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3D Printer Reproduction Begins | LMNts

3D Printer Reproduction Begins

Our current 3D Printer – the Objet Alaris – “requires” that we print at least a small part every 48 hours to keep the machine in top shape. The good folks at Objet explained that this is because the build material in the vacuum leading to the print heads is at high temperature and needs to be purged every 48 hours. Whether this is entirely accurate or just a great excuse to keep us buying material is unclear to us. However, the machine is an awesome tool and we want to keep it in good working order…so we have developed a routine of “2 Day Parts” when there is a lull in the architectural model printing cycle.  We use these parts to test the printer’s limits and print small objects that could be part of larger assemblies. One of the first things we started printing – one small part at a time – was a second 3D printer…

We decided to start building the second generation of self-replicating RepRap printers: the Mendel. Roughly 49% of the Mendel’s parts can be 3D printed. The rest of the parts are relatively cheap off-the-shelf parts that can be bought online or at a hardware store…with the exception of the electronics and the extruder. RepRap is a community supported OpenSource project: the digital parts are freely downloadable…

So far, we have printed all the parts and managed to gather most of the ingredients. 95% of the STL files were watertight, but fixing those that were open was easy: just a couple naked edges and some flipped normals, but nothing major. Additionally, some of the parts are dependent on the dimensions of the stepper motors you decide to use, so it takes a little customization as well.

All the flat-cut parts took less than an hour to laser cut from 5mm acrylic. We could not locate 2D files for these parts, so we had to use Rhino to “Make2D” from the SolidWorks files.  Having a laser-cutter seems like as much of a luxury item as having a first 3D printer…some of the flat-cut parts could be rather labor intensive to do with a saw and drill. Certainly not impossible, but the laser cut print bed took all of 10 minutes to cut each part…

Cutting the threaded rod took about 30 minutes with a hacksaw… RepRappers recommend a +/- 1mm tolerance, so we cut as carefully as possible for a hack job.

We are planning to use Arduino boards for the electronic controls…simple, cheap and easy to wire and replace.  At left is an image of how the entire assembly should come together.

All we’re currently missing is the extruder, which we are in the market for. We have been humming and hawing over this decision, trying to figure out how important it will be to print in exotic materials…like chocolate. We can always decide to replace the extruder with a different one later…that’s the beauty of DIY: there’s no warranty to void. So we’ll make a decision on that soon. In the meantime, we’ll start assembling the whole thing bit by bit.  We’ll post more on that as it comes together…


For those who might want to try this themselves, the two parts that we found to be “leaky” (i.e.: not watertight) were x-vert-drive-side-plate-360-end_2off.stl and z-tensioner_1off.stl.  We fixed those files and posted them here:

[download id=”17″ format=”1″]




  • Randolph

    Looks like great fun!

    Have you wandered by Createspace lately? They’ve got I think, two or three of these working, and might some extruder suggestions.

    • dbelcher


      So far so fun. Nope, haven’t been by the Createspace lately. I’ll definitely swing by and take a look at their extruders. Thanks.


  • Michael McCune

    Lol!! We are looking into doing the same thing! Although Objet never told us 48 hrs. Might be your specific printer though. They just told me that if I plan on not printing for a month, to fill the lines with cleaner and shut down….

    Can’t wait to see the updates! Can you email me the cleaned up 2d and 3D files?

    • dbelcher


      Nice! Glad to hear you are building a Mendel…first generation Mendel or second?

      I should have been more precise above. The “2 Day Print” practice is actually to avoid the re-initiation cycle (which takes time, as you know) and then purges out the material in the tubes. If you print within that 48 hour period, you don’t waste that material.

      Assembly of the Mendel is going well. I’ve posted the two fixed STL files above in a post update.