Help with some material

[socoj2]

I am building a minigun and for my main shaft i need a specific size of Pipe. its not pressurized its more or less a spine.

It needs to be able to carry a Radial Load of about 15 lbs.

I was going to use some aluminum tube 2.75 Od x 2.62 ID this means it has a 1/16 wall size. This is T-6 6061 aluminum

2.62 is the minimum ID i can go with. i could go with a 3" Od but that means the bearings are almost twice the cost.

So if you know where i can get a set of bearings for a 3" shaft that dont cost more then $40 each i would appreciate it.

[jackssmirkingrevenge]

I can't help you with the materials but this looks to be a serious project, any details of calibre, valve type, pressure source etc?

[socoj2]

I can't help you with the materials but this looks to be a serious project, any details of calibre, valve type, pressure source etc?

Paintball Gun .689, 125ish psi, 3600 BPM

[Jared Haehnel]

I sounds like an amazing project...

Why don' you use a steel spine? Or fill the aluminum rod with epoxy that way you can stiffen it up and save money on the ball bearings...

I would imagine the structure of the barrels would be pretty well self supporting and the aluminum rod left alone should be ok...

It would be hard to judge without seeing a picture of the design though....

What ever you do good luck!!!! 8)

[socoj2]

I sounds like an amazing project...

Why don' you use a steel spine? Or fill the aluminum rod with epoxy that way you can stiffen it up and save money on the ball bearings...

I would imagine the structure of the barrels would be pretty well self supporting and the aluminum rod left alone should be ok...

It would be hard to judge without seeing a picture of the design though....

What ever you do good luck!!!! 8)

Because steel is freaking HEAVY. There are 2 sections to a mini Gun the spining barrel Rack, and the part that doesnt. There has to be an union somewhere. I am using the mentioned Tube for that. I figure the shearing load between the non spinning section and The Barrels is about a 10-15 lbs load on a specific point of the pipe.

[Jared Haehnel]

Ah... well if weight was the factor... you still might consider filling the hollow tube with epoxy or using a solid rod. Epoxy won't add too much weight. Probably be lighter then the solid aluminum rod and it will stiffen it up greatly.
How long will the shaft be? If its just a short length you can thread the aluminum rod into the steel and sacrifice weight for strength. And if probably would be a bit cheaper...

[Gippeto]

Have you considered a thrust face and torrington bearing? The center attatch point could use a smaller shaft and ball bearing, while the centrifugal loads are handled by the torrington. Possibly lighter? Don't have pricing, but you only need one.

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