Devin's Astromech Build

Droid builds and other club-related projects
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Joined: Mon Oct 28, 2013 8:29 am
Location: Fort Collins, CO
Name: Devin

Re: Devin's Astromech Build

Postby R2DEVO » Wed Nov 06, 2013 6:29 pm

But wait, there's more!

All this time I've been borrowing my friend's Spektrum DX7 transmitter and AR6200 receiver and it's finally time to give it back.
Time to swap it out for my new radio stuff I've been too lazy to install.

Cheap transmitter from Hobby King. Build quality ain't bad for $54 and so many channels.
Image
http://www.hobbyking...?idProduct=8991

They offer a backlight kit for $5, so I grabbed that too. Fairly easy to install.
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http://www.hobbyking...idProduct=16720

LiFe battery. Had to replace the connector with the one that came with the actual transmitter.
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http://www.hobbyking...idProduct=14076

Battery charger that supports LiFe batteries
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http://www.hobbyking...idProduct=14857

Gotta have a lanyard!
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http://www.hobbyking...idProduct=11982

The receiver & module combo that came with the transmitter (should have bought the transmitter without them) did not support a failsafe mode that you can set. So I bought this FrSky module and receiver. The module fits into the back of the receiver, although a little cutting is required. But now I set the failsafe so that everything just turns off if the signal is lost.
This also supports telemetry (sending data back to the transmitter, like battery voltage and other sensors). Not sure if I'll ever use it, but it's cool to have.
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http://www.hobbyking...idProduct=14355

~$142 + shipping

I swapped everything out yesterday and it runs great! The menu on the transmitter is kind of crappy, but there are open source alternative firmwares that apparently make this cheap transmitter just like the fancy expensive ones. Even without that, I was able to set it up just how I had it before with drive motors, dome motor, and safety relays.

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Name: Devin

Re: Devin's Astromech Build

Postby R2DEVO » Wed Nov 06, 2013 6:32 pm

Finally worked up the courage to cut open my rear skins for a door. This will come in handy.

Image

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Re: Devin's Astromech Build

Postby R2DEVO » Wed Nov 06, 2013 6:33 pm

After the Maker Faire, you could say I got inspired to get some more work done, again on the R5 dome. I decided to try out my idea, at least cutting out the plates since I don't have the right hardware yet.

I used some 1/8" hardboard from Home Depot and a jigsaw.

It all fits!

Image

The plate that gets fixed to the inside of the dome.
The overall side of this part is a little tricky. The dome is not perfectly round, so when I place the plate in there it looks a bit off. I didn't want the routed area to cut through to the outside of the dome, but I also couldn't make the dome plate much smaller because there wouldn't be material left to mount to.
Image

The plate that stays on the Rockler bearing. the screws that interface both plates will need to be countersunk on the bottom, otherwise the screw head will run into the dome drive wheel.
Image


Then I'll need to make a plate for my R2 dome that has the same inner bolt pattern at the R5 and they will be interchangeable.

Hopefully it all still works when I get the hardware in :cool:

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Name: Devin

Re: Devin's Astromech Build

Postby R2DEVO » Wed Nov 06, 2013 6:34 pm

oh baby, more eye candy for Cal :P

Seems to work well enough.

Now to make a dome plate for my other dome so I can put it back on using the new bolt pattern

Watch on youtube.com

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Name: Devin

Re: Devin's Astromech Build

Postby R2DEVO » Thu Nov 14, 2013 9:32 am

Quick video of some progress in my model...wish it was progress on the real thing :)

This concept could work, but needs a lot of tweaking. Won't be as fast as what is seen in the movie, but I could live with that.

Watch on youtube.com

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Name: Cal

Re: Devin's Astromech Build

Postby MonCal » Sat Nov 23, 2013 8:33 am

Nice. Is there still enough room for electronics in there?

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Re: Devin's Astromech Build

Postby R2DEVO » Tue Nov 26, 2013 9:43 am

MonCal wrote:Nice. Is there still enough room for electronics in there?


Should still be plenty. I moved some things around and I think I can comfortably fit 4 of the 9Ah 12V batteries I've been using (because why not add more weight???)

And the electronics might not end up all on the same panel, not sure yet. I am thinking of adding a panel that flips out the back hatch for easy access. I didn't get that option when I bought the frame so I'd have to add it myself :?


I also think I solved my speed problem by using high speed / low force actuators and having the mechanism be self-locking, basically an over-center clamp, at least for the center leg. For the shoulders, I am thinking I could use some hard stops when they get into position. This way, none of the actuators are taking the loads from hitting sidewalk cracks, etc and it all goes into the frame/lock mechanism/hard stop.

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Re: Devin's Astromech Build

Postby R2DEVO » Sat Nov 30, 2013 7:47 pm

well...r2 got all sorts of disassembled on this long weekend.

Goals:
1. get foot details in place
2. install battery boxes
3. install new utility arms

Achievements thus far:
1. 2 of 3 feet have their half moons and other details on
2. one battery box put in place so far, and it just barely clears the skirt when I transition from 2 to 3 legs. It's about 1/8" apart at it closest, but that works for me!
Image
Watch on youtube.com

3. Got some newfangled aluminum utility arms a couple weeks ago from Rotopod and wow, they are fancy utility arms. After much sanding of the shaft in the paw, I got them assembled and put in place.
Image


Now I'm concerned about how to attach the battery boxes and the ankle to the foot shell. Because the hole I shove the ankle bolt through would be covered by the battery box, and I don't think I can get the battery box on with the ankle already in place (due to the large NPC motors) :?

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Re: Devin's Astromech Build

Postby MonCal » Mon Dec 02, 2013 3:17 pm

Nice. I was worried you wouldn't have clearance when folding the legs in. I actually didn't think R2's design would allow for that. That's pretty cool.

As for the attachments, hmm.. I would have to see what the dilemma is in person. There are always magnets. I keep my back door on with magnets and it works perfectly.

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Name: Devin

Re: Devin's Astromech Build

Postby R2DEVO » Tue Dec 03, 2013 7:52 am

Yeah, at first glance you'd think the battery box would hit the skirt. But the trick is that when the legs move back, the foot assembly also tilts down at the same rate, leaving just a bit of clearance.
It's still very close, in fact I'll still have to move mine back a tiny bit. When I tried taking him off the stand and doing the transition, it did end up just barely making contact. I'll move the battery box about 1/8 - 3/16" back to give some extra clearance.


I think my other problem has been solved. There were two issues: attaching the battery box and just getting the dang thing over my motors with the ankles already attached.

With the help of my machinist neighbor, we milled out my battery boxes just about as much as we could and that let me slip them over the motor with the ankle in place.
Image

Now for actually attaching them, I decided on tapping some 4-40 holes and just bolting the thing on. It's pretty solid now. I can access the bolt heads from the rear opening and the bottom of the foot.
Image Image



Got the foot shell details installed on my other foot last night, just need to get the battery box on then get that leg back on the body and I'll be ready for Saturday

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