I had a side gig as the printer mechanic for a small company that 3D printed bracketry for their product. They used both genuine and “knockoff” (open source ftw) Prusa Mk3s. I’d kinda like to staple Josef Prusa’s foreskin to the ceiling. I think it would make him have better ideas than the extruder-and-hot-end-assembly that those machines currently have. Deal breaking issues I’ve had with them in service:
Nothing is connectorized at the business end. If you need to replace either of the two fans, the extruder motor, the PINDA probe, the temperature sensor, the heater cartridge, you have to partially disassemble the extruder mechanism and unwrap the wiring harness. The filament runout sensor is connectorized at the tiny little board, but…
The wiring harness passes through a hole in the back of the carriage plate and most of the wires have to fit into one of two little slots as the extruder mechanism is attached to the carriage. It’s really easy to pinch or sever wires like this, and it means you can’t replace a broken fan or something without partial disassembly.
The PINDA probe mount is about 3 planck lengths thick. It’s subject to some load from the thickness of the PINDA probe’s cable, it’s rather near the hot end and the heat plate, so I’ve seen them warp or break under continuous use. And it’s built into a foundational part of the mechanism so it’s not a quick swap, it’s a 100% teardown and rebuild from scratch.
The whole thing is a demented sandwich with like 25 printed plastic parts. It’s a convoluted thing to work on, even if it’s not printed in gloss black so you can make out the shape of everything. But they print it in gloss black.
It’s not designed to be built up as an assembly that can be easily and quickly attached and detached from the printer. In service, this makes it impossible to have a spare extruder assembly built up so when you get “Number 3 needs a new nozzle” you can swap in the spare assembly, return the machine to service, and then work on the part at your leisure. No, the production manager is breathing down your neck with a machine in many pieces. Hand me my stapler, I just want to talk to him.
Those goddamn pressed in square nuts. If you want to re-use the hardware because one of the many plastic pieces partially broke in a way that means you HAVE to replace it, re-using the hardware is just one more jumper cable to the cornea.
It’s not specific to the Extruder mechanism, but because nothing is connectorized at the business end, you end up having to open the main board’s enclosure and dealing with shit in there, and there isn’t room. It’s turned the wrong way; the connectors and shit should be on the OUTSIDE of the printer so you could get to them easier and most of the cover should hinge or bolt off.
For an 8-bit AVR-based Mendel pattern machine they work surprisingly well when they’re in good shape but they are a PAIN IN THE TAINT to keep running in a production environment. I have the skills to do better than this but I’m not doing it for free.
Some of this I think still goes for hobbyists if they plan to buy the printer as a kit. The first (of like, eight) Prusas I built I had a hell of a time assembling the extruder mech because it’s not designed to be easy or sane to assemble, I still pinched wires, not bad enough to break anything but still. And I had built several 3D printers and a couple laser engravers prior to this.
And that PINDA probe mount is still hilariously delicate.
As a hobbyist machine that will spend most of its time powered off, they’re fine. For their gantry mechanism and the 8-bit control board, they’re surprisingly high quality if slightly slow printers.
Oh there’s another thing: The Prusa community is in the bad habit of sharing G-Code rather than STLs, because everyone everywhere has the same printer, right?
My personal printer is still my first manually leveled Folger 2020 i3 with some customization of mine, and I don’t need another.
I had a side gig as the printer mechanic for a small company that 3D printed bracketry for their product. They used both genuine and “knockoff” (open source ftw) Prusa Mk3s. I’d kinda like to staple Josef Prusa’s foreskin to the ceiling. I think it would make him have better ideas than the extruder-and-hot-end-assembly that those machines currently have. Deal breaking issues I’ve had with them in service:
Nothing is connectorized at the business end. If you need to replace either of the two fans, the extruder motor, the PINDA probe, the temperature sensor, the heater cartridge, you have to partially disassemble the extruder mechanism and unwrap the wiring harness. The filament runout sensor is connectorized at the tiny little board, but…
The wiring harness passes through a hole in the back of the carriage plate and most of the wires have to fit into one of two little slots as the extruder mechanism is attached to the carriage. It’s really easy to pinch or sever wires like this, and it means you can’t replace a broken fan or something without partial disassembly.
The PINDA probe mount is about 3 planck lengths thick. It’s subject to some load from the thickness of the PINDA probe’s cable, it’s rather near the hot end and the heat plate, so I’ve seen them warp or break under continuous use. And it’s built into a foundational part of the mechanism so it’s not a quick swap, it’s a 100% teardown and rebuild from scratch.
The whole thing is a demented sandwich with like 25 printed plastic parts. It’s a convoluted thing to work on, even if it’s not printed in gloss black so you can make out the shape of everything. But they print it in gloss black.
It’s not designed to be built up as an assembly that can be easily and quickly attached and detached from the printer. In service, this makes it impossible to have a spare extruder assembly built up so when you get “Number 3 needs a new nozzle” you can swap in the spare assembly, return the machine to service, and then work on the part at your leisure. No, the production manager is breathing down your neck with a machine in many pieces. Hand me my stapler, I just want to talk to him.
Those goddamn pressed in square nuts. If you want to re-use the hardware because one of the many plastic pieces partially broke in a way that means you HAVE to replace it, re-using the hardware is just one more jumper cable to the cornea.
It’s not specific to the Extruder mechanism, but because nothing is connectorized at the business end, you end up having to open the main board’s enclosure and dealing with shit in there, and there isn’t room. It’s turned the wrong way; the connectors and shit should be on the OUTSIDE of the printer so you could get to them easier and most of the cover should hinge or bolt off.
For an 8-bit AVR-based Mendel pattern machine they work surprisingly well when they’re in good shape but they are a PAIN IN THE TAINT to keep running in a production environment. I have the skills to do better than this but I’m not doing it for free.
Ouchie. OK, I get all that, not gonna argue.
But I’m in a completely different position as a hobbyist, I have completely different criteria.
Thanks for sharing!
Some of this I think still goes for hobbyists if they plan to buy the printer as a kit. The first (of like, eight) Prusas I built I had a hell of a time assembling the extruder mech because it’s not designed to be easy or sane to assemble, I still pinched wires, not bad enough to break anything but still. And I had built several 3D printers and a couple laser engravers prior to this.
And that PINDA probe mount is still hilariously delicate.
As a hobbyist machine that will spend most of its time powered off, they’re fine. For their gantry mechanism and the 8-bit control board, they’re surprisingly high quality if slightly slow printers.
Oh there’s another thing: The Prusa community is in the bad habit of sharing G-Code rather than STLs, because everyone everywhere has the same printer, right?
My personal printer is still my first manually leveled Folger 2020 i3 with some customization of mine, and I don’t need another.