The piece no longer fits properly, and the spray arm fails to spin and rinse the dishes in the upper shelf.

Disassembling the arm was very easy. The problem was getting the replacement part from Frigidaire. We tried several times, got the wrong part once, and ended up with an utter failure. I’m sure a repairman would have been more successful, but given how simple this repair is, why should I have to pay for that? This is where the MakerBot at CrashSpace comes in to the story.

CrashSpace has a MakerBot. This was a good excuse for me to learn how to use it to create a replacement part. The MarkerBot is a 3D extrusion printer. Above the red platform you see in the picture on the left is the extruder. It heats a thin strand of ABS plastic and extrudes it on to the red platform. The platform moves left to right and back to front until the plastic creates the first layer of the piece you’re trying to make. The extruder then moves up a small amount and the process is repeated until the entire piece is created.

ABS plastic is extremely strong and comes in a variety of colors. We have black, white, and red material at CrashSpace. LEGOs are made out of ABS plastic so you know how strong they are. The MakerBot  had no problem making a replacement part for my DishWasher.

These are the $7 digital calipers that I bought from Harbor Freight. They allowed me to measure the part so that I could model it. They can be set to millimeters or inches. Millimeters worked very well for several reasons. First, the calipers show one decimal point, so that means I could get down to 1/10th of a millimeter. Second, the rest of the tool chain used for the MakerBot is referenced in millimeters, so there’s no additional scaling required. Finally, 1mm seems to be minimal feature size that is reasonably handled by the MakerBot. It can move in smaller increments, but it’s very tricky to do anything smaller.

The dishwasher piece is pretty simple. It is really three cylinders with a cylindrical core cut out of the middle. There’s also two little “antennae”  at the top. I looked at how the piece fit in the dishwasher and it seemed that I could leave the antennae off. I made my drawing solid all the way up, and thought that I could always cut away the extra material to make the antennae if they were necessary. I also noticed that on the original part the largest cylinder was really thin. That’s why it wore out so easily, but given the way it fit in the other pieces it could be as large as I wanted. I made it 2mm thick, which should make it hold up much better.

This is my final model in Blender. Blender has a rather steep learning curve, so I won’t go in to much detail here. I’m putting together a Blender for MakerBot class that I’ll give at CrashSpace in the near future. The short description is that I created 3 mesh cylinders with the required sizes. I used the transform tool to enter the precise location of each piece. Next I joined them together in to a single object. Then I created a fourth cylinder that match the hole in the middle of the cylinder and used a technique called constructive solid geometry to subtract the cylinder from the piece. That leaves the picture to the left. That file is saved for Blender and as an STL file which we’ll feed in to the MakerBot software.

This is an image from the ReplicatorG software. On the left hand side you see the model. It has generated the g-code, which are the instructions that control the motions of the MakerBot. On the right hand side you see the path that the print head will take as it creates the part.

Once I created the part and made sure it looked like what I expected, it was time to head over to CrashSpace and connect my laptop up to the MakerBot. It takes a few minutes to connect everything up, let the extruder warm up, and position the head to the starting point. Once I pressed the build button the printing itself took about 5 minutes. I printed a couple just in case.

This is the final part. I forgot to include something for scale in the picture, but it’s about the size of a quarter. You can see the ridges from the bead of plastic. The plastic can easily be sanded if needed.

Another thing to note is that the original part has quite thin walls, but my piece is solid. That should make it stiffer and hold up much better with use.

These are the three pieces that make up the entire assembly. The new piece is placed inside the cog shaped piece at the top. The thinest cylinder fits through the hole and the widest cylinder fills the inside area, preventing the piece from dropping through the hole. Finally the arm is press fit on to the thing protruding thin cylinder.

When the dishwasher is turned on water will flow in to the center region of the cog, through the center of the piece, and finally out the arm. The arm has holes in the ends that push the water out the side as well, which causes the arm to turn.

The thin cylinder needed to be the right size so that the arm would press fit on to it, and still rotate smoothly. I measure carefully, but I also suspect the ridges on the side of the part helped make it fit nicely.

This image shows the pieces fully assembled. The black piece is hidden away in the middle where you can’t see it. The arm swings smoothly. The cog piece screws in to a fitting in the top of the dishwasher.

We made a few test runs and it seems to be working great. I think my version will hold up much longer than the original one.

I’d like to leave you with a few final comments on the process as a whole. It would have been cheaper (if you include my time) and easier to call a repairman. The hardest part was dealing with Blender to make the model. Blender has a rather steep learning curve, and it took me quite a while to get a hang of it.

