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
F-Engrave 1.50 has been released and is now available on the F-Engrave page. Here are a few of the highlights from this release:
Modified helper program (ttf2cxf_stream) and F-Engrave interaction with it to better control the line segment approximation of arcs.
Added straight cutter support (cutter will follow design inside or outside of lines)
Added option to create prismatic cuts (inverse of v-carve). This option opens the possibility of making v-carve inlays.
Added option for radius format g-code arcs when arc fitting. This will help compatibility with g-code interpreters that are missing support for center format arcs. (I think GRBL will accept the radius format arcs)
One of the most exciting new things you can do with F-Engrave now is v-carve inlays. Below is a video I put together showing the process of making an inlay with F-Engrave.
Here is an example of an inlay that i made during testing of the new features. The eagle is a slightly modified version of an eagle I found on WikiMedia.
Here are the parts before gluing them together to form the inlay.
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.
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.
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.
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.
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).
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.
As a challenge to myself I decided to make a very simple foundry setup for melting and casting aluminum. I have a larger more involved equipment but I thought it would be interesting to revisit some of the methods I used for my first castings. I also wanted to explore some new ideas I had for setting up a simple aluminum foundry.
If you have ever thought that you might like to try doing some aluminum casting “One Day” my “One Day Foundry” web page and the accompanying video may be of some help. The steps I used to accomplish the task were intended to get to the end result quickly with few tools. There are many ways to accomplish the same end result, I present only one.
I carefully selected my supplies and hand tools before I started and took the picture shown below. After I had the necessary items I did all of the preparation work using only hand tools and an electric drill. When I started casting aluminum I did not have much more than those simple tools in my possession. Below is a picture of the tools and equipment I started with. The only items that I did not have laying around the house were the two 8 foot 2×2 boards, fire clay and fine sand. Wood and sand were obtained at a big box home improvement store. The fire clay is a little more difficult. I went to Continental Clay in Minneapolis and purchased the clay (Hawthorn-50 mesh fire clay). They do sell by mail order but finding a local source is probably worth the trouble for most people.
I was able to complete the project in less than one day. I captured the build in the video embedded below. More details, including tools/parts list, can be found on the project page: One Day Foundry project page.
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).
Ever since I first saw a lithophane in a YouTube video I have thought they were really cool. I have made cylindrical lithophanes previously with my CNC machine. When I bought my 3D printer I thought I would give printing lithophanes a shot. I tried working lithophanes into Christmas ornaments with marginal success (See some of the ornaments here). After a little refining I printed some pictures on a cylinder and a night light cover. I removed the original night light cover and replaced it with a 3D printed version. The nightlight worked out well since it was a purposeful back light for the lithophane. Below are some pictures of the results. The cylinder is back lit by a battery operated tea light candle (the pictures are the front and back of the same cylinder). I spent a bunch of time making the STL file only to find that there are utilities that other people have made available for making cylindrical lithophanes. Here is a link to one I found on Thingiverse: Customizable Cylinder Lithophane Lamp.
The call for makers for the first Minneapolis/St. Paul Mini Maker Faire is now open. I thought I would throw my hat into the ring to present a few projects. I picked out a few projects for which I will show some of the intermediate steps. The projects I have chosen have built upon each other over the years. The projects presented below are the projects I proposed in my Maker Faire call for makers application I will edit as needed as the mini maker faire approaches.
Injection Molding Machine
My injection molding machine was made using plans from the book Plastic Injection Molding Attachment for the Drill Press by Vince Gingery. This book features a small injection molding machine that relies on an external mechanism to push the ram. Generally the external mechanism is a drill press. For my machine I have fitted the molding machine on an arbor press. The temperature control is accomplished using a purchased PID controller, thermocouple and cartridge heaters. The use of an external mechanism for load application and purchased components for the thermal management makes the remaining parts of the injection molding machine a simple piston with the necessary features to interface with the purchased components. I plan to have the injection molding machine producing small parts during the Mini Maker Faire. More information on my injection molding machine and molds is available on my Home Plastic Injection Molding web page. As shown in this YouTube Video the injection molding machine was in part made using my Gingery Lathe which is another project I plan to display.
A Gingery Lathe is a lathe made based on the book The Metal Lathe by David Gingery. Gingery Lathes are often started by makers that are trying their hand at aluminum casting. In the past very few working lathes could be found on the Internet. The number or working lathes seems to be increasing. My lathe is by no means perfect but it is an example of a functioning lathe that I continue to use. I plan to display wood patterns I used in the process of casting the lathe parts out of aluminum. My aluminum foundry which I used to create many of the lathe parts is another project I plan to display.
