RFQ: Aluminum BB cannon parts

[Greg McFadden]

Alright, I am looking at whether this design is even remotely feasible to make, and so I figured I ought to just ask.

First off, any tips at making the parts more inexpensive will be appreciated.

I have attached iges solids of the 5 parts. I am looking for 5 or maybe 10 sets (each set consisting of one of each). Material is 6061T6.



One part (Canister.igs) has some funky contours and drafted edges. A step down on the draft of .0250 is perfectly acceptable rather than actually trying for a smoothly drafted surface. (at least that is what I did in my prototype). for the contoured section, a step over of .030 with a D=3/16" ball end mill is perfectly fine. There are some inside corners, which can be radiused up to R=3/32".

The canister.igs and cap.igs can have overall OD tolerances of +.040-.005 from the as drawn state and thickness tolerances of +.050-.010 so long as the noted thru holes go through.

The file called "piston_cap.igs" has 4 holes drilled in the side (the only 4 making it a 2 op part). those holes have positional tolerances of +/-.040 so long as they penetrate into the open chambers and depth tolerances of +/-.060 (same caveat applies, must penetrate into milled pocket)

On hub.igs, scalloping as high as .020 is fine on all external curved surfaces. The .10650 inch diameter holes can be drilled through if desired.

thanks
Greg

[cdlenterprises]

The parts all seem readily machinable. Of course, we're not sure if there are any really tight tolerances or anything of that nature. It's tough to say what would make it easier to make without seeing the entire design, or if this is the design, how it goes together.

[besc]

Greg. When importing the iges files with my CAM system there seems to be some lost surfaces. IGES just does this to me. Could you send some STEP or DWG files to the email of my web sight at conmach.com thanks. Mike.

[larry53]

Some of the files I am having trouble with. Could you also send me a step file?

[iamscottym]

I'm guessing these cannons are for R/C warship combat. I've been trying to get involved in that for about a year, there just isn't a group nearby that I liked (NW suburbs of Chicago). I like QO and NTXBG type rules, they allow a little more freedom for new systems (targeting systems, etc) than other groups.

Anyway, I've got a couple designs floating around for better weapons (sealed breech style), if I find them I'll send them to you. In my opinion, you might as well buy off the shelf guns, unless you go with a closed breech design, or can make them yourself. It will take less time, and it will probably cost less.

I'm looking into buying a grizzly X3 and cnc'ing it, just for this type of thing. Of course, I'm an engineer so I'm always working on some project or other. But really, even if you're just using it for rc warship guns it will pay for itself pretty quick. Figure $3k to buy and cnc a mill using cncfusion kits, geckos, etc, or $2000 if you make it all yourself. At $250 per gun, you've only gotta equip a couple ships before the mill pays for itself. And that's not including all the other ship stuff you could make (gear boxes, water tight boxes, turrets, etc).

-Scott

[Greg McFadden]

I will get step files made tonight.

I actually have a cnc mill, it is just that my buddies were interested and I don't have time to make that many sets... I am out in Washington State playing fast gun (but the locals are letting me mod the local rules a bit to try out some things)


-Greg

[iamscottym]

I know some guys in QO let other guys use their shop to make whatever, as long as they make some for him too. You might try that with your friends. Of course they'd have to learn to mill first. If they need a lot of guns, it would be worth their while to try. If they screw up, they're out $50 in aluminum, whatever. If it works, they save $200 per gun, and could potentially sell them to others.

[besc]

Still waiting for step files. Mike.