Sanding Dome Panels

This is pretty straight forward post. I finally got around to sanding all of the dome panels all the way to 2000 grit. I followed the same method as with my dome. Started with 320 on an orbital sander, next 400, 600, 1000, 1200, 1500, and finally 2000.

After 600 Grit

After 2000 Grit

Dome Panel Automation

I was excited to automate the dome panels for a while. I already had the panels all cut and the hinges mounted.

The next step was to mount the servos securely. Since i cut my dome in 2 pieces, there wasn't really a way to just stick the servo to the inner dome. I saw on Chris's blog over at http://www.artoo-detoo.net that he made little servo mounts from angled aluminum. I basically used the same idea but i only had square tube in hand. I just hacked it in half and made some angle out of it. A little ugly but works.

And with a servo mounted. I'm using HS-65 MG servos. These are sub micro with metal gears and the seem pretty good. 

Next I had to build the linkages. This was pretty easy i just bought some parts on hand at the local RC car shop.

Here is the part breakdown. If your interested in using the same linkages. 

1. 2-56 Threaded Rod ---------------------------------------------------------------------$1.20
2. 4-40 Threaded Rod ---------------------------------------------------------------------$1.20
3. 2-56 Safety Lock Kwik -Link Linkages DU-BRO #815---------------------------------$2.39
4. 4-40 Nut---------------------------------------------------------------------------------$0.02
5. 4-40 Lock Nut---------------------------------------------------------------------------$0.10
6. DU-BRO heavy duty 4-40 E/Z Connect  #490-------------------------------------------$2.29
7. Spring from assorted spring pack from home depot (one box will do whole dome---------$4.40
8. 3/32 Plated Brass Dura-Collars #138----------------------------------------------------$1.89

Instructions:
-Cut the threaded 4-40 Rod so that a nut will fit outside of the hinge.
-Remove the pin and lock from the 2-56 Safety lock kwik-links and drill the hole larger to fit the 4-40 make it kinda snug.
-Expand the hole in your servo arm just big enough to fit the E/Z Connects  through.
-Assemble rest as seen here.  Trim off the extra 2-56 rod.

Here's a couple vids with some test movement.

Dome Sanding and Polishing

I thought i liked the spin lines on my dome until i saw some other Bay area Droids, Specifically Capodimusica's and Chris's.

This made me wanna sand out those spin lines. This wasnt too fun i must confess but heres how i did it.


I used 220 grip sandpaper on an orbital sander and this quickly removed the spin lines. Probably 5 minutes for the whole dome. I sanded it on the frame so i could spin it on the rockler bearing. I also used a plastic bag over the inner dome to keep all the gunk out of it.


220 Orbital Sander


Next i hit it with 320 Grit on the Orbital Sander. This was pretty quick as well.


After this i moved to 400 grit wet dry and went in circular patterns. I used the pie panels as reference where i started and did one "pie" section at a time. I used 1/4 of a sheet for each section.


Next the same but with 600 Grit


Then 1200 and one more time at 2000 Grit


Once this is done i took some Mothers Mag aluminum polish and a cheap harbor freight buffer and buffed the dome. Once the polish starts turning black you then just buff it off with an old tshirt etc. The more you buff the shinier it will get.

Looks a bit different in person, ie a little less shiny, but here's the result. I think just the right amount of shine.



Now i gotta do the panels ugg...Also what mess...

PSI

Well r2 needs lots of lights. I didnt take many pics way back when i started the electronics. But here are a couple of shots of building the Teeces 3.1 boards. Wow thats a lot of soldering!

I didnt know where to get the "flangless" LED's so had to use a nail clipper and cut all of the flanges off of hundreds of LEDs ... uggg.. wanst too bad actually.

Next i needed a way to mount them. I first milled out some PSI spacers from 1/8" aluminum. 

Next i got a couple properly sized pvc fittings for the housing. 

and last cut some oak rings and sanded a taper on the rings so they fit very tightly with the curve of the dome. 

Here it is turned on. As you can see i need some more diffusing so the lighting is more even.

Hinges!!!!

Woohoo hinge time!!!

I want every panel to open and close on this little guy. Due to the shape of dome with all its curves its acutally very hard to hinge the doors. The hinges are specially designed to not bind. Here is how i installed them.  First had to put them all together.

