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Cpvc Crossbow Write-up

CPVC'ed, with a twist.

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#1 Z4

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Posted 05 September 2008 - 04:31 PM

My Crossbow has been the victim of many mods. It’s been CPVCed, PVCed, Rawray’d, and experienced a failed attempt at a bolt action breech. The Rawray incarnation was definitely the best, but the brass was a little loose on my darts, and didn’t take advantage of the raw power of the gun. So I decided to CPVC it again, this time with a bit of a twist. I give you Emrys, my Level 4 Crossbow.

Supplies:
1 Nerf Crossbow
3/4in. CPVC
1/2in. CPVC
3/4in to 1/2in CPVC adapter
Plumber’s Goop
2 8x32 3” machine screws
4 #8 washers
2 8x32 nuts
26 ga. sheet steel
Rubber washer

Tools:
Power drill
Dremel
Drill bits
Grinding stone Dremel attachment
Pipe cutters
Hacksaw
Tin Snips
Vise or pliers

(*Note: I had already done most of this modification before taking pictures for a write-up. The following steps are listed as if the Crossbow is fully stock at the start.*)

Open up the gun. The first part of this modification deals with the plunger chamber, which is the big yellow piece in the middle of the gun (mine’s mostly black). Disconnect the old yellow barrel and yellow hose from the plunger chamber. You won’t need either for this mod, do with them what you will.
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Cut your 3/4in CPVC to 2” and Plumber’s Goop it to the end of the plunger chamber. This needs to dry about 24 hours for full bond. Try to make sure that it is well centered and straight, the 1/2in CPVC needs to be able to fit over the little yellow nub at the end of the chamber.
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While that’s drying, you should do basic reinforcement. Cut a piece of sheet steel to the right length and width to sit in front of the spring rest, and use a vise or pliers to bend it to a right angle, and goop it in. Then cut out a slot for the plunger rod to go through, your cut should be flush with the walls.
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For the plunger rod, I did this.(thanks to Gengar003) I also reinforced the back of the spring rest with bolts, like Renegade (thanks to you too) did here. I also suggest using a rubber washer behind the head to improve the seal.

Now that your ‘bow is solidly reinforced and your Goop is dry, take your 3/4in to 1/2in adapter and your Dremel with its grinding stone attachment.
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Dremel down the ridge inside the piece that stops the CPVC from going through. The 1/2in CPVC should be a perfect fit in it: the pipe should be able to slide into it with little difficulty, but should not be loose enough to fall out.
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Now put the adapter on the end of the 3/4in CPVC. The 1/2in barrel should be able to slide in and be very stable, but fairly easy to remove. The 3/4in pipe and adapter provide much more stability than a simple coupler. An 8-9" barrel seems to work best. (All the pictures are with a 12" one but I was still testing when they were taken).
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Dremel out all the stuff between the end of the plunger chamber and the opening at the front.
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Now you’re done. I find the new coupling system much more stable, but easier to remove than any other system I’ve encountered. I’m in the process of modifying this design to be turret compatible, and will have another write-up in a few days.
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It averages ranges in the mid eighties. (with a pair of mini bungees)

Questions, comments…?

Edited by .Z4., 05 September 2008 - 04:37 PM.

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#2 Bomberman

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Posted 05 September 2008 - 04:40 PM

This is a good mod, but I have one quesiton; do you ramrod darts, does it vaccuum load them, or do you just put them at the end of the barrel and not push them down at all? In my expiriences with CPVC, I can never ramrod darts at all, and they just stuck at the tip of the barrel, and I had horrible accuracy, so I had to switch toa shorter barrels. How is this working for you with the weight of your darts, the legnth of your barrel, and the other variables? Is it pretty accurate? And I'm not very familiar with the "levels" of modifications for an xbow, so, since you reinforced it, have you put in any new springs or bungees?; do you plan to?
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QUOTE(silentsnipe) View Post

It's not like that. I put lube on it and its the same. Its just stuck. And when I cock it back it goes farther back then usual. Also I push as hard as I can and it wont go back in. I've tried the methods and they wont work. Also pics are up.

