I’m in the process of designing and implementing my 3D printing strategy. Woah! Yep, big words there. So I have bought a projector and I will be making a DLP printer. BUT, I have also realized that there are some advantages of a filament printer. In particular I’m looking at some of the materials available. So I am building a combo machine. Or at least that is my current plan. A DLP printer only requires one axis of movement, so this isn’t a problem, I’m going for a top down approach, so this is further simplified. You know what, forget I mentioned it. I’m not sure it’s relevant at this point.

Let’s start again. I’m going to be making/modifying a filament printer. 2 print heads are required. This is because I want to print dissolvable support material for intricate prints. A heated print bed is required, because I want to work with a few different materials.

As I’m on a budget, aka poor, but still willing to spend a bit of cash, I have been looking at refurbishing some used printers for my needs, or building my own.

So I’ve been looking at some used makerbot replicator 2 printers. I realize that the 2x printers have 2 print heads, whereas the makerbot 2 printers (without the x, do not). My questions are a matter of economy. Any advice or responses are appreciated. I’ve been thinking about the cost of parts, and if buying 1 or 2 used printers for parts is worth it.

The print area, if I’m going to do FDM, isn’t large enough for my needs, I’m thinking 24” x 6”, not 11.2” x 6”. So I have been considering joining two used printers together. I’m certain I can bolt / weld the two boxes together, and rotate the Z axis to the ends for two Z axis at the edges of the box(s). I can replace the linear rods for the long axis with larger diameter (and obviously longer) ones and remake the carriage the extruders sit on, actually thinking about having the rods turned down on a lathe at the tips to fit into the already existing side carriages.

My questions are as follows:

1. Can I simply combine two print heads together to make a 2 print head machine? Just enter the offset between the nozzles in the software? (still haven’t figured that out, I’d like to get it built then sort out the software side).

2. For the electronic hardware that comes with the makerbot 2, can I easily upgrade the software? Can I add more motor drivers and motors to the hardware? An extra print head requires an extra driver slot and motor, an extra driver and motor also for an additional Z axis, and potentially adding another driver and motor for the Y axis (there are two of them, not the gantry the print heads ride on, the other two). This of course doesn’t even mention the added complexity of homing and leveling with extra motors.

If the electronic hardware won’t or can’t support these changes, it brings into question if it’s worth it to scrounge for parts? I’m looking at the motors, 2Z, 2Y, 1X plus 2 for the print heads for 7 in total, will the existing boards handle this expansion of potentially 3 motors (2 minimum, extra print head, and extra Z) ? If not, what should I be looking at? Arduino? Raspberry Pi?

Like I said I’m looking at doing things simply, reusing existing parts, etc. Even that number of Nema 17 motors will cost about 1/4 or more of what the used printers might cost, not to mention all of the reused hardware, toothed gears, belts, frame, carriages, etc. All advice is appreciated.

1. No, you cannot. What you need is a larger print surface, the print head (extruder) can manage whatever size surface you want, the problem is one of allowing it to move with needed accuracy over the entire surface of the print surface. Think of it this way, they now have what are essentially giant 3D printers that can print houses out of an aggregate material. The limitation isn't the print head, but the surface area. Just remember that if you're building in 0.1mm layers, the larger the print area, the longer the thing is going to be printing, since there's a limit to how fast it can do its thing. Larger print surfaces present their own challenges, which is why these things are usually limited. The larger the area, the more precise the fit and finish needs to be for the rods and bearings that allow the print head to move. Longer surfaces are more prone to sag without a lot of stiffening. All of this makes the printer more complicated and expensive.

2. I don't have much experience with that specific printer, but in general, if you can do the programming, you probably can. I'm guessing that you probably aren't a software guy, so probably you can't.

In general, I'm having trouble envisioning how you think that this is going to work. From the questions that you're asking, it seems like you are thinking of sticking 2 printers side by side, and somehow making one larger print. Since every 3D printer that I've seen moves the print part in at least one axis, this would mean that both printers would need to be EXACTLY synchronised moving in whichever axis this is. It also means that the print heads would need to be able to get to very nearly the same place, within .1mm of each other. This would have to be scheduled with the print code so that they don't collide as well. This makes the programming even more tricky, if it wasn't already with the need to synchronize the movement of the printed part. (Though if movement is in the X or Y axis, at least collision is physically impossible.)

Multi-head printers don't run both print heads at the same time, they run one or the other in order to use different colours or materials for parts of the print.

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

Thank you for responding to my thread.

I'm not sure I explained it well. I would be replacing the bed with a larger bed, that would now be driven by two screws instead of one, and 4 linear guides instead of two, reusing parts from both printers. Many printers have a Z axis driven by two motors, with two screws, and multiple guides. The boxes would be extensively modified and reinforced so it would look like one larger homogeneous box.

The side mechanics would be kept the same, but the new longer axis would have larger diameter rods and a new carriage, with the beefier components being used to account for the increase in length.

No intention of using both extruders at the same time, and I would remount them on a new carriage, side by side. Essentially, I would be reusing most parts to make a single larger machine of a similar design, but larger.

I have built very large CNC machines so I am very adept at doing the mechanical things. I know this is totally doable. How the longer travel distance would change the dynamics, even with larger diameter rods, is unknown, worst case is that it would need to print with slower speed / acceleration settings than the original.

You're right, I'm not a software guy, nor do I have any intention of writing my own software. Just wondering if the components on this, perhaps it's a common arduino controller that can be reflashed or something? and if it's possible to add extra motor drivers, I don't know? That was really my question. The rest I have covered. My recent research makes me think it's not possible.

Truth be told, I was looking for a way to do this cheap, and this would do it, however they sold for way more than I was willing to pay. I was looking at buying two machines for less than parts costs, and doing a mod. I've given up on this idea because I didn't get the cheap parts.

I've since decided to build my own machine from scratch. I have decided to make a new thread about my electronics questions for that build here:

[forums.reprap.org]

Thanks again for your reply.

I don't see much reason for splicing two machines together, I think at that point you might as well scrap them for parts and work from the ground up. You might also want to thicken the rods of the short axis, as they now need to take considerably more weight, even though their span remains the same. Software wise I'm sure someone here would be willing to help once you get there, and if not there are lots of guides and tutorials out there.