Custom

[Anonymous Coward]

I posted this on the VM68 forum, but I think this fits nicely here too. Yes pictures are below!

Note: I did not make this bolt, Dan Sergison did. I designed it, sent him the plans and money, and he made it for me. I don't have the mechanical skills, equipment, or knowledge to make these. I just came up with the design and had Dan make it for me. He was very kind and professional in making this for me. Now onto the fun.

I needed an antichop bolt for my VM, not because I'm stupid fast on the trigger( in fact the opposite), but because I'm the unluckiest fool on the field. If I can chop paint, it will happen to me. Initially I went with the JAM anti-chop design, but this wouldn't work for two main reasons. 1) The clearance needed in the hammer throw what longer than the bolt's valve orientation to where the spring compression could take. Meaning even with a light spring, by the time the hammer finally hit the valve I would chop the ball. 2) On a blow back the force of the air as it comes up into a bolt is in two directions. One direction is the gas pushing against the ball, the second is the counter force pushing the gas against the bolt in a rearward fashion. With a spring it's at it's weakest when completely uncompressed. Thus the bolt would misalign over the valve port.

What I needed was a solution where I had a strong resistive force up front that could break and have a diminishing counter force. Because right now the spring idea is the complete opposite. I came up with the idea of using neodymium-iron-boron magnets (rare earth) as they are super strong even for very small magnets. The problem with these magnets are the are very brittle. ( I have lost over $75 worth of these magnets in them zipping over a foot in distance smacking each other into splinters. These are the larger magnets that I'm experimenting with a springless blow backs. So be careful!) So what Dan did was use the guts of a JAM bolt and attach one magnet to the inner collar and then another bolt to the rear screw. The bolt itself was hand made by Dan. This allows me to tune/tweak the breaking force pull between the magnets as I adjust the depth of the screw. Meaning I can adjust the breaking force based on the thickness of the shell of paint I'm shooting.

Here is the initial design I sent to Dan:
http://webpages.charter.net/chcarver.../anti-chop.png

What happens is during normal operation the two magnets are strongly attracted to each other, so when the gun is fired the force bond between the magnets are not broken. If a misfeed happens, the bond between the magnets are broken and no other force is applied to the pinched ball. Unlike other spring anti-chop designs, where their force is increased as the spring compresses.

Now here we see the new bolt and the new pin hole in the hammer. This design is universal, so while the VM needed a new pin hole, this doesn't mean all guns need this too. You will see a spring and that was initially needed to reset the bolt to latch the hammer if they disconnected it. I resolved this problem by placing a bumper behind the bolt so on disconnect the bolt and hammer would always reconnect 100% of the time.
http://webpages.charter.net/chcarver...anti-chop2.jpg

This is showing the old and the new bolt:
http://webpages.charter.net/chcarver...anti-chop4.jpg

Here is the collar and bolt adjuster. On the left (black part) is the screw that has one of the magnets on it that goes in the rear of the bolt. On the right (white part) is the collar that the pin slides into. It too has a magnet in it.
http://webpages.charter.net/chcarver...anti-chop5.png

Here is a quick time Dan sent me of it working. I don't have video skills to post my own yet (working on that).
http://webpages.charter.net/chcarver...s/P1010333.MOV

The overall design can easily be used in many different markers. This should come in really handy for pump guns. I'm always slicing a ball in the frantic chaos of a good pump game.

[jhyan]

brilliant

[secretweaponevan]

Fantastic idea.

[HP_Lovecraft]

Originally Posted by jhyan

brilliant

I agree.
The VM version I tried to make 10 years ago suffered from the same problem that many of the antichop methods have: linear resistence.

Basically, the force of feeding the paintball, and blowback creates a large amount of inertia, which if there is nothing between the bolt and hammer except for a spring, then the bolt might not shut fully before the hammer hits the valve.

This magnetic version is brilliant because it creates a non-linear resistence. Meaning, its only strong when connected to the magnet. As soon as counter resistence builds, it seperates, and all resistence stops.

The one that I tried to make, years, and years ago looked like this:


Though instead of levers, I tried to use simple spring-loaded ball bearings to provide initial resistence, which drops if a pinched ball makes the bolt "slip'. Never worked, though a similar system is what is now used on the Tippmann anti-chop system.

nick

[HurtCow]

Amazing idea, though I'm sure it's infringing on a SP patent somehow. Call an attorney asap.

[fog]

OMG, an i was just drooling at that one on motm,,, ahhhhhhhhhhh,,


i need a cigarette

[Pepper]

Allot of peeps have ideas but never act on them, Taking it from concept to the real thing is just awsome!

[Skippy]

A lawyer representing Smart Parts inc. will be contacting you shortly with details of your patent infringement.

But seriously, this is brilliant. I'd suggest first getting a patent for it, then pitching it to someone to put it into widescale production. Unless, of course, you can do it through the guy who made this particular piece. But seriously, this is a brilliant piece of work. Simple and elegent, but extremely functional. I can see a lot of people buying something like this.

[Anonymous Coward]

I consider this Open Hardware freebie! May it make someone else rich or at least rich enough to buy a burger, fries, a soda, and super size it. I don't even want credit. Make it your own and have at it.

[Railgun]

I'd love to jump on the congratulatory bandwagon with everyone else but the links in the first post are giving me a 404. I guess I'll try a little later. Maybe it's down for some reason.

In concept the idea is fantastic and I tip my mask at you for sharing with us. This truly does sound like the mechanical equivalent of eyes on the electros.

I'll gush my praise anew once I get to study the pictures...

And I agree about chopping a pump. There is nothing that makes your toes curl and your liver leap to your throat leaving behind a huge vacuum in your gut like feeling the slght resistance followed by the slicing action coming forward to the pump handle.