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Showing posts from December, 2012

Moving code from ESP8266 to ESP32

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A while ago I made a mashup of Dan Royer's code CNC 2 Axis Demo with my own code for trapezoidal motion stepper and servo control for ESP8266.

I assumed porting the code to the ESP32 would be trivial, and that was true for the most part: changes like library name being Wifi.h instead of Wifi8266.h were not a problem. UDP now does not like multicharacter writes but you can use print instead. So far so good.

However, when it came to the interrupt code I was stuck with the stepper interrupt causing an exception sometimes. And to make things weirder, the servo interrupt worked flawlessly (both of them had the IRAM_ATTR directive if you ask me).

Going little by little, I could narrow down the culprit to a floating point operation during the interrupt, that would cause problems sometimes but not always. Browsing around I found this post. Where the solution was simple: do not use floats within the interrupt routines but doubles. The reason was the float calculation would be performed by…

On extrusions speeds

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I have been losing a fight with my latest extuder/hotend combination. It works ok as far as I do not want it to work too fast. I want to keep the PG35L motor not too hot or it will break. So I am powering at 500mA, which seems to be well beyond its maximum rated current, so it gets hot. But I've added a passive cooler to it so won't get dangerously hot. Should I used a higher current, as someone suggested, maybe my mileage might vary, but at the expense of needing a fan blowing directly to keep the motor from frying itself.

One of the things that was bothering me was the maximum printing speed I could use with this new setup on my Prusa i3. Extrusion speed on Pronterface software (the host I use) is user selectable but measured in millimeters per minute, while travel speed is usually configured in the slicing software in millimeters per second. But doing the apparently simple math of dividing by 60 will not help here, among other things because the extrusion speed is the 3mm …

Building a Prusa i3

I am very happy with the Prusa I built, and so I am with the Printrbot, which much smaller but it does a nice job too. In fact, most of the parts (on different shades of blue) of my new Prusa i3 have been printed with the Printrbot, but the black ones, which are ABS parts, have been printed with my Prusa.

Having two working 3D printers seems to leave you in a difficult position to explain your wife why in hell you're building yet another one, but somehow I managed. I was curious to learn how this new version from Josef Prusa would do compared to what I was familiar with.

I've done a short picture album of the process with some comments in them whenever something different or creative was done there.


My first impressions are that this printer can work really fast and it seems very stable at high speeds. It feels much sturdier than the previous Prusa's and more stable than Printrbot. To its advantage has the reduced mass of the new compact extruder which I have not mastered …