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Slide Breech Rev.3


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#1 CaptainSlug

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Posted 04 September 2008 - 05:18 PM

I had not bothered to start a topic about this because I made these with the intent to use them only with my +Bow. But Since they're made to fit in couplers I've been using it with my Big Blast as well.

The first version worked very well and I was happy with it when I tested it at Millcreek Park in January.
Posted Image
However, since it relied upon glue to hold the locking tab in place I had problems with it breaking off. Also, the thin PETG was not sturdy enough and broke as soon as I tried to barrel tap someone.

The Rev.2 slide breech was made out of pure overkill with an emphasis on modularity. This design basically acts as a very long pipe coupler and therefore allows you to switch out the barrel piece by simply removing the screw that acts as the locking tab.
It is sort of difficult to machine though since the inside has to be bored out to a precise tolerance. In hindsight this one could have been made much more easily out of 3/4 SCH40 pipe.
Posted Image
Mechanical Drawing: http://www.captainsl...ide-breech2.gif

The Rev.3 slide breech was made to reduce weight and complexity. Discovering that I can actually use a 1/2" ID barrel effectively with my foam it made it very easy to find thickwall polyester tube. This negated the need to have the part compatible with 1/2 pipe and therefore the machining was a bit easier.
Posted Image
Mechanical Drawing: http://www.captainsl...ide-breech3.gif

The Rev.3 design could be made out of 1/2 SCH40 PVC, but I had 1" OD black delrin on hand and couldn't resist making it out of that because it's such a nice material to machine.

1. I used the lathe to drill the ID to 5/8", then used a needle file to widen and soften the front half of the inside. This allows the breech to slide open easily.
2. I lathed down the OD of the rear 3/4" of the piece so that its OD is 0.84" (to make it compatible with pipe fittings)
3. I used the knee mill to cut the opening and add the notch for the locking tab
4. I cut a 3/4" length insert of polyester tubing to nest in the rear of the breech
5. I drilled and tapped a hole in the 12"-long barrel and added a screw to it (making sure that it did not protrude into the barrel)

Edited by CaptainSlug, 04 September 2008 - 05:21 PM.

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The little critters of nature, they don't know that they're ugly. That's very funny, a fly marrying a bumble bee. I told you I'd shoot, but you didn't believe me. Why didn't you believe me?

#2 Magic

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Posted 04 September 2008 - 05:24 PM

Great mod, how hard out of 10 is it in your opinion to make?
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#3 Daecu

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Posted 04 September 2008 - 05:43 PM

Awesome write up! I had been having trouble with some designs for breeches for a while, this will help a ton, thanks!
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#4 sam

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Posted 04 September 2008 - 06:17 PM

How does your new barrel material compare to say OMC's thickwall PETG, mostly ID-wise?
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#5 Aimless

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Posted 04 September 2008 - 06:21 PM

How does your new barrel material compare to say OMC's thick wall PETG, mostly ID-wise?


I assume Slug is using the 1/2"ID 5/8"OD petg tubing from McMaster so it's a tighter fit on darts. If you want a barrel material with the same ID as OMC's thickwall, then look for part #1658T49 on McMaster, .527"ID and 5/8"OD, aluminum tubing.

Edited by Aimless, 04 September 2008 - 06:22 PM.

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#6 CaptainSlug

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Posted 04 September 2008 - 06:34 PM

Great mod, how hard out of 10 is it in your opinion to make?

If you have the tools you need, 3/10.
The Rev.2 design would be very easy to make if you have any kind of lathe with a jaw chuck that can hold 3/4 SCH40 PVC. And since PVC is so easy to cut, the opening does not have to be cut with a mill and could be done with a power drill and a rotary tool.

None of these designs are likely to be made using any tool other than a lathe.

Edited by CaptainSlug, 04 September 2008 - 06:35 PM.

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The little critters of nature, they don't know that they're ugly. That's very funny, a fly marrying a bumble bee. I told you I'd shoot, but you didn't believe me. Why didn't you believe me?

#7 Galaxy613

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Posted 04 September 2008 - 06:56 PM

Your designs make me want to become an engineer only so I can have access to a college workshop so I can use all the tools needed to make your stuff CS. Alas, I'm probably going to be a IT major. :huh: VERY nice job on your breech! I bet you could easily add a deoderant magazine to it.

Edited by Galaxy613, 04 September 2008 - 06:56 PM.

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#8 Soothsayer

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Posted 04 September 2008 - 07:32 PM

I have an erection for that breech, is that weird?

Just one after another you make this thing more and more awesome, relying less and less on shit that can screw up/is difficult to repair. Next to a few favorites, this is one of the best cannons ever thought up.


Could we see these breeches on the market any time soon?
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yeah I'm that guy who made that cool thing with the cool paint.


#9 CaptainSlug

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Posted 04 September 2008 - 07:41 PM

I don't know. If I can get more practice making the Rev.2 breeches out of PVC I might be willing to make a batch of them. Will include the 12" length of 1/2 SCH40 PVC, and a choice of threaded or non-threaded connection. I can't include a barrel, but it's extremely easy to nest whatever you want.

Edited by CaptainSlug, 03 August 2009 - 12:26 PM.

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The little critters of nature, they don't know that they're ugly. That's very funny, a fly marrying a bumble bee. I told you I'd shoot, but you didn't believe me. Why didn't you believe me?

#10 Rogue Warrior

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Posted 04 September 2008 - 08:56 PM

This might just be the most flawless PETG breech out there, nonetheless the most flawless breech.
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