300mm Dome Build
Really there's no option. The 300mm Dome from Darren is really a must. Yes it is costly, but wow - what a masterpiece. I read some background
information and various blogs and really although costly it really sets off your R2. I'd highly recommend that you get the pennies together and purchase it.
Darren also provides everything that you need, so although you think its just the inner and outer dome, its all the other parts that are just too hard to source individually.
The dome comes laser cut, so its just a process of using a saw to remove and label the panels. I should have taken an actual shot of my dome but got so carried away, I had to start on it.
Once you spend any time reading the blogs, you then see the effort builders put in on getting a shine on the dome, and you realise that no alternative is going to give you that
r2 look you want. The aluminium dome is the crowning glory and so I do think there's no choice.
So measuring from the BOTTOM of the inner down up about 1/4" or 6mm (you will need to make your own careful measurement, as i did (see pic and ruler) I drew
a line and then cut on that line.
To ensure I got an even line I placed the dome on a table and raised a felt pen tip 6mm up and moved the dome round drawing the line.
Using a dremel cutting disk, I cut a slot so that I could insert my hacksaw blade and began to cut. It was difficult, and immediately I thought "Why on earth did I do this". It was extreemly difficult to
keep a steady and level line, so I adopted a method of cutting across the dome along the line at a tangent, by doing that I could keep a
very level line, although it
took several cuts and a considerable long time until, at last, the
small 6mm ring was removed. It was then a bit of smoothing and sanding to get a nice edge, but now there is
no visible gap, so I'm pleased with the end result.
Once the inner and outer domes were fitted I realised I couldn't now see the numbers I'd written on outer dome to match the panels. But I was
able to work out what these were. I wasn't going to bond the panels using araldite but using clear silicone (the same white silicone you may use to edge your bath to the tiles
in your bathroom. This I felt meant I could prise them off. So I drilled 8mm holes in the innerdome panel. So that once the panel was siliconed, it could be pushed off from behind.
You can see in the picture the inner dome at the bottom, not quite as shiny. Here i will drill holes through into the nylon ring. The
blue ring will then cover up the screws.
I found that I needed considerable tension on the motor spring to allow the dome to turn, and when it did it was pretty noisy. So looking at various
I decided to replace the 5/16" metal ball bearings with
ones (ref 9614K57 ).
It was a fairly simple process. Remove the screw on the side of the rockler bearing and all the ball bearings drop out, This allows the rockler to come apart.
I then cleaned the grease off using Acetone, and used grade 1600 sandpaper to sand out any imperfections on both halves of the bearing. I then
added the new bearings, and replaced the screw. I had 200 (2 packs) of the bearings but left enough space for the acetal bearings to move. This
made an amazing difference.
I wasn't happy with the dome drive . It just kept slipping with the heavy aluminium dome. It was ok with the
dome off but the rubber wheel kept slipping. So I sanded down the inside of the ring with heavy grit sandpaper. The idea being more grip. This didn't work.
So I posted . on astromech for help. It was suggested to use grip adhesive, like that on ladders ie something too
make more grip. So I cut a strand, and stuck it to the wheel.
unfortunately this didn't work
I was reluctant to
increase the strength of the springs, but i added a spring that had twice the resistance, this really ensured a good grip to the rockler strip, but it still slipped. I reduced the motor
voltage to 9 volts, so not such a torque when drive applied. Made no difference. So I purchased the A&A dome gear.
This immediately cured the problem. It works so well now. The domegear consists of a toothed ring thats bolted to the rockler. I then replaced the rubber wheel witf
the small toothed gear. I had to drill 4 holes in the toothed wheel and i used the mounting hub i used for my wheel.
I had heard that increasing the sring resistance could burn out the motor, so this gear is by far the better option.