#3 rork

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Posted 05 September 2008 - 04:42 PM

That is nice. I like the coupler system, and it's good to see a crossbow thread that's something other than "wtb." Also: realistic range claims make me happy. ~Rork
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#4 Z4

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Posted 05 September 2008 - 04:45 PM

The barrel is removable. I basically made a coupler instead of using a factory made one. I have fairly slender foam as well, and CPVC works best for it. I use CaptainSlug style darts, and it is very accurate. I can hit the pole on a basketball goal from about 30'. I use bungees, but don't plan to replace the spring.

EDIT: Thanks rork. I too have noted the dearth of real Xbow threads, so I figured I'd go ahead and post this part of the write-up.

Edited by .Z4., 05 September 2008 - 04:46 PM.

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#5 doubleshot

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Posted 05 September 2008 - 05:10 PM

I thought your barrel was a pixie stick for all of 2 seconds. Nice mod, I plan on doing this to my crossbow sooner or later.
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#6 Falcon

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Posted 05 September 2008 - 05:38 PM

Well done!

Now, I KNOW I'm gonna get flack from several people for this (or at least, the'll THINK about writing something disagreeing with me). That's okay. The forum is here for discussion, and not everyone is going to agree. I can live with I thI've never used an Xbow with CPVC for the barrel. but I DO know that CPVC is the same ID all the way down, and thus, will be in full, sealed contact with the dart at all times.

I imagine that your darts have an excellent seal with the barrel. However, typically, an excellent seal with a barrel does not mean that they are TIGHT in the barrel. If your darts are comfortably smooth sliding in the barrel, you might consider adding a short (like, 1-1.25" long) piece of nested brass at the back end. It would certainly help that 80' along. If they ARE fairly tight, that probably isn't necessary.

Rork, I smiled when I read what you said about seeing realistic xbow ranges for once. 120-130' IS realistic. It's just uncommon, hard to obtain, and even then, the gun doesn't always hit the range. Ranges will vary dart to dart whetherr it be slightly or drastically, as I'm sure we all know. For that matter, I think the integrity of my plunger seal and/or the strength of my bungee are deteriorating, because I've dropped in ranges in the past few years. Not sure what it's at right now, but I'm definitely not hitting a solid 130' anymore. Probably right around 90-100'.

Moving on, back to YOUR ranges. Your crossbow gets ~80' ranges, as per your post. Great!

Captain Slug's felt-tipped darts, which I see you are using a green felted variant of, are lazer accurate, as he claims. But in examinations and tests I did after his visit with a number of his darts I found during a post-geddon sweep, I found that they have a bit of a range wall. They fly beautifully and straight, and then suddenly, I see them visibly deecelerate, and begin a smooth, but rapid descent. Like they suddenly lauched a breaking parachute. Odd, but it's there. If your observations are different, by all means, discuss.

So there's a possibility that you could acquire better ranges by switching to a more standard hard-tipped dart. HOWEVER, accuracy is everything, so I'll leave that to you. My darts are accurate too, but there is more deviation from the flight path, however slight, in mine as compared to felt-tips.

On the other hand, you could easily gain some additional range by shortening your barrel. I've seen SO many ridiculous lengths for crossbow barrels...it's mesmirizing. My crossbow's barrel is a whopping 6 3/4" long, and only 5 1/2" of that is the main piece of brass. The crossbow's plunger isn't big enough to truly take advantage of an extralong barrel. I'm not going to attempt to tell CaptainSlug, or any of the other crossbow/+bow users that their barrels are too long, but I certainly don't agree with their barrel length. I'm in no position to tell Slug that his +bow's sliding breech barrel is way too long, but if it were mine, I'd certainly shorten it.

Then of course, you might wonder if this would reduce your accuracy. If you stick with the felt darts, I think their tendency to not deviate in windless conditions will make up for the shortened barrel.