Casting aluminum opens a world of possibilities for makers and hobbyists. Aluminum casting can produce very strong aluminum components using a pattern made from wood or other easy to work with material. In addition the aluminum used for the castings can come from many sources including old aluminum frying pans and broken lawn mower engines. Since the material comes at little or no cost I even use cast billets from my foundry for making the molds used with my injection molding machine mentioned above. My foundry setup is based primarily on information from BackyardMetalcasting.com but once again Gingery publishing also has a great resource in the form of the book The Charcoal Foundry by David Gingery. I plan to show my foundry tools and some castings in various stages of completion. My foundry setup includes welded crucibles which brings us to the last project I hope to show at the faire, my home made arc welder.
Home Made Arc Welder
The final project I plan to show is my first home made arc welder. The arc welder is made from re-wound microwave oven transformers and some standard arc welding cable, a ground clamp and electrode holder. Various web sites detail the process of rewinding the transformers scavenged from old microwave ovens to achieve a voltage that will work for stick welding. I plan to show my completed welder and microwave oven transformers (MOTS) in various stages of the rewinding process. I also plan to show my steel crucibles that I made using my home made welder.
This is a collection of bottle openers that I made from 16D common nails. Some of them work better than others but I tried to incorporate a variety of designs. The plaque hangs on a wall and the bottle openers (nails) are held in place by magnets (neodymium magnets from hard drives) installed in cutouts in the back of the plaque. The YouTube video embedded above shows each of the openers in action.
Here is the basic process that was used for each of the bottle openers. My son Derek (age 9) did all of the hammering for the pictures shown below. (I worked the torch and held the nail with the pliers) The Anvil in the pictures is also Derek’s. I have a chunk of railroad track but Derek wanted the anvil shape so he asked for an anvil for Christmas last year. He thanked his Grandpa for the anvil before opening it (the weight gave it away).
Start with a nail (16D common):
Heat the nail up, in the area to be bent, with a Propane torch:
Hammer the nail (or bend with pliers) to achieve the desired bend and repeat as required:
The nail can also be flattened to achieve additional features. Derek has even flattened nails and added a twist for decoration:
In the picture below the shape of the opener is complete:
To increase the strength of the nail we heat it up and quench the nail in a cup of water. This is needed to varying extents depending on the design of the bottle opener.
That completes one bottle opener. Time to put it to use:
The embedded video above shows closer views of the other bottle openers and includes video of each design opening a bottle.
A couple of years ago Fran posted a really interesting video demonstrating friction welding. Fran used a cheap harbor freight rotary tool and some plastic (styrene) rod from a craft store. Her demonstration showed how strong friction welded joints are. Friction welding has been bouncing around the back of my brain ever since. Lately I have found a couple of applications for the friction welding technique. Having recently purchased a fused filament 3D printer (PrintrBot Simple Metal) I have some failed PLA 3D prints laying around. I also happen to have some ABS scraps and some 3mm injection molded ABS rods from another project. Experimenting with these materials I have found that friction welding works well for both ABS and PLA. As part of my experimentation I repaired a failed Maker Faire Makey figure. The following video captures the process. (I have since printed a successful Makey Robot on my Printrbot simple Metal)
After some experimenting with 1.75 mm PLA and 3 mm ABS I have come up with a few friction welding tips:
3 mm filament can be used in a standard 1/8 inch collet.
You could also use a Dremel chuck to hold the filament if you have one.
Don’t run the Dremel at full speed. I try to keep the speed as low as I can. If the Dremel tool wants to jump away from the part you are welding increase the speed. (thicker filament requires more speed)
Don’t let too much filament hang out of the collet. Too muck filament will start to whip around and break off.
The filament will wear away quickly. Stop to extend more filament before the extended length of filament gets too short to grab and pull out with a pair of pliers. Otherwise the collet nut will need to be completely removed to pull more filament out.
In addition to repairing failed prints friction welding can also be incorporated into the assembly process. Smaller parts can be welded together to form larger structures.
For example I printed 20 hexagons and friction welded them together to form a truncated icosahedron (same shape as a buckyball). In this case the finished part would have fit inside of my printers build volume but the same process could be used to create much larger structures.
Friction welding is a quick, strong and easy way to join plastic parts together. The great part is that welding the parts together eliminates the need to add additional adhesives keeping the part a homogenous material. Additional structure can even be added if needed for strength. For extra strength prints could even include bevels for strong traditional weld joints.
The files for the truncated icosahedron can be downloaded here: