illustrations, but Rhino has a superior user interface and can be used for pretty much all types of applications. Caligari went out of business so True Space isn't even around anymore. Corel had a pretty horrible 3D modeler for a while. I've never liked Sketchup much and think it is a poor choice for modeling objects for printing. I think Sketchup was primarily designed for architectural modeling of large structures and not small, detailed parts. The big-name engineering modelers like Solid Works of course have all the nice analysis features and add-ons, but you pay big bucks for that. Even Rhino isn't exactly cheap, but my wife was in college at the time I bought it so I was able to get the student discount and picked up Flamingo at the same time. I'm still on version 4 though and upgrading to 5 would cost me the full upgrade price so I've been putting it off.

I used Rhino to design the blimp and it was nice having the feature for calculating volume and center of mass-- both of which are crucial for blimp design. The unroll feature worked well for converting the curved panels into 2D fabric templates too. The real inflated blimp looks exactly like it did in the Rhino model. The next inflatable I do is going to go directly from Rhino to a CNC cutter, so that will be nice never having to deal with physically translating to templates.