Again, I know I'm playing with fire here, but just take my words with a grain of salt. If you're happy with how it performs and it does what it needs to where it's at right now, have at it! If you're not and you want to make a few adjustments, I'll leave it up to you. Either way, you do beautiful work, and I'm loving how your crossbow turned out.

EDIT:
Just read through one of your replies again, and it made me chuckle. You shoot at your basketball pole too, eh? 30'...that sounds about right, from the sliding door at the back of my house to my pole...yeah, I think that's it. Woo hoo basketball poles!

Edited by Falcon, 05 September 2008 - 05:42 PM.

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#7 Z4

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Posted 05 September 2008 - 05:59 PM

You have some excellent points. I would say that my darts are actually tight in the barrel, they don't require twisting or anything, but I can't blow them out of it, or even budge them (I'd consider myself to have above average lung strength too, 3 years of alto sax'll do it). I haven't really watched my darts, I see where they go but generally don't make observations of their flight paths, I'll look into that as well. I prefer accuracy over range, but I'll experiment with standard darts too to determine the best performance. I had honestly never considered a barrel shorter than 8" or so either. That will also be part of my impending investigations.

Again, I know I'm playing with fire here, but just take my words with a grain of salt.

I am by no means inflamed by your words. I recognize that they are the words of a far more experienced Nerfer, and I value your input. You have my gratitude for helping me get the best out of my gun. Thank you.

EDIT: Yeah, I'd say basketball posts are about the best targets around, that and water bottles, and old soccer jerseys hung on trees.

Edited by .Z4., 27 October 2008 - 01:38 PM.

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#8 AssassinNF

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Posted 05 September 2008 - 06:14 PM

I've always been confused by people's use of CPVC for barrel material. In my experience CPVC is extremely tight with all of my darts, stefan and stock (and my darts are loose in OMC's PETG). I have to twist darts to even get them in halfway. It seems to me that the ID of CPVC varies greatly depending on who makes it... and I apparently live in the land of uber-tight CPVC.

Great mod, btw, Z4. I like the paintjob as well.
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#9 Icespartan 1114

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Posted 05 September 2008 - 06:40 PM

Ahhhhh, The beauty of the crossbow. Well done. I especially like the paint job, One question though. What is that big spot on that one shell of the gun? Was it a paint defect or something? Nice work.

Edited by Icespartan_1114, 05 September 2008 - 06:41 PM.

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#10 Z4

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Posted 05 September 2008 - 06:52 PM

AssassinNF-My foam is fairly thin, CPVC is the best thing for high powered springers with it.

Icespartan-That spot is where I had a Crossfire clip epoxied on that I broke off because it interfered with everything. I had only primed when I decided to glue it on.

Thanks for all the compliments!

Edited by .Z4., 05 September 2008 - 06:53 PM.

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#11 Gears

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Posted 05 September 2008 - 06:55 PM

That's a million. I remembered you posted this on the HQ before the 2 month setback. I was looking for it everywhere.

All the praise that I could say has already been said. Props.
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#12 Z4

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Posted 05 September 2008 - 09:19 PM

Thanks. I figured I'd go ahead and post this as my other write-up that I'll have up in a few days is influenced heavily by it.
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#13 Mr Tubb

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Posted 05 September 2008 - 09:28 PM

Great modification and ranges! I also like the paintjob; it reminds me of triple chocolate goodies.
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#14 Z4

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Posted 06 September 2008 - 03:05 PM

For some strange reason, every hardware store in my town is mysteriously out of CVPC, so until I can get over to another one (later today or tomorrow), Part II is on a brief hold.

Edited by .Z4., 06 September 2008 - 03:06 PM.

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Z4 of the NIC
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#15 Guest_Killakit_*

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Posted 28 September 2008 - 04:34 PM

Very Nice modification. If I had a crossbow I would definately do that. And incredible paintjob. Good job.
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