The never-ending 3D printer project

MegaMax has been and continues to be my main project for the last 2+ years.  I am currently working on some upgrades that will make him more Mega and even more Max.  The Y axis is being converted from belt drive to screw drive and the round guide rails are being replaced with linear guides and bearing blocks.  The X-axis will also get converted to linear guide and bearing block and change from 5mm pitch belt to 2 mm pitch belt drive.  I feel confident saying that once these modifications are complete the flaws/errors in prints will be due primarily to the nature of liquid plastic squirting through a nozzle, not positioning system errors.

I recently updated my web site with a sort of historical look at the project, including all the mistakes I’ve made along the way and the often failed attempts at correcting them.  Here is the page that shows how it all started, how it has ended up, and where it is going.

Don’t ask me why I do this-  I have no choice.

MegaMax beginning

From this…






















MegaMax present state...

To this…

MegaMax is Too Noisy

As part of my effort to reduce the noise and vibration in the Y axis, I am going to try using a screw drive instead of the 5mm pitch belt.  I rescued a screw drive assembly from a big XY table but it uses a 200W servomotor for which I have neither power supply nor drive electronics.  Never fear!  The motor was a NEMA-34 size, so I designed an adapter to mount the NEMA-23 stepper that MegaMax uses in the NEMA-34 motor mount.  Next I needed a shaft coupler- the screw has a 9mm diameter attachment and the NEMA-23 motor has a 1/4″ shaft.

Adapter plate on NEMA-23 motor

Adapter plate on NEMA-23 motor














I used DesignSpark Mechanical to design the motor mount adapter and  flexible shaft coupler.  I uploaded the motor adapter to Thingiverse ( and it proved surprisingly popular so I designed another that adapts a NEMA-23 mount for a NEMA-17 motor (  I had to make two attempts at the flexible shaft coupler- the first design proved a little too springy and flexible, so I tried again with a more beefy design.  It turns out it is pretty easy to design this sort of thing in DSM.  I probably spent 30 minutes on the first one and about 10 minutes on the second one.

I sliced in Cura because Slic3r was having some problems.  The prints look a little rough because of all the support material required to print the springs, but they work fine.

Flexible shaft couplers

Flexible shaft couplers- not-so-springy and super-springy.













Adapter and shaft coupler on motor

Adapter and shaft coupler on motor
















Motor mounted on screw assembly

Motor mounted on screw assembly













I’ll post an update when I get the screw mounted on the machine.



A phone with a frickin’ laser!

My recent acquisition of a Meade ETX-90 telescope with computer go-to system for locating objects in the sky got me thinking that it would be nice to have a system to locate objects in the sky when you’re looking through binoculars or a telescope that doesn’t have a computer and motors to drive it.  To that end I came up with the idea of mounting a green laser pointer, commonly used by astronomy nutz to point out objects in the sky to noobs, on a cell phone or tablet running a program such as Google SkyMap or Skeye.

sky laser all parts

CAD rendering of the parts

After much thought and a few prototypes I came up with a system that allows a laser to mount on a phone and that assembly to mount on a tripod, a handle, or a telescope.  The tube that holds the laser has adjustment screws to allow the laser to be aligned with the SkyMap on the phone.  It also has to slots that fit over standard gun sight rails.  On one side I have a phone/tablet bracket that has a gunsight rail and slides into the laser tube, and the other side can be used for a rail that mounts on a tripod or a handle.  Extra rails can be mounted on telescope tubes.  I haven’t yet designed a binocular mount, but will soon.



Parts printing on MegaMax

I printed the parts on MegaMax with Octave fluorescent red filament (that’s why the colors vary in the photos- the flash apparently excites the fluorescence in the picture with the handle).   All the parts fit VERY tightly together but I included screw holes for extra security.  The phone/tablet mounts on the bracket using velcro tape.  I think it may be better to print or buy a cheap case to fit the phone than screw it to the phone/tablet bracket.  I’ll be posting the design files to Thingiverse shortly.


Phone and laser mounted on handle


Phone and laser on a tripod



Milwaukee Maker Faire Preparations

We’re planning on setting up a Nerdy Derby track at the upcoming Maker Faire Milwaukee so to that end we are preparing car parts.  We recently received a generous donation of filament from Inventables (thank you!) so MegaMax and others went right to work printing wheels for the Nerdy Derby cars.  The goal is to print 4000 (!) wheels before the Maker Faire.

A small batch-test run of twelve wheels

A small batch-test run of twelve wheels


Printing 40 whimsical wheels and once!

Starting a batch: printing 40 whimsical wheels and once!

6 hours later, almost done!

6 hours later, almost done!

































MegaMax printing 40 wheels in one go.  Go big or go home!

3D Printable shock mount for PCM-M10 digital recorder

PCM-M10 Shock Mount

PCM-M10 Shock Mount

Several years ago I played with a lot of audio stuff including making binaural recordings of things like cicadas, train rides, and festivals in Japan, and the singing of tree frogs in my back yard when I lived in a forest in Missouri.  Those recordings were done on a MiniDisc recorder because it was the best available audio quality recorder for people on a budget (i.e. cheapskates) like me.   Time and technology wait for no one, and I’ve been getting the itch to do some recording again, so I recently picked up a Sony PCM-M10 recorder.   This little machine records in many different formats up to and including 24 bit/96 ksps (though self-noise really limits the machine to about 15 actual bits).  The audio is recorded onto micro SD cards so unlike the MiniDisc, you get access to the raw digital data without any compression or associated quality degradation.

