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#355691 Stryfe Mod - 3D Printed FWC

Posted by oddron on 21 August 2016 - 10:46 PM in Modifications

I've had zero issues with hot glue holding micro switches. What happened to yours? Daniel (the head of the group, might have been able to help also)

 

I haven't had a problem using hot glue to hold in a microswitch either, as long as the I modified the shells so that they were both "sandwiching" the microswitch with the hot glue merely acting like something to hold it in place for the shells to do their work.


I took a look inside my Stryfe. The switch is slightly loose, but that isn't the problem. The problem is that I failed to secure a small plastic cover that guides the acceleration trigger. Without that cover the trigger will slip sideways (toward the camera) and fail to actuate the microswitch. I suppose I could put a blob of hot glue on the other side of the shell to press against that plastic cover to keep it from moving.

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This project is a major ongoing learning experience. By replacing a relay with a microswitch, I learned that hot glue is questionable (that switch is loose, after all), and I learned that screw holes don't work after being cut in half. I am also learning how to use tools. Hollowing out the battery holder is the first time I ever used a Dremel. When I cut that brass rod, it was the first time I ever attempted to machine anything from metal, and the first time I ever used a hacksaw for a non-destructive purpose. (I have used a hacksaw before, twice to remove a padlock and once to cut a long metal object for disposal.) I feel like I am learning more from trying to modify a blaster in the first place than what I am learning from trying to make my own 3D-printed flywheel cage.

Meanwhile, by choosing not to repair my Stryfe at the war, I gained the opportunity to try a different loadout, which was a Strongarm and socks. Among many other things, I learned how a Strongarm can get jammed, I learned that my throw is an opportunity for improvement, and I am continuing to learn how to be effective in a Nerf war. So far, I am enjoying every aspect of my investment into Nerf and my hope is that I will just keep growing.




#355672 Stryfe Mod - 3D Printed FWC

Posted by oddron on 21 August 2016 - 01:23 AM in Modifications

Look up southern md house of nerf on facebook they have a war this saturday

 
I went to this war (in Waldorf, MD) and had a blast, but not with my Stryfe.  During round 1, I learned the hard way that I shouldn't use hot glue to secure a microswitch.  Fortunately, I had a secondary.  I fought the entire war with my Strongarm and two pockets full of rolled up socks.




#355574 Modifying a Mega Mastodon

Posted by oddron on 16 August 2016 - 09:11 PM in Modifications

You like hellcats, don't you?

Could you post a link? Thanks

-Montymarks

Here you go. http://www.containme...t-category/mtb/

I chose Hellcats based on the motor database archive and other research.
 

Why not just print an adapter for the original motor to be usable? The only way it might work would be with fewer teeth on the one gear since that gear is what controls the pusher going forward.

Good news - The original motor doesn't need an adapter. It was a press-fit, secured in the holder by a circuit board.  I was able to press-fit the original motor, with a little etape wedged along the side for an extra-tight fit.
 

I'd also wager the stock motors on 3S would perform better than Hellcats (more torque, similar FPS), and the stock pusher is no slouch at 3S either. Sometimes motor upgrades aren't worth it haha

Sometimes different motors are not "upgrades" at all.

Stock motors on 3S would be worth testing, however I found that the stock pusher motor on 3S immediately produces a distinctive odor while running. The other issue is that the stock FWC does not seem to provide a means to remove the flywheels. I didn't see any access holes, and I was unable to pry the flywheels loose with a screwdriver. Ultimately, I pried them off with brute force, which left a ring of stress marks around the axle.  I strongly suspect that if I try to remove the flywheels again, they will break.
 
The only things left for me to do are to (1) add a fuse to protect my lipo (for when the pusher motor burns out), (2) carve out some plastic from the battery tray to make space for the lipo, and (3) bring it to a war for field testing.



#355568 Stryfe Mod - 3D Printed FWC

Posted by oddron on 16 August 2016 - 06:41 PM in Modifications

Wow, as someone with a computer science background, OpenSCAD is a revelation. I've been able to make any adjustment I can think of in a matter of seconds having never used it before. Thanks a ton!

You're very welcome!  I remember about a year or two ago I looked at a long list of CAD software and tried to pick out the "best" one.  I have chosen wisely.

 

It looks like I'll only be able to work on the design on the weekends, so I will be curious to find out how other people improve it.
 
