March 2008 Summary

Summary of work and posts for March 2008

Posted by Chris on March 31st, 2008 in Update | Comments Off on March 2008 Summary

Leg/Ankle Screw Update

I wanted to report that the new method of attaching the JAG legs and ankles worked. I didn’t have any problem with screws working loose while at WonderCon, unlike at C4, where I had to constantly tighten them up – and had two screws sheer on me.

Back in December of last year I’d decided to use pan head screws with a combination of fender and lock washers , instead of the recommended countersunk machine screws.

They’re do stand out a little but, but once I’d painted them up nobody really noticed them.

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Posted by Chris on March 30th, 2008 in Legs | Comments Off on Leg/Ankle Screw Update

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Attaching Battery Harnesses

Another quick post with old work, this time on how I attached the battery harnesses to the boxes.

If you’ve been reading any R2 blogs for any length of time you’ll notice that most builders love silicon. It’s a very versatile and used to attach all sorts of things on your droids.

I’ve found out the hard way that not all silicon is created equal. Victor highly recommends GE Silicon II, and I have to second that. I’ve tried the generic brands and found they sometimes do not dry as well, especially if it’s a used tube, and often it will not bond well to aluminum or pull away after a while. This could be my lack of experience, but I’ve yet to have a problem when I’ve used the GE product.

I don’t think you need much silicon to hold the battery harnesses in place. I decided to add some to the top and the back side of the top swivel bracket.

And then gooped inside the lower bracket

I then moved the around until I was happy with the position and clean up the excess silicon before it had time to set.

Posted by Chris on March 29th, 2008 in Feet | 2 Comments

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Slip Rings

A slip ring, in electrical engineering terms, is a method of making an electrical connection through a rotating assembly.

In our case it could be used to route power and other signals into the dome, but still allow it to rotate continuously without tangling wires.

I’ve been toying with the idea of putting a slip ring in my droid for a couple of reason

  • Remove the needs for extra batteries in the dome and save weight at the same time
  • Easier charging of the batteries
  • I’m upgrading my RC setup to 2.4Ghz in the next month, and this would allow me to eliminate an expensive second receiver in the dome.

Here’s a quick picture of a sample I picked up today.

Slip Ring

It’s pretty small, but offers 18 circuits, each capable of 2A. The company that sells them is close to where I work and they also sell a much smaller 6 circuit design as well as 12 and 24 in the same size package as above.

I plan on testing it out in the next couple of weeks and will report back on my findings.

Posted by Chris on March 27th, 2008 in Electronics | 7 Comments

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Attaching Battery Boxes

Here’s a quick run down on how I attached the battery boxes to the feet.

I have the steel feet from JAG which include pre-cut key mounting holes for the battery boxes. I’d already fixed screws to the boxes when I cut out the holes for the motors.

But one of the problems with using the screws/key holes is that’s it’s almost impossible to set them correctly to get the boxes to fit (and hold) the boxes tight to the feet. I think if I didn’t have the NPC motors sticking well into the boxes, then the setup would work, but with the motors in place just getting the boxes on is challenge enough – without worrying about the key holes.

The other problem I had was the boxes were not even close to being straight/true, so when the front was tight to the foot the back had a gap, and vis versa. I’d tried tweaking them without much luck.

Originally I’d tried using some large beefy magnets to help fix the boxes to the feet. They kind of worked, but were easily pulled apart and had a problem getting the front and back to sit flat due to the warped boxes.

Gerard gave me a great tip to just screw the box from the back inside to the bottom of the foot – and it worked a treat.

I just held the box in place, marked and drill a hole in the box and thru to the foot

I tapped the hole from the underside of the foot

I’m still using the side key holes as well, but the new screw holds everything in place and stops the boxes from springing away from the feet.

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Posted by Chris on March 27th, 2008 in Feet | Comments Off on Attaching Battery Boxes

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RoboGames 2007

Here’s a short video from RoboGames last year. My droid pops up in a few spots.

I’m hoping to be there again this year.

Thanks Vern for sharing.

Posted by Chris on March 26th, 2008 in Events | Comments Off on RoboGames 2007

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Mounting the Side Vents

This is another retroactive post on something I worked on sometime ago.

I wanted avoid permanently attaching the side vents to the skins to allow more flexibility, but it’s not as easy as just making a simple bracket and screwing it to something like you could on a wooden frame.

I’d experimented with a few different methods but wasn’t happy with any of them, and I was convinced I’d end up using silicon to stick the vents to the skins permanently.

But at the last minute I gave this idea a shot – I tried attaching an aluminum plate to the back of the vents and hoped that a combination of sandwiching them between the opening in the skins and the pressure from the new aluminum plate from the inside would hold everything in place.

I took some of the same aluminum sheet I used for the side panels.

And cut squares that were slightly bigger than the vents and bent them to roughly the same curvature of the body.

This a shot of the new plate from the inside of the frame covering the side vent hole

I then used silicon to attach the plate to the backside of the vents

Then it was just a matter of waiting for the silicon to dry and wedging  them between the skins.

Posted by Chris on March 26th, 2008 in Body | 1 Comment

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Side Panels

It’s funny, the side panels are one of the few things you’ll not see discussed often on the Y! Group or on builders blogs. I’m not really sure why. My theory is that most likely this is the last thing that you work on before rushing off with your new droid for the first time – and sadly overlooked when sharing building tips.

What exactly are the side panels, well they’re the small nondescript flat square pieces that fill the holes below the side vents. They’re typically not included with frame or skin part run, unless you’re using a fiberglass body. So material and implementation is left up to each builder to figure out.

Here’s a shot of the side panel on the the ILM Uber R2 – which incidentally has them molded into the skins.

I’m guilty as most builders and left this part to the last minute – but thought I’d do my duty and share the solution I came up. At the time I thought it would be a temporary fix, but most likely it’ll stay this way for a while.

The plan was to cut the panels out of aluminum and attach them to the frame using the same bolts that attach the skin mounting blocks to the frame. Here’s a good shot of a skin mounting block.

I started off by cutting some spare aluminum sheet to fit in the gap.

I cut it slightly too long as I wanted to bend it over and create an L shape. Don’t ask how wide the plate is – I made it to fit snug in the groove in the lower ring of my aluminum frame, and in this photo it extend all the the way down and touches the frame ring where the mount block is attached.

I cut a few notches from the corners as it needed to fit around the frame vertical supports.

I then bent it along the line I’d marked earlier, making an L shape

I marked and drilling the mounting holes

Then test fitted and tweaked the edge until it was flush with the skirt and skins

I added a couple of quick coats of paint using the same formula as the skins (metal etching primer, gray primer Rusoleum satin white)

Here’s the final version of the panel bolted to the frame ring and skin mounting block

I’m pretty happy how it came out, and it’s one of those parts that nobody really pays much attention to anyway.

However, one of the issue with the panels sharing the same bolt with the skin mounting block is that when putting on the skins I find it easy to get them to fit by keeping the mounting blocks little loose. But once the skins and panel are in place it’s incredibly hard to then get inside to tighten the screw up to hold the side panel firmly in place. It’s hard to explain, but trust me even with small hands it’s really difficult to juggle the skins, side panels and mounting blocks to get everything tight and aligned.

Posted by Chris on March 25th, 2008 in Body | 4 Comments

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