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3d printed rivals flywheels help

rivals flywheels physics 3d printing

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#1 Quack

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Posted 09 January 2016 - 04:15 PM

After finally getting my hands on a 3d printer I've decided to take on a very ambitious project. I am attempting to 3d print a flywheel rivals blaster. However I have hit a problem when working on my first prototype. How it works is you hold onto the handle and press the button with your thumb, and then you feed balls into it with the other hand. The moters, which are just some old rapidstrike motors I am using until I get some shark nsr 40's, are powered by three trustfires and a dummy battery. Everything worked well until I started testing. pushing the HIR's in I would only get about a 5 foot range, I adjusted to flywheels so that they would only compress the HIR's 0.5mm instead of 2mm, but I only ended up with about a 10 foot range increase. What I've been thinking is that my stock motors don't have enough torque (something that would be fixed by dropping in sharks), but while I'm at it, I've also been wondering how flywheel weight comes into the equation. My flywheels are standard weight but is there any advantage to making them lighter or heavier? Hopefully some modding experience and maybe a little physics can help.

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Prototype

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Side view

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Battery pack

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Flywheel bottom

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Flywheel top

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Flywheel side


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#2 TheNerfZilla

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Posted 09 January 2016 - 05:07 PM

My assumption would be that the HIRs, since they're balls, the flywheels don't contact them for nearly as long. This means that you need much beefier motors to get the same performance, much less 100 fps. I want to say that the Zeus uses 330 or 380 size motors, but I'm not sure.
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#3 Quack

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Posted 09 January 2016 - 05:18 PM

My assumption would be that the HIRs, since they're balls, the flywheels don't contact them for nearly as long. This means that you need much beefier motors to get the same performance, much less 100 fps. I want to say that the Zeus uses 330 or 380 size motors, but I'm not sure.

That makes sense, I'm pretty sure it's just a torque thing. I'll have to try with the sharks.


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#4 jwasko

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Posted 09 January 2016 - 08:17 PM

Few things:

 

I have a Zeus and it's a little hard to measure with the concave flywheels but the gap that the HIR balls are pushed through is around 0.35inches (9mm). HIR balls themselves are 0.9inches (23mm) in diameter. So they get squeezed around 14mm!

 

The toque on Shark NSR40 motors is 205gcm, which I'm sure is higher than stock rapidstrike motors  (which may be getting 130gcm)...but the torque on even stock Zeus motors is likely to be 400gcm minimum and maybe more like 700-900gcm. Those stock motors are 360-sized motors. In theory, you could pull the motors out of two stampedes or vulcans (if you happen to have them sitting around) and try those.

 

Also, you'll be hurting the torque of any motors by using trustfires. They can't put out enough amps while the motors are stalled, their voltage will sag because of that, and the thus flywheels won't have the strength to push the balls through with any speed.

 

Lighter flywheels will reach their maximum speed faster, but heavier flywheels will tend to maintain their speed while propelling darts/balls.

 

 

Nice job on the flywheels. Many say that 3d printed ones will be too unbalanced to be usable, but these seem okay?


Edited by jwasko, 09 January 2016 - 08:55 PM.

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#5 Quack

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Posted 09 January 2016 - 09:58 PM

Few things:

 

I have a Zeus and it's a little hard to measure with the concave flywheels but the gap that the HIR balls are pushed through is around 0.35inches (9mm). HIR balls themselves are 0.9inches (23mm) in diameter. So they get squeezed around 14mm!

 

The toque on Shark NSR40 motors is 205gcm, which I'm sure is higher than stock rapidstrike motors  (which may be getting 130gcm)...but the torque on even stock Zeus motors is likely to be 400gcm minimum and maybe more like 700-900gcm. Those stock motors are 360-sized motors. In theory, you could pull the motors out of two stampedes or vulcans (if you happen to have them sitting around) and try those.

 

Also, you'll be hurting the torque of any motors by using trustfires. They can't put out enough amps while the motors are stalled, their voltage will sag because of that, and the thus flywheels won't have the strength to push the balls through with any speed.

 

Lighter flywheels will reach their maximum speed faster, but heavier flywheels will tend to maintain their speed while propelling darts/balls.

 

 

Nice job on the flywheels. Many say that 3d printed ones will be too unbalanced to be usable, but these seem okay?

