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Homemade ERTL catch

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#1 atomatron

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Posted 09 January 2012 - 03:35 AM

Initially I intended to post a full writeup for an identical blaster but I am working on a pump action variant and I don't really need another one of these, hence the post-build writeup.

The purpose of this build was to take the simplification of catches to as far as possible; the catch is the trigger.

I made a basic pull back snap/rainbow type blaster as the testbed. I recycled the nylon plunger rod from the rainfire, a snap style CPVC plunger rod could be used instead, I recommend using that.
It's 1 1/4" PVC, the spring rest is a 3/4" endcap, it has a k26 and I haven't tested ranges and probably will not.
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A shot of the trigger pulled. This causes it to fire after it is primed....
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Here you can see the catchface; a dremeled-to-fuck piece of polycarb, I will not be using this design again. Instead using a 3/4" endcap; it is much less work as it is already the right general shape and you would just need to bevel the inside edge to get the same functionality.
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Here's an Ms paint drawing in case you don't get how this functions by looking at actual pictures.
Blue = trigger/catch
red = plungerhead+plunger rod
blapck = plunger tube
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Fun tips for making this sort of thing; the longer the catch arm of the trigger/catch is and the closer the pivot point is to the plunger tube the more stably it will catch.



Additionally, since I know someone will ask about the handle; it's made of some sort of plastic+sawdust decking material I found in the scraps bin at my nearby Menards. It is easy to machine and basically the best stuff ever.
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I'm sure there will be a lot of questions because this is so retardedly simple that it can't be understood.

Edited by atomatron, 09 January 2012 - 03:37 AM.

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Perche Germolgi. [Because it shoots]

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#2 chavez guy

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Posted 10 January 2012 - 05:44 PM

Well seeing as it has been a couple days and nobody has done it yet and you more than deserve it, I give you major kudos for this.

And I do have one question. I know it is probably pretty obvious, but how do you keep the catchface in place? Is it like attached to the plunger rod or do you rely on the spring to keep it in place?
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Hablamos Espaņol

#3 Pause

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Posted 10 January 2012 - 06:39 PM

So this is basically a polycarb SNAP design? I know they are different in construction, but they have the same concept.
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-Pause-

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Heh.

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#4 ChaosPropel

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Posted 10 January 2012 - 07:42 PM

Very nice. I think this is a nice alternative to the snap for those who want something a bit more elegant.
How are you making your seal? How did you achieve that awesome cup?
Also, does the wood you used for the handle take holes/threads well? I may try to get my hands on some, to try it out.
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Preheat oven to 350 degrees F (175 degrees C).

#5 shardbearer

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Posted 10 January 2012 - 10:07 PM

This reminds me of the bullpump, which used a 3/4" wooden trigger. Do you think high quality 1/2" or maybe 1/4" birch plywood would be strong enough for this?
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Thanks for listening to the nonsensical ravings of a lunatic madman.

#6 atomatron

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Posted 11 January 2012 - 06:08 PM

Well seeing as it has been a couple days and nobody has done it yet and you more than deserve it, I give you major kudos for this.

And I do have one question. I know it is probably pretty obvious, but how do you keep the catchface in place? Is it like attached to the plunger rod or do you rely on the spring to keep it in place?

Thanks.

It's the force of the spring pushing it against the spacer I have that keeps it there. I could goop it there If I wanted to but it's a fairly tight fit on the nylon.

So this is basically a polycarb SNAP design? I know they are different in construction, but they have the same concept.

Yes, they are the same and for most designs, interchangeable.

Very nice. I think this is a nice alternative to the snap for those who want something a bit more elegant.
How are you making your seal? How did you achieve that awesome cup?
Also, does the wood you used for the handle take holes/threads well? I may try to get my hands on some, to try it out.

My seal construction is as follows: (screwhead) 7/8"(od) steel, 1 1/2" rubber, 1 1/4" rubber, 1 1/4" steel, (plunger rod). Tightened until the cup is formed, I find that drilling the hole in the plunger rod as close to strait as possible does a lot to keep the seal consistent all the way around, if it's a little off the rubber washers will deform one one side much more than the other.

Yes, the wood plastic decking (as I have found it to be referred to) takes to both very well, additionally it is very fire resistant, I found it in the 'premium wood scraps' bin.


This reminds me of the bullpump, which used a 3/4" wooden trigger. Do you think high quality 1/2" or maybe 1/4" birch plywood would be strong enough for this?

I can't say for sure; I think that it could work. You would need to make the catch arm of the trigger much thicker to distribute the stress adequately. It's worth trying if you don't have access to polycarbonate.
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Perche Germolgi. [Because it shoots]

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