Friday, 22 May 2015

-=( induction and capacitive proximity sensors )=-

Over the years there have been some interesting movements in endstops we've gone from crude mechanical switches to optical and hall effect switches, some of us of course haven't been using any and opted to manually position the nozzle before a print.

The latest fad is these proximity sensors which can be had for as little as $2 for inductive and $5 for capacitive (including shipping):

The mounting is normally done with a large nut and washer on the top and bottom:

The colours of the wiring seem to also be somewhat standardized brown for V+ blue for Gnd and Black for the signal output

The downside is that they require more than the 5v powersupply that is available on most endstop connectors and that the output when triggered is also the same as the voltage supplied to run them so you cannot just hook them up directly, however with a simple voltage divider we can bring that down to just below 5v again and hook them up using only two resistors:

The resulting output voltage is around 4.8v.

Something else to be aware of is that on some brands the colours aren't written in English and potentially may not be using the same colours as everyone else.

to use inductive sensors you will need something metallic as a flag and the sensing range is around 2 - 4 mm depending on the material, you can use just about anything though eg tinfoil, small screws even though the manufacturer will say the sensing range is for example 4mm it doesn't actually mean you can sense an aluminium bed through 4mm of glass.

to use the capacitive sensors there is usually a small tuning screw on the back since the sensor will pick up just about anything around it's sensing tip make sure when you turn this screw to tune it that you keep your fingers clear of it , it's also a good idea for repeat-ability sake to use the smallest practical sensing distance.

Tuesday, 12 May 2015

I decided that it was time to take apart my Bulldog XL extruder after running it for around a year and half in the production printing environment: