The syringe is made from PVC pipe using mostly standard fittings.  One piece that wasn’t standard was the plunger that fits inside the syringe tube and pushes on the chocolate contained therein.  I had to design and fabricate the plunger.  PVC pipe isn’t perfectly smooth or perfectly round inside, so I needed something compliant enough to ride out the pipe’s bumps and constrictions while maintaining a seal.  The seal needed to be tough, yet safe for use with food because it will be in contact with the chocolate inside the syringe.  I found some food-grade silicone casting material and ordered it.

While waiting for the silicone to arrive, I designed a 3D printable core for the plunger and a mold and jig.  The core fits on the end of a linear actuator that will provide the push.  The jig centered the core a few mm above the bottom of the mold.  The mold was tapered and the widest part -the bottom- was a few mm larger diameter than the pipe, and several mm larger diameter than the core.  The silicone envelops the core and is locked in place by holes that connect top and bottom side of the core.  The plunger squeeze-fits into the pipe to maintain the seal against the uneven inner surface of the pipe.

Mold, jig, and core for syringe plunger

Mold, jig, and core for syringe showing core inserted into jig.

Mold, jig, and core assembled for silicone over-molding.

I measured and mixed the silicone, coated the core with it and then set the core and jig in/on the mold and let it cure for 24 hours.  Then I removed the jig and broke the now silicone covered core out of the mold.  Result: a perfect, tight fit inside the syringe tube.

Core in mold with silicone.

Finished plunger removed from the mold.  The mold had to be broken off by design.

Plunger mounted on linear actuator.

The assembled syringe.

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!

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…

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:  http://www.amazon.com/gp/product/B006YITGY8

5mm brass tubing:  http://www.ebay.com/itm/360828686174

5x16x5mm (625Z) bearings:  http://www.ebay.com/itm/321062568303

Plastic gears:  http://www.sciplus.com/p/PLASTIC-GEAR-SET-WITH-BUSHINGS_40234

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

You can DL the STL files for the printed parts here:  http://www.thingiverse.com/thing:261037

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

Fingers crossed!

Whew.  This project was a D-O-O-O-ZY!  We needed to enclose our giant industrial arm so he can’t run away and join the robot circus…

Well…maybe not for THAT reason, but when we start cutting stuff with this robot, we need to keep spectators out of his reach and make sure that if a cutting bit does break, it doesn’t go flying out into the shop and maim someone.

This entire project was the work of several people and really shows why the Milwaukee Makerspace is a great place to build stuff/hang out with friends/play with power tools, etc…

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Step 1: Design it!  I used Solidworks and modeled each and every piece of wood that went into this project.

Step 2: get the wood!  We made multiple trips to Home Depot, which thankfully is only 5 minutes away and we had great weather during the whole building process.  I love having a truck!  Fortune also shined upon me, as we had a new member join up right before I started this project, Jake R., and his help in building the wall was immeasurable.

Step 3: Bolt the wood to the floor so we know where to put the wall, and then build some framing!

Step 4: Put in the windows, drywall paneling and metal wainscoting.  We were very lucky to get seven pieces of slightly-smoked Lexan from one of our members, Jason H.  We also cut small holes in the ceiling tiles and ran 4 braces up to the metal ceiling trusses above.  This enclosure is ROCK-solid stable!  Thanks to Tony W. and Jim R. for helping with that!

When I went to Home Depot, I thought my truck could handle a 48″x 120″ sheet of drywall.  Not so much… one of their employees helped me split 10 sheets of drywall in half, in the parking lot…so I would later find out that I did not have drywall tall enough for the wall corner.  Hence the need for more “framing” so I could use smaller pieces.

The large cabinet that powers the robot arm is right next to the enclosure; I placed it outside to keep it away from foam & wood shavings.  However, we will need to have the programming pendant next to the machine every now and then….hence the need for 2 small pass-thru doors next to the cabinet.

I used doweling to help hold the door frame components together…..probably not needed, but it ensures a STRONG door!

Again, hooooray for the Makerspace and all its tools! We have several LONG pipe clamps that came in VERY handy for gluing the door frame pieces together.

Here’s the outside of the enclosure.  The big metal control cabinet will go right here, hence the framed “mouse hole” in the lower right corner so we can pass the cables through from the cabinet to the robot arm.

