3D Imura Hybrid Revolver 2.0 printed, Test Firing Soon

Gun Watch ^ | 11 May, 2015 | Dean Weingarten

[marktwain]

An Imura revolver, 2.0 has been designed by that intrepid 3D engineering designer, Wayfairy.   He had to redesign the system, but the prints have been done and the prototype has passed the basic, non-firing function tests.  From 3dprint.com:

One particular member of the community, known as ‘Wayfairy,’ has taken a particular interest in the Imura story. In fact he has set out to create a 3D printable gun honoring the incarcerated gun manufacturer, called the ‘Imura Pistol.’ Basically what he has done is take the original .38-caliber Zig-Zag revolver that had led to Imura’s arrest and revised it, making several key changes, designing a new gun from the ground up.

The major question is whether it will withstand the tensile forces that tend to separate the cylinder from the barrel and drive the case to the rear.

As you can see, the design is a hybrid, using metal tubing and 3D printing, that takes advantage of some of the best of both materials and technologies.

The gun itself uses .22 long rifle ammunition, and a .225″ ID 316 or 308 stainless tubing from McMaster. As for its appearance, just take a look at some of the images above and below. It’s a masterpiece in our opinion, and the only question left to be answered is whether or not it will actually fire a bullet without exploding in one’s hand.

As I wrote in September of 2014:

I see one weakness that the designers have probably noticed.   There is very little tensile strength in the proposed design.   Convention revolvers use a metal frame to contain the forces generated by firing a charge.   The chambers contain the pressure at right angles to the barrel, but the frame, chamber, and case, if one is used, must contain the pressure to the rear.   The projectile contains the pressure to the front, where the force is used to propel it out the end of the barrel.

 

If I were designing this revolver, I would consider the use of a bolt as a center pin for the cylinder to turn on.   A simple backplate of steel could be made to screw the bolt into, adding tensile strength.  It would not need to be circular, as long as it supported the rear of the chamber being fired.  Removal of the bolt would allow the cylinder to be removed from the side of the design, so as to facilitate loading.  Many conventional revolvers use this design feature.

 

Wayfairy did not use my free advice, but it is possible that the ABS plastic used will have sufficient tensile strength to fire a few shots.   The potential points of failure that I see are; cracking of the ABS backing plate at the firing pin hole, and cracking of the lower split hinge.    

If that occurs, there are fairly easy design fixes.  A properly sized steel washer could be inserted between the  backing plate and the cylinder.  Size the washer just big enough so as to not quite reach the firing pin holes and it would not need any machining. That would likely solve cracking of the backing plate. 

If the lower split hinge cracks, it should be possible to increase its diameter by 2X, or even 3X, which would increase the tensile strength by 4-9 times.   If that were insufficient, my original suggestion of a center - pin made from a steel bolt would greatly increase the tensile strength.  There is plenty of room in the cylinder for this, if it is necessary.   If the bolt were combined with the washer, it could be threaded into a nut at the front or back during loading of the cylinder.  Because this design does not rely on a center pin for indexing, and given the repeatability of 3D manufacture, several cylinders could be pre-loaded and used as a means of quick reloads during firing.  

I would have no qualms about test firing this revolver, given a few safety considerations.  I would wear gloves and ballistic eye protection, and hearing protection.   My hat is off to Wayfairy, who is working under considerable constraints.   The combination trigger, hand, and sear is an ingenious design.

As the people creating this interesting revolver are intelligent, they will likely function fire the prototype with primed casings, to insure ignition.  In my first firing test, I would use Aguila Colibri .22 cartridges.   It is likely that this design will have sufficient strength for them.   They could move forward from there to destructive testing if they like, with more and more powerful .22 cartridges.  The Colibri cartridges would be proof of principle, and would make a wonderful YouTube video with popping balloons or smashing Oreo cookies at a yard or two.  They are as powerful as many air rifles.

These wonderful pictures are from  3Dprint.com, in the article by Brian Krassenstein.

©2014 by Dean Weingarten: Permission to share is granted when this notice is included.  Link to Gun Watch

[marktwain]

Steel tubing, pins, bolts and washers are industrial commodities. The design could easily be modified to use stud driving blanks and cast lead balls where cartridges are difficult to come by; or it could be made as a percussion cap design, or as an electrically fired muzzleloader. These variations would be relatively minor design changes. The idea of several pre-loaded cylinders adds considerable firepower to the system.

[taxcontrol]

Max pressure for a .22LR is 24.000. If that can be achieved in the design, that pressure level would allow a whole lot of cartridges:

22WRM
380 Auto
38 Special
44 Special
45 Auto
45 +p Auto
45 Long Colt

[marktwain]

Chamber pressure is only one consideration, and in the .22 LR, it is highly variable, depending on the cartridge. The Colibri round has a much lower chamber pressure, I would suspect, as it does not use any powder charge.

The total rearward thrust is also important.

But, you make a good point, which is that the design is adaptable to many other cartridges.

[Ruy Dias de Bivar]

WOW! Another automatic revolver! Definitely not like the Dardick! More like the Webley auto revolver.

[marktwain]

No, not an automatic revolver, even though it looks a bit like one.

It is just a double action revolver using the zig-zag type of indexing and advancement.

I find the idea of extra, pre-loaded cylinders to be intriguing. As the cylinders are mostly plastic, they would not be much heavier than speed loaders...

[smokingfrog]

kewel

[Charles Martel]

Max pressure for a .22LR is 24.000. If that can be achieved in the design, that pressure level would allow a whole lot of cartridges:

The amount of material surrounding each cartridge in the cylinder is a factor, of course. The hotter .22 Magnum might be possible, but a scaled-up redesign might be required for larger bore sizes.

[JoeFromSidney]

The outside of the cylinder might be wrapped with glass fiber or a strong plastic fiber to add some strength to the cylinder.

[marktwain]

The outside of the cylinder has little stress on it in this design, because the stress is contained in the steel chamber liners.

If there were no chamber liners, then fiber reinforcement would be useful.

I do not know if any of the 3D printers produce fiber reinforced materials, which would be another way to increase the strength of the cylinder.