JASP - load cell spool holder
JASP - Just another spool holder
But -this spool holder is special !
It has an load cell implemented 😀
The theory :
Load cell - an electronic device for measuring the weight of something. In this case the filament spool. You can calculate the leftover length of the filament if you know the weight and the specific density of the material.
The weight is proportional to the resistance of the load cell, its also proportional to the voltage, finally you got an value for calculation the leftover length of the filament on the spool. Of course we measure the spool and the printed parts too, but we can substitute it, because they are well known.
You can buy cheap load cells with A/D converters from eBay : http://www.ebay.de/itm/162165193587
I recommend an load cell with max. 3kg for 1kg spools and a cell with max 5kg for the big 3kg spools. I bought an 2kg cell, its just at the end of the max. range !
OK, there is an display missing. I have some OLEDs in spare which I bought for some months : http://www.ebay.com/itm/160889283903
The "rest" is an Atmega with some BASCOM coding 😉
Build it up :
I printed some parts
Implement the load cell
mounted it on the top of the cabinet
Re: JASP - load cell spool holder
The printed top plate is to better distribute the pressure on the acrylic glass plate, otherwise it runs risk of cracking
Mount the spool holder
With attached spool
Re: JASP - load cell spool holder
From the other side
Spool holder "in action" 😀
These are the electronic parts which I have to equip and to program
Yes, sure ! It's just an spool holder without the Scales ...
... to be continued ...
Thomas
Re: JASP - load cell spool holder
I love that benchy tray thing. 😉
Did you design that yourself?
Re: JASP - load cell spool holder
The stackable Benchy Tower 😎
look here : http://shop.prusa3d.com/forum/hall-of-fame-best-3d-prints-f15/stackable-benchy-tower-t3947.html
Thomas
Re: JASP - load cell spool holder
Interesting. It would be even better is you integrated it with a raspberry pi with octoprint and when the filament is almost over, use the octoprint api to tell the printer to beep a warning or even send a change filament command.
Re: JASP - load cell spool holder
Yes, good idea, but I'm not firm with a rasPi and octoprint 🙁
If you have some proposals and an workflow, you're welcome.
How I do ?
I have 2 very old rasPi but I never use them.
Thomas
Re: JASP - load cell spool holder
To install octoprint just go to: http://octoprint.org/
You can download an image and install it to an SD card. To do this check https://www.raspberrypi.org/documentation/installation/installing-images/README.md . After that you can configure the network (instructions on the octoprint site).
Then just put the card on a raspberry and turn it on. Play around with the web interface to see what you've been missing 😉
Then, you can check how to send commands to the printer through octoprint. I'm doing it with a simple webpage that sends Ajax requests, but I think you can also do this through the command line. In the end, you'll have to use the GPIO pins on the raspberry: https://www.raspberrypi.org/documentation/usage/gpio/ and use your load cell to send a signal to the raspberry through the pins. I will be doing something similar as I want to use temperature sensors.
Thankfully, there are octoprint plugins that do this kind of things, like these:
https://github.com/vitormhenrique/OctoPrint-Enclosure
http://plugins.octoprint.org/plugins/enclosure/
I haven't searched more, but there might be more plugins that might work for you, or at least there are numerous examples on the net showing how to wire sensors to the GPIO pins. There are even complete packages you can install on the raspberry that give simple access to the pins through the command line.
Re: JASP - load cell spool holder
The scale is working 😎
Thomas
Re: JASP - load cell spool holder
Project completed 😀
Thomas
Re: JASP - load cell spool holder
Clean installation. Looks professional 🙂
Re: JASP - load cell spool holder
Nice install, I do however hope the cap on your lead screws isn't holding them in place.
Re: JASP - load cell spool holder
Parts for printing :
http://www.thingiverse.com/thing:2272321
Thomas
Re: JASP - load cell spool holder
I like the idea. Have you checked how accurate is the measurement?
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: JASP - load cell spool holder
It's very accurate, only the pull of filament from the extruder bastardizes the measurement.
But if there is no force on the filament, the measurement is of about 1g or 3m.
Thomas
Re: JASP - load cell spool holder
Are you using battery for power supply and have you posted code anywhere? I concur that the design is very nice. Also, are the red and yellow items button switches or LED lights?
Re: JASP - load cell spool holder
- Power supply is from the PSU of the printer
- no, I didn't post code anywhere until now
- red button - Tara
- yellow button - choose filament type
Thomas
Re: JASP - load cell spool holder
That is really cool. I've considered using one of the filament length plugins for octoprint but I'm too lazy 🙁
Re: JASP - load cell spool holder
With your filament guide staying in one spot like that, you might consider building a reverse bowden into this. Will keep the filament spool from potentially tugging your extruder upward if any tension were to happen.
My MK3 Parts: [Bowden] [New Shoes] [TPU Micro Springs]
Re: JASP - load cell spool holder
Yes correct. I'm working on that problem, but it's only a minor issue.
Thomas