370 replies to this topic

[Prometheus]

Could someone post Bolt's pic of the SCAR-N bolt? It doesn't appear when I check it out, on multiple pc's and browsers (also his forums don't work anymore). Also, what holds the ejector in for real rifle ejectors? Just a suggestion. Also, a spring that might work, but a little harder to find, is from my snowmobile carb. It is a mikuni slider carb (very common), they all have return springs for the slider, and (no measurements yet) they look like the will fit in 1" thinwall, for any mega designs still going.

Edited by Prometheus, 05 March 2007 - 12:37 AM.

[Meaker VI]

CH, Bolt kept his ejector in by cutting a slot lengthwise in the dowel/carbon rod/whatever he used.

Like yay:

--____o---
-----------

He then put a pin (the "o") through the bolt and into the slot, the slot was long enough so the thing could be pushed all the way in and would go out as far as necessary.

Hope that helps.

[Commonly Hunted]

Meaker, I know that. I have the FAR schematics but I think the SCAR-N bolt is too small to use a pin the way he did in the FAR.

Promy:






Or go here.

Your welcome.

[SHADOW HUNTER ALPHA]

I finally understand how to make the gun pump-action now (thanks to my slow computer, which slowed the animated bolt lockup detail on boltsniper's webpage, and CH's link to that page). I may still build the bolt-action variant, but I will probably build the pump version first, now that I understand it.

[Commonly Hunted]

Got some more done today. But I have some terrible pictures.

The shell. Not glued together right now.



I think it came out okay but I was very surprised at how small it seems in my hand. I have the peices for a second shell but haven't assembled it yet. The stefan next to it is about 1.5" long.

The rotating bolt. About 90% complete.



Does not have the brass part of the bolt in it and the locking lugs haven't been shaped. The "opposing" lugs that go in the barrel chamber are cut but not glued in the chamber.

Plunger. Not glued, no catch.


I want to make the plunger catch like the one in Ompa's MEG pistol but the plunger head is like the one CaptainSlug used in his LongShot or like Carbon's in the SNAP-1 Mk2.

I accidentally resized the third bolt picture twice but will re-upload it and fix it after by camera's battery charges. I have no idea why these pictures were so bad, I didn't do anything different from the last time I took pictures. I suspect that the lense was dirty. I might replace the pictures tomorrow.

[SHADOW HUNTER ALPHA]

The bolt seems a little thick in the picture, but the locking head seems alright. I don't really like that plunger design, but that's just my opinion. It looks a little too flimsy at the head.

[Ronster]

No offence CH, but do you know how to focus a camera???

[murakumo32]

It may be that he is taking pictures too close for his camera to auto focus. I would suggest moving further away from the object so your camera can focus, or set your camera to ULTRA SUPER CLOSE <whatever> focus mode (I'm not familiar with camera terminology, but that much, I know).

[Commonly Hunted]

I told you guys that I took the pictures the same way I did the last time. The pictures just didn't come out the same, don't know why.

And there is no manual focus on the camera. All it has is a switch with a pic of a mountain (for scenery) and a flower (for close ups, the one I used) at the ends. It is very cheap and I keep asking for a new one but get nothing.

Anyways, I glued the shell and I think the back ring is one size too big because it fits in the bolt too tight. I thought I saw that the back was smaller than the body in the old pic Boltsniper posted but wasn't sure. I might be able to fix this one but I'm going to be making the second one today in the correct size.

I will also cut the ejector and find out how to keep it inside the bolt.

[Retiate]

Wow this thing looks like it's really coming along. You all are doing a great job on it. If I had any experience with homemades I might've attempted this. Though it looks really confusing.
A question about your shells... You are using 1/2" sch. 40 PVC, right? What is that they are fitting into? Is that 3/4" thinwall or something?

[Commonly Hunted]

Yeah, the magtube, where the shells are loaded into, is made of 3/4" thin-walled PVC.

But with my brass shells I might have to use 1/2" PVC. I just don't know if I want thin-walls or not because the shells will fit in either.

[SHADOW HUNTER ALPHA]

If I had any experience with homemades I might've attempted this. Though it looks really confusing.

Confusing? I'm still in the design phase. I need some down time to finish and begin construction (probably around spring break). I know how the gun would work, but I need to figure out the exact part sizes in the plan before I go and spend $100 on screw-ups and attempts at solving them.