That's good knowledge for further development. The blaster I'm designing is meant to be like a stryfe sized Zeus with Apollo style magazine placement. I've been trying to reduce the flywheel size but I might end up needing the 360 sized motors. However with the increased ball compression, I guess the flywheels will be closer together. This has turned out to be a difficult project.


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#6 Kilomona

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Posted 09 January 2016 - 10:50 PM

That's good knowledge for further development. The blaster I'm designing is meant to be like a stryfe sized Zeus with Apollo style magazine placement. I've been trying to reduce the flywheel size but I might end up needing the 360 sized motors. However with the increased ball compression, I guess the flywheels will be closer together. This has turned out to be a difficult project.


I think you could use the dart pusher from a rapidstrike to feed the HIRs (after you figure out the flywheel problem). I think it would fit sideways in a stryfe size shell behind the clip/magazine near where the dart pusher assembly is on a stryfe. Also, Ireally like your idea.
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#7 Quack

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Posted 09 January 2016 - 11:14 PM

I think you could use the dart pusher from a rapidstrike to feed the HIRs (after you figure out the flywheel problem). I think it would fit sideways in a stryfe size shell behind the clip/magazine near where the dart pusher assembly is on a stryfe. Also, Ireally like your idea.

I might actually design my own pusher mech if I decide to make it automatic. The flywheels keep having to be shifted forward so that there is room for a trigger. In the end, an automatic blaster might be easier (the pusher arm won't auto retract though, too much work), because otherwise the trigger pull will end up being like 4 inches without some smart lever work. Also thank you for your positive feedback, the goal of this project is to make a viable product for sale so stay tuned. Back on the topic of motors, I've been doing some research and I have a couple questions. To start off, I'm assuming all of these larger motors have a sizable amount of torque, but when looking at their specs the only thing possible related to torque is their thrust (since they're model airplane motors). What should I look for? The other spec I've been looking at is Kv since I'm pretty sure it's related to rpm. The highest I've found is 11,500Kv but the motor looks too small. Here are two I have found. #1 #2


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#8 Agles

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Posted 10 January 2016 - 05:19 AM

huge question on the 3d printing side of things that no ones asked. ABS or PLA?

 

personally i print in ABS and if you are. id look into doing a acetone vapor bath. this helps the plastic adhere to itself and gives more strength. plenty of videos on youtube on ways of doing this.

best way to describe it is like taking ice cubes , letting it melt alittle so they got water all over them, then freezing them again. causes the cubes to stick together really good. 


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#9 Quack

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Posted 10 January 2016 - 11:24 AM

huge question on the 3d printing side of things that no ones asked. ABS or PLA?

 

personally i print in ABS and if you are. id look into doing a acetone vapor bath. this helps the plastic adhere to itself and gives more strength. plenty of videos on youtube on ways of doing this.

best way to describe it is like taking ice cubes , letting it melt alittle so they got water all over them, then freezing them again. causes the cubes to stick together really good. 

I'm using PLA but I'm planning on using the solvent tetrahydrofuran to smooth out the final product.


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#10 jwasko

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Posted 10 January 2016 - 01:34 PM

Here are two I have found. #1 #2

Both of  those are brushless motors, which I'm pretty sure you'd need a speed controller in order to run. Although they are generally more powerful than brushed motors (more rpm, more torque), that controller adds cost and complexity.

 

Kv is RPM per volt. For instance 1000Kv would be 3000RPM at 3 volts.

 

If you can find a motor with a full datasheet, it will also list the torque at stall. For instance: http://www.kysanelec...p?recordID=8765has a link to its datasheet.

 

You probably want something that'll spin 25,000+RPM at 12volts or less. Like I said before, I'd bet torque needs to be over 400gcm.


Edited by jwasko, 10 January 2016 - 01:35 PM.

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#11 Quack

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Posted 10 January 2016 - 01:45 PM

Both of  those are brushless motors, which I'm pretty sure you'd need a speed controller in order to run. Although they are generally more powerful than brushed motors (more rpm, more torque), that controller adds cost and complexity.

 

Kv is RPM per volt. For instance 1000Kv would be 3000RPM at 3 volts.

 

If you can find a motor with a full datasheet, it will also list the torque at stall. For instance: http://www.kysanelec...p?recordID=8765has a link to its datasheet.

 

You probably want something that'll spin 25,000+RPM at 12volts or less. Like I said before, I'd bet torque needs to be over 400gcm.

