Dynamically changing tool connectors during a print

Merlin246

Hello,

I've had this idea for a while and wanted to see it's feasibility in the Duet ecosystem.

Imagine having a tool changing printer that has no permanent wires to any tool. Instead each dock would have dynamically connecting pins for CAN such that when the tool is docked, the tool can be controlled through those pins.

However when the tool is picked up, the tool head would have a set of CAN pins that would dynamically connect to the pins on the tool so that it is controlled by the toolhead and not the dock while it is picked up. When it returns to the dock, the dock pins take over.

This would also allow a sort of tool-magazine as there are no connecting wires to a fixed point on the printer (like the E3D Toolchanger), so you could have more tools at your disposal.

jens55

@Merlin246, POGO pins would give you the dynamic ability to connect stuff on the fly but I question if the connection is reliable enough in all situations. You will still need to feed filament to the tool (assuming it is an additive tool of course) and while I am unsure about the reliability of the POGO pin connection for low level signals, I am doubly concerned if you want to attempt to run heater power trough POGO pins.
Hopefully somebody has run some tests on the idea of POGO pins for the tool head ....
I have no idea about the programming/scripting involved to make this work.

deckingman

@Merlin246 My memory isn't what it used to be but I have a feeling that this was the concept that E3D originally envisaged for their tool changer but they ran foul of a patent. I might be wrong and maybe I just dreamt it. Also in that dream, is a feeling that the open source jubilee project uses such a system (in which case, printers are not built for sale so patents do not apply).

jens55

@deckingman, I run a Jubilee printer and the standard model does not dynamically connect the tool head. Each tool head has their own umbilical connection.

deckingman

@jens55 said in Dynamically changing tool connectors during a print:

@deckingman, I run a Jubilee printer and the standard model does not dynamically connect the tool head. Each tool head has their own umbilical connection.

Ah, OK. I stand corrected.

dc42

@Merlin246 yes it would be feasible (with some firmware changes to handle tool disconnect/reconnect), but there are at least two potential issues:

There is a patent (now owned by Stratasys) on using pogo pins with CAN bus in a 3D printer;
The tool would cool down when not in use, so it would need to be reheated when re-selected.

Merlin246

@dc42 thanks for the information

Ah that sucks. I wonder how they managed to get a patent using pogo-pins and CAN bus, seems like it wouldn't be unique enough but I'm not a lawyer.
I imagined every dock would also have a PWR/CAN connection for the tool so it would never be disconnected for very long (the dock controls the tool until it's picked up, and with new ceramic heaters (like Revo) that heating time shouldn't be very significant.

2b. It would be cool if there was a way to do it where the tool never loses it's PWR/CAN connection (instant swapping between two CAN addresses) when it is in electrical contact with both the dock and toolhead.

deckingman

@Merlin246 I'm no lawyer either, but I don't think a patent can prevent you from building a machine as long as it's for you own personal use. Or were you planning to sell machines commercially ?.

Merlin246

@deckingman definitely for something personal (maybe commercial down the road, who knows?).

I was involved in a patent once and it was a lot of work putting together everything and making the argument that the invention deserved a patent, something like using specific pins (that already exist in the market) doesn't really make a strong case to me, but anyways I digress.

deckingman

@Merlin246 ......and the other annoying thing about patents, is that you have to employ an army of lawyers to have them enforced. Even then, the (let us say, oriental) cloners don't give a sh#t and make copies anyway. I know one company founder who has tried to have cease and desist orders enforced and who claims to have received extremely aggressive threats to him and his family - even death threats from said oriental cloners.

T3P3Tony

@Merlin246 said in Dynamically changing tool connectors during a print:

It would be cool if there was a way to do it where the tool never loses it's PWR/CAN connection (instant swapping between two CAN addresses) when it is in electrical contact with both the dock and toolhead.

or just leave each tool with the same CAN address. no need to change it.

Merlin246

@T3P3Tony Ah yes I was thinking about it backward, great point.

I do not know how the electrical would interact as at one point the CAN board would be connected to just one set of pins (the tool dock), then two sets of pins (tool dock AND tool head), then back to one (just tool head), or vice versa for dropping off a tool.

MihaiDesigns

@dc42 on the topic of the patent, as I'm working on a tool changer myself, is it this particular one or something else? https://patents.google.com/patent/US8926484B1/en

This one seems to cover most aspects of tool changing and I wonder how E3D and Prusa managed to work around it. Or perhaps there's a different patent? I read that not transferring power from the gantry to the tool might avoid the patent, but am not sure.

My solution transfers power to the heater via POGO pins, and reads the thermistor. Wondering if moving these specific wires outside the gantry would not infringe. Still not sure how to do this for 14 hotends though.