Auto Bed Leveling - inductive vs microswitch January 31, 2016 12:14PM |
Registered: 8 years ago Posts: 168 |
Re: Auto Bed Leveling - inductive vs microswitch January 31, 2016 12:26PM |
Registered: 11 years ago Posts: 5,780 |
Re: Auto Bed Leveling - inductive vs microswitch January 31, 2016 12:59PM |
Registered: 8 years ago Posts: 168 |
Re: Auto Bed Leveling - inductive vs microswitch January 31, 2016 01:03PM |
Registered: 12 years ago Posts: 548 |
Re: Auto Bed Leveling - inductive vs microswitch January 31, 2016 04:04PM |
Registered: 8 years ago Posts: 3,525 |
Re: Auto Bed Leveling - inductive vs microswitch January 31, 2016 04:29PM |
Registered: 10 years ago Posts: 14,672 |
Re: Auto Bed Leveling - inductive vs microswitch January 31, 2016 04:34PM |
Registered: 8 years ago Posts: 1,873 |
Re: Auto Bed Leveling - inductive vs microswitch February 01, 2016 09:40AM |
Registered: 12 years ago Posts: 1,450 |
Re: Auto Bed Leveling - inductive vs microswitch February 01, 2016 11:23AM |
Registered: 8 years ago Posts: 1,035 |
Re: Auto Bed Leveling - inductive vs microswitch February 01, 2016 11:38AM |
Registered: 8 years ago Posts: 1,873 |
Re: Auto Bed Leveling - inductive vs microswitch February 01, 2016 02:57PM |
Registered: 8 years ago Posts: 1,035 |
Re: Auto Bed Leveling - inductive vs microswitch February 01, 2016 04:01PM |
Registered: 8 years ago Posts: 3,525 |
Re: Auto Bed Leveling - inductive vs microswitch February 01, 2016 05:04PM |
Registered: 8 years ago Posts: 1,035 |
Quote
DjDemonD
The fsrs I use come with a "trinket" (their name not mine) board which interprets the fsr signal and provides three wire output for direct connection to z min endstop. I presume it helps when you have 3 to smooth out the signal, but I'd probably use one even for a single fsr, it's probably a few $ and purpose designed for the job.
Re: Auto Bed Leveling - inductive vs microswitch February 01, 2016 05:18PM |
Registered: 8 years ago Posts: 3,525 |
Re: Auto Bed Leveling - inductive vs microswitch February 01, 2016 05:25PM |
Registered: 8 years ago Posts: 3,525 |
Re: Auto Bed Leveling - inductive vs microswitch February 01, 2016 05:56PM |
Registered: 8 years ago Posts: 1,035 |
Re: Auto Bed Leveling - inductive vs microswitch February 02, 2016 05:53AM |
Registered: 8 years ago Posts: 3,525 |
Re: Auto Bed Leveling - inductive vs microswitch February 02, 2016 07:33AM |
Registered: 8 years ago Posts: 413 |
The strain gauge works by its resistance being related to its "length". It needs to be stretched or compressed along its longest side. Forces acting on its sides (large area) as you show will not work.Quote
realthor
I'll take the risk of cross-posting because my other thread doesn't seem to have too much success ...I'll link my idea here:
Now, ideally, without an additional board the pink FSR in the image should have the two wires coming out one in the Z-min and one in the Ground (or whatever the wiring of an FSR is) on the board. In the Kossel FSR Wiki they say that "We use three FSR wired in parallel, connected to the Z_MIN endstop pin. This allows calibrating the print surface with 0.02 mm repeatability, which is good enough for printing PLA[...]The endstop (digital) input pin works just fine, without any additional parts."
So in theory this should work although the repeatability should be better.
Considering that the Strain Gauges work in a similar fashion (am I wrong?), I wonder why the output from those can't be sent directly to the Z_MIN . Is the output too small that it can't be picked up as a difference in resistance?