Ok, does anyone know if watts is related to torque. All of the motors have watts listed. I think I might go with these.


Edited by Quack, 10 January 2016 - 01:50 PM.

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#12 jwasko

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Posted 10 January 2016 - 05:33 PM

I think I might go with these.

You do realize that's still brushless, right? That's cool, just make sure you know how to use it (I don't).

 

Ok, does anyone know if watts is related to torque.

 

http://www.rcgroups....d.php?t=2020674

Apparently, no.


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#13 Quack

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Posted 10 January 2016 - 06:30 PM

You do realize that's still brushless, right? That's cool, just make sure you know how to use it (I don't).

I realize they are brushless and I have been doing some research into how it works. The only problem besides the need for esc's is the need for the esc's to connect to a receiver. Does anyone know a way where I can just control throttle through a switch? Or does anyone know of brushed motors with similar specs. Brushless motors might just not be feasible.


Edited by Quack, 10 January 2016 - 10:32 PM.

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#14 Remzak

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Posted 12 January 2016 - 01:53 PM

You can do throttle control for brushless speed controls with a servo tester. That would be cool, having a power control on a dial on the side of the blaster.


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#15 Quack

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Posted 12 January 2016 - 02:42 PM

That's what I was thinking. However I still want control over my flywheels. Where can I breech my circuit for the rev trigger where the motors don't have to go through a setup every time? Could it be between the esc's and the servo tester?
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#16 DjOnslaught

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Posted 12 January 2016 - 03:19 PM

That's what I was thinking. However I still want control over my flywheels. Where can I breech my circuit for the rev trigger where the motors don't have to go through a setup every time? Could it be between the esc's and the servo tester?

What do you mean here? Are you trying to avoid full stop to full review each time you pull the rev trigger?
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#17 Quack

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Posted 12 January 2016 - 07:26 PM

What do you mean here? Are you trying to avoid full stop to full review each time you pull the rev trigger?

Exactly. I want maintain a rev trigger without having the esc's boot every time I press it. I Know if I place the rev trigger switch on one of the battery leads this will happen. Can I put the switch on the positive lead from the esc's.


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#18 DjOnslaught

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Posted 13 January 2016 - 07:32 AM

I'm not sure what the answer to this one is. Short of using a arduino board with a motor controller on it, I'm not sure. Unless you used a on off with some sort of regulator in the wiring to keep the rpm low until you reved...
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#19 Meaker VI

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Posted 13 January 2016 - 10:32 AM

Lighter flywheels will reach their maximum speed faster, but heavier flywheels will tend to maintain their speed while propelling darts/balls.

 
It helps to think of flywheels as an energy storage mechanism. A heavier one can store more energy at lower speeds, and so each shot takes proportionately less of that energy and you get more consistent shots. A lighter wheel doesn't store as much energy but can spin faster with the same motors, so you might have a higher max dart energy but shot consistency goes out the window.
 
It also helps to know that a circular saw blade is a flywheel, and cuts by transferring that energy to the material being cut.
 

Nice job on the flywheels. Many say that 3d printed ones will be too unbalanced to be usable, but these seem okay?


I'd also be concerned about the internal structure of these things. Flywheels can endure a lot of stress, and plastic isn't actually all that strong - NERF doesn't make flywheels out of ABS and instead uses Derlin IIRC. I'd hate for them to blow up on you.

A better use of 3d printing is to print the housing for the flywheels, motors, mag, etc; while using milled (or otherwise manufactured) wheels.

ED: This could easily go in Homemades; that you are home-making a blaster for RIVALs rounds hardly matters.

Edited by Meaker VI, 13 January 2016 - 10:33 AM.

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#20 Agles

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Posted 13 January 2016 - 11:41 AM

That's what I was thinking. However I still want control over my flywheels. Where can I breech my circuit for the rev trigger where the motors don't have to go through a setup every time? Could it be between the esc's and the servo tester?

 

i seen this done with a stryth. infact, there a thread on this site about thit. 

http://nerfhaven.com...er-to-a-stryfe/

sorry to say, i didnt read to see if it was worth doing or not.

also, as DjOnslaught said. id put in a switch to turn it all on/off 

 

<--- rc guy

OMG you said brushless now.... HUGE basket of food for thought... and i mean HUGE!!!

