Wednesday, April 16, 2014

RS Tactical completion

Or at least complete for now, until I get some cells to make a 3S battery for this gun; and/or give the Xtremes a shot with it.

 In the meantime, though, I got some images of some stuff that might not be that well documented in the NIC.

This is the pusher box with a FK180 motor installed. Note the shell modification is not very complex; the formerly enclosed endbell area (to fit a 130 motor) is removed.
 180 install with the shell open showing the worm installed.

The stock "socket" part of the mount does not need to be modded, only the end that would interfere with the 180 can length.

Once the screws are installed, this is a tight fit. Movement of the motor is not likely, although something to retain it positively is desirable. I usually make that part of the external motor cover.
This is the receiver hole location for a 180 pusher swap.
A cover like that for the flywheel motors will be provided.

Unfortunately, I painted before realizing that this receiver mod had been left out. D'oh.
Flywheel cage.

Of note here are the problems many people have had with installation of 180 motors.

The mount sockets are designed for the finished can diameter of a 130 motor. While theoretically of the same cross-section (but different lengths and endbell designs), the FK180 (or perhaps just FK in general) can is slightly larger than the FA/FC130 can and thus the fit is objectionably tight, to the point you might break something trying to install motors, or at the very least create a problem with mount deformation and accuracy.

These mounts have ribs inside used to achieve the relevant dimension, so those need to be shaved a bit. Use of a grinder is not advised. A knife is more suited. Also, if you have a tight press fit in the final setup (which you should if you don't plan on running brackets, screws or hold-down straps on the motors like stock) you should lube the front end of the motor can very lightly before shoving it in.

Also note the orientation of the red endbell plug (polarity marking) is toward opposite ends of the cage. This gets the correct rotation direction with leads going straight across the cage. In this case the rear terminals (green wire) are positive for forward rotation.

Yes, you do need to fully seat the motor can into the mount or you will have trouble. A few cases of flywheels coming off the shaft have been described and the likely causes include insufficient shaft engagement because the motor was not seated before installing the flywheel in its final position.

Note the position of the bearing snout, flush with the mount surface.
This is the usual teflon insulated 16 AWG, MIL-W-22759.
Good practice is to keep the wire away from any kind of severe contact with the motor can. The rear edge of a FK can is sharp and can cut insulation. If you use PVC insulated wire you also don't want wire to touch anything that could get hot in some condition, including motor cans.

Be careful with the magwell wire cover in the RS. It is easy to pinch the wire and damage insulation.

Terminals visible through the endbell cover.

Speaking of terminals, the terminals on FK motors are very fragile and stick out exactly where they are most likely to get whacked. Be very careful of them when installing motors, cover your terminals up as soon as possible after installation, and avoid having to learn the broken terminal lesson for yourself.
Now... this was unplanned.

I got it wired up normally, modded the FCG as in the Standard Rapidstrike guide, and... the pusher took right off at full fuel as soon as I pulled the trigger. No active braking.

Is the wiring correct? Yes. Bad solder joints? Nope. Internally broken wire? Not that either. Bad switch?

Uh, Houston...

It was the cycle control switch, which was physically off-spec somehow (or perhaps it was the follower for the pusher rod being off-spec, in either case this whole gun as it came from the factory was very disappointing, a giant mess of off-spec parts and shoddy workmanship that wouldn't have worked out of the box, thumbs down Hasbro). If I pushed on the switch toward the follower it would brake normally.

Tried to remove the switch and PCB from the clips molded into the FCG shell and...

As these ultra-cheap crappy switches love to do, it fell apart and spilled its guts.

You can see how these things work - they are a sort of knife-switch type contact, 3 stamped copper alloy blades with integral terminals mounted into a piece of FR-4, with little copper clips with some kind of coated contact surface that slide along the blades, a nylon carrier with the button integrated, a spring and a steel housing and that's all there is to it. These ones are the DPDT version which in the Standard RS (and stock Stampede, Swarmfire, Vulcan) are paralleled to SPDT for better current handling.

(As a sidenote it is amazing the kind of durability and service these give under our abuse...)

Well I didn't bother reassembling it, troubleshooting it or cleaning it. I was having quality rage by now, I was sick of these cheeseball switches, and I ripped it out. And its twin on the trigger, too. I have long known about UK builders having their 3D printed FCG shell half and a favored model of Omron mini microswitch, but I guess it took a failure to finally make me do something.

This was all smashed together in an hour. No real fabrication. Just cutting webs and bosses off the stock FCG shell half. It may not be the highest-spec or the first full micro FCG, but at least the stock shell use was proven.

New cycle control is a mini microswitch, roller lever actuator.

Note that the configuration shown is flawed as the actuator will be caught and smashed by the pusher rod on the return stroke. Thankfully I caught the problem before anything got trashed and modified the actuator. You will see the necessary bend later on.

