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Constant force Cf spring test coil

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#26 DjOnslaught

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Posted 18 July 2016 - 11:11 AM

I was thinking more like a test-bed that would allow for 1-to-1 comparison against a [k26] or [k25]. Here's my concept for a horrible chimera of a PCSR, ESLT, and +bow. The foregrip slides on the two guide rods to push the plunger rod backwards into the stock. The nicest feature is that there are no slots to cut in PVC.
dcfs_00.jpg
The catch is the +bow Rev.3 type, just working backwards so I can avoid have a linkage. The redirect piece is mounted to the back of the grip frame, which means that the frame piece itself is retaining the o-ring or shaft seal that the plunger rod slides through. The dual constant-force springs are in an optional cassette at the front. The back of the plunger tube still has room for a full-length [k26] or [k25] should you want to switch to one. Or you can add a trimmed one of either to act as a plunger "booster".
 
And the solution to the "No Wars Near Me" problem is to host one yourself.


I see what you did with the mock up rifle idea, and could definitely see having the swappability of the 2 springs being a good idea

As for hosting one myself, it's something to consider.
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#27 blitz

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Posted 19 July 2016 - 09:22 AM

I was thinking more like a test-bed that would allow for 1-to-1 comparison against a [k26] or [k25]. Here's my concept for a horrible chimera of a PCSR, ESLT, and +bow. The foregrip slides on the two guide rods to push the plunger rod backwards into the stock. The nicest feature is that there are no slots to cut in PVC.

dcfs_00.jpg

 

 

 

I really cannot stress how much I love the design, but I have severe reservations of the 1/2" nylon rod in the front. I realize it's pretty short, and therefore less flimsy, but I really don't trust it not to flex. Plus, I worry that the single (?) runner plate on these rods (connected to the front handle) would be annoying and cause undue friction when priming. 

I despise slots as much as anyone, but I worry that this effort to void them may be in vain. I will be building this if you release templates however.


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#28 The2ndBluesBro

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Posted 19 July 2016 - 10:13 AM

I realize it's pretty short, and therefore less flimsy, but I really don't trust it not to flex.


The 2-11 uses this exact method without issues, and I believe the 2-11's rods are longer (not completely sure though). The older +bow designs are very similar, too.
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#29 CaptainSlug

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Posted 19 July 2016 - 11:57 AM

There are two runner plates for the foregrip, and I've added aluminum tubing to help guide the foregrip more smoothly on the guide rods.

 

I only use delrin rod now. Nylon is nowhere near as nice to work with.

dcfs_01.jpg

The frame at the front that holds the spring pair. The two rods also feed through the front of the grip before attaching to the catchguide plate.

 

Also, compatibility with an ESLT spring? Sure, why not.

 

dcfs_02.jpg


Edited by CaptainSlug, 19 July 2016 - 02:57 PM.
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#30 snakerbot

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Posted 19 July 2016 - 07:48 PM

I was thinking more like a test-bed that would allow for 1-to-1 comparison against a [k26] or [k25]. Here's my concept for a horrible chimera of a PCSR, ESLT, and +bow. The foregrip slides on the two guide rods to push the plunger rod backwards into the stock. The nicest feature is that there are no slots to cut in PVC.

 

[snip]

 

The catch is the +bow Rev.3 type, just working backwards so I can avoid have a linkage. The redirect piece is mounted to the back of the grip frame, which means that the frame piece itself is retaining the o-ring or shaft seal that the plunger rod slides through. The dual constant-force springs are in an optional cassette at the front. The back of the plunger tube still has room for a full-length [k26] or [k25] should you want to switch to one. Or you can add a trimmed one of either to act as a plunger "booster".

 

And the solution to the "No Wars Near Me" problem is to host one yourself.

 

The stock on mine is already two inches longer than it needs to be, so there is room for a compression spring behind it, although I don't think a full-length [k26] would fit. I feel like this wouldn't offer a good 1-to-1 comparison though, at least not with a pcsr. Having the rod in front of a plunger head seems like it would create a lot of extra friction, since any side load from the spring would make the plunger-spring system want to buckle and require a greater radial reaction force on the plunger head. That might be insignificant though, who knows?

 

I'll take a look at it and see what kind of room there is for a [k26]. Maybe it'll work fine.


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#31 CaptainSlug

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Posted 19 July 2016 - 08:05 PM

Friction manifests from mis-alignments and tight fits, and sideways force from the spring can be reduced by adding stubs that prevent it from becoming serpentine when compressed. Preventing any other mis-alignment requires having enough structure to avoid them. When compared to a normal pull-style plunger rod the only piece of this configuration that is likely to add any friction is the o-ring (or other seal) around the plunger rod, so that seal will need lubrication. Just as it would in every other redirect blaster.

dcfs_03.jpg

 

The only novel things I'm adding here are a redirect device that can be made out of pipe fittings, and a trigger/catch that doesn't require a linkage or a slot cut in the plunger tube. Avoiding slots entirely will make this blaster less time-consuming to make. Or at the very least more accessible and requiring fewer specialty tools.

dcfs_04.jpg

The redirect is now a pipe plug with two tapped holes, a through hole, and an o-ring seat added to it. A pipe coupler. A polycarbonate "shower grate" to act as a stop for the plunger head. The end of the plunger tube. And a 5/8" hole drilled into the coupler and plug which a CPVC stub gets glued into.

 

Discussion on this design moved to http://nerfhaven.com/forums/topic/27111-trishula-3-rods-and-3-kinds-of-springs/


Edited by CaptainSlug, 20 July 2016 - 12:22 PM.

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#32 Meaker VI

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Posted 20 July 2016 - 08:27 AM

The only novel things I'm adding here are a redirect device that can be made out of pipe fittings, and a trigger/catch that doesn't require a linkage or a slot cut in the plunger tube. Avoiding slots entirely will make this blaster less time-consuming to make. Or at the very least more accessible and requiring fewer specialty tools.
...
The redirect is now a pipe plug with two tapped holes, a through hole, and an o-ring seat added to it. A pipe coupler. A polycarbonate "shower grate" to act as a stop for the plunger head. The end of the plunger tube. And a 5/8" hole drilled into the coupler and plug which a CPVC stub gets glued into.
 
I can split this off into a different thread if you would prefer.


Please do! that thing could open up the redirect pieces to the masses, and I'm open to not needing to print them for *every* blaster.
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