Rotozip shreds 1/8" acrylic

More experiments in cutting circles with Acrylic. For the first time, I pulled out some of the 1/8" acrylic and decided to experiment on that. What a difference. It shatters very easily. Even drilling holes. Using the rotozip with this leaves very jagged edges and totally unusuable. Maybe I went too fast with the rotozip. Regardless, I'm putting the rotozip away for awhile.

Next I drew a circle on a piece of 1/4" acrylic and used the band saw to cut them. The circle actually came out pretty good. I then used the band saw to experiment with on the 1/8" and it also came out well. I created a crude hole cutting jig for the bandsaw and it cut a perfect circle. Hmmmm It looks like I need to build a quality hole cutting jig for the bandsaw. There's no other way. But I'll have to cut the inside holes with either the rotozip or a scroll or jig saw since you can't do that with a band saw. I'll probably spend all weekend building the jig. My wife and son are out of town for a week so I'll have plenty of time to build.

Also I noticed Lowes sold acrylic and lexan. Not cheap but they have it.

Microphone

Painted the microphone I made out of the home depot knob. Also did some sanding of a few miscellaneous pieces. Tried to figure out the best way to create the ankle hinges and attach them to the knee plates.

A new bandsaw !

Saturday wasn't as productive as I had hoped and actually quite frustrating so I'm taking it easy today and will just straighten up the workshop to get ready for bringing Brad's RoboCop car over. Later in the day I built my microphone out of the home depot knob and it came out great. I also sanded the neck pieces I made and filled some flaws. I also worked the resin torso hooks.

Bought a band saw today and will work with that more. I wish I would have bought a band saw in the beginning instead of the scroll saw I got. The price of these power tools are ridiculously reasonable.

I'm going to take some time off from the acrylic until I build my own circle cutter. One that works.

More going in circles

Acrylic circle cutting II
Today I made some wooden circular platforms that I could screw the acrylic to and clamp to a bench. This made a very stable place to cut my acrylic and supported it from the bottom. I countersunk the screws so they wouldn't interfere with my circle cutter.

Despite having this new cutting platform, I still can't cut acrylic circles with any accuracy to save my life. The circle cutting tools I have stink. My one rotozip circle cutting attachment works ok up to 12" but I have a few circles that are 13" and 15". But even under 12" I found out that I didn't compensate for the size of the cut and was about 1/4"-1/12" off on all my circles and I was very disappointed. Wasted more acrylic.

Tried using that circle cutter 2 generic cutter and it's pure garbage. As you pull the rotozip, the tool opens a little more so the circle expands. You can't tighten down the tool enough. JUNK JUNK JUNK. Too bad because this tool is the size I need.

Jawa is born

Did more work on the Jawa. Added body and hands but the hands are temporary. This is another good example of my extreme A.D.D. (Attention deficit disorder) kicking in.

Robots/droids and Jawas go together

Today was another example of having to do everything twice. I cut out all my acrylic circles for the collar and was not happy with the results. It was ok but not as perfect as I want it to be. The collar is an important piece and can't be screwed up. So my only alternative is to keep working on it until I perfect the art of cutting circles in acrylic.

My methods needed improving so I asked on the B9 builders forum for tips. A lot of good information was offered and I should have better luck my next round. Instead of clamping the acrylic to a table, I'm going to support it with a piece of round wood underneath the cut and try to do one continuous circle without hesitations. The repositioning and moving of the rotozip is part of the problem. Plus I have a crappy circle cutting attachment that I need to return.

Ribs and resins

I neglected this journal last week so I'll summarize the events of the last week.

I created all the vent ribs and spars and created an extra set for Brad since he needed vents. I also did a lot of resin work and used the TASK4 resin in addition to the 321 resin. TASK4 was different and seemed stronger but it took 16 hours to demold as opposed to 30 minutes. They both have their pluses and minuses. They both need to be sanded and a lot of finish work will be required to make them look good.

Since I was unable to get a response from the B9 supplier of the neck bracket and brain cup, I made a set of molds and cast some resin pieces. It was difficult drilling them out correctly but I finally got some acceptable results. I had to use a hole saw, various drill bits, my drill press, the dremel and my rotozip. Oh and lots of sandpaper and filler. I'm not sure how a resin piece will hold up once I add Scott's cam to make the finger lights move but what I now have is better than nothing.

I didn't get much else done on the robot last weekend because I got a 60's coke machine from a friend and had to rebuild some shelves in the garage. Most of the wheels for Brad and I are done casting. Just need a bunch of the small outer wheels and will be done.

How do you spell disaster - R. U. S. H.

Here's a summary of events in the dramatic sense. Used smoothon 321 urethane.

Right after I got home from work my wife went to pick up some dinner because she wasn't in the mood to cook. So I figured I had a good half hour. Just enough time to mix up some urethane and set up a few wheels. So she gets in the car, takes off and I hustle off to the garage, grab the urethane and start mixing up a batch. Everything looks good. I had the molds all ready and this just was too easy. So I pour the urethane into the molds and stand back like a fool admiring his work. Then it hits me. Panic !!!!!!! Fool !!!! You skipped the mold release spraying part !!!!!

