...and I decided to build it with the Cyclone Dual Sector Gear. The high FPS tuning (what I usually do) doesn't require too much skills but on the other hand high and extreme speed involves a little bit more thinking. For this story I would discuss more about this product and by next week present to you Danny, the mastermind of Siegetek Concepts, for the meantime I need to answer my need for speed.

Some players try to do anything to make their rate of fire a little faster. The most common way to achieve higher ROF is to remove a teeth off the sector gear and/or piston and create a short stroking gearbox. Probably this method led to a cool idea which is basically a dual short stroking gearbox. A short stroke sector gear won’t do too much for most of its cycle and this is why Danny included an extra sector on the empty side of the sector gear. It may sound easy (and crazy) but this requires two complete feeding cycles under one revolution and sometimes managing even that one perfect cycle is hard.

First let me say a couple of things about the donor AEG. Because of its barrel length and furniture I've picked the G&P Sentry. It's a VLTOR M4 with great details, 8mm gearbox and that's exactly what I needed. The gun features a 7-inch quad rail, folding iron sights, VLTOR receiver with markings and a VLTOR collapsible stock what I had to get rid of and changed it to a JG short fixed stock in order to house my huge LiPo battery. The gun is pictured with the modifications I made and not in its stock form. I am planning to use a motorized box magazine later to feed this BB-hungry beast so I used a bipod grip because that will keep the gun from resting on the box mag when I put it down. The Sentry was pictured here with a STAR mid-cap magazine.. This gun won't be a sharpshooter rather than a room sweeper so quick target acquisition is important and the Trijicon RX-30 is perfect for that. Lighting up dark corners and halting enemy advances will be done with the Surefire Millenium M952@120 Lumens (incandescent bulb).

I have asked for the whole gear set instead of just getting the sector gear because I wanted to eliminate the possible errors using two or three different brands. Based on my request (to reach about 380fps) Danny recommended his balanced gear set with 20.15 ratio.

Two cut-off cams on the bottom and two knobs on the top side of the sector gear will help maintain the two feeding cycles. Eight teeth per sector, the parts of the gear were pressed with a 20-ton pneumatic punch to keep them together. The used material is hardened chromium-molybdenum alloy steel just like the step gear and the spur part of the bevel gear. The look of the step (middle) gear is quite unique and at first I couldn't believe that this will stay in one piece but Danny sent my worries to rest. As far as I can tell with my primitive caliper this a very well made gear set. The slight discoloration on the gears are caused by a protective coating and it wont affect the performance in any way.

Cyclone is not a brand new design so Danny has years of experience with it. After reading most of the comments at airsoftmechanics.com I was determined to build my own insane ROF AEG and he helped me a lot by recommending quality parts and giving me guidance.

Here is the list of parts:

• Siegetek Concepts Cyclone Balanced Gear Set (20.15 ratio)
• Siegetek Concepts spring spacer with shortened M110 spring
• Deepfire Titanium coated piston (full teeth)
• Modify bore-up cylinder and piston head plus nozzle
• LCT 190; Guarder 170; Prometheus MS210; MAG MA150 springs
• Modify 8mm ceramic ball bearing
• Guarder torque motor
• G&P  and Modify Torus gearbox with 8mm bearings
• Hurricane  and Modify tappet plate
• Intellect 11.1V Li-Po 2100mAh 25C+

Because of the dual feeding cycle and the limited cylinder volume several parts needs modification but with the help of the manual downloaded from siegetek.com this won’t be a problem.

I thought that the original barrel might be too long because of the limited cylinder volume but it was able to pump enough air to properly send BBs through the 260mm copper tube. Removing the second tooth (and the third partially) off the piston rack is highly recommended to avoid catastrophes and reduce engagement errors. Timing is everything here and if you look at the close-ups you can see how short of a window you have during which the piston has to reach its starting point before the first tooth on the next sector lines up to grab the rack again.

Angle correction (Angle of Engagement) on the first tooth is also very important and that can be corrected using shimming material on the cylinder head to make the piston assembly slightly longer. Also fixing the piston rack to the piston with epoxy glue is recommended.

Removing a part of the tappet plate’s “tongue” will ensure that feeding is perfect. An original tappet plate used with dual sector gear will not function properly because it would pull the nozzle back before the air transfer completes. That part of the tappet plate need to be reduced to 10mm measured from the base of the plate.

First I wanted to see how the concept works so I only installed the Sentry's factory spring and a standard cylinder set with Sorbo pad. I thought I cannot ruin things with a weaker spring installed, but I was wrong. It was working properly for a day and produced 48-50 ROF @ 240 FPS but it started to make a funky noise so I looked inside. Two of the six ball bearings were gone and only their outer shell was in place. The bearings of the motor and sector gear were gone from the same of the gearbox. The cost of this little experiment: a brand spanking new Modify Torus gearbox. Other than the bearings and the gearbox housing there were no marks on the gear set or piston and this is quite weird.

I had to move everything back to the G&P gearbox but this time I've used the ceramic bearings, the bore-up cylider set and an M150 spring. Now the gearbox is working properly and last measured 39 ROF @ 360 FPS which is close to the targeted 380fps but far from the desired 45+ ROF. Danny suggested to try other motors or different battery packs and I am currently awaiting these new components.

I really enjoyed my short experience with this gear set and I am sorry I couldn't complete the project fully, but I think I'm on the right track. A few people told me I will experience serious feeding issues using this setup but there were no empty cycles and the gearbox sucked the BBs right out of the magazine and not even a single BB fell out at mag change. I can only recommend the Cyclone if you follow Danny's instructions and you're a bit skilled with gearboxes. Great learning experience and great fun to use it as well. 30+ ROF is not a usual thing on the field (not counting Taiwan and Philippines) and people will be shocked by the sound of your gearbox. I can't wait to line up all the right parts and continue the project so I can test the Siegetek Concepts shortened spring with spacer or experience close to 50 ROF for the first time. My main goal is to make it right and then push it to its limits just like we always do in our workshop.

I've shared my experiences with Danny and he told me that in order to reach my goal I am going to need a motor capable to deliver higher performance and I will also need battery pack with higher voltage (at least 14V) and higher discharge rate. Danny took the effort to crunch my numbers and this is what came out: first build with ~26.75Watts; current build ~46.96 and to reach the peak I need around 60 Watts. Of course I also need to improve other things such as shimming, wiring, lubricant, inner barrel, ammo and when I am done with those things then the gearbox might show higher ROF with the currently used M150 spring. My first build was suffering great energy loss probably because of the cylinder assembly I used, but with the current build I think I am on the right track even if I have a long way to go and probably nothing else tells this better than my last picture where you can see how easy to mess up things. This is the leftover of two Modify ball bearings.

Many thanks to RiotSC and Attila for their support.

Some more tidbits from Siegetek Concepts:

A 9 teeth dual sector gear is under development and the work on the SR25 torque gear set didn't stop either. You can expect some parts for your TM guns as well, one gear set for the Type 98 and one for the Shock & Recoil Engine (S&RE). All the gears are made out of durable Nickel Chromium Molybdenum alloy steel and Nitride case hardened. The parts on the dual sector gear are reduced from 5 to 2 in the process and the sector gears for TM guns are made out of one single piece now. We can shortly see some fine CNC work rolling out of Danny's workshop that's for sure. He is at the final stage of testing and expecting the first mass produced batch should have already been out.