This is the switch I used, which is locally available. This was not planned for. There are superior switches to this part at a superior price in the same form factor, such as those Omron units the UK community uses.


This is the completed FCG minus the left shell half. You can see the CC switch modified actuator to work with the stock pusher rod. Also the trigger has been fitted with the same switch. The rev switch (green) is a full-size for comparison.

Of course, the timing can be adjusted at build time as it was here, and if I was going to take the time on one of these conversions, it would be adjustable later by loosening 2 screws, but this one works for now with the switches glued down. I will save the optimization for when I have the proper switches.

And with that out of the way and the pusher eager to spam some darts (but only some darts, down to and including one), it's finished.

After putting the battery in this stock (which is the one you have seen before), it is ready to close.

There is, by the way, a single 1N5551 diode feeding the pusher power lead to clean up some nagging stability problems with the FK pusher/2S combo. Obviously, when a 3S battery is fitted, more diodes will be inserted there.

Only needs that pusher motor cover.

100-110fps 650RPM.


  1. I have followed your posts and have a problem with my version. I rewired using 18 gauge wire and changed out the flywheel motors for Tamiya JR Mach-Dash Motor PRO 15433 (130's). The flywheels work great on stock batteries but the pusher runs REALLY slow if the flywheels are running. If the flywheels aren't running the pusher runs at normal speed...and idea what I may have done wrong?

    1. That's not anything wrong with your wiring, that is voltage sag from the stock batteries that are overloaded. The Tamiyas are a very current-hungry motor as 130s go, being that they can make power at unusually low voltages and that power has to come from somewhere (P = V*I disregarding losses that are not in the tamiyas' favor) other than thin air. All you need to fix that is a better battery, which will also improve the flywheel performance greatly.

      It does however get a bit more complex with regards to pusher motors. The proper battery voltage for the Tamiyas is 3.6/3.7V (1 lipo cell, or 3 NiMH cells) which is a cell less than you have now. That will still have the pusher running slower than it "freewheels" now, although it won't drop while revving the flywheels or firing darts.

      Do you have a desired ROF? Perhaps a Blade on 3.7V would give stockish or slightly better ROF.

  2. I had the same problem with the stock switch, I didn't test it before I started a rewire but the switch just kinda fell apart on me. I removed the whole thing and searched through my scrap and found a three pronged switch from a stryfe (I believe it is the on from the jam door). I just skipped the PCB and soldered everything in the right spot somehow. I had to use some hot glue to keep the smaller switch centered. Everything works so far.

  3. Better batteries are in the mail, so I will install them and see if it helps. Overvolting the Tamiyas to 7.2v....bad idea? If not this should give an acceptable ROF (slightly over stock) without going crazy. I also have the Blade motors coming but I would rather use them in another build where I am already modifying the case.

    1. You won't want to run Tamiyas on 7.2V. You will have a durability/heat problem and quite possibly throw the flywheels off the shafts from excessive speed, depending on what motors you use.

      If you want to use 7.2V and 130 size motors, stock RS motors are not a bad option. If you put carbon brushes in them, especially so.

      7.2V plus the stock pusher motor will get 400RPM plus, BTW.

      If you want to use those Tamiyas, I would use them with the proper 3 cell NiMH or 1s lipo. In the RS that's a simple matter of choosing pusher motor to get desired ROF with said battery. Of course, Tamiya motors themselves are an option for the pusher, though you will have to drop some voltage if you don't want high ROF.

      Or you could use them for a Stryfe, and use the higher density of a single cell lipo to your advantage to put more juice in the stock battery box.

    2. Thanks, I will look into separate volting for the pusher and the flywheel motors. I like the motors at 6V from the C cells but voltage sag is killing the ROF. It may be interesting to see if 7.4 (had the wrong battery specs) is too much....after all there is no success like excess!

    3. I went ahead and moved the Tamiyas into a rewired Stryfe for my boss...worked quite well on stock AA batteries. Looking to keep things with stock appearance but the Tamiyas really woke the blaster up! I didn't change the acceleration switch...interested to see how long it lasts until it melts down...

  4. A little bit of a noob question but, how long does the battery last generally that you put in the stock? Mostly I'm just worried that after playing for a while if I need to replace the battery or charge it in-between games that I need to open up my gun every time... So I guess how convenient is the battery in the stock?

    1. That battery pack in this post uses the same 1300mAh cell that is in the flat packs for the RapidSwarm, so it's not any change for me (in fact battery life of this configuration would be increased because the motors pull less current with 2S than with 3S). Commercial LiPo packs that would fit in the stock seem to have similar capacities to the 1300 and 1600mAh packs that I have been using.

      However, this cell format (18650, high-current type) with current technology (or the latest that you can get your hands on) can go up to 2600mAh. Also, the 180 motor options are uniformly the worst-case with regards to battery life.

