Thursday, September 30, 2010

Pondering what to use inside the dome for servos

As I start to think about the next few steps ahead, one thing I am considering doing is using micro-servos for all the dome's hinged panels.

I've used them before but wasn't happy with the flimsy plastic horns they came with.  Too much flex when attached to the metal push rods.

However upon doing some research, I have found both metal mini-servo brackets and aluminum servo horns.  For me, this makes the idea of using a micro-servo much more appealing.  Plus, there will be some weight savings using these versus the regular sized servos.

With the lower panels I have chosen to hinge, I will need 6 of these and the top, pie panels, 5 more.  

It'll take a while to get these as the R2 building fund is pretty low lately!  But, for now, I can at least plot out what I will need.

Tuesday, September 28, 2010

Trying out the inner dome hinge process

Tonight I took some time to file the dome panels a bit more uniform and then cleaned up the excess slag from that.  Again the dremel made quick work of this with the sanding bit.

I wanted to do a test run with one of the dome panels and try attaching one.  I was curious what spacers, screw length and such I would need to get a good fit.

First I used one of the backs of the hinge and lined it up even with the edge of the panel.

Once I had the holes marked, I tried to find my center punch.  I couldn't locate it so as a result, one of the holes I drilled wandered up a bit.  

With the holes drilled with a 1/8 inch drill bit, I countersunk the hole so the 4-40 screws would fit flush.  I screwed the bolt and nut together and could tell I would need something behind the hinge to accommodate for the curvature of the dome.  I think a very small, rubber washer will be ideal.

I would like to also replace the 4-40 nuts with larger, 4-40 lock nuts with nylon inserts.

With that attached, here's how it looks from outside...

I think the process will work well.  I just need to accommodate for the dome curvature with the hinge mount....and of course, find that center punch!  No more wandering drill bits!


Monday, September 27, 2010

Inner dome work continues

This evening I continued work on the inner dome.

First I had to assemble the JAG hinges I would need a bit later on.  

My assistant then stole my chair as I prepared to work on the inner dome...

While Mokey took over my chair, I had all kinds of slag to file from the cuts I made yesterday.

Being in a curved surface, I decided to go with the Dremel flap sander bit I have.  Make sure you have eye protection, breathing protection and long sleeves when you do this.  Using the 120 grit flap wheel, I was able to make quick work of all the rough edges.

I placed the outer dome on the inner to see how the panels looked.  It wouldn't fit just right since I still have some more filing to do.  However, with the outer dome on, I can see just how much filing I need to do to "square up" some of the cutouts.

That's it for tonight.  More work tomorrow!

Sunday, September 26, 2010

Cutting the inner dome panels

Today I did some cutting of the inner dome panels I had previously marked out.

A few weeks ago, while removing the head of a screw, my 7 year old Dremel made a POP sound and died.  Now I have replaced the Dremel with the latest and greatest model.  This also means the better cutting wheels will work on this model.

The goal is to cut the panels out, file them, then I will use the JAG hinges to bolt them into position.  I'll counter-sink the screw holes so that the end result will be perfectly flush.  My thinking is that by using the inner dome pieces, I will not have to mess with the troubles other builders have had.  Some have had difficulty getting the panels to close or open completely, more notably in the dome pie-panels.  Since all of these panels will be attached to servos for quick opening and closing,  I want to make sure they all close flush.

First I wanted to make the cut lines more pronounced, so I took a flexible metal ruler and pencil to them.  

The vertical lines were easy, the horizontal, due to the curvature of the dome, were a bit tricky.

Speaking of to cut the dome panels was my next hurdle.  Since the panels are all near the bottom, I would need to find some way to cut them safely.  What I came up with wasn't exactly ideal...but worked!

With that, it was time to start cutting...

Next up is to file the pieces.

However there was one boo-boo.  I cut through the bottom so I mixed up some JB Weld, put it in the overcut and set it so I can sand smooth tomorrow...

More tomorrow!