SpudFiles

Just relised this build and hybrid.

Real inspiration, i love everything about it.
Clean control box too

mobile chernobyl wrote:If you can chuck up 1.75" plastic round stock and would like to mill something for me I'd me more than happy to outsource it to you, as a fellow spudder and all

The problem is that swing over slide for my little sherline is 1.88 inches so it's a little close and time consuming.

A properly discarding sabot is the only challenge that remains.

Using full bore fins allows you to simply use a disk as a wad, no need for complex petal sabot designs.

Some of you will notice this because you were the ones that complained about the originals Well the original barrel clamps have proved to be insufficient at holding it back even during light payloads like a golf ball - so before I put anything heavier in, I'll need some legit clamps made up

haha about time said as one of the original complainers

OMG where did you get this part ? got its DIN number or (whatever thing is used for standardized parts)?

If your talking about the elevation adjustment part, sure - its DIN number is PIMP6969.

That's no standardized part son! That's 100% homemade pretty much. Here's a dimensioned drawing if you happened to have a welder and a metal cutting saw and some spare time.

lol I just realised something

you could have used this

I guess it's called roman screw... it is used for tightening guy wires and stuff like that

mobile chernobyl wrote: PIMP6969

We call them thar things turnbuckles in the sailing world, and I happened to have quite a few nice stainless ones, but not large enough.

This build required a throw of about 6.5" to accomplish the desired adjustment range. I had a few 4" throw models, and a 6" model with the proper eyeleted mounts (you have hook mounts pictured) would have cost me at the cheapest - about $25 to have it shipped to me. I didn't have that much money at the time (college kid budget) but I did have raw material, and with that I build the model you see on the gun now.

The turnbuckle was a very close alternative to what I have now, inspired in part because Utron used them on their 45mm test platform and it looked pretty bad ass.

I'm very happy with my adjustment method though - I have nearly zero back lash in the adjustment which is essential because of barrel rise.

The main draw back I noticed with the rather high quality turnbuckles I had was the back lash - these things are designed to be used pretty much only in a tension environment. For mine it's in a compression state most of the time, so there arose some lash that was pretty much unacceptable for a gun of this much power shooting at distances farther than 2 feet like most people seem to do lol. Most of my shooting is 30feet and up so I need the shot to go exactly where I aim it.

mobile chernobyl wrote:Most of my shooting is 30feet and up so I need the shot to go exactly where I aim it.

Given the recoiling wheeled carriage that does sound a little pointless because the movement caused on firing is far greater any backlash.

I still think you should have some sort of buffer system in place that allows the barrel and chamber to recoil independent of the mount.

I think it deserves a m107 style muzzle brake.

jackssmirkingrevenge wrote:

mobile chernobyl wrote:Most of my shooting is 30feet and up so I need the shot to go exactly where I aim it.

Given the recoiling wheeled carriage that does sound a little pointless because the movement caused on firing is far greater any backlash.

Not when inertia of the system is compared to polar moment of inertia from the gun and cradle - it's relatively well balanced... I typically have to aim about 3-4 inches low of the target at 45feet.

jackssmirkingrevenge wrote: I still think you should have some sort of buffer system in place that allows the barrel and chamber to recoil independent of the mount.

That would be cool... This gun is pretty much just a testing platform though so no more major work will be done for it except the barrel split clamps. - To the extent of it being a testing platform, I've been able to better design the next hybrid, and I can confidently say there will probably be no more pneumatics produced by myself... I had an avalauncher concept drawn up, but its more likely it will resemble a mini-Vera now

::Small Addition::

Just a note on how education can sometimes be useful lol.

During the 10X shots this past weekend, I started noticing some interesting things happen to my ignition design. As I would shoot, every 4th or 5th shot I'd notice that the coaxial outer spark rings would be converging onto each other. I had theorized 1 or 2 reasons why this might be, but having the ability to set up a static test using an FEA module, I've pretty much narrowed it down to the exact reason!



Basically the inner coaxial insulating material (a polymer) was compressing jussssssst enough that the OD of it was decreasing by about .0005" not much? well that's enough when your dealing with a press fit! Added to that is the momentum of the hot combustion gasses exiting the chamber (to which you must consider brass's not-so-small coef. of thermal expansion, which could make the internal gap between spark ring and polymer even bigger!), and the recoil force of the gun - and what was happening is the spark rings were sliding forward just a little bit more each time. The spark rings are made of brass, and were under the same chamber pressure form all faces.

Solution? well the caveman approach would basically be to use a center punch and give the spark rings a reason to stay in place by putting a dent into them - which will press into the polymer insulating layer and eliminate movement.

All useful information for aiding in developing a higher powered hybrid with a long-life multi-point ignition system.

Well thanks to the magic of H.264, I've not gotten everything from 720p/60fps, to low res 420fps, and my still shots all on a nice 720p video for y'all.

Enjoy! and let me know if you guys have any suggestions for targets, hard or soft. If it's something someone would throw away, chances are we can find one and put justice to it in the form of supersonic love.

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haha brilliant!

I love the pumpkin "mist" hanging in the air.

Yes, I need to make you some APFSDS... Some 45mm acetal stock purchase is on the horizon.

Well when I visited the metal yard today to pick up a new motor for my lathe project - I found a bathtub equivalent full of these little guys! A quick mic'ing of them led me to find out they are appx 1.62"... with my barrel being 1.68" I just couldn't say no!

So as I brought them to the counter to pay - I found out they are ceramic tumbling balls - so they are very dense and made for abuse! Sound like a great combination for something being shot out of a barrel eh?






Can't wait to see what these guys do! In the mean time look out for some sabot's being turned out - my lathe project is just about done and ready for use!

I'm jealous, even though they're far too small for my barrel I could shove a sock down the barrel as a sabot/pusher plate or something

Though, I still have a 1.25" steel ball bearing I need to fire, that will be fun

By the way, what kind of wire are you using that leads to your electrodes? Recently, my spark has been shorting out through the rubber insulation between the two wires.

Those will be awesome to shoot! NICE find!! Shoot them at something super hard to see if it will shatter