Summary July 2008

Summary of work and events for July 2008

Posted by Chris on July 31st, 2008 in Update | No Comments


Life Form Scanner – The search for a short antenna

Well I’m almost done with the mechanics of my dome periscope, and I’m turning my attention to the life form scanner, in particular the antenna to raise and lower it.

Just like with the periscope the limitation will be the height of the dome. I can’t extend the antenna into the body because of the slip ring cross bar on the top of the body – so anything I come up with has to remain within the 9-10 inches of the dome.

Everyone has a different approach to things. I plan on making my own radar screen and body/cap assembly. My rough sizing calculations have it coming out around 6″, maybe a little shorter, from the top of the radar screen to the bottom of the body.

From studying photos of what other people have done, most seem extend the antenna into the body, but as I said – I don’t have that luxury. But what they also do is un-attach the antenna from the spool/motor housing. This allows you to rotate the antenna 90 degrees saving some space, rather than having the motor adding to the height.

A couple of weeks ago I bought the shortest antenna I could find on eBay hoping it could get it to work, the jury is still out but I suspect I’ll need to find something even shorter.

It’s a Harada MX-1 and once I removed some housing and un-attached the mast from the body this is what I was left with

Unfortunately, the mast was still too long, collapsed it’s close to 7″, and once I stick the LFS assembly on top that’s still too tall.

This is a rough drawing on what the plan is

So I’m still looking for a short (and cheap) antenna. I did find this one (a Metra 44-PW32) which is meant for old school Minis, but the cheapest I’ve found it is $73 – which is more than I want to pay at this point.

The mast is approx. 5 1/2 inches when collapsed which should work if I extend the body of the LFS assembly over it

So if anyone has a lead on something please let me know.

See Also:

Posted by Chris on July 26th, 2008 in Dome, Electronics | No Comments

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TRU Clone Wars Midnight Madness

Just got back from the TRU Midnight Madness – and was it madness. Over 100 people were in line when I arrived at 11pm. People had been camping out since noon today.

Unfortunately, I didn’t plan ahead so I was on my own. – Alas all my buddy’s in the RL/501st are down in Comic Con this weekend, but I had a blast anyway and everyone loved Artoo.

My embarrassing moment from tonite was when someone in the line heckled “2-3-2, do 2-3-2, I bet it doesn’t do 2-3-2″. I came back with “Well, where’s your droid?”, and he answered “It’s at home, I’m the guy who bought Jerry Green’s R9!”. Too funny.

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At 11:50 they were still assembling the display and people in line were getting mad, especially as there were only going to be 60 of the special General Grievous.

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This is Bobby who bought Jerry’s R9.

More photos here

I was able to snag the new artoo as well as some new figures with the “1st Day of Issue” sticker that may help pay for the gas tonite via ebay :)

Posted by Chris on July 26th, 2008 in Events, Finish/Paint | No Comments

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Lift Mech Support Bracket

I replaced the original drawer slider bracket with something a little bigger. It’s cut from a piece of alu angle and makes the whole setup a lot more solid. You can see the original bracket in the background.

The slots make it easy to align on the dome ring

I still need to work on the riser below the periscope assembly and fix it to the lifter.

Posted by Chris on July 24th, 2008 in Dome | 1 Comment

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New Periscope Lift Mech Prototype

I’ve been busy prototyping a new periscope lift mechanism for Artoo.

Some of you may remember my earlier posts and videos demonstrating a mechanism I’d purchased from Daniel, unfortunately I gave up on it a very long time ago. In my opinion the design was flawed from the start and I never did get it to work well, but not for the lack of trying on my part.

Now that I’ve finished adding servos to the dome I was anxious to get the periscope working. I remembered seeing photos of Wayne Orr’s lift mech and thought I’d try and do something similar. Rather than fabricate something new he uses a drawer slide as the basis for the design and a small motor to hoist the periscope up on a platform.

The only catch with Wayne’s implementation is that the periscope and life form scanner mechanisms extend deep into the droids body. I don’t have this luxury as I’ve left the top ring cross bar in place to support the slip ring. So anything I come up with would have to fit within the approximate 10″ height restriction of the dome. The periscope assembly itself is around 6″ tall, so that would be the minimum requirement but if I could get more height that would be a plus as I could add an additional riser or have room for a servo to rotate the periscope once extended.

I’d shopped around and bought a selection of drawer slides, but couldn’t find anything shorter than 16 inches locally. Once I had them on the workbench I realized that it really didn’t matter because whatever extended out would need to be hacked off anyway. In the end I picked a 20 inch slider made by KV because it’s two sliding components worked in lock step, which was important to my design.

I removed the stops and hacked it down to just over 10 inches and cut a small section of the inner slider that would run up and down on the sliding bearing, which itself ran inside main track.

This is the start point with the slider on the right

And it extended all the way to the left. Notice the two part slider has moved and not just one piece.

http://www.artoo-detoo.net/gallery/v/build/gadgets/IMG_1339.JPG.html?g2_imageViewsIndex=3

Unfortunately I have to jump a few steps as I didn’t take many photos of my late night tinkering with the lift platform and various iterations of how I tried to move it.