      So I wouldn't say there is really any problem with getting enough energy crammed into that stock.

      Your mileage may vary. I could probably play a whole game of HvZ with moderate combat on a single 1300mAh pack. My motors aren't on unless I am shooting. A friend of mine, though, drained a pack in a single mission with the Rapid^2 because he is always blipping the motors absentmindedly.

    2. Oh yeah, and the having to open the gun to change packs is annoying. When I get the 3S made for this, I will have an external charge connector. It may also be possible to make the stock removable.

  5. I really enjoyed this post and hope to reference it in repairing a RS of mine that broke in a similar manner. Could you please describe the changes in wiring to the two new microswitches instead of to the PCB's?

    Also, I'm wondering if a full rewire would fix a fishtail issue I have. After I broke the same switch/PCB on my first RS, I obtained a second and performed a partial rewire (rewired the flywheel cage and replaced battery terminals) and am using 3 3.7Li-mn IMR's for power with stock motors. When running the same batteries through a completely stock RS, it was fine, but with the rewire it fishtails like crazy. I'm hoping getting rid of the pre-rev would take care of this, but am not sure.

    1. There are no changes in wiring between stock switches and any aftermarket replacements including these. The only differences are the positions of the common, NO and NC terminals, which are clearly marked on the microswitch case.

      Regarding the fishtail issue, more information on the exact issue would be helpful. How are darts behaving? This could be anything from normal high-velocity behavior of stock darts, to a mechanical problem, to a motor dead, motors mismatched or defective. Are both motors turning and sounding roughly similar in speed?

      Pre-rev removal and rewiring will likely not be a solution as the problem is elsewhere. It may be that you just picked up a few FPS by losing the parasitic resistance in the cage and battery terminal area, thus you exposed an ammo problem. In that case I would advise you to reevaluate the ammo you are using as it may be shot or iffy. New ZS Elite won't be too bad even at 120FPS. Koosh darts would apparently be superior as well.

    2. I didn't think there would be changes, and of course the switch is marked, but the PCB is not, so I wouldn't be sure of which wire goes to which terminal. But after looking over your pictures and your wiring diagram from your Standard Rapidstrike write up I think I'm understanding the wiring diagram more then I ever did before. It's a little thing, and probably elementary to others, but it feels good for the light bulb to finally go on.

      As to how the darts are behaving, some of them are fishtailing immediately upon leaving the barrel while others fly fine. I don't think it's the motors. My first build of the partial rewire was using Barricade motors and the issue occurred. I switched to stock Stryfe motors (wondering if the cade's weren't any good) and the issue continued. Not sure it's the power set up, as the same IMR's are used in my stryfe (stock 'cade motors, complete rewire with 18AWG wire, all locks, thermistors removed and a acceleration switch swap) and that fires fine. Don't think it's the darts as we switched to koosh darts, and again the stryfe fires them without issue. Both motors do sound fine and are turning (again the face that the issue occurs with two different sets of motors suggests that the issue may not be with the flywheels). I have a video that includes some of the crazy shots that I could put up if that would help.

    3. Video would help.

      It sounds like you are correct that the power system is not involved in the trouble. Have you checked assembly and alignment and verified there are no obvious geometry problems with this gun? Do you have the rubber sheet left in (remove if so)? Have you tried a different magazine and/or applying forces in various directions to the magazine while shooting?

  6. This is a good write up. But I don't see the practicality in emptying an eighteen round mag in less than two seconds other than to either troll others or to show off. I can get 375 RPM from the stock motor with the resistors removed running from a 9v Li-ion battery and I'm happy with that. When the bushes eventually turn into dust, then I'll replace it. But 100-110 FPS @ 650 RPM is a good result :)

    1. If you ever empty a mag in a single trigger pull, with very few exceptions (showing off is one, absolute emergency situations are another), you are misusing full auto. The proper use of automatic weapons is in a controlled manner.

      I find that the rates of fire I can reliably and stably achieve with Rapidstrikes are not high enough that they are uncontrollable or cause any inevitable increase in ammo consumption. However, I have been playing full auto for years and I have run loadouts that are entirely full auto. That is how I work best; in fact I tend to waste lots of ammo and get nothing done with semi, and forget pump.

      The benefit of a higher automatic rate of fire is not something I will attempt to fully explain in a comment, but believe me, 600 versus 375 is a significant gap in effectiveness in a lot of situations. I just used this RS in its first game, and it performed flawlessly.

  7. Have you tried to run this in the rain or use wet darts with this? If you have, how does it perform?

    1. They don't like wet ammo any more than any other flywheel gun, but with FKs (torque) you are probably less likely to jam on a wet round.

      We did have rain at the UGA HvZ invitational. We had 2 Tacmods and 3 or 4 RS in the unit. There were a couple malfunctions and 10-foot shots when stuff got soaked but for the conditions I would say they did as well as you could ask.