The same area viewed from inside the enclosure.

Here’s the ginormous sliding door.  It’s mounted on a barn-door track-rail and supported on the bottom by two custom-made wheel brackets.

Here’s how I made the wheel brackets.  I got two lawnmower-style wheels and bearings from Tom G., then Tom K. enlarged the center holes on the wheels on his Bridgeport mill so I could use bearings for smoother action.

I figured on four carriage bolts for a super-strong connection to the door frame.

This is the track and wheel bogies that hold the sliding door to the wall.

Bolting the brackets onto the door was “fun”…I forgot that the very bottom of the door framing is two horizontal pieces, so the very bottom bolt had to go.  ‘DOH!

Here’s the final, assembled view.  You can see the robot’s control cabinet in the lower right corner.

Now that the fabrication is complete, we’re working on decorative ideas for all that blank-looking drywall.

Whenever I look at this finished project it feels like to took several months to get it up, even though construction only lasted about 2-1/2 weeks.

Thanks to Jake R., Tom G., Tom K., Tony W., Jim R., and Bill W. for their assistance with this project!

The video shows the last few layers of the calibration cube “printing” at 414% speed (according to my LCD display).

The Bucketworks 3D printing meet-up on 8/12 paid off big-time!  Gary Kramlich helped me debug a problem that was preventing me from flashing the firmware on the controller board for the MegaMax 3D printer.  After a few tweaks I was able to get it moving.

MegaMax 3D printer based on MendelMax but bigger and minus plastic parts.

This is my on-going project at the Milwaukee Makerspace.  It is a 3D extruded plastic printer with about 1 cuft build envelope.  I want to print life-size human skulls (among other things) from CT scan data.  The printer is made mostly from salvaged parts and materials so the cost has been very low.  When it’s finished it will have a heated 12″x12″ bed (13″x13″ if I can find an aluminum plate that big) and dual extruder so it can print in two colors.

I have learned a lot on this project- some things that work and others that don’t work so well, and how to use a milling machine to drill holes precisely and square the ends of the 8020 extrusion pieces used to build up the frame of the machine.

I could not have done any of this without access to the people, materials, and tools at Milwaukee Makerspace.  Every time I go there to do some work on this project someone says something that gives me new ideas for improvements to the design.   I frequently find materials and parts left for me on the machine’s cart by other members who know what I’m trying to do.  If you have a project idea find your local Makerspace and get busy- there is nothing that will get your creative juices flowing like being around a bunch of people with similar interests and different skills and experience!

The “South Shore Frolics” formerly known as the “South Shore Water Frolics” is a Bay View institution. The current celebration of summer & joy starts on Saturday July 16th at 11:00 in the morning with a parade leading to South Shore Park, after which there is a festival and a variety of activities including fireworks for the remainder of the weekend. The Frolics is an event that I have participated in as long as I have been alive, and it is a very integral part of my summer. Of course I was thrilled when the Makerspace agreed that this was a worthwhile use of our time and talents.

Our goal for Milwaukee Makerspace’s representation in the parade is to produce some electric vehicles, ride some previously produced power wheels racers, as well as present a unique parade float. 

Thus far the main work was completed by Tom Gralewicz who re-powered the Makerspace’s “pots of gold” (two electric vehciles that have a parade heritage) with new motor controllers. Now that we have two functioning platforms, we of course wanted to turn one of them into an 8′ mechanized cylindrical sign. (that will resemble a beverage container) 

The build on that commenced last evening. Here are some photographs from the madness & joy:

Matt N. always measures twice and cuts once. 

I don’t know how many times these guys measured, but they always made the right cut!

Here the team cuts the circular bases that will anchor the piece. In the background, there is a serious discussion about logicstics…or something. 

Matt G. shows us the pride that comes with making.

Kevin B. tests out the fit and finish of the first circular support on the vehicle platform.

So far so good! I can’t wait to see how this comes together!

Come and see us at the South Shore Frolics Parade!
Saturday July 16th, 2011
Parade starts at KK & Lincoln at 11:00am
Joy will be had by all!
If you consider yourself a Milwaukee Maker, you are welcome to walk the parade rout with us & represent making in Milwaukee!