Author Archives: Scorch

3D Printed Lithophanes

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.

Proposed Projects for the 2015 Minneapolis/St. Paul Mini Maker Faire

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.

Gingery Lathe

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.

Aluminum Foundry

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.

See You at the Faire

Of course if you see me at the Minneapolis/St. Paul Mini Maker Faire you are also welcome to stop by and chat about my CNC software (F-Engrave, G-Code Ripper, Dmap2gcode) or ScorchCAD (OpenSCAD clone for Android)

Bottle Openers Made From 16D Common Nails

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.

Friction Welding (with a Dremel Rotary Tool)

Makey Before and After

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.
1.75 mm filament can be used in a 1/16 inch collet (available at most hardware stores. usually in a set of four Dremel collets )
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:

Update 12/26: Why stop there below is a quick GIF of a dodecahedron made from pentagons.

Lithophane Christmas Bulbs

I have been playing with making spherical lithophanes with my new 3D printer (PrintrBot Simple Metal). I wrote some Java code to read the image data and then map the image to a sphere. The thickness of the sphere is determined by the darkness of the image. Below are some pictures of the results. I illuminated the bulbs by drilling a small hole in the sphere and sticking a Christmas light into the hole. My Christmas tree lights are colored resulting in the bulbs appearing colored when illuminated.

Here is a shot of some of the bulbs without illumination.

I would like to add features to the balls to make them look more like traditional Christmas bulbs but the mesh that is produced by my Java program is so large that I have not been able to perform even the simplest Boolean operations on them.

Maker Faire Tradition – Hitch Covers

When my kids and I went to Maker Faire Kansas City we made a Maker Faire themed cover for the hitch receiver on our minivan. For Kansas City we used the themed graphics right from the Make web page. Well this weekend we are heading to Maker Faire Milwaukee. Unfortunatly Make does not have any site specific graphics for the Milwaukee faire. So I made up my own graphic for the trailer hitch. Makey the robot with a cheese hat.

Here is a picture of our first hitch cover for Maker Faire Kansas City.

ScorchCAD Version .04

After a summer break from ScorchCAD development I am back at it. The latest version of ScorchCAD is available on Google Play. ScorchCAD is also now available on the Amazon App Store.

Here are the highlights of the new features:

Hull
Multmatrix
2D shapes (circle, square, polygon)
2D boolean operations
Resize
Intersection_for
Nested for loops (i.e. for(i=[1:5],j=[1:5]) )
Polyhedron
norm
cross
min
max

Additionally there are some usability changes. ScorchCAD will now backup the current data in the code editor when the compile button is pressed. This data is reloaded when a new session of ScorchCAD is started. This will allow for data recovery in the event of a crash. Additionally ScorchCAD is now associated with *.scad, *.stl, and *.dxf file extensions. So from a file manager you can click on one of these files and ScorchCAD will show up in the available programs to open the file. File associativity also works for *.scad files in e-mail attachments.

Dmap2Gcode (image to g-code) Update

I released a new version of the image to g-code conversion program Dmap2Gcode. The new version is 0.02, the updates to the program are listed below:

Added option to disable arcs in the g-code output (useful for GRBL/ShapeOko compatibility)
Fixed bug resulting in the selection of columns then rows having no effect
Added automatic scaling of all linear dimensions values when changing between units (in/mm)
Fixed bug when using a configuration file (“dmap2gcode.ngc”)

A Much Faster F-Engrave (V1.40)

The latest version of F-Engrave includes major improvements to the v-carve calculation speed. The first is based on input from geo01005. He shared his work on his BLOG and in this YouTube Video. The added code that breaks up the design area into a grid and stores the grid locations that are within the tool diameter. The v-carve algorithm uses this data to skip over line segments that are farther than the max tool diameter from the current line segment. F-Engrave had previously skipped some segments but geo01005’s implementation was significantly (2 to 3 times) faster.

