Combatting Endstop Noise

Talk about all things CNC
Post Reply
MeanderBolt
Posts: 560
Joined: Mon Nov 04, 2013 6:45 pm
Location: Georgia
Contact:

Combatting Endstop Noise

Post by MeanderBolt » Fri Mar 14, 2014 2:47 am

I saw this on Hack-a-Day today... It is an article about reducing the noise on the end stop lines of a RepRap. An interesting read.
Shapeoko 2 # 3569 - DW660
Current tool chain > Draftsight > CamBam > ChiliPeppr
Build log

twforeman
Posts: 1351
Joined: Tue Jan 29, 2013 4:51 pm
Location: Minneapolis, MN
Contact:

Re: Combatting Endstop Noise

Post by twforeman » Fri Mar 14, 2014 2:56 am

Excellent. I will probably implement this when I replace my optical switches with mechanicals.
Ender 3 3D Printer
ShapeOko v3 serial #0004 - upgrade thread
All of my ShapeOko related blog posts

MeanderBolt
Posts: 560
Joined: Mon Nov 04, 2013 6:45 pm
Location: Georgia
Contact:

Re: Combatting Endstop Noise

Post by MeanderBolt » Fri Mar 14, 2014 11:36 am

Hey twoforman,
Is there a reason that you will be switching to mech? I would have thought that the optical option would be more precise. Not so?
I personally have a really cool set of smd hall effect sensors I have been saving for a special project, but I have also been looking at some slot optical switches.
Shapeoko 2 # 3569 - DW660
Current tool chain > Draftsight > CamBam > ChiliPeppr
Build log

veng1
Posts: 250
Joined: Fri Nov 30, 2012 12:09 pm

Re: Combatting Endstop Noise

Post by veng1 » Fri Mar 14, 2014 12:00 pm

Having owned a lot of through-hole and SMT manufacturing equipment and fixed a lot of it, I rate Hall Effect as the most reliable, then mechanical and finally optical. In general, optical suffers from the chance of getting chips or dust on the sensor that the others are not susceptible to. This assumes good quality switches that are rated for low voltages. Switches rated for high voltage and higher currents often do not have plated contacts or a cross-point configuration and work fine initially then become intermittent as they age.

Interestingly, Siemens SMT equipment sometimes uses ultrasonic to detect boards arriving on the conveyor although I don't really see an application for this in our world...yet.

I have also seen a home brew CNC machine that scribed through etchant resist on printed circuit boards by using a force sensitive resistor to adjust the Z-height. It worked very well, much better than iron on toner methods.

I am wondering if a retractable probe and a force sensitive resistor would make a precise way to find the Z-height of the work material?

WillAdams
Posts: 8625
Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15
Contact:

Re: Combatting Endstop Noise

Post by WillAdams » Fri Mar 14, 2014 12:19 pm

Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

twforeman
Posts: 1351
Joined: Tue Jan 29, 2013 4:51 pm
Location: Minneapolis, MN
Contact:

Re: Combatting Endstop Noise

Post by twforeman » Fri Mar 14, 2014 12:47 pm

MeanderBolt wrote:Hey twoforman,
Is there a reason that you will be switching to mech? I would have thought that the optical option would be more precise. Not so?
The optical switches are very precise and I hope the mechanicals will be as good. Time will tell.

I'm switching out the opticals because when I mill something that creates a lot of dust, like MDF, it gets into the switches and trips them. It's so bad that right now I'm enabling the limit switches, homing the machine and then disabling the switches again.

I have a pretty workable dust collection shoe, but the dust still gets everywhere.
Ender 3 3D Printer
ShapeOko v3 serial #0004 - upgrade thread
All of my ShapeOko related blog posts

Will Winder
Posts: 435
Joined: Fri Apr 20, 2012 2:40 pm
Location: Hudson, MA
Contact:

Re: Combatting Endstop Noise

Post by Will Winder » Fri Mar 14, 2014 9:07 pm

I spent $2 and got 4 mechanical micro switches shipped from china to my front door. They were installed in a 3D printer and I have to say I'm shocked at how accurate they are. I hadn't adjusted the Z-Axis on my 3D printer in over a year and it would still home to exactly the right spot.

I'm using an Azteeg X1 instead of a generic RAMPS board, I don't know if it has some sort of filtering like this built in.
ShapeOko #367: Dual-Y drive, Belt on outside, 1000mm Y-Axis, DW660 Spindle, Nema-23 X/Y motors.

Primary developer on Universal Gcode Sender.

Post Reply