Prototype Big gun cannon (New design and operating theory)

This is a placeholder to remind me to put up pictures as the first build progresses slowly. but first a big shoutout to cannonman who cranked out a couple of prototype cannon parts for me (the only parts that require machining in this design that can't be done via dremel)

I will post some pictures as I get time to work on them (and get the required parts in the mail). At that time I will post the theory of operation and any test results sofar. I expect at least 3-4 iterations on the machined parts assuming it can be made to work well. the prototype is designed around 1/4" shot.

-Greg

 

And now for the quick one barreled mockup no more teasers until I get in more hardware. that part is the only set of parts that can't be readily produced with a drill/dremel tool by anyone. Shown below again, is the 1 barreled start... should that work the plugs in the side will be removed and two additional barrels will be added.... making one up tube to the breech for 3 barrels.....

 

o-rings and steel barrels are on order... a non-optimal brass tube size is on order also (what I wanted was just too expensive for what it was, and I have a stub to check to see if it is really needed).

I plan to do as little permanent assembly as possible to test the single barrel configuration, if that works as planned, then we will see. I just hope I don't need any shims for th breech, although if I do I'll figure something out

-Greg

 

if it works (or doesn't) I will let you know. I plan to test the single barrel config first.... then multiple... now if gainful employment would only come faster I would be able to get more done


edit... passed first test tonight. no o-rings but rounds feed and are selected properly for the 0th test.... many more to go but that is a good start.

 

nope.. and the standard O-rings for the parts are a non common mix. the large one is metric, the small one is well, small

 

yep. everything should come in early next week for the feeding check tests.... after that I need to get employed so I can get the high pressure leg set up and a straight mag built. I did some checks last night and it seems like the forward bearing has a tolerance band of between 0.3 and 0.5mm in axial position... more tbd once o-rings come in.

 

I got the parts yesterday. so far so good. uncompressed O-ring requires about 0.4N of force to pass the round through, which should allow for good compression characteristics (equates to a bit under 2psi pressure). I need to add either spanner wrench holes or flats for tightening. Barrel nut bore is about 0.005 inches larger than I would like compared to the stainless barrel. The stainless barrel is on the tight side of the tolerance band as well, and might need to be honed out a skosh (11$ bore hone from mcmaster carr would work perfectly)

Other than that it seems to work at low pressure but I have a bunch more low pressure feeding tests to do

 

that was an oversight on my part. it does need flats. I had hoped to get the O-ring sized sufficient that a light twist on the barrel was all that was needed

 

move on dec 4th but I will be in temporary housing for a few months so no permanent address or place to work till then

 

O-rings are as follows:
large one 2.4mm thick, 6.3mmID metric O-ring, BUNA, 70A
Small one is standard, -103 o-ring size, probably needs to be the softest silicone O-ring available for sealing reasons.

Let me know how the playing goes... Mine are sadly boxed

 

Lets see how it works. I am hopeful that with a properly timed system (or sensed system) that the aft O-ring could be done away with... but we will see. I fully expect us to come up with some variations on the theme