Author Topic: Project Fury 20mm BIGbore. 3100FPE! (Read 86429 times - 2 votes)
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MJP · « **Reply #460 on:** July 13, 2022, 06:43:54 AM »

Balancer cylinder modified, micro honed and hard anodized.

Hard anodizing is the same as normal, you just need to keep the solution cold, and use enough current.
On 7075 when the surface is getting darker gray you got a decent hard anodized surface.
Scribing tip just glides on the surface without leaving a mark.

Marko

Chickenthief · « **Reply #461 on:** July 13, 2022, 01:20:41 PM »

Inconel for valve stem?

MJP · « **Reply #462 on:** July 13, 2022, 03:13:44 PM »

Gr5 titanium, need to keep the weight down. There is quite substantial inertia in the moving parts while the valve cycles.

Marko

MJP · « **Reply #463 on:** July 17, 2022, 05:29:14 AM »

Testing done, should be ecstatic but slight hint of disappointment.

Valve dwell is little too short for heavier slugs.
As the weight doesn't give much difference in power, only around 100 extra joules.

Heaviest bullet shot yesterday.

And one of the velocity readings for that.

4089J or 3016fpe on 300bar air alone.
Pretty happy that we are on the same power levels on air that we got on helium air mix with the last valve system.

Oh yeah for got to add, the light 95g bullet goes on average 284m/s
Good speed and ok energy retention, drops to 268m/s at 100m

Marko

Rob M · « **Reply #464 on:** July 17, 2022, 09:35:59 AM »

congrats Marko.. over 3000 fpe is insane !

Back_Roads · « **Reply #465 on:** July 17, 2022, 10:24:42 AM »

Seems sane to me

sb327 · « **Reply #466 on:** July 17, 2022, 11:32:42 AM »

I wonder what accuracy is with that slug fired backwards.

Dave

MJP · « **Reply #467 on:** July 17, 2022, 01:52:03 PM »

Thanks guys,

Well accuracy is pretty good with any of the slugs I have for it, and it's pretty same if shooting them backwards.
If you manage to hold the beast without shifting throughout the shot it's going to hit where the crosshairs point.
Some lighter slugs

New mold from old

Marko

subscriber · « **Reply #468 on:** July 24, 2022, 12:59:41 PM »

Quote from: MJP on June 22, 2022, 07:14:29 AM

recoil is snappy.

Looks like a muzzle brake should help. One that looks like a field howitzer brake should do the job. Possibly a bit like this; or flat without the cones to make it even simpler to machine:

This one has features to enable 3D printing, that can be deleted for machining. You may want a threaded barrel stud version...

Insanity · « **Reply #469 on:** July 24, 2022, 01:36:50 PM »

Dose your mold ever have issues moving or warping when it gets hot? That thin bit between the cavitys looks like they will flex when heating up to me.

Spacebus · « **Reply #470 on:** July 24, 2022, 05:07:52 PM »

Quote from: Insanity on July 24, 2022, 01:36:50 PM

Dose your mold ever have issues moving or warping when it gets hot? That thin bit between the cavitys looks like they will flex when heating up to me.

I was thinking the same, but looking at where the large cavity reaches the outer edge. That bit is even thinner.

MJP · « **Reply #471 on:** July 25, 2022, 04:43:32 AM »

Quote from: subscriber on July 24, 2022, 12:59:41 PM

Quote from: MJP on June 22, 2022, 07:14:29 AM
recoil is snappy.

Looks like a muzzle brake should help. One that looks like a field howitzer brake should do the job. Possibly a bit like this; or flat without the cones to make it even simpler to machine:

I have a muzzle brake, flow optimized 3D printed from stainless steel.
Without the brake recoil was intolerable.

Marko

MJP · « **Reply #472 on:** July 25, 2022, 04:46:38 AM »

No issues with mold warping on any of my molds. Not the first ones to wonder that, and I'm kind of curious why is everyone thinking that?
Never have had any issues with molds, none. I don't generally treat the molds too gently but they just keep working.
And I'm not too concerned as I can make a new one just by putting a raw one in the lathe and pushing a button.

Marko

subscriber · « **Reply #473 on:** July 25, 2022, 02:42:35 PM »

Quote from: MJP on July 25, 2022, 04:43:32 AM

I have a muzzle brake, flow optimized 3D printed from stainless steel.
Without the brake recoil was intolerable.

Marko,

Do you have pictures of the brake. Please post them if they are handy.

Spacebus · « **Reply #474 on:** July 25, 2022, 10:24:48 PM »

Quote from: MJP on July 25, 2022, 04:46:38 AM

No issues with mold warping on any of my molds. Not the first ones to wonder that, and I'm kind of curious why is everyone thinking that?
Never have had any issues with molds, none. I don't generally treat the molds too gently but they just keep working.
And I'm not too concerned as I can make a new one just by putting a raw one in the lathe and pushing a button.

Marko

I was curious because I accidentally warped a .22 cal NOE pellet mold using a rocket stove to melt my lead. Maybe less material is better?

MJP · « **Reply #475 on:** July 27, 2022, 03:41:39 AM »

I need to take a picture of the brake. I have deleted all the old ones.

I always preheat the molds before pouring lead in them and never had a problem.
Have seen warped molds at swap meet and even bought one as I can mill it and use it as a core.

Marko

MJP · « **Reply #476 on:** July 28, 2022, 05:40:32 AM »

Couple of pictures of the muzzle brake.

3D printed in stainless steel as it is impossible to mill that out of one piece.

Marko

subscriber · « **Reply #477 on:** July 28, 2022, 06:43:58 AM »

Thanks Marko,

The brake is a thing of beauty. Looks like it directs the air backwards by a few degrees, for more recoil reduction than just rocket effect cancellation.

Do you have an equivalent recoil to compare it to? Something like a 1.25 ounce 12 gauge slug at 1600 FPS, shot from a 7 lb shotgun.

I presume you have to use good hearing protection to shoot this thing.

rsterne · « **Reply #478 on:** July 28, 2022, 02:40:23 PM »

I'm curious as to the strength of 3D printed stainless steel?....

Bob

MJP · « **Reply #479 on:** July 28, 2022, 03:43:25 PM »

Quote from: rsterne on July 28, 2022, 02:40:23 PM

I'm curious as to the strength of 3D printed stainless steel?....

Bob

Material data sheet says ultimate tensile strength for H900 1180-1230MPa if I read it correctly.

Marko

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Project Fury 20mm BIGbore. 3100FPE!

Author Topic: Project Fury 20mm BIGbore. 3100FPE! (Read 86429 times - 2 votes) )

Author Topic: Project Fury 20mm BIGbore. 3100FPE! (Read 86429 times - 2 votes)
)