Saturday, December 19, 2009

Complete tear down and upgrades!

The time had come to do a teardown and inspection of R2-D2, to get a better idea of what was working well and what was not.

One of the major issues I wanted to address was the body sway I was seeing.  The source of which I thought was limited to the center foot having problems with its casters.

I also wanted to find a way to build some sort of shock absorber into the the center ankle or foot.  Whenever R2 rolled on uneven surfaces, the crash and clang was rather severe.

One thing I stumbled upon while looking for a way to solve this was a rubber muffler hanger.  This piece is about the size and thickness of a bar of soap.  Cut in half and it would not only fit well, but would also make R2's feet level.  For $4.99, it sure looked promising!

Finally I slowly took everything off, getting down to the frame.

One thing I noticed right off was a few of the screws holding the skins on were missing or very loose.

Upon inspecting the frame, I went around each frame rod and plate, checking for snugness.  The horizontal piece ath shoulder level was very, very loose.  Other frame rods required a few turns with the screw driver.  This was a big part of the swaying I was seeing.

To help stabilize the frame, I decided to put back two vertical frame rods that I had removed eailer.  The rods were located in a spot that would prevent hinges from being installed on the large, vertical doors on R2.  There are 4 large vertical rods that I removed.  To even the load, I put back two, with one in the front and one in the back, diagonal from each other.

The center foot was next. 

One thing that I checked first was the bearings that allow the caster to rotate.  It was very clear that they were in very poor condition.  When I tried to spin the casters around, they did so but not very freely.  Imagine 150 pounds (or more) on them and I can see why its been such a struggle to get R2 rolling. 

I beleive the problem is the holes I drilled too close to the groove near the bearings.  In order to mount the foot plate into the foot, the bolts had to pass thru the casters. 

The replacement casters are the same size as the previous ones, 2.5 inches.  They seem to be the same material, just a different color neoprene.

This time, rather than trying to drill through the casters at all, I came up with a better idea.  I decided to run 1 inch long (10-24) screws and using a lock waster and nut on each.  This way, when I bolted the mounting plate into the center foot, there would be 8 screws pointing upwards.  I placed the rubber muffler mount I cut in half in the middle of each, then slid the casters into position on top of them.

Without too much force, I then used a small washer and a lock nut on each until the casters were snug and the casters have the rubber 'shock absorber' them and can ride up and down a bit as needed....

Once I had R2-D2 all back together, I had another thing to do....pick up the great Santa hat my Mom made!

Looks good, yes??