I’d originally added a roller to the top (similar to Wayne’s) which would guide the rope, but in the final design it wasn’t really needed – and currently acts as the end stop.

Right now I have a fixed motor on the lift platform that pulls itself up with a piece of string attached to the top of the slider. It uses gravity to lower itself back down as the motor unwinds the string.

I’m using a small Vex motor, but basically it’s a servo that can continuously rotate, so I can plug it directly into my receiver without the need for a speed controller.

It looks like the platform is sloping in this photo, but I’m hoping it’s just the angle of the shot :)

Here’s a short video of it in action

I have a lot more work to do on this and not sure how well it will work inside Artoo, especially at an angle. My short list of things to work are:

  • Add support to help stop the drawer slide shaking.
  • Extra weight to the platform to help it lower.
  • Make sure it’s all level
  • Limit switches to stop the motor
  • Possibly automate with the PICAXE micro-controller, rather than control it manually via the Futaba transmitter.

In closing I also wanted to mention that I’d experimenting with having a spring loaded wheel on the motor (same position as it is now) that would run along the side of the drawer slide to pull the platform along. I still like the idea and may give it another try later. It definitely had a smoother action and having a wheel on the motor made the lift a little faster – Unfortunately I couldn’t get the spring mechanism to work right.

Posted by Chris on July 22nd, 2008 in Dome, Electronics | 10 Comments

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Dome Pie Panel Control

I’ve almost finished the electronics and programming to control the new hinged pie panels. I’m using a small 18X PICAXE micro-controller coupled with a few buttons on the RF remote.

Check out the video of the panels in action.

I’m also in the process of replacing the veclro that attaches the servos to the dome with something a bit more permanent. The brackets are made from aluminum angle (1.5″x1.5″ and 1/16″ thick).

http://www.artoo-detoo.net/gallery/v/build/dome/IMG_1319.JPG.html?g2_imageViewsIndex=3

They’re attached to the top of the hinge and the bolts from the mounting plate that already fix to the dome.

As a side note, if I was doing this again I’d adjust the hinge position a tad. The pies open to the vertical position, but it would have been nice if they’d open a little further, and I figured out (too late) that the lower the hinge is on the pie panel the further it will open – but too far and the hinge will not clear the dome properly.

See Also:

Posted by Chris on July 17th, 2008 in Dome, Electronics | 2 Comments

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Life Form Scanner Screen Material

I’ve finished re-installing the pie panels using hinges and servos, so now I’m starting to think again about the gadgets that pop out, like the Life Form Scanner as seen in ESB.

Yesterday at Ace, I found some perforated brass sheet that’s close to the screen material used in the movie. It was $25 and probably big enough to make at least 6 screens. According to the label the product is distributed by K&S Engineering, Stock No. 6412, UPC 6 76116 06412 2.

I’ll have to paint it silver, and the perforated design is not totally accurate but it’s close enough for me.

I’ve also been researching mini/compact power antennas for the Life Form Scanner lift mechanism.

Posted by Chris on July 12th, 2008 in Dome, Electronics | 3 Comments

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Dome Pie Panel Servo Setup

Spent the last few evenings working on the dome pie panels, and after some tweaking I think I have a setup I’m happy with.

I ended up keeping the extra plate on the inside of the pie panel. It adds some detail and I like the sound the panels makes because of the extra weight. I left the hinges in the default configuration with no tweaks apart from drilling some holes to attach the servos.

I glued the hinges in place using CA glue, which sounds like it may not work so well, but I used the same glue on the hinges on the body and they’ve held up well.

Notice how the hinges are angled slightly to follow the curve of the dome.

I could have just glue the hinges directly to the dome, but I wanted to make the panels removable, so I created a small plate that glues to the dome and then then the hinges are screwed to it.

For the front Holo projector I’d purchased some push rod assemblies to attach the servos, but they were pretty expensive for something so simple, and I thought I could do better – this is what I ended up with.

It’s made up of some very cheap and readily available parts you’ll find at any hardware store. It basically some #4-40 and #6-32 screws in varying lengths, and short length of aluminum tubing that I cut up to make some linkages. I think it cost me less than $4 to make four push rod assemblies.

The long push rod is a #6-32 screw which attaches to the hinges via a piece of the aluminum tube that’s tapped at one end for the screw.

A long #4-40 screw passes through it horizontally to fix it to the hinges.

On the servo end I tap a small section of the tube on each side, and drilled a hole in the middle that allows the long screw to freely pass thru until I lock it on the side.

The servo is currently attached to the dome with some heavy-duty Velcro, which works fine right now, but I know it will eventually fail so I’ll be making a mounting brackets next.

Here’s a short video showing the setup in action

The next step is to wire all 4 servos into a PICAXE processor and tie it all together with some software to trigger sequences from the RF remote.

See Also:

Posted by Chris on July 10th, 2008 in Dome, Electronics | 1 Comment

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