Recent Work and Overheard

So, the other day Courtney and I drove down to Kent cause I got a hot tip on some powdered red jewelers rouge at Jerry’s Rock and Gem. We went in and it was pretty clear from the start that by gem they mean “Crazy people crystals”. This was confirmed when while standing in line I heard the lady next to me (dealing with another clerk) say “Well, you know, if the¬†cataclysm¬†comes I hope you have 4 or 5 big trucks to get all of this stuff to higher ground.”

She said it in hushed tones and you could tell she was just dead serious.

That being said, Jerry’s was pretty cool. They did have the rouge I needed (more about that later) and they had a great selection of tumbling supplies, petrified wood sculptures, all kinds of interesting minerals and all kinds of rock and gem related stuff. Neat place.

So, since my last post about my clock I’ve been working on my clock and one other thing. For the clock, I decided I would make 5 total, complete clocks and then be done with it forever. The clock has a lot of parts to make a single enclosure so I spent some time trying to speed up the process of making some of the parts.

One of the components of the clock is these tiny 1/4″ polished aluminum rings. I made the first 8 for the original clock by hand but it took forever and was very difficult. I cut the little pieces of my bandsaw and then bored them out on my drill press but the parts are so small it was difficult to get them in a vise without ruining them.

So, what I did this time is I made a “ghetto lathe”. I took a piece of 1/2″ aluminum plate, drilled a 1/4″ hole and a few 10/32 tapped holes and then a 10/32 tapped hole in the side to intersect with the 1/4″ hole. Into the 1/4″ hole went a stubby 1/4″ drill and I put a set screw in the side to hold it. In one of the tapped holes I put a lathe tool post and a lathe cut-off tool. Then I put my polished tube stock in the chuck of my mill and wrote a program. The program would push the spinning stock down on the drill to bore it out and then run it against the cut-off tool to cut off a perfectly sized ring. This worked perfectly! I made the 40 rings I needed in just a few hours. There’s a video of the process below.

The next thing to do was to make the 40 metal plates that make up the body of the clock. Each clock uses pairs of 4 different shapes for 8 pieces each. I made a little fixture out of MDF on my mill and cut these all out in the course of one long Saturday. Nothing special there.

The special part was that I did not want to hand sand all of those parts, so I went to Harbor Freight and picked up a 18 lb vibratory tumbler for the low, low price of $149 and set to learning how to use it. I got some plastic triangle media from a local friend and threw in my parts in batches of 10 for about 6 hours each. This put a nice matte finish on the parts, rounded all the corners and removes burrs, which was great! After that I used walnet shell media with the aforementioned red rouge to polish the endcap pieces as these will be anodized. I let those run for about 36 hours and they came out very nice. A few steps from a “mirror” finish.

Now I am at the anodizing stage. I’ve done a lot of reading and I feel like I will try doing it myself. I picked up a bunch of plastic buckets at one of my nearly daily Lowes trips the other day, got some lye yesterday, got 5 gallons of sulphuric acid today and need to pick up a few more supplies tonight. I’ll probably wait till the weekend to give it a try and assuming I have some success I’ll write a post about how that works.

My next project, and the one I expect to consume me for the rest of this year and maybe longer is OpenPnP. I decided that I would like to own a small pick and place machine for doing PCB assembly but I don’t like the $30,000+ price tags. I figure this is something that would be fun to build and maybe in the mean time I can revolutionize home PCB manufacturing! My hope, and goal, is to design and build a fully functional pick and place machine that that can reproduced for around $1,000. I will make all the designs and software open source and maybe, if there’s interest, produce some kits or something.

OpenPnP is still in it’s very beginning stages. So far I have bought a few basic parts and I’ve been making some parts on my mill. My goal for this month is to have a working, high precision 2 axis “cartesian” platform and to be working on adding motion control. My target is to get a basic 2 axis CNC made so that I can start working on the head design, which is where all the hard work is going to be. The CNC doesn’t need to be complex, but it needs to be precise and fast. To that end I am using THK linear guides for X and I am considering Hiwin linear guides for Y. I bought the THK guides off eBay to get started but will probably spec Hiwin for both axes in the final version.

So, that’s what’s new. I’ll be posting quite a bit about OpenPnP over the next several months. Now that I have officially announced the project I intend to document my progress as much as possible.

In the mean time, if you are interested in OpenPnP please go to it’s homepage and read what I have there. I am currently interested in talking to people who have experience with computer vision systems as I expect that to be a very difficult part of the system.

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