Re: Auto Bed Leveling - inductive vs microswitch February 02, 2016 07:47AM |
Registered: 8 years ago Posts: 1,035 |
Re: Auto Bed Leveling - inductive vs microswitch February 02, 2016 07:57AM |
Registered: 10 years ago Posts: 14,672 |
Re: Auto Bed Leveling - inductive vs microswitch February 02, 2016 07:58AM |
Registered: 8 years ago Posts: 3,525 |
Quote
MCcarman
I am not familiar with the auto levelling feature although I know its in the firmware, but I don't see that you have to use the nozzle at all. You can run a simple code to raise the hot end a specified distance, fit a spacer of known size to your sensor (extends below the nozzle), test the various locations. Then remove the spacer and calculate the offset to put in your slicer. You may need to develop a fudge factor but once you have worked it out it shouldn't change.
Re: Auto Bed Leveling - inductive vs microswitch February 02, 2016 08:07AM |
Registered: 10 years ago Posts: 14,672 |
Quote
DjDemonD
The issue is that offset probes of any type have limitations, you are unable to probe any area on the bed (unless you can mount your probe a few mm from the nozzle - almost impossible), with deltas you can get effector tilt meaning the probed points might not translate to above-the-bed-heights for the nozzle, they occupy space and add mass to your print head/effector.
Using the nozzle as the probe satisfies many requirements, the exact x,y position you probe gives you an exact z height for that point for the nozzle itself, you can probe the whole bed, generally there is little or no mass added to the print head/effector (thinking fsr's under the bed for a delta).
I have an i3 and a kossel mini, the i3 uses a capacitative proximity sensor at a significant offset 37mm in x direction, the kossel uses fsrs under the bed. I know which printer performs better when it comes to bed adhesion and generally has fewer problems with the bed being level - the kossel. As such we are trying to work out the simplest and cheapest nozzle based solution for a cartesian printer. I think it probably would be to pass a current through the nozzle to a conductive bed surface like aluminium, so long as the nozzle was clean (or hot) when probing. But you're then limited to a metal bed, I prefer printing onto printbite or glass.
Re: Auto Bed Leveling - inductive vs microswitch February 02, 2016 08:37AM |
Registered: 8 years ago Posts: 3,525 |
Re: Auto Bed Leveling - inductive vs microswitch February 02, 2016 08:40AM |
Registered: 8 years ago Posts: 1,873 |
Quote
dc42
For a strain gauge, you need to use an instrumentation amplifier, not an ordinary op amp. You will also need up to 3 precision resistors, depending on the configuration of the strain gauge. So it's not a cheap and easy option. If you want something really cheap, I suggest a microswitch.
Re: Auto Bed Leveling - inductive vs microswitch February 02, 2016 09:48AM |
Registered: 12 years ago Posts: 1,450 |
Re: Auto Bed Leveling - inductive vs microswitch February 02, 2016 12:45PM |
Registered: 8 years ago Posts: 1,035 |
Quote
leadinglights
I have just mentioned in another thread [forums.reprap.org] that the Sparkfun HX-711 breakout board will interface to a full bridge strain gauge load cell and is really cheap (£2.99 in the U.K. and £0.99 post free from China.)
Difficulties are:-
So I am not accused of stealing anothers thunder, this can be found in realthors first submission.
- The output from this is a two wire serial output not a digital on/off signal. There may be some supporting software in the article [www.instructables.com] but I haven't yet had time to read it.
- The biggest single problem is to make or buy a load cell element that will support the extruder & nozzle firly while providing a good sensitivity
Mike
Re: Auto Bed Leveling - inductive vs microswitch February 02, 2016 08:31PM |
Registered: 8 years ago Posts: 1,873 |
Re: Auto Bed Leveling - inductive vs microswitch February 03, 2016 12:42AM |
Registered: 8 years ago Posts: 541 |
Re: Auto Bed Leveling - inductive vs microswitch February 03, 2016 01:59AM |
Registered: 8 years ago Posts: 1,035 |
Quote
tjnamtiw
Amazingly, no one that I saw mentioned the BLTOUCH. I have this working now on my FT 2020 for $33 shipping included from S. Korea. It took about 2 weeks to get here. [www.ebay.com]
My biggest problem was that, while it worked right out of the 'box' with my laptop hooked up, it required a separate 5V supply on the ramps board. Some people can run it off of the Ramps power and others like me can't.
Re: Auto Bed Leveling - inductive vs microswitch February 03, 2016 02:51AM |
Registered: 8 years ago Posts: 1,035 |