Design First, Measure Second

11 March 2022

My objects repository is full of OpenSCAD code. At the top of each file you’ll find a collection of variables in the code: the measurements of the model.

We don’t need to get bogged down with those exact values to start modeling, but we know that we’ll want to identify certain parameters to size our models. We can start banging together some shapes (with union and difference), and any time we’re tempted to guess at a measurement and plug it into the code, we want to first see if we can give it a name (a variable name, that is) and use that instead and define a rough value for that variable at the top of the file. Next we can think about that value and decide if it’s related to any other values we already have. Often, one value should be calculated relative to other values: overall_width = inside_width + 2 * side_thickness. Once a measurement is defined in terms of other values it’ll automatically update as we start providing more precise measurements.

By starting with some guessed values and later plugging in real measurements, we prove that our parametric model is being correctly calculated from the measurements. We should be able to use this code time and time again to generate variations on the model based on new measurements. Our SCAD model with all the parameters at the top is ready to upload to Thingiverse and the Customizer can let users easily provide their own measurements to generate new models from our code.

ADVi3++ 4

26 August 2020

I had a bit of downtime with my Monoprice Maker Select Plus 3D printer, so I decided it was time to upgrade the custom firmware, ADVi3++ 3.0.x, to the newer 4.0.6.

I’ve done the upgrade previously to get the 3.x firmware in the first place, so I knew I needed to upgrade in 2 steps: the LCD via a microSD card and the main board via Cura over USB.

I dug through the manuals and directions a bit, and decided I could copy the contents of the raw zip onto a formatted SD card instead of writing the img file to the raw SD device with dd. That fit on a handy 2GiB card. I took the couple screws out of the front panel, inserted the micro SD card, powered it up, and watched the LCD display all the new images it was loading. When it’s done, I turned it off, and replaced the screws.

Then I could easily connect the printer to the Linux laptop via USB, and upload the custom firmware hex file from Cura’s Manage Printers screen. I did need to take a moment to add my user to the dialout group to get access to the USB ports for serial communication to the printer.

Upon reboot, the printer wiped out the old incompatible settings, and I rebooted it again to see the new startup screen and version numbers. I ran through some tunings: PID and extruder, and kicked off a test print that went fine.

I currently have the thermal protection enabled, and I’m hoping it’s not too sensitive, and I can keep it turned on. I expect this upgrade will hold for a long time until I see 5.0 available, and it’s had some time to settle.

2018-03-12 Sanding Stick Fix

12 March 2018

The sanding stick needed a little adjustment to be assembled successfully.

2018-03-11 Sanding Stick

11 March 2018

I finally modeled a sanding stick for small sandpaper belts I bought a year ago to kickstart the project.

All the Posts

March 2022

August 2020

March 2018

February 2018

January 2018

February 2016