Now it starts looking like a "I Love Lucy show" as I pour the urethane back into the bucket from the molds. Then I drain the molds on a towel by tipping the molds upside down. In a panic, I grab some other molds I had waiting and quickly spray mold release into them. Sloppy and quick .... Not to mention all the urethane that slopped out the side when I picked up the molds to pour them back into the bucket. I of course had the urethane up to the lip. What a mess !!! Plus I didn't have rubber gloves so I'm getting this stuff all over my hands and it's hot. It just keeps getting worse. I quickly pour the urethane back into the other molds and had a lot left over but no time to dump it. I then grab a pack of paper towels and start wiping the slop out of the molds that I didn't have any mold release in. By this time it was the consistency of snot. And it's all over me !!!! I was able to get most of the stuff wiped out of the molds but not everything. I fear those may be ruined. I can always make more but ... Then I rush to the bathroom to clean the formulating snot like substance off my hands. Everything is in chaos as my wife pulls up to the garage with our food. She walks in as I'm staring at the hardened mess of urethane in the bottom of my good bucket that I never did get to dispose of properly. Plus the mess on the table. She shakes her head and walks into the house with our food.

I finally pull the wheels out of the molds and they are all bubbly. They actually came out ok other than the all the bubbles in the urethane. I must have done something else wrong too. Maybe pouring it out of the rubber mold and back into the bucket did that. The stuff gets hot. I guess this is how you learn stuff.

After dinner I slowed down and after cleaning up the mess, tried again with much better results. However the pieces I really wanted (Brain cup and neck bracket) didn't come out very well. I may need to create better molds. The 2nd batch of wheels came out fine though. Some bubbles but not as many. This time we did them indoors because the humidity is one of the reasons for bubbles.

Collar rib day

Created a few more rubber molds of Brad's brain cup and neck bracket. In 16 hours they should be dry.

Today is collar day. My dad came over and we spent the day forming collar ribs. It's time consuming and a lot of fun. The trick is to not rely on a timer but to make sure the acrylic is flexible enough. I used a toaster over set at 300 degrees and left them in about 4 minutes. We ended up redoing a lot of them but I think in the beginning we didn't leave them in the jig long enough until they cooled into the correct shape. After doing all the collar ribs, I trimmed them and then formed the vent ribs.

Final tread belt work

AM - Slit one of the 2" pieces of tread down the middle with a razor blade and then trimmed the loose pieces of foam. Then I put on two coats of caulk in the freshly cut areas. That should be the end of caulking ... FINALLY.

After putting a few coats of plasti-kote on the treads I realized I should have caulked BEFORE attaching the square treads to the belts. They just look barely acceptable. It's beginning to feel like I need to redo everything on my robot at least one time.

Making rubber molds

After adding more coats of caulk to the treads, I decided to try my hand at creating a rubber mold. I used the trial containers of rubber from smooth-on thinking that would be enough rubber. I prepared the item I was going to make a mold out of, sprayed the release agent on and mixed the two part rubber. Brad at Smooth on said to make sure you thoroughly mix each part separately and then mix them together thoroughly. After doing that, I poured the rubber into my frame (a rubber tupperware container) and was disappointed to see that I mis-judged the amount of rubber that it would take. After pouring, it was about 1/2 inch short so I quickly set up two smaller molds I had prepared and poured the rubber out of the first mold into the smaller two. Pretty messy cleanup but it was interesting. Now I wait 16 hours to see how the rubber mold formed.

I sprayed one of the treads with a coat of plasti-kote and have to say the results are not what I expected. It's ok but not the quality I had hoped for.

I went to Kinkos tonight with a copy of the collar PDF and they printed a full sized template that I can use to align my collar ribs. This is so much more accurate than trying to tape individual 8" x 11" pieces of paper together. I tried that and the kinkos plan is much better. They only charge $4.50 for a 24" x 36" printout. If you don't live next to a kinkos, you can print it online and have them mail it to you.

UPS brought my urethane 321 from Smooth-on tonight.

Garage sale B9 parts arrive

Just added more coats of calk to the treads. Ycccch.

Today a package from Scott Sanderson arrived with my garage sale specials. The brain, knee hinges and crown. I also purchased a brain cam from Scott. I prefer to get a bargain like this and restore the parts to like new instead of buying everything ready to go

Redoing tread belts - messy caulking

Today I redid the treads we did last weekend. I used a papercutter to cut the 1" rubber pieces out of the armaflex tape and they came out much smoother and more consistent than using a knife or scissors. I used the botched tread section as a guide where to attach the treads and they went on easily. I spaced them out a tad more than 1/4" to make it easier to lay in the caulk.

The caulking job was a mess and the worst task so far. On first tread strip I took my time and tried to keep it neat. That wasn't a good idea because the caulk dries quickly before I was able to straighten it out. And no matter how careful I was, it was a messy job. It was a lot of work but it still turned out ok. On the next 2 treads I took a different approach. I quickly slopped all the treads up with a lot of caulk and then used a wet sponge (with bucket of water nearby) and towels to immediately smooth it out. Although this was a tremendous mess, the final result were a lot better. They will definately need at least one or two more coats of caulk because that armaflex tape is like a sponge.

Robot in the studio

Today I brought the B9 indoors and set it up in my green screen studio. Also screwed in the small lights and chest lights. After the arms went in, it really looked like the B9 robot. Now I just need to finish the treads and build that collar.

I called smooth-on today and told them about the wrong materials they accidentally sent me. They're sending me a gallon of the correct urethane today at no charge. That made my day ! They are a good company to work with