MAV and DjOnslaught, I wonder when the next war in Maryland will be. Baltimore, NYC, the NJ shore, and York, PA are all within a 2 hour drive from Trevose, PA.




#355553 Stryfe Mod - 3D Printed FWC

Posted by oddron on 15 August 2016 - 10:13 PM in Modifications

Any way I could get a look at the project files for the cage? I'd love to move the screw ports around and adjust it to fit in my Desolator.

 
I guess the easiest way would be to put the OpenSCAD design files on GitHub.  Keep in mind, this is very much a work in progress.  Good luck!
 
https://github.com/o...n/flywheel-cage




#355532 Modifying a Mega Mastodon

Posted by oddron on 14 August 2016 - 10:46 PM in Modifications

TLDR - Amazon had a sale last week, and I picked up a new Mega Mastodon. I replaced all three motors with Hellcats, and now it doesn't work because the pusher motor is too fast.

The Mastodon requires 6 D batteries. How am I supposed to indulge my megalomaniacal fantasies of world domination when I'm being held back by the bulk of a bunch of D batteries? It's just not fair.

I never actually installed D batteries.  In fact, I don't even own any D batteries.  Instead, as soon as my Mastodon showed up, I took it straight to my laboratory to be dissected. The stock motors are wider than Hellcats and similar in length, so I decided that all 3 motors would need to be upgraded. To make Hellcats fit in holes that are too large, all I needed to do is make a few adapters.

l13udM1m.jpg

I also traced the wires. The Mastodon contains 2 safety switches and 3 functional switches: the dart check, the jam door lock, the acceleration trigger, the main trigger, and the pusher switch. Once the dart pusher starts to extend, the pusher switch forces the pusher motor to keep running until the cycle is complete and the pusher is retracted.

Rather than try to replace the 3 functional switches with high-current versions, I decided to add 2 relays. The result? This mod includes more sins than I care to confess.

DmtTYPem.jpg

Much to my dismay, the Hellcat pusher motor is too fast for the rest of the blaster. When I press the trigger, the blaster fires one dart and then the drum fails to turn. When I release the trigger (but not the acceleration), the pusher fails to stop firing. I strongly suspect the problem is that the pusher is not retracting fast enough. Since the pusher uses a return spring to retract, I could try upgrading this return spring, but then I might have to upgrade the thin rubber shock absorber at the back of the gearbox.

ZPhVM0Tm.jpg

Now that I have cut the original motor mount and added an adapter, I cannot easily go back to the stock pusher motor. I could try to replace it with a slower 180-size 12V motor. Another possibility would be to make the pusher motor run slower by supplying it with a lower voltage.

It looks like my fantasies of world domination will have to wait another day.




#355531 Stryfe Mod - 3D Printed FWC

Posted by oddron on 14 August 2016 - 10:38 PM in Modifications

So I worked some more on my Stryfe this weekend.

First, I can take advice when I feel like it. I removed the relay and replaced it with a switch.

s2ogLwym.jpg

Second, I modified my FWC to angle the flywheels. One flywheel is angled 5° forward, and the other is angled 5° back.

XSQW6Hkm.jpg

Before adding the brass barrel, I tested the blaster, and I found that every dart came out whirly-birding. This means the canted flywheels are doing their job. After adding the barrel, and based on indoor testing, the darts seem to come out fairly straight. On the other hand, I had a few misfires and some chewed up darts, especially if I try to shoot fast.

iTPTJ7Tm.jpg

I strongly suspect my barrel is part of the problem. Too bad I already glued it in place.

3cq9Qgum.jpg

Since I have never cut brass before, it took some experimentation to find a way to cut out the holes for the flywheels. Using a dremel, here is what eventually worked for me. First I used the black disk attachment to cut a slot in the brass, and then I used a 1/8" drill bit to cut sideways. Too bad I didn't know it would leave rough edges inside. What would be a better way to cut holes in brass?

Regarding the design, I think there are still a couple of issues to work out. In particular, when I make space for the flywheels, it seems to cut slightly into the walls. I would be interested in sharing my design files, which I created with OpenSCAD. What would be the easiest way to do that?

Attached File  stryfe_fwc_5deg_version_0.stl   4.17MB   204 downloads

Attached File  stryfe_fwc_5deg_barrel_template_version_0.stl   1.2MB   161 downloads



#355461 Stryfe Mod - 3D Printed FWC

Posted by oddron on 09 August 2016 - 10:41 PM in Modifications

See McMaster-Carr page 932.


