Cylinder Holders

Well, I said I made good progress today and I didn't lie. I was also able to cut out the 2 cylinder holders for the outer legs. I had plenty of scraps lying around so I chose a .75" piece of plywood that I would be able to get both pieces out of. I used my router table to cut the small arcs and then my table saw to cut the length of the piece.

The uncut Cylinder Holders (upper top left) after Routing the arcs

Since the scrap piece of wood I was using was round I needed to create a flat edge to run along the table saw fence to ensure a good straight cut.

Cylinder Holder Straight Cut

And here is the end result after the cut was made

Ankle Cylinder Holder

Now, this piece sits flush up against the ankle cylinders so I still need to sand the bottom of the cylinder holder so that I can get a good clean fit. I originally hoped I could find a core box router bit large enough to achieve the clean fit but I could not find one that has a radius cut of .6875". I figured it was a long shot but had to try anyway. So as I mentioned earlier I will just need to sand it by hand. But that is a job for another day.

Center Leg Ankle

I made some good progress today in my build. I was able to get the center leg ankles pretty much done. As mentioned in a previous post, I had taken a 6.25" diameter drainage pipe and cut a strip out of it to represent the arc of the ankles and then cut that strip into 4" pieces. Now I needed to cut an angle into the edge of the piece. Using some suggestions from other blogs that I've read, I set up the 4" piece as in the following photo.

Cutting the Angle in the PVC Arc for the Ankle

Setting the table saw blade at 35 degrees, I decided to practice on a scrap piece of the PVC before working on the good ones. Once I saw how the saw and PVC reacted to the cut I moved forward with the good pieces and ended up with a clean cut on the PVC.

Finished Ankle Cut

Once I finished the cut on the other piece I cut a piece of styrene to fit on the ends. In order to get a nice fit on the styrene, I cut the piece a little too big (not much) and decided I would sand it down. The end result turned out pretty nice. I repeated with the second ankle.

Completed Center Ankle

I still need to prime and paint but it's a little cold where I live so I decided that instead of painting the pieces in the garage and moving them to the basement to dry, I will just wait until spring and paint as many things as I can then and let them dry outside.

Center Leg

Today I was able to get the center leg for my R2 cut out. It consists of 2  .75" and 2   .5" pieces of plywood. The .75" pieces will be on the exterior of the leg and the .5" will make up the interior.

4 Pieces of the center leg (2 on left are interior, 2 on right are exterior)

I set up my router table so that I could get the nice arc on one of the .75" pieces of plywood. Once I was satisfied with the arc I had, I placed that piece on top of the uncut .75" piece and using the trim router bit was able to make and exact duplicate. For the interior .5" pieces, I found a straight piece of wood and used that as a guide for the trim router bit to get the nice angular cuts on one of the pieces. Again, once I was satisfied with what I had, I used the finished piece as a guide for the other .5" piece.

Center Leg Unglued

The above picture is a good idea of what the pieces of the leg will look like once they are glued together. As of now, the leg is more that likely longer than what I need, but until I see how it fits into R2 and how I will secure it, I don't want to cut it. You can always makes things shorter, a little more difficult making it longer though.

Books

On Sat I received two books from Amazon which hopefully will fill in some of the knowledge gaps I'm missing in this project. They are "Robot Builder's Bonanza" 4th Edition by Gordon McComb and "Robot Building for Beginners" 2nd Edition by David Cook. Lots of bedtime reading there.

Center Ankle/Foot

Not a lot of posts this week but I have been busy working on the center leg/ankle and the center foot for my R2. First the center foot. I decided that the center foot would be made out of styrene so following a design of a fellow builder I printed out the plans and went to work. After 3 or 4 nights of cutting I have a blisters on my hands and all but 1 or 2 small parts for the center foot done.

Center Foot Styrene Parts

I started gluing some parts together and that proved to be a little troublesome finding a glue that would work. Using some scrap pieces of styrene, I tried several different glues to see which would hold the best. I started with Loctite Superglue and Testors model glue and neither would hold at all. After that I moved to a hot glue gun and that held but the glue was too thick and even after clamping it seemed to show a gap in the pieces. Next, I tried plumbers PVC cement and that seemed to work but was a little messy to work with. Finally, I found some JB Weld epoxy and that seemed to do the job well.

