This thing has an odd shape to accommodate the odd shape of the camera.  I designed the adapter in two pieces so it could be printed without any support material.  After printing the two pieces were glued together with a little super glue.

Unassembled 3D printed WebCam adapter and eyepiece.

Assembled adapter on the eyepiece.

The adapter fits over the barrel of the 32mm fl eyepiece and stays put.

I shot a short video to test it and it works perfectly!  The cars driving by are about 1/2 mile away.

If we ever get a clear night I’ll try shooting Jupiter or Saturn and then run Registax to enhance the images.

Files are here:  https://www.youmagine.com/designs/web-cam-adapter-for-meade-telescope-eyepiece

I reused what I could including a lot of the 8020 extrusions in the frame, the Z axis screw assemblies and drive belt, and the X and Z axis motors.

Changes include:

• ball screw drive Y axis with high torque motor- precise but noisy
• linear guides in X and Y axes instead of 1/2″ round guide rails and linear bearings
• SmoothieBoard controller instead of Arduino/RAMPS
• BullDog XL extruder and E3D v6 hot end
• RepRapDiscount graphic LCD control panel
• narrower frame design without giving up print volume- easier fit through doorways!
• polycarbonate panels to enclose the print area yet provide a clear view of the print
• electronics in a drawer for easy service and transport and neater appearance
• DSP motor drivers and 32V power supplies for X and Y axes
• Liberal use of screw terminals to make servicing easier
• Modular X and Y axes that can be removed for service and replaced in minutes.

SoM will be making his public debut at the Milwaukee Makerspace very soon…

Son of MegaMax electronics drawer

Side view of Son of MegaMax

32V Power supply for Y axis motor. No regulation necessary!

Smoothieboard is supposed to read the config.txt file from its uSD card (conveniently accessible via USB) every time it boots.  That makes changing configuration very easy and fast – all you do is edit the config.txt file, save it , and reboot the board.  Firmware is updated the same way.  With the ATMega2560 you have to find the configuration variables by searching through multiple configuration files, make the necessary changes, recompile the firmware, then flash the controller.  I said the SmoothieBoard is supposed to read the file every time it boots, but it wasn’t doing it.  I’d make changes and they would not appear in the behavior of the printer.  Hmmmm.

Layers kept shifting in the X-axis- I expected Y-axis problems, but not X!

I attempted some prints and managed to get two decent ones in about a week of screwing around with it.  I tried dozens of combinations of speed, acceleration, junction deviation (smoothie-speak for jerk) and even tried different slicers.  The machine went completely nuts on two occasions and ignored the Z-axis limit switch and slammed the extruder into the print bed, gouging through the Kapton tape and into the aluminum!  I decided I needed some professional help so I got on the #smoothieware IRC channel and discovered that the developers of the board/firmware hang out there quite a lot.  After a lot of back and forth Q and A and testing someone suggested it might be the uSD card causing the problem.  I picked up a new card at Walmart, put the firmware and config files on it , booted the machine, and attempted a print.  PERFECT!

The new uSD card worked! The small round post is 4mm diameter.

I have made several prints since last night and they have all come out fine.  I still have a little tweaking to do and to test the limits of the machine’s performance, but I think the problems are behind me.

Next up:  X-axis redesign/build.  I’m replacing the two guide rails with a single linear guide.  I have also ordered and received a BullDog XL extruder to replace the hacked up QUBD unit I’ve been using.  I’ll be adding a DSP driver and 32V power supply for the X-axis motor, too.

After that, I have some ideas for a filament respooling machine and ways to fix the retraction problem in the SnakeBite extruder.

It never ends!

1) I can now adjust the bed leveling screws from the underside of the bed using thumbwheels instead of a screw driver.  I know, I know, everyone else in the world has been able to do this from day 1…

Thumb screw for leveling print bed. Screw is threaded into teflon block.