[LastManAlive]

I hear you there SHA. I am still in the design phase as well. I have some sizes that I have thought up and put into the process, but nothing surefire. I am going by what I think looks best right now. And I pulled some ID and OD sizes for nominal pipe sizes off the net to use. I have drawn the barrel assembly (note: not the breech yet), the plunger tube, and some of the body. Again, just to give an idea of what to go by. Most of the actual body and parts will be freehand designs.

[SHADOW HUNTER ALPHA]

Since I'm not proficient with CAD programs yet, I intend to trace the outline of an airsoft gun that I really like the fit of (I.e. stock length, grip position, and overall length), then modify it to be something machineable with PVC. Then, I'll just insert 1:1 scale drawings of the parts I need so there are no conversions to do. I find this much simpler for my needs.

LMA:
What website did you get the ID and OD measures from?

Edited by SHADOW HUNTER ALPHA, 24 March 2007 - 10:35 PM.

[LastManAlive]

http://www.harvel.co...ch40-80-dim.asp

That page has most the sizes we can get in hardware stores in both Schedule 40 and 80.

[Prometheus]

LastManAlive, good for the measurements. Any measurements for thinwall PVC? Oh yeah, I just finished my FAR bolt today, but don't have pictures up yet. I also have a new ejector design that I will make some diagrams of, as mine is inside the bolt, so ya can't see it. Unless you are Superman with some X-ray vision. Which is cool. So yeah, pics I am currently working on.

[Commonly Hunted]

You're making a FAR?

Cool.

Do you have anything else besides the bolt?

I'm very interested in the new ejector design. Could you explain it while we wait for you to show us diagrams?

[LastManAlive]

I only recall seeing thin wall once, and I didn't know enough about PVC then. Only thing I can't remember about the experience was where, when, and what...I think I was at a friends house and we were playing with some until it snapped. And I remember from that that it was thin. And since I started nerfing, I have never aquired thin wall PVC.

But thank goodness for internet right? I did some research to find the scheldule on thin wall and what not. Turns out thin wall has an alias called SDR. It's schedules include 13.5, 21, 26, and 41. So, it is rated for low pressures. Here's where I got my information:

http://www.sonomawin...r/photo/pvc.htm

Now about those deminsions. I looked at the Harvel PVC site I provided above for Sch. 40 and 80 piping and there is a section for those schedule of pipe:

http://www.harvel.co...pvc-sdr-dim.asp

I am not sure about what nominal size you use, but I am guessing about 1/2inch. You should be ok for the Sch. 13.5 since they only list one row for 1/2inch 13.5. And if you are using 3/4inch or slightly higher, which I dought you use anything above 1.5 inches for homemades/mods, they only give dimensions for Sch. 21 in 3/4inch and higher.

Sorry if I couldn't help you out enough, but I hope it does help.

[Flaming Hilt]

Usually thinwall PVC is hard to find, but when you find it, you find it in abundance. For example, there was an ACE near me that carried all thinwall PVC. Then... they lost their rent. Every other store around here carries thickwall (or, regular, I guess).

As long as I'm posting, I may as well tell you guys I'm still going to build a shotgun eventually but am going to do some mods and other homemades first for practice.

[Prometheus]

Thanks a bajillion LastManAlive.

CH - I found the bolt pretty simple to build, just time consuming. I also have the barrel done, just waiting for another O-ring before I glue it all together in place. I am still working on a mag idea. Anywho, this bolt will be for my shotty next, as I like megas for some reason. Picture a slot in your coupler, right? just a straight in, but it does not go all the way through lengthwise. If this confuses you, picture BS's FAR bolt where the extractor is, same idea. A piece of PVC will slide in and out of there no problem. But how to keep the ejector in? Well, widen that slot, but not at the edge, so you get a demented and oblong "L" shape: (0's are empty space, the post would not display properly)

--------------
-----000000------
00000000000000
--------------------
Like this. Now cut a piece like this:

------
-------------
-------------
It will fit in the other piece (the original coupler,) and still slide well. The insert your pen spring in behind it. You might want to notch the ejector piece a little to help the spring stay in place. I also noticed that you must have a thin extractor ring on your shell, or else it will catch on the side of the bolt. I have to cut mine all down a bit so they ejected easier. There is also a piece that I glued in to the "L" shape to preven the spring from moving to the other side (I made the diagram with the piece not cut out).