 

i see you pointing to an inrunner. all the moving parts of the motor are on the inside. these are used mainly in cars and such. because they dont get dirt and such inside the workings. 

i say toss that aside for an outrunner. my thought is kill 3 birds with 1 stone.

here a video of one. 

 

by using the outer bell as the flywheels (not sure how good the metal will work, maybe coat it with rubber) you save space.

next, do to the higher torque you will get less rpm drop after each shot. 

also, outrunners run cooler then inrunners. so less heat.

 

only downsides i see is cost. brushless cost more, same with needing 2 speedcontrols. 

do to it being an AC phase you cant run 2 off 1 like you do with brush. and alot of work to fit this all in place. 

 

well as i said, its food for thought. 


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#21 Quack

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Posted 13 January 2016 - 04:23 PM

 

I'd also be concerned about the internal structure of these things. Flywheels can endure a lot of stress, and plastic isn't actually all that strong - NERF doesn't make flywheels out of ABS and instead uses Derlin IIRC. I'd hate for them to blow up on you.

A better use of 3d printing is to print the housing for the flywheels, motors, mag, etc; while using milled (or otherwise manufactured) wheels.

ED: This could easily go in Homemades; that you are home-making a blaster for RIVALs rounds hardly matters.

 

I wanted to make this blaster consist of as many 3d printed parts as possible so I could control the manufacturing process. I see your point, but I know derlin let alone custom flywheels will be expensive. I knew this might fit in in the homemades, but I thought more of the flywheel guys would hang around here.

 

by using the outer bell as the flywheels (not sure how good the metal will work, maybe coat it with rubber) you save space.

next, do to the higher torque you will get less rpm drop after each shot. 

also, outrunners run cooler then inrunners. so less heat.

 

How about these. They are outrunners getting the same Kv as the other motors, they come with the esc, they can work off a 3s, and they're cheaper. I'm just worried about quality. I might test them out.


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#22 Agles

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Posted 13 January 2016 - 08:00 PM

Quack, that motor and speedcontrol are made by Suppo. just being sold under a different name. you find that ALOT in low cost rc stuff. 

i been selling those for like 8 years in the shop i work at. 1 thing ill say, you get what you pay for with them. i tell most people if they will be replacing them within a year. most end up doing so, with more of the same. some people just love low cost. 

 

i dont see any reason to not get those for testing. 

 

things to know wiring wise. you will need to disable the BEC in 1 speedcontrol, wire the battery pack to the 2 speedcontrols, then use a servo Y harness from the speedcontrols to the Servo Tester.

here is a video showing how to wire that. do note, you will want one to spin left and one right. 


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#23 Quack

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Posted 13 January 2016 - 09:42 PM

Quack, that motor and speedcontrol are made by Suppo. just being sold under a different name. you find that ALOT in low cost rc stuff. 

i been selling those for like 8 years in the shop i work at. 1 thing ill say, you get what you pay for with them. i tell most people if they will be replacing them within a year. most end up doing so, with more of the same. some people just love low cost. 

 

i dont see any reason to not get those for testing. 

 

things to know wiring wise. you will need to disable the BEC in 1 speedcontrol, wire the battery pack to the 2 speedcontrols, then use a servo Y harness from the speedcontrols to the Servo Tester.

here is a video showing how to wire that. do note, you will want one to spin left and one right. 

I watched that video while trying to figure out my setup. It's great for anyone new to this sort of thing who wants to learn. Thanks for the advice on the motors and esc's. I'll keep that in mind. One last question. Do I have to get a programming card for my esc's? I'm going to order all the parts and post the results in this thread. Hopefully I can find a solution. 


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#24 Agles

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Posted 14 January 2016 - 01:28 AM

i dont see you needing a program card. only reason i have seen for using them is motor breaks. 


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#25 Milfpounder

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Posted 14 January 2016 - 02:21 AM

 
 

You can do throttle control for brushless speed controls with a servo tester. That would be cool, having a power control on a dial on the side of the blaster.

 
 

I'm with this guy! A servo controller is all you would need, considering you use the same size/brand of motor/ESC.

As far as not interrupting power to ESC while not wanting motors revved up, I'd say find a good speed with the servo controller then place the rev switch on the red wire coming off the ESC (The power source for the servo tester) And if that won't work maybe place the rev switch on the black or white wires so the servo tester stays on, but you interrupt it's communication to the ESC...


Edited by Milfpounder, 14 January 2016 - 02:31 AM.

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