Last week I decided to get myself a hot air rework station for my growing interest in SMD components and general electronic engineering. And today it arrived! Let’s see what was in the box.
These first pictures is what you would expect, a box with some foam inside to keep the things safe.
But what I didn’t expect was to get 3 different sized, and insulated, tweezers, some tools for applying solder paste, and a little can of solder gel.
What I did expect was this, the rework station itself. It comes with the rest for the handle unmounted, and you can then put it on either side of the station. As default it is made to sit on the left side on the station, for right handed people, but since I am left handed, I have switched it over to the right side of the station. To switch it from one side to the other, you only need about 2 minutes and a philips screwdriver.
The first thing I decided to try, was to replace the resistor for the power led on the Cheap-O [SMD] endstop I made last week. The problem here was that the led was way too bright, it actually lit the whole room up when all light was out while being within the rated current. But with this rework station, it should be easy to try different resistors, and it was! Only problem here is that I might have been a bit hard on the two capacitors just above the resistors for the led’s. To prevent that from happening another time, I could have used kapton tape to shield it from the hot air, specially when just doing experiments. I tried 4 different resistors before I found one that made the brightness of the led look like something I wanted, so when looking at the minimal damage done, I am still pretty pleased with the result.
Next up I decided to bump it up a bit, and actually solder an entire board by reflowing it with the rework station.
Before using the rework station, I used my normal soldering iron and some 0.48mm solder to pre-tin all the pads with a thin layer of solder. After that I started the rework station and heated the pads up again for FET1, then placed the package on the pins and heated around it to make it settle in the hot solder. I repeated for FET2, then did the current limiting resistors followed by the pull-down resistors. After those I did the resistors for the led’s and then lastly the leds.
And here is the result. The components are not perfectly aligned with the pads as they would have been if I had used the right solder paste and did a proper reflow of the board, but let’s see if it will do the trick anyways!
After soldering the pinheaders on for connecting the board to the controller on my 3D printer, I used M42 to turn the pins on and off. SUCCESS!
The led’s came on and off for the pins I activated, so it looks like everything is as it should be, time to connect something!
I originally designed this board to handle extra fans on the printer, so why not just try that?
On the top of my hotend I got a little 25mm fan to cool the PEEK barrel of my hotend between the extruder and nozzle. (this is an old picture from when I still had my old extruder, click here to see my new extruder)
Since this is just for connecting low current items, the wires and connectors are just some small ones that are easy to work with, route wires for and easy to get hold of.
The connector to the right is the input, which is just connected directly to the power input from the power-supply, and the connector to the left is going to the fan on the hotend.
To control the fan I am using some functions I put into Sprinter and Marlin.
Here is an example on how I use them:
#define CONTROLLERFAN_PIN 44 //Pin used for the fan to cool controller, comment out to disable this function
#define CONTROLLERFAN_SEC 60 //How many seconds, after all motors were disabled, the fan should run
#define EXTRUDERFAN_PIN 59 //Pin used to control the fan, comment out to disable this function
#define EXTRUDERFAN_DEC 80 //Hotend temperature from where the fan will be turned on
With this the digital pin 59 (the one I connected the fan to just before) will turn on when the hotend reaches, or is above 80c, and will be switched off again when it drops below 80c. So when the printer is idle, the fan on the hotend will be off too, until you preparing your printer to print and heats the hotend. I decided to use 80c because that is about where pla is starting to get soft but without melting, I would not recommend any higher temperature.
Another thing this board easily can do also is to cool motors or stepper drivers, this I put on the pin right next to the pins used for the hotend fan. That pin is numbered 44, and it will turn on as soon as any stepper driver is activated. After the last driver is disabled, it will then wait 60 seconds before turning off again, to allow the fan to cool the hot parts down before stopping.
Before signing off on this post, that got way bigger than I planned and covered things I didn’t even think of when I started writing, I would like to thank Kliment from 0xfb.com, for helping with the development of the FETboard.
(FETboard will be open source, and the files put on github when I am done making the board a bit smaller, and maybe made a second batch to check if everything is as it should be)