don’t make me clamp you…

Trying to push the envelope in print volume on the Robo C2 printer, I’m finding that the part wants to curl on the bed (since the latter isn’t heated). Hmm…


This is a common occurrence, I understand.  It’s due to the uneven temperatures of plastic on the bed versus the new (hot) layers of added plastic. To get a part this big, I actually had to lie to the software and to suggest that the printer has a bigger range than this. This sort of tweaking is commonplace.

Hairspraying the bed is a known gimmick for 3D printing, but as you can see, the painter’s tape is well-stuck to the part.  Instead, I’m thinking of 1) printing the raft at the bottom, 2) pausing the print at this point, 3) removing the bed, 4) applying clamps around the edges and finally, 5) resuming the print job.

Tool-Making 101

From my experience in a plastic manufacturing plant, I learned that if something doesn’t work:  modify it, build a helper tool or change the process somehow so that it does work. Here, I’m opting to build a set of clamps to assist in the 3D print process and to insert a pause into those instructions (“GCODE”) at the proper moment.

Half the battle, then, is designing and building a number of clamps.  To be useful, they should allow their placement at a variety of distances from the edges of the bed. They should hold throughout the job even if things are vibrating and moving around. They should never restrict bed movement. Since the print job goes for perhaps ten hours, they must not fail in any way if I’m not there to watch their performance.

The other half of the battle is to create something which modifies the GCODE instructions to place a pause at the right moment (as soon as the raft has been laid down). My guess is that this will look like an OctoPrint plugin. There probably already are a number of plugins which pause at a particular z, meaning that they will pause the print job when it comes to a particular vertical layer. I was thinking that I might invent a different approach somehow in this space but I’ll see what I can come up with. I like the concept of pause after raft, though, and would imagine that this would be useful enough to others.

This should save a lot of print jobs from curl, I hope. And that should translate into a lot of money saved in filament, as well as time.


the robo 3d c2 printer

For months now, I’ve been wanting a 3D printer to create plastic parts and I’m guessing that I just made the best choice by buying the Robo C2.


First Impressions

First of all, it’s an attractive printer in the same way that EVE (from the WALL•E cartoon) was cute.  Perhaps you can see the resemblance?


Second—and you guys should know by now how I love them—this printer is driven by a Raspberry Pi 3 computer inside!  I hope to clone the microSD card in that computer and go to school on their efforts to hack an even better printer out of it.

Third, the product is open-sourced and crowd-funded.

Fourth, they’re a local company.  Their office is maybe a 20-minute drive from where I live in San Diego.  Given that most people would have to purchase this online and have it shipped, they wouldn’t get to see it in action like I just did.

Fifth, it includes an iOS app which allows you to control this and any other Octoprint-enabled printer.

Sixth, at 20 microns, it looks to have the best resolution of any of the printers I saw at Frye’s Electronics and most of those had a price tag above $1400 to reach the 50 micron resolution level.

Finally, it looks like it comes with a one-year license for Autodesk Fusion 360 which appears to be a very nice program for designing.

Research and Past Experience

I spent a fair amount of time before purchasing this by researching 3D printing, the types of plastics, the pitfalls to overcome, etc.

This particular printer doesn’t have a heated bed (the place where the project is made) so it may not do a great job with ABS plastic without a lot of trickery.  The standard voodoo that is necessary is to get inventive with the bed covering so that the project adheres nicely, doesn’t skip around and further, doesn’t warp due to uneven heating.

So for an unheated bed, the PLA type of plastic is the suggestion here and I’ve purchased an additional two rolls of the stuff to get things started.

Interestingly-enough, a few years ago I worked in a large plastic manufacturing plant so I have a little experience making plastic of the rotomolded variety.


In this industrial-sized version, colorized plastic powder is measured and put into aluminum molds on a steel frame wheel.  And this wheel then is inserted into a very large 700°F oven.

But for the consumer variety, you spend most of your time in a computer-aided design program, send a job to the printer and then wait hours (usually) to see how it turned out.  This ought to be interesting.


I have a few projects in mind for this.  I snagged a Robo Drone Kit while I was at Frye’s to give me a project which should produce some reasonable results.


I hope to design and print an enclosure for the e=mc2 project from earlier.  Although it’s difficult, I hope to make this a clear enclosure ultimately.

I’d like to work up a design for a heated bed for the Robo C2 since it sounds like this would make ABS-related print jobs more successful.  I think I’d also like to test new bed materials since the field of 3D printing is still new and inventiveness is required here.

Given that the Robo C2 has a Raspberry Pi computer inside with OctoPi software running on it, I should be able to modify the design, add things onto the printer and do notifications, for example.  I could add an internal webcam to it, for example.

And then finally, I think I’ll spend some time on post-print finishing techniques to see what I can do in this area.


Here’s the first printout from the Robo C2 after some upgrades and dialing in that critical z-adjustment.  Obviously, it’s a money clip.  It’s light blue but the red background makes it look gray otherwise.  It’s very smooth for a 3D-printed project and amazingly so for the $699 price tag on the printer.  The small, flat piece is called a “raft” and is meant to make things stable during printing, btw.