Yin-Yang | 3D printed dual mtb motor mounts [Development]

ESK8 Builds
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#1

As someone who wants cheap and cheerful, but then ends up spending wayy too much on parts just to fully bodge it up. It hurts when I see that mtb motor mounts are so expensive. so I thought I would try my hand at designing my own, which hopefully work and are much cheaper than the alternatives.

Luckily I got some Trampa Infinity trucks on the cheap so I can test the designs as they iterate.

The aim of the project is to make a dirt cheap, solid, motor mount that eventually can get versions to work for the most common types out there. easy to make, easy to repair, easy to mod, and mostly cheap. (because my wallet definitely cannot afford quality stuff :stuck_out_tongue: ) And luckily I own a pretty bawller 3d printer to test stuff on.

Currently this is what I have come up with. (real tests yet to come)

mmountain_board_dual_trucks_2018-Jan-11_02-41-20AM-000_CustomizedView5356642790
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This current design is supposed to be used for dual motors. The backing plate locks the mount into place as the trucks get larger the closer to the center they get, and can probably be modified later on to have a plate for lights and other LED goodness. As for the material thats being printed, it would be PETG. mostly because I have loads of rolls laying around, and im too lazy to worry about the hydroscopic tendencies of nylon yet is incredibly strong as an engineering material - especially printed completely solid.

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Other than the tempory bolts holding together the parts. the mounts feel super solid. It was easy to assemble, and by the looks of it no strain on the mount themselves.

next is mounting them to a standard longboard so I am going to have to make some angled mounts that wont break instantly. But I am looking forward to it - if anyone wants to throw in some ideas they would like to see added just ask away, Ill see what I can throw up. as for the current iteration, other than designing some indentations for the bolts and nuts, I think its ready for an alpha test.

. .

EDIT: Completely forgot to mention the name. I own two motors, one a high KV, one a low KV, im going to be testing them together to see if there are any benefits to multiKV setups. That and my printer can print two things at once, and one can print in black, the other is in white, hence the name (and it cuts down on printing time)

11 Likes
#2

I’ve 3d printed a lot of stuff but I would expect a printed part to hold under the load that a typical motor mount is. The edges will probably wear in after a fair amount of accelerating and breaking and then the mount would be prone to fail during a hard acceleration/deceleration. I wouldn’t want that to fail when I am going 20mph.

I also doubt 2 m4 screws are going to do the job.

2 Likes
#3

This is excellent work so far! Will you be sharing the Stl files or the full design files? I can’t tell from the photo, are both mounts identical and you just flipped one over? Having them be symmetrical would be so much easier to work on. I agree with kylepls that the material matters and you should perform some long term stress testing to see how it holds up over time. I’m working on fenders for trampa wheels at the moment, it’d be great to be able to design bolt holes or even the fender itself right into the mount!

1 Like
#4

That is something I am semi worried about, no matter how I look at it the material is always going to be quite soft in comparison to aluminium. when its mounted Ill see how far it can go before starting to fail. it might just be simple enough to add washers to spread out the force.

If you have the spacings for the mounting holes, I can see if I can impliment them, maybe even make an adaptor. would be nice to make them compatible with other products.

after initial testing, Im probably going to remake them but printed in either Polycarbonate, or again in PETG but at 600Microns instead of 200, it should streangthen the part substantially.

#5

Hey man, i see you followed through (we talked on reddit). I agree with @kylepls, you should try to add more/bigger screws and also consider grub screws. I’m using threaded inserts molten into the plastic for my 4 grub screws and they seem very solid. Otherwise i really like the look of the mount, very interested in seeing it in action! :smiley:

1 Like
#6

Glad you like the look of it. tried to keep it similar to what we know without doing something insane. definitely going to try to add some form of grub screw based assistive locking - should increase stability a decent ammount)

one thing I am going to change is how far apart they are. at the moment they only fit 11mm belts due to thicker pullys clipping the wheels tread, which I personally do not use, im a 15mm person, so I am going to try to change that up a little bit.

plus as to increase strength of the parts and reduce possible plastic damage, im going to try to thicken the parts and have indentations for the motor and other screw parts.

unfortunatly doing so would mean the motor doesnt have any adjustment, but it does mean I can thread all the holes, and probably add a belt tentioner if people would want to use one.

#7

Are you worried about printing the nylon or the properties during use? I’d say those made of taulman nylon or maybe carbonx would be pretty hard to break.

1 Like
#8

mostly the properties after printing, when fresh they are super strong, but it absorbes water over time weakening it. Cant really risk my life on a material that degrades when in moisture. otherwhise it would be perfect. the next material im tempted to test is Polycarbonate, but thats only if this doesnt work.

#9

And If polycarbonate doesnt do the job (which I think it will) Try POM

1 Like
#10

Hm I dont think it really weakens it just makes it crap to print with also you can anneal it after printing. Also since strength is an Issue I’d make every 90 angle that does not need to be one a radius.

1 Like
#11

Im hoping it doesnt come to that because it would increase the price and remove the ease of modding. but if it doesnt work, next would be injection moulded parts, that way they can be much more dense and probably stronger.

edit: do you know where I could get that material, I havent heard much of it before.

@bimmer You might be right on that. I just dont want to risk it incase it does. annealing is probably a good idea tough. going to do some research into correctly doing it!

#12

do yourself a favor and put metal rods as support inside the mount. printed mounts on their own will not hold with 6374 motors. they usualy break on the plate where the motor is mounted on.

take a look onn my build diary for info on how “not” to do it :slight_smile:

1 Like
#13

Very interesting read. nice to see your development process. lots of stuff to keep in mind aswell. First I am going to test what I have printed already to see how long before it inevitbly breaks, then change the design based around that!

The idea to inset rods into it is actualyl a good idea. its cheap to get threaded rods so I might have a look at trying to get some of them!

#14

doesnt even need to be a threaded rod probably (shouldnt? because those are usualy made from iron). get those steel rods for RC cars, they will do the trick.

something like this. https://www.amazon.de/gp/product/B00QC2DMKA/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

1 Like
#15

Did you consider using the plus shaped default mounts that come with the 6374 and I think all of the SK3s? I’m working on printing a mount that attaches to the default mount so I can use PLA without it warping due to heat.

#16

Personally I didnt consider it incase other people would want to use non sk3 motors which might not come with the backplate. If heat isnt a problem, PLA with the right design should be fine.

at the moment devolopment has come to a standstill while the new machine is being renovated ( picture incoming - coke bottle for scale )

#17

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3 Likes
#18

seems like some pretty big stepper motors for the X/Y axis… What are those, nema 23?

1 Like
#19

Will you be sharing the files? :sunny:

#20

Maybe to make them stronger wrap them in fiberglass