BLTouch / 3DTouch Alternative Z-Probe by svogel7808

Last crawled date: 2 years, 11 months ago

This is a remix of the Solenoid Probe by willfly : thing:4390007
A Big thanks to willfly.
I have been thinking of ways to make my own bed level sensor with bin parts that is similar to the BLTouch and Touch-MI probes, but with simplicity in mind.
I got the details to make the coil and plunger from willfly’s design.
The dimensions are similar to a BLTouch, and thus the same mounts could possibly be used.
The bed levelling process is similar to that of a BLTouch, but this is a dumb sensor without any alarm triggers and auto testing features, similar to the Touch-Mi probe.
This can be used as a Tuch-Mi probe with the manual deploy option enabled. Stowing will be done by moving the Z-probe close enough to the bed till the magnet pulls the probe towards the set screw.
Assembly:
Print the Solenoid_Spool and Body.
Superglue the Spool and Body Together.
I just glued the veroboard and connector in place as well.
Solenoid and Servo Controller:
Extract from willfly :
“The coil is wound from 0.14mm enamelled copper wire, length approx. 24 m. The coil resistance is 25 ohm, leading to a current draw of 200 mA for 100 ms when the coil is operating.
The wound coil length is 10 mm. An M3 screw at the top grabs the stowed plunger. It has to be adjusted so that it is not actually touching the plunger, or else probe won't deploy -
the electromagnet has less repulsive force compared to the magnetic attraction of the 5mm rare earth magnet used.”
The current draw of approx. 200ma at 5 volt. I obtained the copper wire from a 80mm 5v fan I had in the parts bin. I unwound the stator coils giving me two lengths of coil that I soldered and insulated to create a continuous wire length.
The solenoid is controlled via a modified 9g servo motor controller.
Remove the board from the servo, unsolder the motor and POT.
Solder two 2k2 resistors to the board in place of the POT to create a 1:1 voltage divider.
The board is then connected to the printer main board to a servo connector.
The servo controller can manage up to 700ma.
I installed the controller in my printer's main board and PSU enclosure.
Probe:
The probe is from the shaft of a faulty 30mm cooling fan from the hot end of my 3d Printer, superglued to a 5mmx2mm neodymium magnet. Alternatively use a 2mm ferrous metal wire cut to about a 10mm length.
The other end is similar, but I glued a length of PETG filament instead of wire to keep weight down.
Sensor:
The sensor is made from the hall effect sensor from the 5V fan. This had 4 pins with two as outputs, and two for power. A 3 pin Hall sensor should also work.
The 4 pin sensor allowed me to connect two LED’s. One for stowed (Safe/Triggered - Green) and one for deployed (Pin Dropped – Red)
A 2n222 - NPN transistor's base is connected to the the hall sensors output, the Collector to Z_Min enstop signal and Emitter is connected to the printer’s Z-MIN end stop Gnd.
I assembled the hall sensor and LED's on a piece of vero board and glued it in place.
Configuration:
Please note - This is not a tutorial on configuring z-probes.
You will need to reconfigure Marlin and flash your Printer.
Please do your own research as I will not take responsibility for any damages to self or property, or your sanity.
The Servo-Hall probe is configured as a servo probe in Marlin.
Marlin v2.0.7.2 has a new wizard to simplify the configuration the Z-Probe offset making setup much easier.
A Side note:
I first tried to use the coil without a servo controller to simplify the design. A single 2n222 or similar transistor can drive the coil to deploy the probe, stowing will be done the same way as the Touch-Mi probe by lowering the Z-Axis until
the probe is stowed by magnetic pull.
An output on the main board could drive the base of the transistor to do this. However, I struggled to configure Marlin for my board (MKS SGEN L V1.0).
I still want to configure/edit Marlin to employ a self test and some fail safes for dumb probes as this.
Please do not hesitate to assist and provide your comments for improvements and point out any mistakes.
Please keep in mind that the idea is to keep the design simple and cheap.
Thanks