Building a RepRap Mendel


We’ve had our MakerBot (#1136) since April, and have learned quite a bit about it through the tuning and setup of it.  We also built another MakerBot (#1290) that lived with us for a few months and was considerably well tuned and upgraded before moving along to it’s rightful owner.  While we had access to two ‘Bots, we took the time to print a number of pieces for a RepRap Mendel, another DIY 3D Printer system.

The RepRap project focuses on being able to print it’s own parts, and requires very little that isn’t either printable or standard hardware store fare (within reason.)   The latest revision is called ‘Mendel’ (the prior was ‘Darwin’) and the initial challenge to building one is that it requires approximately 100 printed parts to be built.

There are other solutions to getting those initial parts, explained in detail on the website, but one of the most common ways is to print them on a MakerBot or buy them from someone who has done the same.   With perfect prints it takes about 53 hours to print a complete Mendel;  this is no small feat.   Ours below is the eight one we’ve printed – 5 large and 2 mini –  for a total of about 380 hours of prints.

The RepRap website has a detailed list of what’s needed, where to get it, and what it should cost.   The focus on print-ability in this model means that it ends up using a LOT of hardware — about 1,400 pieces between bolts, washers, nuts, rods, and bearings.

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MakerBot ACME Threaded Rods


One of the common complaints about the MakerBot Cupcake 3d printer is that the threaded rod used for the z-axis movement is often not very straight, and that this causes ‘wobble’ in taller prints.  There are a number of devices and mechanisms on Thingiverse designed to combat the idea of wobbly threaded rods, and many people are swapping in straighter rods to help combat the problem.

In most high-end CNC devices, the leadscrews use ACME threads – the thread profile and pitch is designed so that there’s very little backlash, and they’re designed to work well under load. When rolling these new rods on glass there’s no measurable wobble at all.

Swapping straight ACME rods isn’t an easy solution since they need to fit into the upper and lower bearings.   We got a set of rods specifically machined for a MakerBot from Precision Tech Machining in Florida, who usually sells them on eBay.


Here are the basics of the upgrade process. All of the photos lead to larger versions on Flickr. These are the stock rods with the oem wood nut traps:

MakerBot ACME Rod Install

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Laser Etched MacBook Pro


In March 2007 I decided to take my Core2Duo Macbook Pro to Adafruit Industries in New York City to be laser etched on their Epilog laser. The etching at Adafruit is done by Phillip Torrone (of MAKE: Magazine fame) and Limor Fried (electronics hacker guru).

The procedure and settings for doing this work were originally worked out at Squid Labs and Phil etched one of the most seen powerbooks ever etched, his O’reilly Tarsier design. This kicked off a few more people etching them at Squid Labs, with new designs and new ideas coming out relatively quickly.

As a MAKE: Magazine subscriber and MAKE: Blog fan, I’d seen the early work done and knew that when I got my MacBook Pro I’d need to get something done to it.

While it’s certainly not cheap, an Epilog laser similar to the one being used for this — and all of the associated parts / ventilattion — can be purchased for under $20K USD. Phil has sort of taken the ‘open source’ approach to this potential business by releasing all of the settings and templates for free so that anyone can set up a business doing similar work.

I speak at a lot of conferences and there is an increasing number of people showing up with Mac laptops, so I wanted something that would stand out a bit without resorting to a laptop covered in stickers (that’s what my old iBook is for.) I’ve also had people suggest to me that it works as a rudimentary ‘anti-theft’ measure, since it’s sort of hard to hide and MacBook Pro replacement lids aren’t exactly commonplace items.

Designing something for this purpose was going to be hard: I have to stand up in front of groups of people and present from this laptop, so that limited the scope of designs, though only slightly. I didn’t want anything corporate and tried to design something that would be more ‘universal.’ I got to speak with Phil about the original Tarsier design — it was something he liked, but he hadn’t necessarily thought it’d become the well-known image that it’s become. He was working on new ideas for his new MacBook Pro when I met him, and was putting a bit more thought into it this time around. It’s not going to be permanent as somewhere down the line I’ll have a new laptop, but since I need to carry it around for a few years, I wanted to get it right. I started working with variations of the Periodic table, and eventually settled on the entry for Silicon. Though the Periodic Table is a standardized layout, I chose to re-make this symbol from scratch in Adobe Illustrator so that I could specify my own fonts, spacing, and other specific design elements.
Once I had it to a point that I liked it, I traded files and thoughts with Phil a few times before scheduling a visit to the Adafruit Lab. After sending a few revisions back and forth with Phillip, I made my appointment.

I went to the Adafruit Lab with my friend Rich, another avid Make reader. Phil and Limor were great about explaining the process and getting it configured, and in just a few minutes, we were ready to go.

All photos are linked to hi-res versions:

Lining it up in the bay of the Epilog

Before I put my (relatively) expensive laptop into the laser for real, Phil and Limor aligned it and then did a ‘test etch’ — which basically involves taping a sheet of paper to the laptop in the exact location where you expect to etch it, and then letting it proceed at a really low power setting. What you end up with is a lightly burned piece of paper done at full scale, so you can make very sure that it’s what you want.

My paper test 'etch' - Macbook Pro Laser Etching

Once the settings are doublechecked, all that’s left is to adjust the power and hit the ‘go’ button. Here’s the start: you can see the laser starting on the laptop, and you can also see my Illustrator file in the background on the PC that controls the Epilog.

Frickin' Laser`


Because my design had a decent amount of ‘solid’ areas to be etched, it took probably about ten minutes from start to finish. Designs with more line-art would probably be faster. Here’s a picture of it still in the bay, just after finishing. The flash from the camera really makes the etching light up.

Completed w/ Flash - MacBook Pro Laser Etching

And the finished product from another angle:
Another Angle - MacBook Pro Laser Etching

Without seeing it in person it’s hard to explain how ‘shallow’ the etching is — you can barely feel it when you touch it. After a few years of travel and constant use, it’s holding up great! There are a number of places offering similar services commercially now — here is a list of them. Some of them offer stock artwork while others let you create your own — and some even have limited edition ‘custom’ work that they’ve created. Oh, and yes, the Apple logo is really green! I get a lot of questions about it — you can either get a theater ‘gel’ for stage lighting or you can get an insert from iColours, in Canada.

My full set of pictures on Flickr is here: Laser Etched MacBook Pro