CNC Split Gearbox V2 with int. Hop Up Chamber (8mm) - RetroArms

CNC split gearbox V2 with integrated Hop Up chamber is designed for airsoft weapons type AR15 (M4), M16, made of the block of the strongest aircraft duralumin EN AW 7075 T651, which has a higher tensile strength (590MPa) than ordinary structural steel (390MPa) . Thanks to the material used, the gearbox has several times longer service life than a conventional zinc collar gearbox. We produce gearboxes on precision CNC machine tools, directly in our factory. The number in parentheses (8mm) indicates the diameter of the bearing bore.

A split gearbox means that the gearbox is divided into three parts, the Upper and Lower chambers and the Hop Up chamber. A special pocket is milled in the upper part, into which a Hop Up chamber for AR15 (M4) is integrated. A split gearbox has several advantages. It is especially easy to install internal parts in the gearbox. When tuning the air conditioning, the lower part of the gearbox is installed in the weapon and only the upper part, which is held on a pin, is removed, so it is not necessary to assemble and disassemble almost the entire weapon. However, the biggest advantage of a split gearbox with an integrated Hop Up chamber is the absolute coaxiality of the gearbox with the Hop Up chamber, and the Hop Up chamber does not bounce during firing because it is attached to the gearbox. In addition, the gearbox with integrated Hop Up chamber partially compensates for the slightly curved AR15 (M4) bodies, where the problem is performance due to misalignment. For very crooked bodies AR15, we recommend using a split gearbox, but without an integrated chamber, so as not to like the Hop Up chamber.

The Hop Up chamber has a control with a rotating wheel with a click, which means that the set Hop Up does not decide even when shooting. The Hop Up chamber is equipped with our invented collet nut, which prevents the inner barrel from swinging when firing. Due to the collet nut, we had to turn the barrel lock by 180 °, because otherwise the Hop Up chamber would not fit into the outer barrel. The procedure for assembling the collet nut is simple. The inner barrel with the Hop Up rubber band is inserted into the Hop Up chamber, the plastic barrel lock is snapped in, which we hold with one finger so that it does not turn, we screw in the collet nut by hand and lightly tighten with a wrench. Thanks to the groove in the collet nut, the nut deforms and firmly clamps the inner barrel into the chamber so that the inner barrel cannot move during firing.

The recommended nozzle length for the integrated Hop Up chamber is 21.3 mm. Compared to the standard size of 21.4 mm for AR15 (M4) weapons, this is due to the integrated Hop Up chamber, which does not bounce when firing. However, the length of the nozzle can be affected by other factors, in particular the angle of inclination of the feeder arm or the Hop Up rubber neck of different lengths, where in rare cases it may be necessary to use a nozzle with a different length.

Package contains: CNC split gearbox V2 with int. Hop Up chamber (8mm) - QSC in the selected color variant, pressure lever, adjusting wheel, spring, plastic pin, collet nut, set of screws and QSC spring guide.

We have incorporated many useful improvements into the CNC split gearbox V2:

• The spring holders have a notch so that the spring of the feeder arm and the trigger shuttle do not fall.
• Notch for the trigger lock spring to prevent the spring from slipping out during mounting.
• Notch for the trigger spring so that the spring does not slip out during mounting.
• The holes for the bearings have a diameter smaller by -0.02 mm (7.98 mm), so that the bearing does not rotate after mounting and the leading edges are chamfered, which simplifies installation.
• We have increased the grooves for the cables by 1 mm, now it is possible to run cables with a cross-section of 2.5 mm without any problems.
• We have added a protrusion as protection against abrasion of cables from the engine neck.
• All threads are now formed, compared to the cut thread they have higher strength.
• Both halves of the gearbox are centered by milled protrusions and grooves.
• We've added a hole through which the reverse latch can be released.
• For even greater service life, we have further strengthened the very critical point on the outside with a gear at the cylinder head, where there is now a large radius and at this point there is 100% more material.
• We have added a notch for the spring of the backstop so that it does not pop out during assembly.
• The outer edges are chamfered.
• On the outside of the gearbox is the diameter of the holes for the bearings (8mm or 9mm).

The gearbox has a quick QSC spring change, thanks to which the spring can be pulled out by simply turning the Allen key with the spring mandrel, without the need to disassemble the gearbox. With this solution it is necessary to secure the spring guide with a screw, for AR15 (M4) weapons it is done by tightening the stock screw, or for weapons that have, for example, a folding stock, it is necessary to secure the spring guide with a QSC screw. Otherwise, there may be a situation where the spring conductor gets stuck in the spring. This is due to the quick replacement of the spring, the spring guide is not fixed in the gearbox, but so that it can be pulled out by turning the key.

The space for trigger contacts is adapted so that it is possible to install and use common trigger contacts and processor units from commonly available manufacturers such as Gate, etc.

The CNC split gearbox V2 has a surface treatment with protective anodizing, because thanks to the properties of duralumin EN AW 7075 T651 it is practically non-anodizable, due to its high hardness and strength compared to normally anodizable aluminum, ordinary anodizing does not penetrate into the material. If this dural is not protected by a surface treatment, there is a high risk of corrosion of aluminum (large gray spots, sometimes with a moldy appearance).

The CNC gearbox can be installed in airsoft weapons in the Tokyo Marui compatible standard. This also applies to internal parts. Never use brute force when installing internal parts or the gearbox itself. When tightening the screws, use a tightening torque of max. 1Nm, otherwise the wrench will turn in the screw head. It is not necessary to tighten the screws "on blood", if you want to be sure that the screws will not loosen, use an optional thread glue or paint.

Any spring force can be installed in the CNC gearbox, but it is necessary to realize that the stronger the spring, the lower the life of the gearbox.

!! do not use MAXX cylinder head !!

Installing internal parts in a gearbox as well as a gearbox in a weapon requires expertise, experience and skill. Thanks to the large number of different manufacturers of airsoft weapons, where each manufacturer "invents" its dimensions and there are no standards in airsoft as we know common from mechanical engineering such as ISO, etc., one type of weapon from several manufacturers can be completely different, both in size and size. by making internal parts or a mechanism. Therefore, we recommend weapon manufacturers who state Tokyo Marui compatible, where there should be no problem with the compatibility of the CNC gearbox.