Remember back when I cut the holes for the panels. I made the hinged sided around 1/8". This is important to allow the hinge to open fully.  Next  i used hot glue to temporarily hold them in place. The placement is very unforgiving so its best to test fit it all with glue before drilling holes.

Once in place I then glued the outer pie panels on  and checked for binding. Once they were all good i marked the and drilled the holes. I used the same captive screws from earlier. 

I then did the lower panels as well in the exact same way. 

One more hole to cut.  I forgot to cut the hole in the top of the dome... I couldnt use the whole saw because there is already a small hole in the top of the dome. This hole however is not centered.

So i tig welded a little plate so i could drill a new hole centered. Then i cut it with the hole cutter.

Radar Eye

The first step to installing a radar eye is to choose a location. There are so many different placements throughout the films. I chose a position that looked best to me. Kind of an average. I just held it up and traced the position. 

Next The trick is you have to transfer the the holes to the dome. To do this i followed some suggestions from the club. Just break off little pieces of  a sharpie and stick them in the holes. Then line up the eye with the marks from the earlier step and press. Then just cut the holes. 

Then i drilled the holes and temp mounted it. I traced the main eye hole and cut it the same as the other round holes. 

Lower Inner Dome Prep

Ok so now its on to the lower section of the inner dome. First off it needs to be sliced vertically so it can be expanded some. This is pretty easy i just used the jig saw and cut right through the center where the Holoprojector near the dome bumps is.

Next i just took a piece of angled aluminum and cut a few L shaped peices to use as a spreader. This pushes out on the inner dome removing the gaps. They are secured to the inner dome using Captive Screws from http://www.mcmaster.com.

Once this was done i marked all of the panels that needed to be cut and then began cutting.

Here i temp taped some of the panels in place so i had a clear view where the front logic display would be mounted. 

More holes cut the same way i did for the top holoprojector.

More panels cutout and a quick test fit.

Cutting Dome Panels

Here I actually feel i can give some good information. Most builders suggest using a dremel to cut your panels out.  This for me was an incredible pain. I used the quick change reinforced cutoff wheels like everyone suggests. They are very handy when switching wheels. However i had some issues.

First using my dremel was taking forever and the dremel was getting VERY hot. It would slow down when overheated. It would take like 10 minutes a panel.  I happen to have a really powerful Kress Die Grinder for use with my milling machine and decided to give it a go.. Wow it cuts like butter BUT and  a big BUT... The wheel lasts like 20 seconds!  They are not cheap either!!!

Now!! What i found works like a damn charm is a jig saw! Just use the dremel to start a slot allowing you to fit the jig saw in and bam... easy cutting. Just be careful as the saw could bend the dome if you are not careful. Here is a clip showing how easy it is. I'm filming this with one hand and cutting with the other. 

Here is the upper inner dome. As you can see you need to leave a lip for the outer pie panel to rest against. I used 1/4" lip around the top and sides and about 1/8" lip on the bottom where the hinge goes. This is required so you can have the full range of motion using hinges without any binding.

Here I used a hole cutter to cut almost all the way through for the Holoprojector. 

After that i just cut a few slots and wiggled the pieces back and forth until they broke free.

 I used various files to clean up the edges and get them very crisp and square. For the round hole, using a whine bottle wrapped with sandpaper seems to be the best method.

Starting Dome Work - Upper Dome

I dont have a pic of this step but like many other builders my dome did not fit well. I didnt feel like sanding for hours and hours for a good fit. Call me lazy but i first cut the top section of the dome apart from the lower section.

Next I used some dykem layout die on the inner dome  parts so i could accurately mark the panels.
Then I held it in place and added a couple drops of thin CA glue. This holds it tightly in position and can be removed later with little force.

Once glued i scribes all of the pie panels.

And the marks.

Dome Ring

Counter sinking the holes on the aluminum dome ring. This mounts to the plastic dome ring.

Test fit to ensure the screws seat fully.

Rockler Bearing

Preparing the bearing so R2 can spin his head.

Here I'm slightly expanding the some of the mounting holes. 

Next cutting some countersinks so the mounting hardware will sit flush.

Test fit to check countersink depth

Domes HERE!

A couple years ago I got the itch to build an R2.  I put it off for a while and about 6 months ago  I figured the first part i should start sourcing was the dome. After months of waiting I got the hand spun, laser cut dome from Daren Murrer.