
Mark Cohen purchases a Relay Board kit in the Botcave vending machine
Mark Cohen has been a financial programmer for about 25 years, and is currently a developer for a hedgefund (also developing applications for the iPad and Android). The MAKEzine article featuring MakerBot last year drew his attention to 3D printing: four cupcakes later, he is still going strong.
Mark’s son Elliot is a student at Stuyvesant High School in NYC. The two of them often work together on printing projects — the son draws objects in 3DSMAX or Google Sketchup and then exports them to STL files for Mark to print. It was through working with his son’s high school and FIRST Robotics Competition robotics teams that Mark first became interested in CNC. Now, the two of them print out objects with Mark’s MakerBots to replace broken items around the house, and prototype science projects.
When he and his son aren’t printing together, Mark has tuned his bots for a unique print-on-demand service. It turns out that in order to build a self-replicating RepRap printer, you need a reliable 3D printer to print your first set of parts. While Mark himself hasn’t needed a Mendel printer, he has been happy to comply with his customers desires: printing these parts and selling them on eBay, he has earned back the entire cost of his favorite hobby.
One of his four cupcakes is a successful print of Webca’s 3D-Printed Full Sized MakerBot. “It took me a full week to print, and another two weeks to put it together, but it prints!”
For those who wish to print a MakerBot, he recommends taking the time to print duplicates of parts, and then following the following finishing tricks to make sure your parts will work. Apply liquid cement. After the parts dry, sand them down until surfaces are smooth. Paint acetone over the parts with a paintbrush to seal the surface, and then tune up every slot and bolt hole with a file in case any need attention. Mark tested the complete fit of his kit before adding any hardware. Result? Successful replication!

Mark’s approach to settings is unusually simple: he uses almost exclusively Black ABS and performs only minimal calibration beyond out-of-the-box MakerBot settings. In fact, he restricts almost all of his attention to travel rate and feedrate adjustments. He builds each of his bots the same way: when he finds a tweak to positioning that works, he sticks with it. His advice for those building a kit for the first time: slow down, take the build in stages, pay particular attention to the extruder.
The first two weeks I was very angry with my bot — couldn’t get anything to print, and my MK4 print head exploded. But I kept reading the Forums and tried different solutions I found there.
Below the fold, we perform the traditional MakerBot Operators MicroInterview.
Read the rest of this entry »