the beggining of my first eskate...

sn0wchyld

100 kW
Joined
Mar 18, 2011
Messages
1,868
Location
South Aus.
I've been pretty quiet on these forums for a while now... but thats not to say i've been sitting on my hands...

I got a new toy recently...
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and after some assing around getting it working reliably, I got some new parts...
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I made the slots on the 'axle grab part' too tight (right)... and then neglected to use a center drill on the holes I drilled in the 'motor mount part' (left) so the .5 odd mm variation in hole position means that its hard/impossible to get all the bolts in - so ill have to widen the slots a smidge.


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its going to be a belt drive, 14t to 44t, I'll be re-terminating the motor to drop the kv down to 340, and using a second on the opposite diagonal wheel. The plan is to use a couple of hall sensors on one of the motors to determine the direction the board is traveling, and switch 2 phases of each motor accordingly via either relays or some MOSFETs, enabling proper control of the board no matter what direction its rolling. As it turns out I changed the plans after buying some parts, so ill be cutting a 44t sprocket too...
Still need to cut a wheel hub, however the design is done...
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Overall pretty happy with the results so far. Machine still has a few bugs that I need to sort out, as does my abilities in running the thing... I've got a list a mile long of things to build so plenty to practice on!
 

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Hello! Whats the name of your toy and where did you get it? Price? I want one! I have read that you can get hobby cnc machines for around 1000 dollars.
 
Its taking a while.. but im getting there.

Found that with a much larger pulley on the wheel I could put off re terminating the motors... and with the CNC I can make one and save myself the $50+. now Just gotta make another 40-50 and the machines almost paid for itself! :p

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Not sure how well the home made pulley will work... my cnc still has a pretty serious issue with the Z axis not running true. For parts that don't require really tight tolerances or that can be cleaned up after its not a big deal, but for the pulley it means that there is a slight .05 to .1mm lip about half way along each tooth. Once the Z axis is sorted this should no longer be an issue but for now its a bit of a pita.

Havent taken it for a test ride yet... I need to shave off a mm or so from the inside of the pulley as its scraping on the axle, but other than that I just need to build a case for the battery and controller, and wire it all up.

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for those of you asking, the machine cost me just over 2k delivered. I ended up having to buy a Ethernet smooth stepper, as there was too much noise between my PC and the stepper drivers for the machine to operate smoothly ($200). I've since spent about another 500-700 on tooling and setting everything up in a nice enclosure. I've also bought a geko drive ($280) but since the original drivers are now running well with the ESS I'll probably re sell it...

Since its in my living room (which is attached to my bedroom) the CNC is only about 4m from my bed... so I've set up a vaccum system for it since I dont want to use any kind of liquid cooling. Vacuum runs via a home made cyclone-esque separator and into the houses ducted vacuum system. works like a charm and also means I can vacuum up anything from my adjacent workshop and not worry about it clogging up the pipes or damaging the filter in the ducted vacuum system. Shards of metal and plastic, offcuts of wire and shrink tube, even the odd stray washer or coin has gone through it and into the collection bucket.

I'm probably going to end up having to spend another $200 ish on it to get it running how I'd like. The Y axis isn't really stiff enough for my liking (so cutting parts takes longer than it could) and the Z axis troubles are causing major headaches, though it sounds like I can get it fixed by the guys at my uni workshop, so hopefully wont have to buy new parts for that... Not going to have much change from $3k for my setup by the time its all running perfectly. However by then I'll be able to make some pretty aggressive cuts and probably cut my machining time at-least in half, or possibly a quarter. You can get smaller versions of what I have for around $1-1.5k, but they'll really struggle to cut aluminium. They will do it, but typically at a tiny tiny DOC (depth of cut) so you'll need 10-20 passes to cut 1mm deep without excessive chatter (tool killing vibrations). Cutting one of the parts I've made here would take an entire day or more... For timber and plastics though they do fine, from what I've read.

For those considering buying one... just know that there are some notable costs beyond just buying the machine itself, and a pretty long, steep learning curve. 99% of the cheap endmills you find on ebay are shit (ask me how i know this) and the good quality EM's can cost over $40 each. Then you need to factor in some CAD, CAM and the control software (ie mach3) for the machine itself. I knew about these costs and have still ended up spending more than I thoguht I would. Worth it for me though, since I like being able to prototype my own stuff and enjoy the process anyway. There's just something about watching your part emerge from the blank stock that makes me smile...
 

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torqueboards said:
Awesome work. Your mill is great. Wish I had room to make one myself. Your pulley hub setup is nice too. How are you holding your pulley onto the wheel?
3 x 55mm m4 bolts. I need to make a small disk for the other side of the wheel to help hold the bolts in place... but otherwise it runs! well, on my desk. also need to put some flats in the motor axle for the grubs to grab onto.
 
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