Autonomous hybrid IV

[hectmarr]

If you have to re-size or adapt brake cylinder pistons I will suggest a very, very sharp clean file. You have made a great choice for durability, these things last for ever. I've rebuilt a boat load of brake cylinders in my mechanical career and the piston cylinder wears out before the piston 99% of the time in my own experiences.

I will take your advice into account if it is necessary to reduce the diameter of the brake piston a few tenths of a millimeter. I just found one of 32 mm, which should fit very fair. I think I'll have to reduce to 31, 7 mm.

[jrrdw]

If you have enough wall thickness on the cylinder you might want to take the material from there thus trueing the cylinder making them a matched pair. It really does improve performance and reliability.

[hectmarr]

I found these pistons that adapt without any modification to the inside of the steel tube that I have. The one with the red arrow is the one who serves me. I have to check with a Toyota agency about this piston. I hope to get it. I'll have to play with trying some o`rings to fit perfectly.

[hectmarr]

This project continues to advance. I have completed the lever of the air pump, and I have tried this part. It is soft to pump the air and with 5 pumps achieves about 7 bar, for 10 ml of butane gas. I need to install the firing barrel and the handle, stock and piezo igniter, I forgot to buy ...
I'm going to use the piston that I already have, fiberglass, and the brake caliper I'll use it later, because I have not got it yet.
I have also finished the gas charging system and opening the exhaust valve. I'm going to use this system that is simpler, so as not to include the solenoid valve, batteries etc. You can change to this system in the future, because I have left what is necessary to do it without modifying anything important.

[hectmarr]

I did some tests with 6.35 mm lead pellet. Obviously, the power of the shot is not as much as it happens with the bb steel and retention system with o'ring. This was 8X. While firing forcefully, the resistance offered by the pellet in the rifled barrel is much less than the resistance that occurs when the steel bb has to go through the tight o'ring.
Now I am installing the bb's 1/4 "system to compare the results, I should drill a 0.8mm steel plate without problems, which the lead pellet can not do.
As a learning I take clean, it is not convenient to use this system for pellet, I mean the piston and spring system. This works great for bb with retention. For pellet and rifled barrel, (without retention of any kind), it is better to use a normal piston valve.
I leave a picture of the installation of the system for bb's of steel of 1/4 ", (that I want to do again for bb of 8 mm), in the present.
Otherwise, everything works very well, not having a single misfire in about 20 or 25 shots, 8x, and 10 ml of butane gas. The air pump and valves, work excellent. There is a significant improvement over the other hybrids. The only thing that is unfavorable is the weight of the weapon, which is around 2800 gr ... but it's not much.

[jackssmirkingrevenge]

Your attention to neatness for this one is admirable, looking good!

The only thing that is unfavorable is the weight of the weapon, which is around 2800 gr

A "real" M14 rifle weights over 4kg, I think that yours is reasonable

[hectmarr]

The weapon is almost finished. I still need to build shoulder support and install the open sights.
It is shooting bb 1/4 ", to 8X, in the future, when it has more shots made, I will go up to 9X which is the programmed pressure for this hybrid.
I have already tried it and it has enough energy when firing. Burns 10 ml of butane, which is what I provided the volumetric dispenser.
It is interesting to note that the noise is very little, and this is due, in my opinion, to the fact that the pressure drops a lot in the firing barrel, and when hot air comes out of the muzzle, the pressure is low, and the sound not very loud. Much of the pressure has been transformed into kinetic energy, throughout the length of the barrel. It does not need a silencer , because the only thing that makes noise, (it is inevitable), is the objective plate, steel of 0.8 mm, perforates them without any problem, although the projectile is light. I will finish the stock and paint something in the near future.
The firing barrel has a PVC tube on the outside, to improve the finish. Tube to build it in two parts, because it is easier to give the exact caliber, and the union reinforced with fiberglass, looks and looks bad. Inside is a 5/8 "hard brass tube and the resin core lubricated with graphite.
I leave a photos of the bronze piece that compresses the ammunition retention o'ring, of the air pump, (very light to operate, goodbye discomfort in my left arm), and of the weapon as it is in the present.

[jackssmirkingrevenge]

This is shaping up really nicely!

[hectmarr]

Yes, it is more or less what I had in mind, but there are some issues that are different in the operation of the weapon, in reference to those who have a single-stage air pump.
This design achieves the amount of air according to the number of pumping cycles that one performs. The above, on the air pumps of simple effect, it is easier to achieve even cycles, but in this model of double-effect air pump, you have to practice a bit to achieve equal cycles in both directions. If the pumping is untidy, the amount of air varies a little, and the triggering of the shots is irregular, not much, but not so much that it does not shoot. It is not a big problem, but you have to be careful to pump evenly in both directions, and in this way, always shoot the same. The weapon does not have a pressure gauge, it only depends on the number of cycles to achieve the required air pressure.

[hectmarr]

Finished project.
I made a photo of some parts of the HA-IV gun, and a general photo, of all the prototypes manufactured in this project.
All shoot well. The first, on the left side, does not have the air pump, but it is still part of the series. The second, shoots 5.5 mm pellets, the third and fourth, shoot 1/4 "steel balls, and are the most powerful.
The two cartridges hybrids are missing, with a rupture disk, but I do not have them near at the moment, for this reason I have not included them in the photo.
These weapons were constructed with waste materials, recycled, and none of them has any part machined with a lathe or welding of any kind. Absolutely everything is manufactured by me, it was a very nice experience.
In the future, probably, I think I will give the HA-SA I the semi-automatic hybrid again, if time permits.

[jackssmirkingrevenge]

Fantastic, I love the family photo! Looking forward to see the latest addition to the menagerie in action

[hectmarr]

Fantastic, I love the family photo! Looking forward to see the latest addition to the menagerie in action

Oh yeah! I have to make the video accordingly. Just have someone to handle the cell phone, I will.
Thank you very much Jack, for the lessons, I have learned a lot from you, and for the moral support, to carry out this home project.
What follows now, is to combine this type of hybrid weapons, with the semiautomatic system, to achieve an acceptable firepower and faster firing. I have divided into different weapons, these two issues. I have to integrate ...

[hectmarr]

After making many shots, the 1/4 "steel ammunition retention o'ring is burning. At the beginning, when it is new, the power of the weapon is very good, and slowly decreases because the retention it has, logical decreases.
I have thought of manufacturing another type of adjustable retention, such as drawing. It is my idea that having a steel ball, it will not burn anymore. When you adjust the screw it costs more work to go out to the bb which is the ammunition that goes to the target, and this allows me to adjust the maximum pressure peak of the explosion chamber, or to loosen it, to have a variable power weapon.
With the o´ring it works perfectly, but up to 50 or 60 shots, and from this point, the gases that come out very hot, erode quickly, (real data that comes from the practice), and I have to loosen the cannon of shot and replace it. What do you think of this system, any other ideas? Any comments on this?

[hectmarr]

I thought about making bronze, aluminum is very soft and stainless steel, more expensive), this mechanism. Having no o´ring, the diameter of the tube where the spherical projectile is housed must be absolutely round and adjusted to the 1/4 "steel bb, rectified, to minimize losses. In other words, it should be as sealed as it can.
I did some tests and it retains the ammunition very well. The screw where the spring is housed must have an o´ring to avoid hot air leaks.

[Moonbogg]

I didn't see this before, but that's a nice looking group of launchers. I love the look of the new one. Nice work.