Build Log: MFIC

[Blitz]

After thinking about the chamber plug, I felt it'd be better to stick with machining one from the UHMW I bought and nix the epoxy casting idea. The piece cost me $15 and my friend's going to show me how to use a rotary table with his mill and lathe what I want tomorrow. Not bad for $15 and some beer.

Before picture:



(I cleaned it up since then. I bought the other two pieces for other things, figured what the hell.)

[wyz2285]

Good stuff, I wish blocks were sold here so I don't have to always mill one from a cylinder...

[Blitz]

Not even on eBay or something?

[wyz2285]

Not even on eBay or something?

The shipping gets up to 10x the price of the material and most of the time they don't ship to where I live.

[Blitz]

I meant, from sellers in the UK as well.

[wyz2285]

I meant, from sellers in the UK as well.

Still so the shipping just doesn't worth it, because these materials are cheap but heavy.

[Blitz]

Oh, that sucks. Here, if I were to have something like that shipped, the post office has flat rates if it can fit in the box. Sometimes, it can be quite inexpensive.

[mark.f]

Massive project you've got going along there! Good attention to detail on the valve plug... certain members including myself would go for a wrap of teflon tape or two and some screws to hold a cap in place. :p

Also, isn't the "expression" (abbreviated for civility) HNIC, or is that what I get for listening to too much of the hippity and the hoppity and whatnot?

[Blitz]

I'm near a rather large metropolis area, but I'm not THAT urban.

[Blitz]

Gettin' there. Did some turnin'!



Also, I figured I'd show what my chamber fan will probably be. Although I could spend a few more bucks and get a larger diameter. But, 80CFM isn't bad for an 80mm fan

[Gun Freak]

Hard to tell how big that plastic actually is by the picture

I'm very exited to see this finished

[Blitz]

When I took that picture, 7.5" in diameter.

[Blitz]

Having a hard time finishing up my plug (it's mostly done) -- but it's because I haven't had a chance to get to my friend's shop. Either tonight or tomorrow, I promise.

So besides finishing this plug, my next step is creating some support plates. These will serve two functions -- to hold the chamber and barrel together to alleviate stress from the tee and elbow fittings, and to facilitate the structure for the recoil sleigh. I wanted to get vibration-dampening U-bolt clamps for the barrel, as this will also grip it, but those type of U-bolt clamps run like $30 each, and I want four of them! I'm currently exploring a few options for the rails that the recoil sleigh would ride on. Once I'm satisfied with something that's cost effective (as in, not using CNC linear rails/bearings... This was something I briefly considered! lol), then I'll construct the support plates.

In general for most artillery in the 20th century, the recoil sliding use a U-channel that slide on a beam. That U-channel is sometimes part of the recoil sleigh that is part of the gun assembly, and sometimes it's on the carriage. I will likely put that part on the recoil sleigh, as that wouldn't need to be as long of a length. I'm likely going to use Impact-Resistant UHMW U-Channel 1" Base x 3/4" Legs, 1/4" Thick. At $2.64/ft from McMaster-Carr, that's fairly economical. I can just attach it with some countersunk flathead screws or something. Maybe I'll go pick that up today.

Rear view showing the rails on the cradle (carriage) on an M101 Howitzer. My rails would be a bit higher to allow unrestricted movement of the chamber, but similar concept.



Thoughts?

[wyz2285]

You can use a "ball bearing"ed slide rail (for large doors per example)
That's what I did. Offers a smooth sliding yet rigid mounting, also saves a lot of work.

[Blitz]

That was a thought. But those kind of slide rails just aren't economical on this scale, and my cannon is too heavy for anything short of industrial-grade, expensive units. I even looked at rackmount server rails, but they're too small for my needs.