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BattleBots Spinning Top Arena with Makey Robot Fighting Tops

I made a mold for injection molding Makey Robot spinning tops a few weeks ago. The tops are designed to be giveaway items at Maker Faire Milwaukee 2016.  I plan to injection mold them and hand them out during the Maker Faire.  Below you can see a picture of the aluminum mold and a few of the Makey tops that I have molded while testing the new mold.


With all these tops around the house I thought it would be interesting to have a small fighting arena for them.  It made sense to model the arena after the BattleBots arena since the tops that will be fighting in it will be Makey Robot tops.  Our family loves to watch BattleBots and I thought it would be a fun build just in time for the BattleBots season finally on Thursday (September 1, 2016).

Below you can see a short video of the arena and tops in action (we had a little fun with the intro.)  At the end of the video there is a an abbreviated build video.

Homemade EDM (Electric Discharge Machining) Machine

I made the majority of this homemade EDM a long time ago.  Recently I have been finishing this project by making a better structure for the linear actuation, adding labels to the controls and other miscellaneous items.  In the video below I discuss the EDM and show a couple of the parts that I have cut.  At the end of the video you can see a short clip of the EDM in action.  At the end of this BLOG post I included pictures of a neodymium hard drive magnet cut using this EDM.

My homemade plunge EDM (electric discharge machining) machine built based on the book “Build an EDM” by Robert Langolois.  The book consists of a series of articles that originally appeared in The Home Shop Machinist.

I deviated from the book in a couple of ways. First I sourced some of the components from scrap electronics and an electric clothes dryer that I picked up for free on the side of the road. The main transformer came from a microwave oven along with a cooling fan. A smaller transformer was sourced from an old stereo. The heating coil that I used as a power resistor was also taken from the old electric clothes dryer.

Additionally I used a sand cast aluminum part to support the linear actuator components and finished the whole thing off with a few custom 3D printed parts to fasten the linear actuator parts together.

Here are a couple pictures of a neodymium hard drive magnet that I cut using the EDM.  Here is the before picture with the electrode that I used:
This picture shows the magnet set up for cutting. The magnet is placed on a utility knife blade which is clamped into a small plastic vice.
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Finally here are the two parts created by cutting through the magnet with the EDM.



ScorchCAD Updates (Version 2016.05.04)


In the past week I have updated ScorchCAD a couple of times.  The first update helped verify that the autocomplete function in the ScorchCAD Editor was causing cashing and other bad behavior on some android devices.  Since the autocomplete function was causing problems I added a menu option in the editor to disable the feature.  In the latest version the autocomplete function is turned off by default.  The reason I did this is because I imagine it would be very frustrating to download ScorchCAD and have it crash or otherwise act badly in the first few seconds of trying to write code in the editor.  So if you like the auto complete function you will need to enable it on your device after the upgrade.

The second Item that I want to mention here is another menu option that I added in the editor.  This item is called “Link File”.  “Link File” will automatically generate the OpenSCAD code to “include” a file from your devices file system.  The file to link is selected using a file selection dialog then the code to include the selected file is automatically generated.  This essentially links the external file to ScorchCAD allowing the user to edit the linked (included) file using an external editor of their choice.  To compile a file that was edited with an external editor it is just a matter of switching back to ScorchCAD and selecting the compile button.  The link command will also work with STL and DXF files.  STL and DXF files will automatically generate an “import” command rather than “include”.

F-Engrave 1.56: Better line/arc fitting and bug fixes

F-Engrave v1.56 is out with some bug fixes and better line/arc fitting.

There was a huge bug in the old curve fitting which caused the “M” in some fonts to be engraved wrong. This version fixes that and just makes the curve fitting generally better.
The output g-code generated by the new version can be as little as one quarter as many lines of g-code when compared to previous versions.

F-Engrave Download

Stick Bomb Fixture

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I made a quick little 3D printable fixture to aid in the construction of stick bombs.  The type of bomb this fixture makes is my favorite.  If the bomb is long enough a wave forms along its length as the bomb explodes.  Below is an embedded video showing how it all works.  The fixture is available for download on Thingiverse (Stick bomb Fixture)

Lego model of a 3D Printer (Printrbot Simple Metal)


My two boys love having a 3D printer in the house.  I have made a variety of items for them.  My 9 year old, Derek, came up with a great little Lego build.  He made a tiny Lego version of the Printrbot simple metal 3D printer that we have.


He really captured the essence of the simple metal with incredibly few Lego pieces.  It is even sized about right to put it in the workshop in their Lego city.


The parts you will need to build your own and an instructional video by Derek are below.


CNC Lithophane Jack-O-Lantern


Halloween is approaching so I thought I would share the Jack-o-lantern that I made for Halloween last year (2014).   I carved an image, lithophane style, into a pumpkin.  The pumpkin is cut deeper where the image is lighter and less deep where the image is darker. This makes the image appear when the pumpkin is back-lit with a candle.  Various programs are available to generate g-code from an image in this way.  I used Dmap2gcode to generate g-code for my jack-o-lantern.

The g-code generated by Dmap2gcode is suitable for a flat surface but a pumpkin is not flat.  In order to cut the image onto the uneven surface of the pumpkin an additional step is needed.  I used  G-Code Ripper to add an automatic probing sequence to compensate for the non-flat pumpkin surface.  A makeshift probe consisting of a piece of aluminum foil and some alligator clips was used for probing the pumpkin (see video below).  Since the pumpkin was soft I was afraid that any other kind of probe might dent the surface before registering the probe data.

In order to hold the pumpkin I cut the bottom off of an ice cream pail and fastened it to the CNC machine table.  A ring of scrap wood kept the bucket from flexing to much when the pumpkin was placed in it.  Once the bucket was secure I simply placed the pumpkin in the cut pail.  Cutting the pumpkin didn’t generate any large forces because the pumpkin was so soft.  I didn’t have any problem with the pumpkin shifting during the probing/cutting process.  No large forces were generated but a lot of pumpkin flesh was flying around so I covered my machine with plastic sheeting.



If you didn’t recognize it the picture I used was a picture of Linda Blair from the the movie “The Exorcist”.  Below is a short video of the pumpkin being cut.

If you are interested in trying this process here are some of the details of my process:

  • I set the maximum cut depth to 3/8 inches in Dmap2gcode
  • I edited the picture so everything that was not of interest was black.  That way I can un-select “Cut Top Surface” in Dmap2gcode and the cutter will leave unimportant parts of the image untouched
  • I used a grid of 10×10 points for probing the pumpkin only a few of the probed points are shown in the video
  • After carving with the CNC machine I did some additional scraping of the inside of the pumpkin until I was happy with how much light was being let through in the image


Kansas City Maker Faire Trip

This year I took my two boys to the Kansas City Maker Faire for the second year in a row.  We once again had a great time.  This year we attended both days of the faire.  We learned last year that one day was not long enough for us.

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We live in Minnesota so our adventure starts long before we get to Kansas City.  On our way to the faire we managed to find a couple of interesting items.  First was the large art display of buffalo silhouettes cut from steel plate.  These buffalo were located at the first rest stop in Missouri as we drove south on I-35.  It was a bit of a surprise because they were not visible until we were already at the rest stop.  It was a great place to get out and walk around a bit.

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Our second surprise was an antique store in Bethany, MO.  We were stopping for the day in Bethany to stay in a hotel since it was much cheaper than staying in Kansas City.  We had a bunch of time to kill so I took the kids to Jim’s Antiques just east of I-35 (Exit 92).  My kids loved it.  The antique store had a whole yard full of rusty tools, including some old propane tanks plasma cut with various designs including the local high school team logos.  Inside the store there was a vast array of items.  We didn’t escape before my little blacksmith bought an anvil shaped aftershave bottle for $2.  They had some real anvils and a blacksmith vice but they were too expensive for my 9 year old to afford.

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The next morning we headed to Moon Marble Company to see marbles being made live in the store.  The Moon Marble company store had a lot of games, skill toys (throwing tops, yo-yos, puzzles, etc.) and novelty items.  We had plenty to keep us busy while waiting for the marble making demonstration to start.  We were able to stay and watch Bruce Breslow (the store owner) make a marble from start to finish (I would guess it took about 45 minutes).  Bruce did a great job describing what he was doing and keeping the audience interested.  It was a great addition to our “making” themed trip.

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After the marble making demonstration we finally headed to the maker faire.  As usual we had a great time at the maker faire.  There was a lot of variety and a bunch of new things that were not there last year.  The kids had a chance at a variety of activities.  They Flambé-ed someone, checked out their entries in the Make A Robot Challange and were able to try tying a fly for fly fishing (Thanks to Donfishin).

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We were glad we spent two days at the faire.  The items in this post are only a sliver of what we saw and did at the faire.  Check out some of the Make posts and many other blog posts on the faire itself to see the other great many things that were at the 2015 Kansas City Maker Faire.

Owen and Derek discuss their trip in this video

Preparing for Minneapolis St. Paul Mini Maker Faire


We are continuing the tradition of custom Maker Faire hitch covers for our Maker Faire road trips.  Since the Minneapolis St. Paul Mini Maker Faire doesn’t have a graphic logo I made up my own.  My design is a play on the Minnesota Twins logo with “Makey Minneapolis” and “Makey St. Paul” meeting over the Mississippi.

I am also piling up everything we need for our first time displaying at a Maker Faire.  The kids wore out a couple of sleds last winter so I have been cutting the sleds up to feed the injection molder.


Everything we injection mold for a while will be blue and or orange.  If all goes well we will be injection molding live at the Minneapolis St. Paul Mini Maker Faire This Saturday.

High Speed Spindle (Router) Mount for a CNC Mill

I find myself doing CNC work on wood about half of the time so I thought it would be nice to have a high speed spindle.  I decided to mount my existing router to my CNC milling machine.  This is the same router I had previously mounted to my Poor Man’s Milling Machine before I bought the CNC machine (a Grizzly G0463 with the CNCfusion conversion kit).  After doing a little bit of Internet research I settled in on attaching a mount to the quill of my CNC machine.  The best source I found of similar mounts is found on this CNC Cookbook page: High Speed Secondary Spindle.

First I started by casting the rough shape in aluminum.  Below is a picture of the wood pattern that I made and the aluminum part in the as cast condition (after the casting sprue and riser were removed).


After I had the cast part I bored out the two holes to closely fit the quill on the mill and the outer diameter of the router motor I planned to use.  Then I cut slots in the ends and a clearance scallop for the existing gear rack on one side of the router body.  Next I added fastener holes that are clearance fit on one side of the slot and threaded on the other side of the slot.  Fasteners tighten the mount onto the quill and router body to hold them securely.


Finally the router motor is installed in the mount and the mount is installed on the milling machine quill.  This configuration added a lot of mass to the head stock so I also added a gas spring (not shown) to compensate for the added mass.


With the addition of the router motor I am able to cut wood at a much faster rate and get a better finish.  Below is a picture of a couple of plaques that I made for my brother with the new high speed spindle.  (The picture was taken before the edges of the plaques were finished).


The plaques were made to commemorate PHD Baseball’s Worlds Longest Baseball Game that took place in August 2014.