From 0f3db0f7ef1fc6b6e7fc1be5fb7af9db893bb313 Mon Sep 17 00:00:00 2001 From: pyr0ball Date: Wed, 13 May 2020 01:30:17 -0700 Subject: [PATCH] updating 'about' section #docs --- docs/about.md | 48 +++++++++++++++++++++++------------------------- 1 file changed, 23 insertions(+), 25 deletions(-) diff --git a/docs/about.md b/docs/about.md index 5ba1222..3e7a699 100644 --- a/docs/about.md +++ b/docs/about.md @@ -1,36 +1,30 @@ -### What's this for? +## What is this thing? -An Ultra-Sensitive Z-probe sensor utilizing the mechanical force of the nozzle touching the bed, giving a direct measurement with no offsets or referential assumptions to consider +TL;DR: It's a litte circuit that turns your actual nozzle into a z-probe. -Optionally there is a version that incorporates an FFC Cable chain (Flat Flexible Cable) that can carry the entire print-head's signals and current in a clean and organized way +This is a Z-Probe Sensor for 3D Printers that utilizes a piezoelectric element (commonly a 20-27mm piezo disk used in musical pickups) to detect when the nozzle of the printer touches the bed. There have been other Z-Probes in the past that do this, but this is the first to incorporate an onboard microcontroller that automatically calibrates and balances the circuit. Previous piezo Z-Probes all required manual tuning to some extent, usually with tiny hard-to-use trimpots. Due to the mechanical and electrical characteristics of this type of sensor, it has several advantages over other Z-Probes: -### Why is this better than `` sensor? +- There are no offsets to configure or adjust +- It can be configured to emulate either a standard endstop, or any active-high Z-Probe +- It's not dependent on a specific type of bed or hotend +- The builtin signal filtering reduces the amount of false driggers dramatically compared to other piezo sensors. +- It's FAST. Delay between the piezo being actuated and the z-trigger signal being sent to the printer's controller is ***just 26 nanoseconds*** -- Vs. Inductive / capacitative sensors: +### Is there a catch? - No Offset, more accurate, doesn't require special surface +Well, yeah a couple. The sensor requires introducing a small amount of physical instability into the construction of the 3D printer. Something needs to move, even a small fraction of a millimeter. This can be something like the bed being pushed down slightly on it's springs, or adding a hinge and a tensioning spring to the print head. There's innumerable ways to make this work, and I've been working hard with my beta testers to find the best possible method combining as much stability as possble with the highest sensitivity. The other catch is that any oozing filament will skew the leveling results, so you have to decide to either assume there will always be ooze and use a small z-offset, or add a nozzle wipe/clean manuver to your startup gcode before bed leveling. -- Vs. Mechanical touch (BL-Touch, servo mounted endstops): +### How do I use it? - No Offset, more accurate +I designed the sensor to connect to a 3D Printer's controller like any other endstop or Z-Probe. Future versions will have an i2c interface that will allow the 3D Printer's controller to change parameters on the fly during a print or before a fast move. -- Vs. removable pressure sensor: +The piezo element is mounted somewhere on the 3D Printer in such a way that it undergoes mechanical stress when the nozzle touches the bed. So far there have been three distinct mounting schemes that appear to work well: - More accurate, no need for attaching a device only for levelling +- On the extruder assembly +- Under the Print Bed +- In the case of CoreXY or other Gantry Kinematic systems, on either end of the gantry -- Vs. Optical rangefinder / Time of Flight: - - Much more accurate, doesnt require specific surface - -- Vs. Mechanical endstops: - - All the things - -- Vs PrecisionPiezoUK version: - - No potentiometer calibration required, better false-signal filtering - -Features: +#### Features: - Self-calibrating (no more fiddling with tiny potentiometers!) - Ultra-precise z-height measurements @@ -39,9 +33,13 @@ Features: - No plugging in removable sensors for leveling - Tunable over UART / I2C -FFC Cable Chain Extra Features: +#### FFC Cable Chain Extra Features: - FFC Cable chain for a clean connection between print head and controller - Onboard switchable DC buck converter for 12v or 5v fan operation - LED Feedback on all PWM components -Standalone version available for drop-in installation + Standalone version available for drop-in installation + +Credit must be given to precisionpiezo.co.uk for getting me started on this project and giving me a place to start. I did build a version of the FFC cable chain based on their electrical designs but found the calibration of the circuit to be very fiddly, as the range of value on the potentiometers that was acceptable was very narrow. + +I've since started from scratch using my own BOM and designs, while including an onboard microcontroller to handle auto-calibration. Given that every 3D printer is different, I wanted this sensor to be as easy and stable as other sensors available on the market, but with the increased performance of a piezo sensor. \ No newline at end of file