SpudFiles

dewey-1 wrote:If you added more epoxy around the valve and the case lead, it may prevent the arcing. Any sharp points and the HV likes to travel to the point because it is more directional versus a circular ball shape.
Add as much epoxy as possible without interfering with the air inflation device.

The problem is the spark gap is too big internally. The micro hybrid is of similar construction and didn't arc externally even at 28x.

So what was the gap for each one?
I am doing some 3D CAD drawings for your cartridge.
Can you get me:
Length of your Schrader valve:
What is the minimum height of threaded area that will work for air fill device?

Cartridge dimensions that you want:
Length:
OD:
ID:

electrode leads OD and length and bend length.

dewey-1 wrote:So what was the gap for each one?

The micro has literally the width of a paper, with the cartridge I figured it wouldn't take such a high mix so I was a bit more sloppy, there's more than 1mm.

I am doing some 3D CAD drawings for your cartridge.

sweet!

Length of your Schrader valve (including threaded portion) - 20.0mm

What is the minimum height of threaded area that will work for air fill device - 6.5mm

Cartridge dimensions that you want:

Length: 52.5mm
OD: 15.0mm
ID: 13.8mm

electrode OD: 1.0mm, stops at the same level as the schrader as per the diagram.

will you be replacing the 4mm barrel with stainless steel so that it will handle more shots before you have to replace it?

Off topic: I like the new avatar, try flipping it the other way so it looks like he's saying your post

@jsr

What are your assembly sequences as far as the epoxy construction?

Which end do you start with?
Also what depth are your epoxy pours? 6mm to ?

A max spark gap I would thick operable is .5mm or .020" down to .2mm or .008".

As I look at the dimensions to make drawings, it looks as though the max difference from Schrader to your electrodes OD is 1.5mm or .060".
You should have at minimum, about 3 times your spark gap opening.

I have some other ideas for the electrode. What is your electrode material mad of?

Lockednloaded wrote:will you be replacing the 4mm barrel with stainless steel so that it will handle more shots before you have to replace it?

I would definitely be on the lookout for some suitable sized steel, but given the performance of the micro hybrid even at 28x, I'm not sure it would be a worthwhile project to follow through.

I like the new avatar, try flipping it the other way so it looks like he's saying your post

It's cereal guy I actually tried flipping it before but it didn't seem right for some reason.

dewey-1 wrote:What are your assembly sequences as far as the epoxy construction?

I think I see where this is going and I like it see the attached diagram, basically the components are glued to a foam disk then to the cartridge body using araldite or similar quick setting epoxy, then marine epoxy is poured.

Also what depth are your epoxy pours?

Around 10mm in this case

A max spark gap I would think operable is .5mm or .020" down to .2mm or .008".

0.5mm is what I usually aim for, just barely not touching, though again in this case with the cartridge the work was a bit sloppy.

It looks as though the max difference from Schrader to your electrodes OD is 1.5mm or .060". You should have at minimum, about 3 times your spark gap opening.

If I have the theory right, it depends on mix number, ie the higher the mix number, the bigger the difference between internal and external gap should be.

I have some other ideas for the electrode. What is your electrode material made of?

I'd like to hear them, currently I'd using springy steel we call "piano wire", I think it's "music wire" in the states.

Here is the idea I had for your spark gaps.
Does this seem feasible?

Plugs don't work in parallel. One will fire and the voltage won't rise to spark the second one. Other than that it should work as a plug if you want the spark next to the chamber wall instead of out near the middle.

Technician1002 wrote:Plugs don't work in parallel. One will fire and the voltage won't rise to spark the second one. Other than that it should work as a plug if you want the spark next to the chamber wall instead of out near the middle.

I realize that tech, don't forget I was also a Techician back in 1967 .

It is more for redundency as one may wear and also as a method to center the Schrader valve as I will show later.

I like the idea, much easier to build precisely and the redundancy factor is a big plus for sealed epoxy construction

Some progress on this along two lines of development, both still curing:

- cartridge made from 3/4" I/D PVC for a 3/8" bearing projectile, acknowledging that the friction seal is only good for low mixes and compensating with larger volume

- fill rig (basically a sealed chamber with a schrader valve and threaded fitting) that will enable me to fill cartridges without having a schrader on the cartridge itself, possibly using the projectile itself as a "one-way valve" as discussed earlier in this thread. The latter setup (including cartridge) is illustrated below:

Pretty cool... although I think some internal pressure will be lost when the ball gets shifted back to the seal position...

fill rig

damn that's large...
wouldn't it be a better idea to use a copper tube with an ID equal to OD of the cartridge ?

ohhh and place a small rubber washer inside the fill rig... you wouldn't even have to open the rig, insert the cartridge and close the rig to fuel it
instead you could -> insert the cartridge, turn it upside down, press the rig&cartridge firmly against the table surface
(or use a some lock to keep it in place for fuelling)

Gun Freak wrote:I think some internal pressure will be lost when the ball gets shifted back to the seal position...

Fair point but if you dump the chamber pressure fast enough while holding the cartridge vertially as shown in the diagram, it should seal up almost instantaneously, in the same way a piston opens quickly in an exhaust valve.

POLAND_SPUD wrote:damn that's large...
wouldn't it be a better idea to use a copper tube with an ID equal to OD of the cartridge ?

ohhh and place a small rubber washer inside the fill rig... you wouldn't even have to open the rig, insert the cartridge and close the rig to fuel it
instead you could -> insert the cartridge, turn it upside down, press the rig&cartridge firmly against the table surface
(or use a some lock to keep it in place for fuelling)

I see what you mean (illustrated) but I wanted a less specific rig that could be used for various sized of cartridges or any small chamber without the need for a schrader valve - for example if it works, I could make an even smaller version of the pico-ax! Which would be the femto-ax... sounds like a genital deodorant lol

Update on the PVC cartridge:

[youtube][/youtube]

WIN

That was at 6x I tried it at 5x before but the bearing was pushed in a bit too tight so it didn't pop, and the thing didn't blow up

I'll definitely making a barrel and breech for this one, properly designed this time with provision for magazine etc.