Category | Components

Hi rock stars, Many thanks to the thoughtful, smart suggestions in Name that component!, from Kyle, David, AdamT, Kyle@otyp, and Ben. All together, we worked through the panini/linkage idea, browsed camera shops to find ball joints, and really set out to get the best design that's easy to build. That said, it can be impossible to find off the shelf parts to bring a new design to reality. More specifically, I'll say that my current source for searching (McMasterCarr) has lots of really *big* things, lots of door hinges or refrigerator hinges, but not so much in the *small* side of things. Is there...

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Update: 9/25/2010 to http://openpcr.org/2010/07/treat-your-machine-shop-professionally/ Good comment from mo - spread the love around. I want to point out that the relationship with your machine/PCB/acrylic/wood shop can be challenging! It's important but not necessarily easy! If you can't meet in person it's tougher to build repertoire over email or telephone, no matter how charismatic you are. And though I'm usually close to my email, people in shops are on tools and machines most of the time. A phone call is a lot quicker and more personal, but conversations on the phone often lead to miscommunications...

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Welcome to an exciting round of "name that component". Here's your host, Tito! Hi everybody, We are working to design our heated lid so that it can adjust to small differences in the size or height of tubes. In PCR, we're cycling the temperature of a small aluminum block between 50C and 100C. We place a plastic tube in each well of the aluminum block, which contains a liquid DNA sample. Now, if we simply have this setup, we will heat our samples to 100C and they will evaporate and condense in the lid of the tube. This is a problem, which is commonly solved by something called a "heated lid"....

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Another week zooms by! I've been working on sourcing for the aluminum heating block. One thing that's a bit elusive is finding shops to prototype the block out of 1100 aluminum. Most prototype shops stick to 6061, which is a strong material, but we want as high conductivity and low specific heat as we can (reasonably) get, and 1100 is the purest alloy of aluminum. The material itself is cheap but because it's a softer (I think) grade of aluminum, it takes more time to machine. CNC machine time adds up very quickly so Josh and I are both putting out requests for quotes to different shops. Chime...

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New cases arrived this week, acrylic and wood! Nodes rock! That is, when you design them correctly. Working with birch wood, I added 1 simple node on each of the notches for the lid parts. The parts "snap" together, and glue doesn't even seem necessary. With 1/4" acrylic, I used the exact same sized node as with the birch which didn't work out so well. Acrylic is a lot less flexible than wood. I ended up just sanding off the nodes on the acrylic parts to get them to fit together correctly. (I'll read up on what size nodes to use with acrylic, or comments are appreciated!) This was my first...

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If you think I'm making a lot of posts over the past week, it's true! I took 2 weeks off of my day job and have been able to get a lot done on OpenPCR. Back to my day job on Monday :\ We are prototyping 3 1/8" flat aluminum parts for OpenPCR: 1. ~ 2" square plate, with holes for 2 screws for the heated lid. Our prototype heated lid involves a peltier, aluminum plate, and thermal pad 2. ~ 4.25" square plate for mounting the heat sink and aluminum heat block to one surface. This needs holes for the aluminum block and screw holes for mounting the aluminum block and heat sink. 3. 4 cm square...

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This week I designed and sent off requests for new laser cut cases -- one wood sheet from Ponoko, and an acrylic sheet from Pololu. Material: One surprise for me -- I made a slightly bigger case, and adding on 1" to each dimension roughly doubles the material. For instance, take a 4" square, that's 16 square inches of material. A 5" square is 25 inches of material. This can get out of hand pretty quickly! Speed: On the recommendation of a friend, I browsed onto Pololu.com, which offers custom laser cutting services. Pololu doesn't have plywood or bamboo in stock, but they do have 1/4" acrylic...

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Just received the 2 test thermal pads in the mail from Digikey. BER165-ND is 3 mm thick and pliable. It runs about about $3.50 per OpenPCR (28 parts fit in a $94 sheet). 3M9601-ND is 2.5 mm thick and very soft, and about $1.20 per OpenPCR (25 parts fit on a $30 sheet) We'll want to test these out with our current heated lid to see that they work great and make it easy to maintain the temperature of samples. Once we receive the first set of aluminum and a new wooden case from Ponoko, we'll be able to test these out even better.

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All right, went and picked up the heatsinks at the UPS office last night. Broken them open while sitting in my car and made a couple quick judgments. Remember, my concerns are: 1. big enough surface area for the peltier 2. cost - $20 to $30 3. overall size and weight The MassCool, while bigger in all dimensions, just isn't big enough for the 4 cm square peltier. We would still need an aluminum plate adapter between the heat sink and the peltier. The Titan on the other hand has the perfect sized surface for the 4 cm square peltier. It's MASSIVE though. --- I'm designing a quick...

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Now that the heat sink is ordered, on to the heated lid. The lid is a major component of the OpenPCR machine. It eliminates the mineral oil that screws up experiments of newbies and professionals alike. More importantly, it's the one part of OpenPCR that you'll interact with *every* time you do PCR. It needs to be done right. As I've shared with a lot of you, our prototype lid is nichrome wire and silicone tape, sandwiched between two plates of aluminum in a wooden lid and it needs a lot of help. A few posts ago, Josh figured out that a peltier device + aluminum plate would fit the bill, and a custom...

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