With all that, I learned a lot in the process. I learned how my dishwasher works, how to use Blender, how to use the MakerBot, and even something about how modern equipment is created. So while this piece cost me more in time and effort, I think I can do my next project substantially faster. If you just want to print objects that already exist in Thingiverse, then you’d skip most of the hard parts.

There were several things I found interesting about the Merry Go Round. First is that it’s $2.00 to ride and you can get a jumbo beef dog and a large drink for $3.75. That’s pretty great value for your family entertainment dollar!

When we first showed up they had the speed cranked up pretty fast. Later when there were more small children it was slower. I suspect the operator can control the speed.

It’s clear that restoration is in progress. There’s a mix of worn and newly painted pieces. Both of beautiful in their own way.

Some of the senes depicted seemed sort of odd. Some sort of elves chasing fairies and tigers killing deer for example.

You can see the pictures we took in the album.

We also hiked up the hill and down again to end up at the old zoo. The old zoo was built and 1913 and closed in 1965 to be later replaced by the current Zoo. They’ve since turned several of the exhibits in to cook out areas. You can also make your way around back and see some of the sections behind the scenes. Much of it has been vandalized, but it was interesting to see. We didn’t get many good pictures, but I found another site that did.

Overall a really nice day trip out on the motorcycle.

This is the trailer for a reality program called Tiger Team which is going to be airing on CourtTV (which, by the way, will be renaming themselves TruTV in January).

It’s a reality show where they follow a company that does security penetration testing. You contract with them to break in to your facility. They give you a 30 day window in which they are going to attempt the break in, but they don’t tell you when and the don’t want you to warn anyone. During the break in they take/create some proof that they performed the task, and afterward they report back on what they did and how you could improve your security.

Having done some penetration testing in the past, security is still a hobby of mine. I found the show quite interesting. The first episode dealt with breaking in to a high end car dealership and the second episode dealt with breaking in to a high end jeweler. The approaches they took in the two episodes were very reasonable. In fact, they handled them pretty exactly as I would have, but they are much more practiced and have at least one trick I didn’t know about. The level of detail on the show was actually very good. You could follow along with that they were doing. They also didn’t sensationalize it to much.

How real is it? We’ll never know how much was set up by the producers, but my opinion is that it was mostly unscripted. In fact, they described the difficulty of getting the camera man to follow in their path without triggering the the motion detector, and that they had passed on some less safe alternatives for entry.

Someone on another blog mentioned that they were surprised they didn’t include a “kids don’t try this at home” message. I’ll say that here. Kids don’t try this at home. These guys are professionals. If these guys get caught by the police I’m sure they can pull out a letter from the owner saying that it was authorized. If you try this on your own, you’ll like get thrown in jail, hurt, or killed.

My final thoughts from the show:

• Security is only as good as the weakest link. So pay attention to ways people can go around your security.
• Security is inconvenient, more security is more inconvenient. The more security you add the better protected you are, but if you go too hard it becomes so inconvenient you can’t get your job down. (And people will work around that defeating your security.
• There is no such thing as totally secure. (follow on to the previous item)
• It’s a good thing criminals are generally dumb. The techniques used in this show really aren’t that hard. Hopefully criminals won’t get better at doing them by watching it.

We got our groove on Saturday night at Harvelle’s in Redondo Beach with grammy award winning blue artist John Lee Hooker Jr. This was the end of the promotional tour for his latest albumn, Cold as Ice. He puts on a great high energy show. He did a mix a classic blues, some boogaloo, and some funk. He had a couple tribute pieces to his father, but he really stands on his own.

This was my first time to Harvelle’s in Redondo. I’d been to the one in Santa Monica several times. Harvelles Redondo has got to be four times bigger than Santa Monica, but it still has an intimate feel. There are plenty of booths and tables where you can sit down, plus a good sized dance floor. You enter on the ground floor at the pier and then decend a staircase to enter Harvelles.

I was surprised that the place was so empty. Of course, it was the weekend before Christmas, so maybe that explains it. There couldn’t have been 50 people there. So it was just like a private show. Our friend Chris took the photo I linked above. Linda and I got out on the dance floor a couple times. She also got to dance with Chris and a couple other people there.
I had a great time. If you get the chance to see John Lee Hooker Jr, you should take it. It was well worth it. I’m going to keep an eye out for more events at Harvelles at Redondo. It’s got the right vibe.