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Golf Ball Blowforward Semi

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Golf Ball Blowforward Semi

Unread postAuthor: thedeathofall » Mon Jun 15, 2009 11:37 pm

Okay, I know a lot of you have experience with blowforward breeches, but at the same time, many people here don't.

I came up with a simple design that i wanted to share. The coolest part is that the whole breech (minus o-rings and spring) can be made with standard pvc fittings. No funky sizes, no epoxy nessicary (yes it is still optional :roll: )

So we all know that 1.25 inch sdr 21 pvc pipe will fit a golfball. What most people don't realise however is that it also fits a 1 inch coupling.

This is similar to how 2 inch sch 40 pvc pipe will fit a 1.25 inch coupling or cap (for use as a piston).

So by following this trend, we can come up with a blowforward breech using only fittings and pipe.


The bolt is made of 1 inch sch 40 pvc pipe. It has a coupling and plug (or cap if you wish to make it simpler) at one end, and a coupling on the other. (no plug tis time) It has a few holes drilled in it a little ways behind the plugged coupler, and then the whole thing is placed inside a piston.

The piston in this case is a 1.25 inch coupling with 1.25 X 1 inch bushings. The bushings are sanded out to slide over the bolt, and then glued in place.

This bolt/piston assembly is placed inside a housing made up of 2 inch sch 40 pvc pipe. It has a coupler and 2 X 1.5 inch bushing on both ends.


Overall it should look like this.......

Image

(warning! this is not to scale! Just to show everything in its place! Oh and ignore the valve, its a dud...)

O-rings can be added and of course the spring.

I just hope someone can make use of this someday!!

Cheers!
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Last edited by thedeathofall on Tue Jun 16, 2009 10:20 am, edited 1 time in total.
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Unread postAuthor: Technician1002 » Tue Jun 16, 2009 12:32 am

Nice.. I'm not sure how you would service the blow forward bolt if it ever gave trouble. Is there a way to disassemble it for service?
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Unread postAuthor: Gaderelguitarist » Tue Jun 16, 2009 12:44 am

That's a great diagram, although not to scale.
It's the perfect thing for anyone with limited to no machining and fabricating capabilities.

Though it does seem to be a hit or miss deal with no serviceability on the bolt whatsoever.
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Unread postAuthor: THUNDERLORD » Tue Jun 16, 2009 7:09 am

Very nice!!! :)
It will need (2) 2"-1.5" reducer bushings where it transitions from 2" to 1.5".
Also, to get the lengths for a particular design, it's probably best to draw parts to scale on paper and double check.

Epoxy is still probably good to fill in "dead spaces", and there will IMO be some fitment adjustments needed.

I was trying to do a diagram similar the other day, but the proper parts weren't available in local store (got confusing combo's) :oops: (No good with paint or....) still I can draw and post pic OK, 8)

Thanks!!! 8)

EDIT: A 1" sprinkler valve even, works well enough to be impressive for one of these, it could be modded to a piston later even.
I'd prefer propane fill for something like this.
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Unread postAuthor: thedeathofall » Tue Jun 16, 2009 10:11 am

Thanks for the compliments guys.

Unfornatly no, there is no way to service the breech. But with each one costing less than $8 (USD) at my local hardware store (and they WAY overprice things), there really isnt a problem with buying parts for two or even three breeches.

The only real problem to be had would be the spring. If it is too strong, or too weak.
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Unread postAuthor: THUNDERLORD » Tue Jun 16, 2009 10:28 am

thedeathofall wrote:...The only real problem to be had would be the spring. If it is too strong, or too weak.


Idea I borrowed from a coilgun page:
Use piano wire and create your own spring.
For Whatever diameter bolt.
Based on the wire diameter a decent one that's as weak as possible but still functions.

BTW, Not sure right now if they need to be heat treated (probably won't hurt it). 8)
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Unread postAuthor: thedeathofall » Tue Jun 16, 2009 10:43 am

BTW, Not sure right now if they need to be heat treated (probably won't hurt it).


Yes you have to heat them then quickly quench them in oil. Then you have to repeat until it is the strength you want.

In truth, making a spring is a pain in the a$$. I will probably just buy one, or order it from mcmaster.
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Unread postAuthor: SEAKING9006 » Tue Jun 16, 2009 12:59 pm

Hey, it looks just like an X-ACS type blowforward valve! Although, I think the X-ACS would function more reliably if it were built, as the mathematics I used during the early design stages were made quite simple due to the fact that the piston is a piece of 1in with one end epoxied shut. Also, mine is much shorter than this would come out to be, plus it only uses SDR21 in the barrel since it's so much more fragile than SCH40 pipe. My research on building it kinda petered off into nothing after a while so I haven't got but some diagrams and a few calculations, but once I can get my hands on them again I'll see about passing you a copy if you want. I even found a perfect sized spring that has the perfect charictaristics for a GB autogun, and sleeves nicely over 1.25in SCH40. I can't get the data for you today, but maybe someone else has the files laying around. I passed them on to a few people. If it wasn't for that, I might have decided to enter the X-ACS in the summer contest.
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Unread postAuthor: thedeathofall » Tue Jun 16, 2009 1:49 pm

Sweet ill look into it. I honestly haven't heard of the X-ACS (which is pathetic because i have seen almost everything on this site :roll: ).

I will look forward to finding that spring. I wasn't really planning on making this, but I recently found out that my Uncle (who lives on a golf course) was willing to help me out at getting my hands on some golf balls. He can pick as many as a 5 gallon bucket full in a year from his front lawn :twisted:
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Unread postAuthor: SEAKING9006 » Tue Jun 16, 2009 2:05 pm

Try the search, honestly I can't tell where that thread is. I should have kept a link.

Anyway, I'll try and get you the files as soon as I can, I've lost my computer acess AGAIN and can't get to them right now.
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Unread postAuthor: thedeathofall » Tue Jun 16, 2009 2:26 pm

I've lost my computer access AGAIN


Ahh.. the joys of modern technology... :wink:

Thanks for the tip though, ill be looking.


EDIT:

Hey, not to jack my own thread here, but I have a question. How would a 3/4 inch QEV be configured in GGDT. Im working on another gun design at the moment and I'm not sure what it should be.
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Unread postAuthor: Gaderelguitarist » Tue Jun 16, 2009 5:54 pm

Here's the link you need for the X-ACS

http://www.spudfiles.com/forums/blow-forward-autocannon-project-x-acs-t15075.html

I'm glad to hear that you may build this.
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Unread postAuthor: thedeathofall » Tue Jun 16, 2009 8:30 pm

Haha thanks man, but I already found it. It looks pretty cool, but I think I understand my version a little better.

I still need to finish my current project anyway; A small caliber, coaxil made of black steel. It will have a similer layout as Black Hawk's copper hunter.
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Unread postAuthor: Gaderelguitarist » Tue Jun 16, 2009 9:12 pm

Well good luck with this one then! I agree that the other one is a little more confusing that yours. Not saying its difficult, just that yours is more straight forward.
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