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Cognisant
8th-March-2014, 04:52 PM
So I've lost all my patience with this milling machine business, I want to make robots and I want to make them now, I don't care if it's shoddy so long as it works.

This will be part chronicle, part guide, questions welcome.

I have some YM2770 motors on hand so lets start with them (sourced from Jaycar for about $10, expendable crap level components) I've grinded a flat onto the shafts with a dremel 3000, well more of a semicircular indent but that actually works to my advantage. Using thermoplastic (sourced from Plastimake.com, I ordered 2kg and they sent me 2.5kg so I like them, however honestly I have found it cheaper on eBay) I'm making little reels for high load fishing line because I prefer pulleys to gears.

The reason for this is threefold, firstly fishing line is cheap, secondly a broken gear needs to be replaced with the exact same gear which can be a difficult process, replacing fishing line is fast, easy, and I can have all the materials/tools I need inside the robot, finally fishing line is inherently compliant to some degree, making it (and your motors) resistant to impact forces. Actually come to think of it a pulley system can also be much lighter than gears and enables you to actuate small appendages with the motor some distance away, so yeah all in all fishing line is the way to go, or piano wire if you want to ramp it up a notch.

So the semicircular indents on my motor shafts nicely secure the reels, now I just need to wait until 9am so I can go shopping for some fishing line, bushings, tinplate, more motors, some motor controllers and hook ended extension springs.

Hopefully the end result will be something like the ECCE robot.
http://eccerobot.org/

Kuu
8th-March-2014, 10:58 PM
Ok. Robots with pulley systems and plastic parts is an ok idea. So what? Your thread kind of leaves nothing for people to comment on.

How do you shape this thermoplastic?

(Also, for readability sake you could try editing your writing before posting to avoid your comma abuse. I always gets lost in your posts and often give up halfway if not early.)

Base groove
8th-March-2014, 11:03 PM
So I've lost all my patience with this _______business, I want to make ____ and I want to make them now, I don't care if it's shoddy so long as it works.


:D Reminds me of me, honestly.

Blarraun
8th-March-2014, 11:36 PM
I got an exploit block (http://www.avgthreatlabs.com/website-safety-reports/domain/eccerobot.org/linkreport/eccerobot.org%252F/?utm_source=TDPU&utm_medium=OS) alert from the link you provided Cog.

Just what were you really trying to do? Exploit me with this thread?

It seems like a blog, you have it all planned, so I support the idea, you could post some photos or further information of what happened, other than that, nuff said.

Cognisant
9th-March-2014, 04:07 PM
Ok. Robots with pulley systems and plastic parts is an ok idea. So what? Your thread kind of leaves nothing for people to comment on.
I know~ :D

How do you shape this thermoplastic?
Two bowls of water, one hot, one cold, the plastic goes soft at 6O*c and insulates well so you can handle it without being burnt, however the hit water can be uncomfortable.

(Also, for readability sake you could try editing your writing before posting to avoid your comma abuse. I always gets lost in your posts and often give up halfway if not early.)
I have, no idea, what you mean :p

I got an exploit block alert from the link you provided Cog.
I must be getting sloppy.

Cognisant
9th-March-2014, 04:15 PM
So anyway I've cut three 12.5mm diameter wooden dowels to approximately 30cm and made a narrow pyramid out of them with a V at the base, this will be the forearm, I've also got a 1/4 diameter brass rod from which I've cut a length of 5cm, this will be part of the elbow joint. Thermoplastic is a lot like HDPE in terms of friction so between it, the brass rod, and maybe some washers I should be able to make a pretty smooth hinge joint; on the other end the hand will be made entirely of thermoplastic unless I find some bushings or something.