Happy Wednesday Everyone!
First and foremost we’re excited to announce that all kickstarter kits have been packed and sent out! The only exception is for kits for which we don’t have a backer survey (because then we don’t have an address!), those will ship as soon as we have an address.
Now that we’re finishing up fulfilling the Kickstarter kits, we’re excited to be able to focus on supporting the community which leads us to our next two topics.
Router bits and replacement Arduino Shields available in the store, more replacement parts to come
We heard from the community that we need a good source for affordable router bits, and when we couldn’t find one we contacted a machine shop and had router bits made to our specifications. We also heard from the community that the Arduino shield is a part that people would like to purchase spares of so we’ve made those available also. You can buy router bits and spare arduino shields from our website at www.maslowcnc.com/store right now!
If you head over the forums at www.maslowcnc.com/forums you’ll notice that we’ve switched to a new forums system. We heard from the community that it was time to upgrade our forums as the community is quickly growing. The new system is based on Discourse.org, and open source system that gives us a lot more flexibility to expand as the community grows. If you haven’t already been to the forums, now would be a great time to head over and check them out!
Project of the week:
This week we’ve got a pretty big project of the week!
Our intentions with the Maslow project have always been for the machine to have a role in humanitarian work, and we’ve been given an opportunity to explore the machine’s humanitarian potential here in our home city of Portland Oregon. A group called The Center for Public Interest Design has been working with The City of Portland to construct villages of tiny houses to address the city’s housing crisis. The first village to open is the Kenton Womens Village which is aimed at providing a safe space for houseless women. We’re excited to be building an open source Maslow made tiny house (or POD as they are being called) to donate to the project. We will be working in partnership with SERA Architects, whose design was selected to be constructed from a group of 15 submissions. We are excited to work together.
The objective is to design and build an open source POD which can be rapidly and affordably replicated. We’re not trying to build an exclusively CNC structure. We’re going to use traditional building materials like 2x4s when it makes sense to do so. We want to use Maslow to make the critical cuts so that someone with limited building experience could realistically assemble the structure.
This will be our project of the week for the next six weeks or so, and each week we will be sharing how we used Maslow on some part of the project, what we learned along the way, and how we’ve used that information to improve Maslow.
This project pushes the limits of what Maslow can do in big ways. One of the big challenges of this project is that all the parts are aligned with tabs. Calibration (as I’m sure you know by now) has been an ongoing struggle for us, and this project forces us to be sure everything is precise and aligned. Even a small error will magnify over a ten foot span to become a significant issue, and that is exactly what we saw this week.
I was sure that I had my calibration dialed in. My straight lines were straight, my squares were square, but then something strange happened when everything went together. The tabs at the top aligned perfectly.
The tabs at the bottom aligned perfectly.
But in the middle the tabs were off by at least ¼ inch.
The problem repeated itself on each of the four edges, with the same tab in the same place being off. I was stumped. The only explanation I could think of was that while my squares were square and my straight lines were straight, things were somehow being stretched.
I tested the theory that long objects were getting stretched by cutting a 1 inch by 70 inch rectangle, and found that my rectangle was 1 inch by 70-1/4 inches.
To track down the what was happening I wrote a simulator which will let us see how distortions in the measurements of the machine will result in distortions to the parts cut. The simulator is available in this week’s version of Ground Control, you can play around with it yourself by clicking Actions -> Advanced -> Simulation.
The simulation lets you add a simulated error to each of the calibration measurements and then shows the correct grid in green, and the effect of the simulated error in red.
After a few minutes of playing around I found out that that if both the Motor Spacing measurement and the Motor Mount Spacing measurements are off by exactly the same amount, the type of stretching I was seeing occurs. I adjusted the measurements in my machine’s settings, and suddenly my 1 inch by 70 inch rectangle was suddenly actually 1 inch by 70 inches (at least to the best of my ability to measure). Hopefully in the near future, we’ll be able to integrate the things we learn from the simulator into an improved calibration process. Possibly a process which requires only a single set of strategic cuts and measurements instead of the current process of repeated cuts and measurements.
I haven't had a chance to do enough testing to say that the misaligned tab is completely solved, so expect an update on this issue and any other we run into next Wednesday.
We saw a big improvement to the firmware this week. For the last few weeks we’ve been seeing strange and difficult to replicate behavior where some of us were seeing behavior where the right motor would refuse to move entirely, while other saw jerky behavior and others had no issues whatsoever. The issue as it turned out had to do with the Arduino running out of ram, and the version of the Arduino program which was used to upload the firmware had an effect on if the issue would show up or not which explains why we saw the issue come up differently for everyone. We solved the issue by freeing up some memory, so don’t forget to grab version v0.81 of the firmware this week!
Have a great week everyone!
-Bar and Hannah