Sorry it's so big, it was being a pain in the ass to try and get the right URL for the image.

Edited by Prometheus, 16 March 2007 - 02:25 PM.

[Commonly Hunted]

Oh, you didn't post again so I didn't check. But very nice. It looks like a PVC version of Boltsniper's brass SCAR bolt with the thin ejector.

I have to finish the shotgun today because of due dates. I'm actually two weeks late. All I need is the plunger and trigger catch. The brass barrel needs to be inserted but that's easy. And I'm only building enough today to make it functional so I can collect data for my presentation. If I have time I'm gonna biuld the stock and make more shells.

Ompa, if you are reading this, could you explain to me how you made the plunger and its catch in the MEG? I plan on using the desing for my shotgun.

If others know, please answer.

Once the gun is tested, I will post pictures and videos of what I have.

[Carbon]

The plunger is pretty straightforward on the Meg.

It uses the standard plunger head assembly, an endcap with a channel in it. The back end is similar to a FAR plunger, in that it’s a narrower stem. There’s a piece of CPVC placed over the end of the stem to serve as a catchface.

The spring rests against the rear of the plunger head. When pushed backwards, the spring pushes against a ring of PVC nested inside the plunger tube, serving as a spring stop. It’s narrow enough to stop the spring, but wide enough to let the stem of the plunger through. Once the stem pushes past the retaining ring, it’s clear to engage the firing pin.

The firing pin is pulled down by any of the normal types of lever actions needed to activate a remote firing pin (Like in any of Bolt’s or Ompa’s guns).

[Prometheus]

Yeah, sorry about not posting, I've been really busy building lately, and I didn't have any work done on my shotty as I was working on my FAR mag. But Ompa's MEG pistol uses an indexed plunger, which means it can rotate a bit, and the angle PVC ring will still engage the catch pin. Same idea as the FAR, but shorter, thinner ring. When my brother built a Snap-1, we indexed the plunger and it works well, but we noticed that without the metal washer, it quickly strips down the PVC, so sometimes it randomly misfires, or won't engage at all. I highly recommend using the metal washer bored out to fit, or at least glue some lexan/polycarbonate on to increase durability.

[Commonly Hunted]

Carbon, I was asking what material was inside the CPVC of the plunger. Not how it worked, I know that.

Anyways, I finished the plunger and the trigger catch. I tested the gun and it didn't even move the dart from the shell.

All I have is the barrel, the shell, the bolt, the plunger, and the trigger catch. That is all I need for the thing to work enough to test the ranges. I push the plunger down and insert the catch. I insert the barrel, shell, and bolt. I screw the barrel to secure it. And then I pull the catch out of the hole.

But it doesn't fire. I'm losing air somewhere but the barrel, shell, and bolt, are brass and don't have any leaks. The space around the bolt carrier isn't helping but it shouldn't be enough to lose all the air. Before I assembled the thing, I blew down the main assembly and was able to fire the dart without trying hard. So I suspect that the plunger isn't being pushed straight and the air is escaping around it. Even if it was slow as hell because of a super good seal, it would at least push the dart down the barrel. It doesn't do that.

Tomorrow, I'm going to change the plunger head a little to make it fire straight enough to let some air out. But if any of you had this problem, I would like to know what you did to fix this (if you did). I think Carbon and Ompa would be the best help here but don't let that keep the rest of you quiet.

Does anybody know what size end cap Ompa used on the plunger in his version of the SCAR-N?

Carbon, I'm thinking of changing the plunger head to one similar to yours in the SNAP-1 Mk2 but would a 1" PVC section work behind the rubber fender washer? I just want the plunger to be extra stable since it isn't guided by the back end of the plunger kind of like Ompa's. If it wouldn't work, I don't think it would be much of a problem.

And when I get it to work, I will show you what I have.

[Carbon]

I'm pretty sure Ompa used a 1/2" endcap in 1" thinwall, same as Boltsniper.

When you say a 1" PVC section, are you saying that it's in addition to the endcap it's mounted to? I can't see as it would hurt anything.

Sounds like your diagnosis is right, and your plunger is turning slightly...just enough to vent your pressure. Rather than adding something behind it, maybe you could try using two O-rings, like Bolt did on the FAR. He did it for extra seal, but I would think that two rings would remove the inherent tippy-ness of one ring and a short plunger.