In addition to the code changes geo01005 also showed that using Psyco with F-Engrave was of great benefit. Psyco is no longer supported and is not compatible with the latest (or most commonly used) Python distributions. However, the speed improvements were significant enough (3 to 4 times faster) to convince me to downgrade to Python 2.5 for the windows executable distribution. I am sticking with Psyco rather than another JIT compiler (pypy, Jython, IronPython, etc.) because Psyco is easy to implement and compatible with Py2exe. I use Py2exe to generate the windows executable files.

The final speed improvement, which is turning off plotting, has been available for some time in F-Engrave. I have not pushed the use of this feature because the savings has only been a small percentage of the total v-carve time (depending on the design). With the other improvements included in V1.40 plotting has become a significant player in the total calculation time. Now turning off plotting can make the v-carve calculation 2 to 3 times faster (or significantly more depending on the design). I have added a check button to the calculation window so the plotting can be turned on/off, on the fly, during the v-carve calculation.

So if you are paying close attention you can see that all of these increases in speed build on each other (multiply not add) and result in a v-carve calculation 12 to 36 times faster than in the previous versions of F-Engrave.

I have also been digging into the code and fixing various minor bugs and adding some features to make aligning multiple v-carve files easier. Here are the highlights of the other changes:

Changed Default Origin behavior (for DXF/Image files) to be the origin of the DXF file or lower left corner of the input image. (“Bot-Left” still provides the same functionality of the old “Default” setting)
Added automatic scaling of all linear dimensions values when changing between units (in/mm)
Fixed bug in clean up function in the v-carve menu. (the bug resulted in excessive Z motions in some cases)
Fixed bug resulting in the last step of v-carving for any given loop to be skipped/incorrect.

Auto Probing With G-Code Ripper

When g-code is generated by most software it is assumed that the stock material is flat and level. Sometimes the stock material is warped, not mounted level or was never intended to be flat. One way to overcome the problem of un-level stock material is to machine a flat area onto the stock material or to invert your thinking and cut only what isn’t the design you want. An extreme example of the second case is illustrated in the bat I modified for my brother (see the “Man Cave” bat below).

Another approach to dealing with stock material that is not level is to measure the existing geometry and account for the un-level geometry. This can be a tedious task to perform manually and many programs used to generate g-code for CNC machines have no mechanism for accounting for the out of level condition of the workpiece.

G-Code Ripper‘s solution is to read g-code generated for flat stock and modify the code to include probing of points on the stock material using the CNC machine. The resulting probe data is used to automatically adjust the tool paths in the g-code file. The probe points are arranged in a grid pattern and the cut depths over the range of the tool path are determined by Bilinear Interpolation. G-Code ripper keeps track of which points are needed for calculating the interpolated Z positions for the tool paths. Probe points that are not required during cutting are not measured during the probing process. G-Code Ripper allows the tool and the probe to be in different locations, the location of the probe relative to the tool is entered into the probe offsets settings in G-Code Ripper.

Using Auto Probe in G-Code Ripper:

You will need to have a working probe and be running either LinuxCNC or Mach3 as your machine controller. You don’t need anything fancy for a probe. simple momentary switch will work just fine in most cases. I have been using a momentary switch I had in my parts box. You can see what my setup looks like in the embedded video below. There is good information for setting up MACH3 and LinuxCNC probes on the Autoleveller site.

Get G-Code Ripper Here: G-Code Ripper

1. Open an existing G-code file (if it open properly the tool path will be shown in the display canvas)

2. Select the Auto Probe option from the radio buttons in the lower left corner of the G-code Ripper Window.

3. Set the options on the right side of the window. (Details for each of the options can be found here G-Code Ripper Manual)

4. Save the G-code file using the button on the right side of the window.

Background:

The basic operation of G-Code Ripper’s auto probe routine is based on the technique that is used by Autoleveller. In fact G-Code Ripper even uses the same form of the bilinear interpolation equations. However, Autoleveller is specifically geared toward creating circuit boards. Since the circuit board has a conductive surface the probing can be performed using an electrical circuit which includes the cutting tool in the collet and the top of the printed circuit board. Using the cutting tool as the probe has the advantage of ensuring there is no offset between the probe and the tool. Autoleveller also assumes the workpiece is very close to flat (Autoleveller uses the first probe point to determine a new zero reference) G-Code ripper does not make any such assumption.

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