Sometimes a broken part was generally too weak to begin with or does not have much surface area for bonding. To achieve a good repair additional material needs to be added to supply more strength or surface area for bonding. One way that I have used to provide the additional material has been to wrap string around the parts and bond the assembly together into one solid mass. This is essentially a low tech composite material. The resulting repairs are very strong. The scissors in the picture above has taken much more abuse after the repair than it did before it initially broke. I regularly use the scissors to cut cardboard and whatever else gets in my way in my shop.
Embedded below is a video detailing this method being applied to the handles on a cheap dial indicator stand.
In addition to repairs this technique can be used to reinforce items that are likely to fail before they are put into service. The picture below shows a toy that I made for my kids (Lord Garmadon’s staff). The two pieces of wood are joined in such a way that the staff would likely split along the grain if not reinforced. For this item I used school glue and kite string.
The first time I ever saw this method used was in a model airplane. In the airplane there were push rods running from the servos to the control surfaces. The ends of the push rods were made from steel piano wire and the middle of the push rods were made from balsa wood. In order to secure the piano wire to the balsa the instructions detailed how to overlap the piano wire and balsa then wrap the overlapping region with string coated with glue. The procedure produced a very solid push rod assembly.
I have found this to be a reliable method to repair and join parts. I hope you find it useful too.
ScorchCAD is a side project that I have worked on for a while. It is a clone of OpenSCAD written for Android devices. It is a clone of OpenSCAD meaning that it aims to provide the same functions as OpenSCAD but it does not use the same code. So far ScorchCAD is written completely in Java (OpenSCAD is C++). The ScorchCAD program is to a point that it can take input (OpenSCAD code) and return the result to the screen. The features that are working right now are: cube, cylinder, sphere, translate, rotate, scale, union, difference and intersection. There is a lot of work left to do on this program including all of the little things like opening/saving files. The constructive solid geometry (CSG) library is CSG.js converted to JAVA. There have been a lot of improvements to that library by the guys at OpenJSCAD. I either need to upgrade my JAVA code to incorporate the OpenJSCAD improvements or go to a different CSG library (Maybe one written in C++). The video embedded below shows how things are coming along so far.
I made a quick release of F-Engrave Version 1.31 to fix a new bug that was preventing batch mode from working in version 1.30. I have a backlog of other items that I intend to change but this bug fix jumped in from of the other changes because it was a simple fix and it prevented a feature(batch mode) from working.
Hackaday is having a contest to see where people can put the Hackaday skull and wrenches logo. I thought I would take a little time and throw my hat into the ring. The pictures included in this post are of the logo engraved onto a dime. The engraved image is .064 inches tall. The judging criteria is partially based on the size of the logo. That is to say preference will be given to very large and very small logos.
My machine has a lot of backlash (about 6% of the image size) so I set it up to cut scan lines in one direction. Since the machine is always cutting in the same direction the backlash doesn’t show up in the engraving.
The surface of the dime was not flat so I had to make a second pass to cut the right hand side of the image a little deeper (.002 inches). I used Dmap2gcode to generate the original g-code and I used G-Code Ripper to split the g-code in half so I could cut only the right half of the image on the second pass.
G-Code Ripper version 0.03 has been posted to the G-Code Ripper Homepage. The new version has more plotting options including more isometric view angles. The big addition in this version is the ability to map g-code from the X or Y axis to a rotary axis A or B. This functionality is very similar to CNC wrapper.
G-Code Ripper: G-Code Wrapping Features
Graphical preview of the resulting g-code.
Automatically maps g-code arcs to linear movements prior to conversion to rotary moves.
Options for scaling feed rates to make them compatible with the rotary movements.
Interpret g-code variables and equations.
G-code Rippers basic features can also be used to scale and rotate the g-code before wrapping the code for the rotary axis.
I saw a video of a cylindrical lithophane made from a PVC pipe a few years back (You tube Link). I had always wanted to replicate it. Not only have I replicated what was done in the video I did it with all open source software. The picture above shows the PVC pipe lithophane I created on the left. On the right is the same lithophane with a candle inside for back lighting. I used Dmap2Gcode to create the g-code for cutting the image based on the lightness of the picture then I mapped the Y-axis to a rotary axis (A-axis) using a yet to be released version of G-Code Ripper. I will post again when I finish testing and release the new version G-Code Ripper.
F-Engrave now can determine which side of the loops in a DXF design need to be cut. Previously the input needed to be formatted so that the loops in the design were clockwise or counter clockwise to determine whether the inside or outside of the loop was cut. Most programs that export DXF files do not do this automatically. Some hard core F-Engrave users took the time to manually flip the loop directions as needed in Inkscape to get there designs to work with F-Engrave. My hat is off to those users! This release goes out to you guys. Kick back and relax while F-Engrave does the work for you now. The calculations are so fast for small designs you may not even notice the message telling you that the side to cut are being determined.
In addition there is a new “V-Carve Accuracy” setting. This new setting can be used to ignore small features in a design. This is especially useful for small DXF design imperfections which result in bad v-carve tool paths.
I had a chance to sit down for a couple of minutes with a 3Doodler. In just a minute or two I made the little tripod tower in the picture. It is really easy to get started with the 3Doodler you can get creating things right away. I am just not sure what I would do with the items that were created. The doodler is not really for making prototype parts. It is more geared toward creative works. I am not much of an artist but even if I could create a great looking piece with the 3Doodler it would still be made of plastic. A piece of plastic art just doesn’t have the same appeal as other materials. The 3Doodler was pretty neat but I don’t think I would have much use for one.