And now for something completely different,
I’m in need of cutting very small gears out of … what? Acrylic would break. I’m in search for a material which will stand up to wear, yet be possible to cut with an xacto-knife. The gears should ideally be 2mm thick.
Any recommendations? Thanks in advance.
3d printer?
laser cut acrylic?
but yeah, hand cutting will be hard
Pull a RC servo apart 
3d printer’s I have aren’t suited for it, alas. Acrylic woudl be too brittle. Thinking of cutting up a canister of some kind… Still think I’m missing that obvious kind of material :-?
I’ve seen laser cut acrylic gears. As long as you’re not trying toput too much torque they should work ok. What’s the use-case?
I’m wanting to stuff a Cebr40 and transceiver + motor inside one of these for my boy’s 3rd birthday:
http://politiken.dk/tjek/sundhedogmotion/forbrugerkemi/ECE1139415/brios-trae-togbane-fuld-af-giftige-stoffer/
(please DO NOT translate the article from Danish to English! ;-))
That is a great project. Please post the details when you are done.
You bet.
Not a materials engineering expert by any means, but perhaps UHMWPE would be a good material. It’s softer than acrylic, and self-lubricating so it’d likely work better in places where the gears would be subject to friction.
No idea, however, whether it’s practical to laser-cut either material, or whether you’d need to machine them instead.
I think acrylic would work. Not sure about getting it at 2mm thickness though.
I have been doing some R&D with the pressures acrylic can take before breaking. Thin pieces obviously will break easily but parts that have body to them seem to hold up pretty good…like a gear.
Thanks for the suggestion. Where is this used in daily life - as in, where do you reckon’ I could source some?
Thanks for sharing your experiences. I’m gonna go down the acrylic road if the servo-approach won’t do.
Although as devhammer was getting at. I am not sure what exactly you are using the gear for and what the lifetime of the gear would be if it were acrylic. That’s usually why gears are made out of nylon…for the durability of the material.
As devhammer suggested, I’d use UHMW, HDPE or possibly even Nylon.
How small are the teeth? I have a 1/16" end mill that I could cut out a sample with.
Do you have a sample file/design you can share?
Speaking of cutting/making gears - came across this a while back and just found the link again for it:
Pretty cool software!
That is very nice indeed - great link. I haven’t produced an STL file yet - will go with the servo-approach for now. I’ll very likely use that link in the future, though, as I have just gotten a set of miniscule drill bits for my CNC Router | American Made | PROBOTIX CNC ROUTERS. Out of curiusity, have you ever cut nylon or acrylic on your mill - and if so, at what speeds to avoid material meltdown?
That mill is very similar to my Zenbot 1216 [1]. I use Tin Coated 2 flute bits at 6000rpm and around 400mm/min on acrylic and it does a pretty good job. I also cut HDPE and UHMW frequently.
I get most of my bits from either McMasterCarr or http://precisebits.com/ I just got a 1/16" end mill that’s pretty sweet. Have 4 of his precision collets too.
I’m using a Hitachi M12VC router, not a dremel/colt type spindle, so I can feed things a little faster and deeper with larger bore bits, so you may want to back down your speeds and feeds until you do a few cuts and find out how fast you can run it safely. Speaking of which, Use FSWizard (free) [2] to punch in your bit, material type and thickness and it will tell you how fast to run the spindle and how fast to feed and plunge. Will save you (and has me) many sheets of plastic and bits due to incorrect calculations by hand.
Cheers,
Steve
[1] http://www.zenbotcnc.com/all-products/zenbot-1216-cnc-router
[2] CNC Speed and Feed Calculator and Formula
Great intel, thanks. I got my bits from precisebits.com, too - very impressive stuff they do. Think my colt will only go as low as 6000rpm, so should fit the bill! Where do you source your HDPE and UHMW?