2) Unlike everyone else in the world, with fully supported linear guide rails, the print bed does not move in any direction but along the Y axis.  In the old scheme, with the end-supported round guide rails, the rails would flex and the bed would move up and down when applying pressure to it (sometimes even the screw driver pressure to adjust the bed leveling screws).  Now, if the bed moves at all in the vertical direction it’s because the bed plate (1/4″ aluminum) itself is flexing!

A couple bad things were also discovered:

1) The vibration and noise problem I was hoping to solve has not been solved.  It has been made worse, though the character of the noise is improved to musical tones instead of just harsh buzzing and rattling.

2) Several failed test prints at ever decreasing jerk, acceleration, and speed settings have demonstrated that the old motor simply doesn’t have enough torque to drive the screw reliably at reasonable printing speeds.

Shift occurred in Y-axis due to insufficient motor torque.

Further research into the first problem indicates that the vibration and noise are inherent in using steppers, and worse in MegaMax than in machines that use NEMA-17 motors because of the higher detent torque in the NEMA-23 size motors.  Detent torque is the little bump-bump you feel when you turn the motor shaft by hand.  The solution to the problem is to use a good driver for the motor and a higher voltage power supply.  The little A4988 chips in the Pololu drivers on the RAMPS board are very unintelligent- all they do is provide microstepping.  They work OK for NEMA-17 size motors because of the speeds and low detent torques in those motors.  When used with NEMA-23 motors the driver limitations become apparent – as they have in MegaMax- lots of noise and vibration.

Good stepper drivers are DSP based and automatically sense resonance and damp it electronically.  They use phase controlled sine wave currents to drive the motors smoothly.  Fortunately, DSP stepper drivers for NEMA-23 size motors are pretty cheap.   Here’s video of the DM542a driver pushing a NEMA-23 motor around.  I have ordered a DM542a driver.

The best power supply for stepper drivers is not a switcher, and running steppers from a switching supply will often result in a dead power supply.  I will be building a simple, unregulated transformer, rectifier, and filter cap supply to go with the new driver.

Next came the question of how to determine how much torque is needed to properly drive the Y-axis.  A bit of research took me here: Motor size calculator.  You just select the scheme for which you want to size the motor, enter the appropriate data, and it magically tells you how much torque you need to do the job.  When I ran the numbers on MegaMax, it told me that I need about 350 oz-in of torque (about double the torque of the motor I have).  I did a quick search and found a Chinese made (of course) 425 oz-in motor for $50.  Also on order…

The motor mount I am using is designed for a NEMA-34 size motor with which I use an adapter plate to allow the NEMA-23 motor to fit.  Since I’m buying a new motor anyway, why not just get a NEMA-34 motor?  It turns out that the best stepper for the job is generally the smallest motor that can provide the necessary torque.  A NEMA-34 motor could provide much more torque but the detent torque and rotor inertia would work against smooth and fast operation, and require a bigger power supply.

Back side of MegaMax showing motor mount, adapter plate, flexible coupler, and drive screw in Y-axis.

The ATmega2560 and RAMPS boards will be replaced by a SmoothieBoard.  It has a much faster processor, much better connections for motors/external drivers, etc.  It currently lacks an easy way to add an LCD controller, so I may have to connect to a computer to start prints up (it has ethernet and a built in web server so it can be accessed from any computer on the network).  When a clean way to add an LCD controller becomes available, I’ll add it.  SmoothieBoard review

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.  http://mark.rehorst.com/MegaMax_3D_Printer/index.html

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

From this…

To this…

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 (http://www.thingiverse.com/thing:526424) and it proved surprisingly popular so I designed another that adapts a NEMA-23 mount for a NEMA-17 motor (http://www.thingiverse.com/thing:526443).  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- not-so-springy and super-springy.

Adapter and shaft coupler on motor

Motor mounted on screw assembly

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

You can DL the files here:  http://www.thingiverse.com/thing:454265 and get your pew-pew on!

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

A small batch-test run of twelve wheels

Starting a batch: printing 40 whimsical wheels and once!

6 hours later, almost done!

Video:

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

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: http://mark.rehorst.com/Binaural_Recordings/index.html   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

PCM-M10 on shock mount- CAD

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

verse.com/thing:384567

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