1# update on our progress on the z-probe / auto-level / easy-level project
We made a couple of prints on the ultimaker outfitted with the z-probe. They were going great once the offset from the printer's nozzle was calibrated. Which brings me to an issue that arose; I was able to go into the settings of the ultimaker to correct the z-offset but after shutting down the printer, the value was set to the default firmware value. Does somebody know how I might be able to save this value? I thought the feature of saving for example the PLA preheat temperatures in the eeprom was present in past firmware versions.
If you get a shorter one, couldn't it be made to fit the hole for the 2nd hot end in the head, maybe threaded i the aluminum plate?
The sensor that we have right now is the LJ12A3-4-Z/BY. The diameter of this probe is 12mm, it will not fit in the printhead housing without some serious ultimaker surgery. It has a detecting distance of 4mm.
Luckily there is a 8mm sensor out there, which in theory will fit inside the printhead. (for example the LJ8A3-1-Z/BY) Only problem; the detecting distance; it is only 2mm :(
These type of cylindrical inductive proximity sensors are available in many different configurations, a nice overview can be found here: http://www.ia.omron.com/products/category/sensors/proximity-sensors/index.html
Which brings me to the next sensor which I happen to have ordered It's name: TL-Q5MC1
So this sensor does not have the nice cylindrical mounting ability, a small mount to the printhead is therefore needed. The sensor is small enough to fit under the printhead next to the hotend (which might produce more issues and worries but this is for a next post ) Bonus points; it has a detecting distance of 5mm!
To Do:
- Construct a metal mount for the TL-Q5MC1 sensor (Unfortunately printing a mount will not be sufficient as the mount will deform ever so slightly due to the heat of the hotend, precision is key.)
- Figure out how to save the z-offset value in marlin
- Measure if the TL-Q5MC1 sensor can be used on 5V (making a voltage divider redundant)
- Figure out which type of connectors to use for the wire harness (making the sensor plug an play)
- Write a small script to send home commands to the printer and calculate average / standard deviation
- Use the above script to test the concept of using an inductive proximity sensor as a z-probe
- How will heat from the hotend influence the sensor measurements? if the heat has a negative influence; could this be solved by compensating the measurements in the marlin firmware using the temperature measurements from the hotend / bed? -> use the above script to measure temperature influence
- Could this concept be used in combination with a glass bed (with metal underneath)? depends on the thickness of the glass and the detecting distance I suppose) -> do some tests with spare glass plate
- Would it be possible to use the z-probe in conjunction with the 'normal' z-endstop? -> study ultimaker electronic scheme, I think this might be possible with a NPN type sensor.
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meduza 191
If you get a shorter one, couldn't it be made to fit the hole for the 2nd hot end in the head, maybe threaded i the aluminum plate?
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