Thank you. I never though to check McMaster-Carr for switches. Listed on page 932 is part number 7510T12, which is rated for 25 A and costs $5.69 each.
 

Using a MOSFET or relay instead of a a high-current switch is both costly (by comparison) ...


Now that CaptainSlug has pointed me to these switches, you are absolutely correct that a switch is cheaper.
 

... and over-complicated.


I used a relay because it seemed like the "next best" solution when I couldn't find an appropriate switch.

I am considering a transistor because of a post on Reddit, and also because on Saturday (at APOC) someone specifically advised me that I should use a MOSFET because high current microwitches supposedly don't exist. (I don't remember who it was.)

In this Reddit article, one user discussed switch ratings and the idea that the rating for a motor load is significantly lower that for a resistive load. In particular, they discussed an Omron 21 A switch that can handle an inrush current of 42 A maximum. This would not be enough for a pair of Hellcats, which would have an initial inrush current of 48 A (2 x 24 A). McMaster-Carr doesn't specify if their 25 A rating is for a resistive load or for a motor load. Another user pointed out that if I use a MOSFET then I can use any switch I want. Through my own calculations, I have determined that if I use two AUIRFB8409 MOSFETs (either in parallel or one per motor), then I don't need heat sinks, even if the motors are both stalled.

The same post also mentions extra complexity, with at least two users suggesting that a switch would be better. No one mentioned flyback diodes; this extra complexity is essential to avoid damaging the transistor when turning off the motors.

If I assume that the 25 A switch from McMaster-Carr will handle a 48 A inrush current, then it is clearly the simplest option.
 

I guess I don't understand why you made a new cage if you didn't change the design.


I am making a new cage because I intend to experiment with the design. For example, I can change it to angle the motors or adjust the distance between them.



#355452 Stryfe Mod - 3D Printed FWC

Posted by oddron on 09 August 2016 - 05:42 PM in Modifications

so, is it a canted FWC?

Was it canted?


Sadly, no, it wasn't canted. As I continue to develop the design, I plan to experiment with canting angles.
 

My big question is why did you need the relay?


I found a relay before I found a high-current switch. The motors (not pictured) are Hellcats. I am going to replace the relay with a transistor circuit, and then I'll get to test how hot the transistor gets.
 

can i have one?


It's still under development. Just answer these three simple questions, and I might send you a prototype.  :)

1. Are you or have you ever been a member of the Communist Party?  :kappa:
2. Are you willing to help me test it?
3. Do you happen to live anywhere near Philadelphia, PA?




#355380 Stryfe Mod - 3D Printed FWC

Posted by oddron on 07 August 2016 - 01:12 AM in Modifications

I wanted to modify my Stryfe, but I didn't want to wait to order a FWC, so I decided to make my own. I tested this in the superstock rounds at APOC.

UjkzN1Cm.jpg

In testing, I noticed that my darts have a tendency to curve or even whirlybird. I also lost one dart when the head was ripped off, leaving the remainder to jam the blaster. I am going to add a guide to help center the darts as they enter the FWC.

As for the rest of the blaster, I used a relay to run the motors, and I used copious amounts of duct tape to hold the wiring. The relay coil is controlled by the stock trigger switch.

kOBkqYzm.jpg

I was advised to replace that relay with a transistor and internalize my wiring. The puzzle is finding a transistor that won't require a heat sink, and I think I have a solution.  After I test my blaster with a transistor, I'll post an update.

Spoiler

 




#355379 Apocalypse 2016 - August 6th in Ocean Township, NJ

Posted by oddron on 07 August 2016 - 01:04 AM in Nerf Wars

This was my second war and my first APOC.  I brought superstock and participated in the superstock rounds, and it was awesome.  I also got to meet several prominent members of the community in person.  I found out the real secret to surviving HvZ, learned about manufacturing of custom parts, and even picked up advice regarding youtube.  I can't wait for next year's APOC.




#355355 Apocalypse 2016 - August 6th in Ocean Township, NJ

Posted by oddron on 04 August 2016 - 09:53 PM in Nerf Wars

I'm coming, even though all I have is superstock.  It will be my second war, and the first real test of my modified stryfe.  The prototype works; all I have to do is clean up those wires.

 

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