Center Foot Channel

I started gluing some parts together and was able to build the channel which will eventually connect the foot to the ankle. The pencil in the picture was to ensure that the holes lined up while gluing. And this is where the foot work ended this week.

I also started work on the main part of center leg and ankle. The leg itself will consist of 2 pieces of .5" plywood sandwiched between 2 pieces of .75" plywood. There isn't really much to show you for that particular piece because all I did was cut the wood to length and make some measurements. However I do have pictures of the work I've done for the ankle. I read some blogs and posts at the astromech.net forum and found that one member used a PVC pipe to make his own ankles and decided that I could do the same. After all, you get much more satisfaction out of a part you've built yourself rather than one you've bought (although the parts you can buy do look great). Anyway, after much searching and a very helpful Lowes employee I was able to find the PVC pipe that he had used. It was a 2 ft long drainage pipe that had a diameter slightly larger than what the prints called for (6.2" d vs 6" d) but decided it was close enough for what I was doing. Once I got it home, I needed to figure out how to cut it. The part itself only calls for a small arc from the pipe so I would need to make 2 cuts the length of the pipe to get the arc that I needed. In order to make the cuts as straight as possible I screwed a piece of wood to the side of the pipe to run along the fence of my table saw.

PVC Arc Jig

I measured, cut and after much trial and error, I was finally able to get the arc piece to the correct size.

Ankle Arc

Once I was satisfied it was correct, I cut the arc to the 4" length.

Ankle Arcs cut to 4" lengths

Only 2 are needed for a single center ankle on a droid so I have 2 more for the next droid :-)
The next step will be interesting in that I need to cut an angle into the arcs but that is a task for another day. Hopefully, I can find some time to work on both the foot and ankle this week. It would be nice to be able to scratch another part off the list.

Wooden Frame (2)

This past weekend I was able to get in the garage and make the necessary cuts for the top ring of my Senna Frame. With everything to be cut away already laid out it was just a matter of setting the router to the correct depth and taking my time. 

Top Ring after routing

I was satisfied with the end results. Here is a pic of the top ring with the rest of the frame.

Senna Frame with top ring

It looked pretty good but I am having problems with the two upper quarter ring pieces on the front of the frame. They are causing some serious stress and buckling and and won't allow the frame to come together nicely. I'm not too worried about that though. I can do one of two things to correct that: 1) adjust the notches so the stress is reduced or 2) remeasure and cut out two new quarter rings. I will try #1 first and if that doesn't go too well then I will find some scraps that I kept and recut the pieces. Tasks for another day.

 

Wooden Frame

A couple of weeks ago I started to make the 2nd frame for my R2. The first frame I made was based on some JAG blueprints that I had found.

My First Frame

It turned out nice for a first attempt but it had some deficiencies and I was ok with that. Then when one of my cats peed on the skirt and the rest of the frame had an untimely accident, I decided I would try my hand at the Senna Frame. I followed the prints to the best of my ability and ended up with some nice results.

Senna Frame (Unfinished)

I ended up having enough wood left over when planning the frame that I went right ahead and decided to see if I could get a second set out of the wood. I didn't have enough to make a complete second frame but I was able to get an extra .75" ring, .5" ring, and a complete set of uprights with 2 left over. I cut all the uprights at the same time to ensure that I had uniform cuts but left the rings alone. I figured I would wait and see how I did with the first set and if I needed to replace one I had the extra to cut as needed. Always nice to have extras. Anyway this leads us to where I stand today, The bottom ring had a rough cut center hole and I needed to clean it up. I decided to use my router with a trim bit and follow a guide to make a nice clean cut.

Bottom Ring with rough cut center

Bottom Ring after cut

In retrospect it would have been better if I had just used a jigsaw because the guide I was using for the trim bit moved when I was trimming the left side. I noticed it a bit too late. The cut looks bad but it isn't a big deal because it's hidden inside the R2. Lesson learned on this one.

After finishing the trimming I moved on to the top ring. This piece I had done no work on so I spent most of my time determining where I need to cut. I used the dimensions on the plans and then checked them against the bottom ring and everything lined up pretty close.

Upper Ring cut lines drawn out

Next step is to use the router and do some cutting. That however will be for another day.