In order to make printed motor driver sprockets/pullies work, I’ve purchased a 8mm to 1/2" hex adapter and pressed/locktighted it onto the motor shafts. This is the one I’ve been using:
It’s from AndyMark and can be found here: http://www.andymark.com/8mm-Keyed-Bore-1-2-Inch-Hex-Adapter-p/am-0588.htm
I’ve been pleasantly surprised by the durability of these printed sprockets. The wheel sprocket in the above pic is trimmer line nylon and has over 60 miles, while the motor sprocket is eSun PETG and has approx 30 miles. Obviously, these sprockets will not outlast the chain, but they seem to be holding up and should last at least to an average wheel rotation interval.
Also, I’m looking for some open-source cad models of smaller (12t to 33t) HTD-5M pullies for this project. Please let me know if you have any or know where I might find some.
I’ll verify these when I’m back at the home computer, but off the top of my head:
-E3D V6 hotend, 0.4mm hardened steel nozzle (prepared for carbon fiber filled filaments) set to 245c (I used 240c with standard brass nozzles)
-80c bed temp, printed on clean glass (mirror tile actually)
-go slow, I think my fastest speeds are only at 45mm/s
-I think my retraction setting is 3 or 4mm using a direct drive (I’ve used upwards of 6 or 7mm on a bowden set-up and had just a tiny bit of fine stringing).
-Dry it! Everyone says PETG doesn’t absorb water, but that’s incorrect- it doesn’t affect surface finish as much as nylon, but strength is severely impacted- E3D did some testing on this, you can find it on their website somewhere.
This PETG sprocket died due to impact trauma- my 5 year old likes to “ghost ride” my board full speed off of curbs and what not (he has fun, I look at it as stress-testing )
This sprocket had approx 40 miles on it and no significant wear to the teeth. I’m very surprised by the durability of these things, I would have never believed it if someone told me a printed DRIVER sprocket would last more than a couple miles.
I’m running a new PETG driver sprocket (same old nylon driven is working and will probably work for many, many more miles) to see if I can get one to wear out from use rather than abuse. I’ll keep this thread updated. I’ve got some CF reinforced nylon and PETG to try out at some point as well.
Well, for me the sprockets are bend counter clockwise. I could see it without zooming They are stressed but it was a question of time when it will break or the chain slip off.
To be fair, the sprocket pictured above hit a curb so it’s likely you’re seeing the impact damage.
I recently broke another PETG driver sprocket running 16:32 gearing and this one appears to have broken from torque loading- chain was looser than optimal and appears to have fractured the sprocket from shock-loading as I was going up a hill running over twigs, leaves and acorns.
In my experience, PETG as a driver sprocket has a pretty short life span (best I’ve gotten is the 40 miles documented above). I’ve been running nylon (just cheap string trimmer nylon) sprockets for a while now and I’ve yet to have a failure. In fact, I’ve got a 32t wheel sprocket printed in nylon that has over 100 miles on it and is just beginning to show some teeth wear/hooking. The driver sprocket will certainly be the limiting factor in a 3d printed system.
As to noise, nylon sprockets with chain is just a bit noisier than belts.
Also, I’ve fixed my HTD 5M sketch and it is now fully parametric. Just go to the part studio tab labeled “30t HTD5M Wheel Mount” for the wheel pulley or “18t HTD5M 13.3mm Hex Hole” and change the Variable #Teeth and Variable #Width to whatever you need.
#25 printed in nylon for the driven/wheel sprocket hold up incredibly well and are much quieter than aluminum (PETG also works, but they fail unpredictably). I’ve only had moderate success (50 miles max) with printed driver/motor #25 sprockets in nylon, but they are super quiet compared to steel.
As to the durability of printed HTD-5M pullies, I’ve had the greatest success with nylon for both driver and driven.
ah nice, my sprockets actualyl came in sooner than i had thought. delivery is expected for tomorrow but i would love to continue trying to 3D print the sprockets haha. i have a few prototypes printed on ym desk here in PETG
It’s from AndyMark and can be found here: http://www.andymark.com/8mm-Keyed-Bore-1-2-Inch-Hex-Adapter-p/am-0588.htm
Man I wish I had a 3d printer.
They are stressed but it was a question of time when it will break or the chain slip off.
