Cyma CM127 external Hop Up

All the pictures of the printed parts are of an older verion. 

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Parts List:
- 1pc M3x8 zylinder head screw
- 1pc M3 thread inserts (e.g. ruthex “RX-M3x5.7”)
- 1pc ball pen spring

Tools:
- drill (sized for the thread insert)
- sandpaper
-glue

For the external hop-up adjustment you will have to insert a thread insert in to your slide. To strengthen it, I recommend to glue “Part_1_Hop_Up_Adapter” to it. After gluing the Adapter to the slide, you need to drill a fiting hole for your M3 thread insert. The hole for the insert should be above the back edge of the ejection window, the position is marked on the Adapter. After inserting the thread insert, make sure to sand the inside of the slide flush.

The “M3x8 zylinder head screw” is to be heated up and melted into "Part_2_Hop_Up_Wheel". The screwhead should be seated as deep as possible, without poking out through the roof of the wheel.



Bevore assembling, don't forget to unscrew the original adjustment wheel from the hop up. Put a pice of tape on the hop up lever to prevent it from flipping up accidental.

 

The last step is to put the ball pen spring over the screw and screw it in to the slide. The spring should touch the screw head and therefore slide along while adjusting the hop up. If the spring is strong enough, it will prevent the hop up from changing due to vibrations.
In order to not damage the hop up, make sure to only assemble the slide with the screw flush to the slide and adjust it carefully.

 

Because the slide usually is quite loose on the body of the CM127, you will need to press the slide to the body of the CM127. Otherwise the hop will fluctuate badly. You can use a rubber band, zip tie or my “Cyma CM 127 Carbine Conversion/ Rony” for it.