General Reprap Design Idea - cartridges

I've been watching the Reprap project for about a year now and said practically nothing. Its time for a change. :-)

I see lots of work, discussion, and youtube downloads about extruders, controller boards, xyz axis motion systems, and a myriad of other technical details on making the current reprap system better. That is all well and good. I applaud the builders' efforts.

The thing I have come to understand is that reprap machines are a combination of printable and (as of today) unprintable parts. This mixing is more or less throughout the machine with a printable part attached to an unprintable part attached to a printable part. If we were to design future reprap machines with a kind of segregation between printable and unprintable parts there would be much to gain, especially if the printable parts were located where the actual printing occurs. It would take a radically different design but if a maximum % of the controller boards, stepper motors, sensors, extruder, and other purchased parts could be clustered together but mechanically linked to a nearly 100% printed section where the actual printing occurs, good things could happen. Making the near 100% printed zone the place where printing happens would allow the possibility of multiple interchangeable print zones that could be switched out sort of like a toner cartridge is switched out on a laser printer. The cartridges could be prepared in advance and then set aside as the machine is working with another cartridge. When one project is done (or errors out), the next cartridge could then be locked into place and progress could continue. (This process might even be automated some day.) Whether the cartridge would include the extruder or not is a matter of discussion. We might be able to steal an idea from office grade inkjet printers where there are both print head and ink cartridges to interchange as needed. The benefit of doing cartridges is that you can keep the expensive electronics busy while working on any issues about printing. This becomes especially practical if those cartridges are nearly or 100% printed or at least made of components that are extremely cheap and abundant.

Thats my 2 cents. I'd love to talk with anyone about this idea. :-)

My build is not anything like a RepRap, but I am using a similar cartridge idea to mount the actual "head" of the machine, for several reasons. One is to make switching to a totally different head type easily, if not automatically possible. And two, to make it easy to swap in spares. A side benefit is the way that the mount is designed, it makes the head able to "crash" without damage. Lots of stuff like this could be incorporated.
My housings are a combination of metal and plastic, but could be made of printed parts. I just don't have a printer working yet

Good luck with getting the printer working. I'm particularly busy at this time, so I can only observe and comment. I know that once I jump in, this project is going to consume a lot of my time, a luxury I cannot afford right now. :-)

The whole switching out of modular components is very critical. Remember how interchangeable parts made the rifle much more practical? ( I know that no one is that old but it is historically significant.) If the system was composed of a control module (<<100% printed) , a print head module (<100% printed), and a print site module (nearly 100% printed), the machine could be kept in production almost constantly. The control module would be the most reliable and would be more or less the stationary part that the other two modules would plug into. When a print head fails, it could then be quickly switched out along with another print site module and the next part could be printed. It would be particularly cool if print site cartridges and print head cartridges could be chained up and advanced as heads fail and as projects are completed or fail. That would take a couple more stepper motors and sensors, expanding the control module but it could keep the action going. Keeping the action going would increase the productivity of the machine a great deal, hopefully much more than the increase in cost of parts, giving the machine better performance. Also the operation of the machine would be less stressful since servicing completed print site cartrages would could be done at times where the machine isn't waiting for it. The same goes for the print heads.

Foxpup,
I have been able to work in the RP world for about a year, and it would be almost impossible to make a Objet knock off. Standard printheads do not have the life span to make any decent size parts. Objet has custom print heads that cost 1200$ each and nobody in there basement could reproduce this quality. Standard print heads are not up for the task to print thousands of lays and push all of that liquid. Also every time you replace a used printhead you have to do an auto aligment. To make the liquid plastic and uv light set up would be a pain. A Sls machine would be 10 times easier and cheaper.

I think effort should be focused into suport technolgy like SSYS machines.

