[Brilliant Idea] Improved spool holder with digital scale
Hi all, I want to combine the good work done in these two projects:
https://www.instructables.com/Digital-Spool-Holder-with-Scale/
and
https://www.printables.com/model/1196950-filament-weight-scale-spool-holder-prusa-core-one
Mods to the originals:
- powered by routing to the USB-C port in the back and using a splitter so that the Core One Buddy Cam and this would both get juice without having to use a buck converter.
- I would also modify the display to mount magnetically in the corner and be rotated so that it is visible without having to go around to the right side of the printer.
My CAD skills are weak (I only use TinkerCAD b/c all the rest require an engineering degree to understand) and I am dangerous around electronics (and people) when holding a soldering iron.
Your input (and assistance) is greatly appreciated. If this works as well as the one in the first link, perhaps Prusa Research can adapt it to whatever spool holding solution will be used for the INDX upgrade.
Carlos Echenique
ce.photography
Prusa i3 MK2s + Prusa Core One (INDX Coming Soonâ„¢)
RE: [Brilliant Idea] Improved spool holder with digital scale
Upon further research I see that a USB-C splitter is not available off-the-shelf. I will have to figure out some other way to get 5V to the unit.
Carlos Echenique
ce.photography
Prusa i3 MK2s + Prusa Core One (INDX Coming Soonâ„¢)
RE: [Brilliant Idea] Improved spool holder with digital scale
Upon further research I see that a USB-C splitter is not available off-the-shelf. I will have to figure out some other way to get 5V to the unit.
USB-C is not meant to be split like that. There needs to be power negotiation between the ports. You can use a hub which would probably provide around 7W per port. If you need power why not tap the 24VDC from the power supply and run it through a simple buck converter?
- Bob Marley
RE: [Brilliant Idea] Improved spool holder with digital scale
Upon further research I see that a USB-C splitter is not available off-the-shelf. I will have to figure out some other way to get 5V to the unit.
USB-C is not meant to be split like that. There needs to be power negotiation between the ports. You can use a hub which would probably provide around 7W per port. If you need power why not tap the 24VDC from the power supply and run it through a simple buck converter?
I'll dig a bit bit deeper into this when I get the chance , and generally speaking you're right mate, but I think that the Core on board only ever spits out 5v on its usb-c port. (I'll verify this later)
What happens with the PD negotiation is that 5v is always present initially, and after negotiation that can be switched to 9/12/15/20 and sometimes others. If no negotiation takes place its stays on 5v.
To the OP:
I had a similar situation as I wrote some firmware for an ESP32-S3 that, and that device needs a 5v power supply.
So I had an unpowered 4 port standard usb-a hub in a junk box, so I plugged that into the usb-c port on the core one that the buddy cam normally occupies (with a usb-a to usb-c adapter), then plugged the buddy cam into one of the usb hubs ports (with a usb-c to usb-a adapter)...that solved my problem, Buddy cam still gets its 5v and works fine, leaving me with three more empty usb-a ports that I could use for powering my esp32-s3.
Of course its important to consider current consumption when doing this, in my case an esp32-s3 supermini consumes a (relatively) tiny amount of power , so this was never really a concern for me, but YMMV.
The only other options are as @hyiger proposed was tapping into the main supply and using a buck converter, or what I was tempted to do was use the 5v that's present on the connector that is used for the accelerometer, I looked into this but didn't have any of the connectors that Prusa use, and was startled to see how much they cost...so I went down the USB splitting route and haven't had any problems in a month or 2 since my ESP has been installed.
I do think this is a slight oversight on Prusa's part, they could've at least given us an extra powered usb port, or even just a connector that can be easily tapped into.
RE:
Here you can choose a cable with a mounted connector for the accelerometer output. The lengths are from 100 mm to 1 meter. Of course, you have to use the right wires. The prices are more than reasonable.
RE: [Brilliant Idea] Improved spool holder with digital scale
Here you can choose a cable with a mounted connector for the accelerometer output. The lengths are from 100 mm to 1 meter. Of course, you have to use the right wires. The prices are more than reasonable.
That's more than reasonable ! Thanks.
I did only make a brief search looking for the connectors/cable, I should've looked on Aliexpress.
It makes sense to use the accelerometer output, I can quite easily power down my espresso machine for the rare occasions I need to use the accelerometer... And that way I can tidy up the mess of usb hubs and connectors that litter the rear of my core one. 100mm is plenty long enough, I''ll probably even trim it down shorter.
Thanks again !
RE: [Brilliant Idea] Improved spool holder with digital scale
Note, according to my recollection of studying the Buddy extension board schematic, while there is a PD chip on that USB-C port only 5VDC is being supplied for a buss voltage. All the extension board can output is 5VDC on the USB-C. That said, because of PD, I doubt anyone reputable would make a USB-C power Y cable. If someone is handy with a soldering iron they may be able to make their own USB-C Y cable. But it will definitely be non-standard.
See my (limited) designs on:
Printables - https://www.printables.com/@Sembazuru
Thingiverse - https://www.thingiverse.com/Sembazuru/designs