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Homemade Plunger

Based off of Boltsniper's

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#1 ompa

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Posted 09 March 2006 - 09:13 PM

At one point I thought that the plunger was going to be the hard part, and the trigger the easy part. I was wrong. The plunger was the easy part.

First, start with your ½ SCH40 pvc endcap. Glue a piece of SCH40 PVC into it, and then chop off the pvc right where you end up level with the endcap. Then, take your piece of ½ cpvc and jam/glue the piece into the endcap/pipe combo. You should end up with something like this.

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Next, just drill a small hole straight through it, and put some kind of bar or reinforcement; this is just to make sure the plunger head won’t fly off on you, even if the glue does fail. I used music wire. You’ll end up with something similar to this.

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Next, just cut small grooves into the endcap, to allow o-rings to fit around them. Now, I had o-rings from ACE Hardware that I believe were labeled “18”. Basically, you want the o-rings to be able to slide around in thin-walled 1” pvc. Next, just stick the o-rings on, and you have a plunger. Yes, it was that easy.

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But while I’m at it, I might as well get into how I made my own plunger housing. I needed a backstop which would contain the spring, but still let the rod of the plunger to slide. I decided to use a ½ pvc coupler, which had a small piece of sanded-out SCH40 pvc in it (similar to the method used to make the plunger head), followed by a washer with a center large enough to let the cpvc plunger rod through.

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Then, I just stuck this combination into the thin-walled 1” pvc and screwed it in place.

The other end of the plunger tube is just the same thing, screwed in place on the other end.

No, it’s not very exact, and when I make my next homemade (currently in design/prototype stage), I’ll get dimensions and everything. But I figure if you’re on NH, and haven’t been banned yet, you have the intelligence necessary to take the information in this writeup and turn it into something useful and working.

All that's lacking is the catch mechinism; whatever form you choose is up to you, I left it out in order to spark some creativity here; do what you feel would work best for you.

~ompa
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#2 six-five-two

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Posted 09 March 2006 - 11:11 PM

can you take a picture of the o-ring package??
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#3 ompa

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Posted 09 March 2006 - 11:45 PM

From ACE Hardware. They didn't really come in packages, more or less in small containers that you just took however many you needed from. I'd recommend just taking thin-walled PVC and finding which o-ring you can get that fits best.

~ompa
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#4 AssassinNF

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Posted 10 March 2006 - 01:56 PM

HOLY SHIT!!!

Thanks!!! I'm making a homemade, but I couldn't find a way to make the plunger, and now I can finish it. This design is perfect for the gun I'm making!!

Thanks :blink:
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Probably dead by now, or something.


#5 boltsniper

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Posted 10 March 2006 - 02:54 PM

As Ompa noted, I have also found that standard #18 O-rings are the best fit for thin walled 1" PVC. They are sold individually or in packs.
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#6 Deaths Avatar

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Posted 10 March 2006 - 08:38 PM

Any suggestions on how to make the grooves for the O-rings? Mine have a tendency to come out "crooked", making my plunger lopsided and useless.

-DA
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#7 ompa

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Posted 10 March 2006 - 08:40 PM

To be honest, I just used practice and a steady hand. But I suppose very careful rotating in combination with a scroll saw may work.

~ompa
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#8 six-five-two

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Posted 11 March 2006 - 01:13 PM

I just use a glasses repairing kit, its so thin it can fit right under, then i just use the lever mechanism to pull it out.

One of my o-rings didnt fit right, so i used electrical tape in the grooves... Bad idea. it made the o-ring very lobsided.
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#9 Maverick Master

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Posted 13 March 2006 - 03:57 PM

I'm making the plunger for my GFFAR and I fitted a 1/2" pvc end cap over a 1/2" cpvc encap so i could cpvc for the shaft and the 1/2" pvc end cap dosn't fit in 1" pvc. So I was wondering how you made it fit.
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#10 boltsniper

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Posted 13 March 2006 - 04:08 PM

are you using SCH40 1" PVC or thin walled 1" PVC? 1/2" fittings will only fit in the thin walled 1" PVC
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#11 betterthanstudying

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Posted 15 March 2006 - 04:28 PM

How much resistance should the plunger have if I'm pushing it? I'm in the process of making a gun that mixes the qualities I like from ompa's gun and the FAR, but after a few early test fires I found that I cannot achieve distances over 20 feet. I suspect my problems come mostly from the seal issues of the plunger and clip, which I eliminated with a lot of tape and by getting rid of all but needed components to fire(ie. the barrel, the spring, the plunger and bolt.).

I've made the plunger according the specs listed in this topic and I am using thin walled 1" pvc, but I have no idea if the seal is good enough or not. Should the plunger move with negligible resistance?
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#12 cxwq

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Posted 15 March 2006 - 05:14 PM

after a few early test fires I found that I cannot achieve distances over 20 feet.

May also want to look into the dart/barrel fit.
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#13 six-five-two

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Posted 15 March 2006 - 07:22 PM

I got #16 O-Rings and even those dont make a good seal in my 1" PVC
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#14 ompa

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Posted 15 March 2006 - 08:32 PM

Next, just cut small grooves into the endcap, to allow o-rings to fit around them. Now, I had o-rings from ACE Hardware that I believe were labeled “18”. Basically, you want the o-rings to be able to slide around in thin-walled 1” pvc. Next, just stick the o-rings on, and you have a plunger. Yes, it was that easy.


~ompa
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#15 six-five-two

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Posted 15 March 2006 - 09:11 PM

Yes I know, I got 16 instead of 18. But 18 seemed to be too big to fit around the 1/2 pipe.

Edited by six-five-two, 15 March 2006 - 09:12 PM.

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#16 ompa

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Posted 15 March 2006 - 09:22 PM

You need a 1/2 coupler, over 1/2 pvc, all around 1/2 cpvc.

~ompa
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