My previous recordings were done using a DIY binaural microphone that used a roughly matched pair of electret condenser mic capsules mounted on a wire bail that held the capsules inside my ears.  Even though those mic capsules were pretty noisy, the recordings came out pretty good.  When you listen to them with headphones you get a real “you-are-there”, surround-sound experience that can be quite startling.  You can hear those recordings here:   Soon, I’ll be starting a new binaural mic project to go with the new recorder, this time using much higher quality mic capsules.

In the meantime I was looking for a shock mount to use when making recordings using the built in mics.  The shock mount prevents low frequency noise from handling, bumping the table the recorder sits on, etc., from being coupled to the mics through the body of the recorder.  I did a web search and found only a couple unsatisfactory designs so I did what any maker would do- I made!

One of the flaws in the few designs I saw was that some of the numerous switches and I/O jacks on the recorder would not be accessible when it was bolted to the shock mount.  They also didn’t look very nice.  After a lot of sketching possible designs on a whiteboard and paring the thing down to a minimal implementation, and spending much too much time making a 3D model of the recorder, I came up with a printable 3-finger design that holds the recorder either on a tabletop or a tripod and keeps ALL the switches and I/Os available.  The only thing you can’t do while the recorder is mounted is swap batteries (but with 40 hours record time on a set of two AAs, that shouldn’t be a problem).

I used DesignSpark Mechanical to make the recorder model and design the shock mount.  DesignSpark makes rounding corners of complex 3D objects easy (nearly impossible in Sketchup), but I did run into some of its limitations that I hadn’t previously considered.  One huge limitation is that there is no way to put any form of text into a drawing without some special work-arounds (use Sketchup to make text, then import into DesignSpark).

CAD drawing of shock mount

CAD drawing of shock mount

PCM-M10 on shock mount- CAD

PCM-M10 on shock mount- CAD

This shock mount design is available here:  http://www.thingi


I printed the shock mount on MegaMax using Coex3D Aqua ABS filament.


SnakeBite Extruder Works!

I repaired the Budaschnozzle hot-end over the weekend and bolted the SnakeBite extruder to it and then to MegaMax and tested it last night.  There’s plenty of tuning to do, but the first print looks promising:


Start of SnakeBite’s first print


More of SnakeBite’s first print


Not too pretty but it shows promise.

Not too pretty but it shows promise.

3D Printable Thermal Enclosure For 3D Printer

Well, OK, not the whole enclosure, just the parts that hold it together.

MegaMax can print big stuff but he’s had problems with large prints delaminating.  The answer seems to be enclosing the printer to keep the prints warm while printing.  I designed this box and 3D printable parts to hold it together so that I can take the box apart easily to work on MegaMax or move him to other locations and put it back together when I’m done.  The box is 38″ D x 28″ H x 32″ W.

box door open











box door closed














The box is made of 1″ PIR foam with corners suitably notched to accommodate the printed parts.  MegaMax has a 450 Watt heater in the printbed so the box gets super-toasty inside.  I suspect it gets a little too toasty but haven’t made any measurements yet.  I’ll soon be moving the electronics out of the box.  I didn’t do anything to seal the seams in the box because it doesn’t seem to be necessary.  I did tape the edges of some of the foam boards with clear packing tape to prevent damage.

Design and stl files are available at

Snakebite Extruder Testing

rev7 extruder with hot-end













One of the biggest problems with FDM 3D printing is hot-end jamming.  There seem to be a lot of causes, most of which are not readily identifiable when a jam occurs.  One thing I have found is that after a hot-end jam I can usually grab the filament and manually push it and get it flowing through the hot-end again, though it is too late to save the failed print.  The most common means of driving the filament into the hot-end is to pinch the filament between a gear and a bearing and have a motor drive the gear, either directly (with 1.75mm filament) or via a gear reduction/torque multiplier arrangement (3mm filament).  When the hot end jams, the large force applied by the gear over the small area of the filament that is pinched between the gear and bearing usually chews a divot in the filament thus destroying the grip.

A couple weeks ago I started designing a 3mm filament extruder for 3D printing.  My hope is that this extruder will provide sufficient force on the filament to prevent hot-end jamming from ruining prints.  My design uses two counter-rotating 6-32 nuts twisting on the filament (like the way your hands twist in opposite directions when you give a “snakebite” to your friend) to drive it into the hot-end.  One is a normal, right-hand threaded nut, the other is left-hand threaded.  When the nuts turn in opposite directions, the torque that would try to twist the filament is cancelled while moving the filament forward and reverse without twisting.

The motor has to turn about 1.26 times to move 1mm of filament so there is a huge torque to axial force conversion.   The gear diameter is about 30mm.  That 1.26 rev moves the gear about 119mm at its perimeter.  That means there is about a 119:1 increase (ignoring losses in the gears, bearings, and nuts) in the force at the filament compared to the force at the gear.  That force is applied over a larger area of the filament than the usual pinch arrangement, so it is less likely (I hope!) to carve the filament and lose grip.  I tried stopping the filament by grabbing it with my fingers and holding as tightly as I could but it didn’t even slow down.

The firmware in the printer has to be tweaked so that it knows exactly how many steps of the motor are required to drive 1mm of filament.  The formula is:

32 rev/ 1 inch  X     1 inch /25.4 mm   X    200 steps/1 rev    X  16 microsteps/1 step   =  4031.496 microsteps/mm

For initial tests I just input 4031.5 using the rotary encoder on the LCD interface to the RAMPS board in MegaMax.

Here are the parts that I used:

Left hand threaded tap:

5mm brass tubing:

5x16x5mm (625Z) bearings:

Plastic gears:

I also used a NEMA-17 motor from a QU-BD extruder.

You can DL the STL files for the printed parts here:

Test printing will start in the next day or so and I will post another video showing success or failure.

Fingers crossed!