Dual Spring CynthiAWP

This remix is my adventure in creating a higher powered CynthiAWP. By stacking an FX-3 full length X spring with a K31 I was able to hit ~330fps. With FX-3 + K26, I was able to hit upwards of 390, but the prime weight was considerable and force cracked the midblock and would likely fail over time.

Warning: A standard CynthiAWP build in PLA + 2 part epoxy, etc, will likely be damaged with the increased spring force. I haven't tested the long term durability of this build.

Provided remixed files

• Grip w/ knurled grip pads. I printed this as a single object with multiple parts, use beam interlocking if using TPU + PLA.

• Buttstock. Based on the buttstock in the longboi Cynthia Remix, but 2 parts (butt pad in TPU). Printed separately and assembled together with m3 heatset inserts. The buttstock has also been modified to have the plunger rod slot extend all the way through (see below)

• Bolt base and bolt cover. Modified to take an m5 heatset insert to use a 65mm M5 threaded rod and M5x22mm threaded ball knob to form the bolt. This also adds m3 heatset inserts and uses m3 socket head screws to tension down the ram.

• Combined top rail. Combined the mid and rear sections of the top rail into a single piece to increase rigidity and because I can fit it in my printer (H2D)

• Plunger cap. Added a lip to fit on the edge of the plunger tube. This provides an extra surface to both ensure correct alignment on the plunger tube and give more surface area for the solvent to bond with.

• PT Guide and Plunger Rod. To fit a full length k26/k31 spring, the raised lip on the inside of the CynthiAWP PT Guide had to be removed and an additional recess for the k26/k31 in the PT Guide was added. In doing so, the Plunger Rod then was too short to stay in place in the PT Guide rear guide hole when at rest. The Plunger Rod had to be extended (and its notch moved back a few mm to catch properly) to stay aligned and in place when the spring was at rest. To accommodate this, the plunger rod through hole had to be extended all the way through the buttstock.

• Plunger head. Added additional lip added to keep the larger X spring aligned and not collide with inner k26/k31.

Assembly and material modifications

• 4-40 self tapping -> M2 Heatsets. For a number of places where recurring assembly / disassembly was required, I use M2 heatsets, screws, and washers in place of the self tapping 4-40 screws. This includes the connection of the rails to the rear/mid body section, the PT guide to the PT guide base and the Buttplate to the stock / rear body block. M2 heatsets can be inserted with only minor reaming out of the existing 4-40 printed holes, so no re-modeling was neccesary.

• Plunger cap and plunger tube bonding. This was the first part to break in my original build, I could not get the PLA plunger cap and polycarbonate plunger tube to bond strong enough with 2 part epoxy. For this build, I printed the plunger cap in PolyMax polycarbonate and bonded it to the plunger tube with SciGrip/Weld-On 16. This is a solvent cement which melts the polycarbonate parts together and so far has proven to be durable under higher impact and twisting of the bolt base.

Other material choices:

• PolyMax Polycarbonate. I also printed the bolt base, bolt cover, plunger rod, top rails and catch in polycarbonate. Ensure you anneal your parts after printing.

• CC3D 72D TPU. The PTGuideBase and plunger head are printed in 72D TPU to absorb impact. Do not print any parts in 72D TPU which are under stress / force when primed. I originally used 72D for the plunger rod and PT Guide and both parts deformed over time.

• Tinmorry PETG-GF. All body blocks / shrouds were printed in PETG-GF