2Robotguy

2robotguy

Because you used the word, Objet, I went to see what it is. It looks like Objet makes some very nice prototyping 3d printers. The only problem is that it seems to be a single print job per setup rig, like most 3d printers. (Like the old Gutenburg printing press was.) Only just today did I see any exception to that rule, The Makerbot with Automated Build Platform, which more or less prints and resets for the next print job and starts again. (Imagine replacing the original press with rollers that can print multiple copies until service is needed) My idea was that you would load a printing platform let the machine print there and then switch the platform at the end of each job, but in some ways the heated conveyor belt idea is better. The down side is that once the part comes off the platform, its position is more or less random which forces further handling to be human or at least very sophisticated, beyond what most people would want to take on. It looks like the Objet is problably an order of magnitude more precise than any reprap system but probably costs a whole lot more per cubic cm to print with. Perhaps a great deal more if someone worked out a decent way to shred and reconstitute recyclable ABS Plastic. (big challenge)

I would expect the extruders to wear out. Only those people who have been printing a lot would know, I suppose. That said, I would think that if the printer rig was made so that the print head moved on only the z axis or not at all, it would be possible to make a mounting surface for it that is stable enough that one could prepare and calibrate a print head elsewhere and lock it in when a replacement is necessary. Regardless, there is still hope of automatic calibration after a new head or print site cartridge is replaced. The idea here is If the extruder needs service, replace it. If the print site module needs replacing, replace it, and find ways to make both replacements straightforward and non-problematic. (a challenge, but doable) I'd bet that rebuilding a print head wouldn't involve that much new material. If the head was designed to be rebuilt easily, that would help. (similarly, some internal combustion engines have cylinder sleeves and replaceable bearings to make rebuilding straight forward.) The idea is to think modular and allow for easy replacement of those modules that need replacement so that the modules that don't need replacing at any one time can stay productive. At this point I think 3 modules are called for, the control module, printhead module, & print site module.

As for the meaning of "SSYS" machines, I am at a complete loss. I do know that I am talking about printing with thermoplastics like ABS or PLA, usually available in the long filament spools like we see all the time or in pellets. I haven't given up on the hope that someone might find a way to collect and recycle ABS and make it usable in these printers. Find a path to that and you find a very cheap source of printing material. PLA plastic is generally made from corn around where I live, so that should stay readily available. (To bad it doesn't hold up at hight temps)

The equation comes down to this. Find a way to get cheap abundant "printing" material. Make a rig that is very fault tolerant, (through switching out failed and completed modules) and you've got a system that can be very productive, especially if you can automate the switching out process. One doesn't have to start out with high precision either. Lord knows there are some **UGLY** print jobs out there, but we start where we start and thing improve over time. As for whether we should be working on one concept or another, things aren't necessarily mutually exclusive. You may come up with a cool idea that helps extruders work better, while I figure out something about the axis control system. Besides, Ideas come on their own terms, to whomever they chose. We just need to be responsive when they come our way.

Just a clarification.

I'm trying to get others thinking about the idea of making 3d printers that work on a modular principle. The machines already are made of a couple hundred interchangeable parts, but I'm talking about separate,yet connected functional units. So far I think it would be good to have 3 modules

(The control module) - would include all circuit boards, motors, power regulators, and as many sensors as can be placed in that system. This would be the most reliable and expensive module and more or less the base that the other two would "plug" into.

(The print head module) - would include the extruder and probably the spool of abs/pla plastic. It would be made to switch out quickly with other print head modules if the extruder fails, it runs out of plastic, or if another plastic is desired. It would connect both mechanically and electrically tothe control module.

(The printing site module - or deck) - Would include the horizontal flat surface that is printed on and possibly (or not) the mechanical parts involved in XYZ motion. This item should be designed to be extremely easy to switch out since the idea in my head is that it would switch out at the end of each print job. It could simply be a horizontal deck with no mechanical systems. (leaving that to the control module) Cheapness and minimal materials here would be optimal.

The idea is that you keep a reserve of extra print head modules and many printing site modules so that the control module could stay busy, while the other modules are repaired & prepped. Additionally one might be able to automate the actual switching out of print site modules and print head modules which would allow for batch jobs involving different materials to be run and automatic loading and reloading of each print job. This automatic reloading would be something to try further down the road. Just making it easy to switch out the "deck" and "print head" swiftly would be of great value. I know the "deck" is pretty easy to switch out right now, but the whole process of setting for each project needs to be streamlined too.

All this is part of further ideas of what I'd like to see happen. I'd be glad to talk with anyone about such ideas but it is beyond the scope of this forum, (at least for today. :-) )

Thanks for listening.