4. Computer controlled cutting¶
This week I worked in Corel Draw and SOLIDWORKS to create files for the vinyl cutter and lasercutter. I am realy proud of how I was able to design a parametric model in SOLIDWORKS. I was able to use three variables and a bunch of equations to drive the model. Below is my initial sketch of the way I thought the model would work.
This was a stretch from last weeks Computer Aided Design assignment where I modeled a bunch of basic parts. The parametric model was a great way to start exploring design tables and variables. Also, I will use CorelDRAW to make a Fab Lab logo for the vinyl cutter.
This video shows the variables in SOLIDWORKS and how I was able to design a model that morphed based on the variables.
The lasercutter was used to cut the model out of cardboard. As you can see, the press-fit construction kit is based on the toy Lincoln Logs.
Click Here for all the files I designed in SOLIDWORKS and Corel Draw.
Parametric Building Board (SOLIDWORKS)
Vinyl Cutting with Roland GS-24¶
I added a little bling to my office window in red to match the building color scheme. I think it looks professional enough facilities won’t even say anything. Below is how I made it.
I started with the vinyl cutter since I figured it would be the simplest win. I designed the file in Corel Draw. I used the Fab Lab logo and traced it with the line and circle tool.
The machine is simple to operate but there are a few things that are critical to setup. To load material is the lever at the rear of the machine is lowered. This disengages the rollers and allows vinyl to be inserted from the rear. The ridges on the front and back of the machine should be used to ensure that the vinyl is straight.
Once the vinyl is inserted straight the rollers should be adjusted to they pinch th edge of the material when the level is re-engaged.
It is important to place the vinyl in a location that allows the rollers to align with the edge of the vinyl and be located in the white area.
The white area indicates where the rollered is textured like sand paper. This texture is what creates friction on the bottom of the vinyl.
The last thing to be aware of when placing the vinyl is that there is an optical sensor in the front of the machine. This sensor must be covered by the vinyl at all times or the machine will stop cutting because it thinks the vinyl was unloaded.
Prior to making my first cut I ran a test cut. By holding down the TEST button for 3 second the machine cut a small circle with a square on the inside of it. The circle should peel off without being stuck to the square. Also, when the square and circle are removed there should be a slight emboss in the paper from the blade at the edge of the square. If the blade cuts the paper the blade needs to be retracted and if there is no emboss the blade needs to be extended.
Finally, I cut my Fab Lab logo and it came out great. I was easily able to weed the vinyl, leaving only my sticker.
The final step for application is the apply transfer tape. We use contact paper because it is just sticky enough to remove the vinyl but not so sticky that is sticks to what the vinyl is applied to.
Epilog Mini 40 Watt Characterization¶
Fab Lab Houston has two 40 watt Epilog Lasers. The Epilog manual has a list of settings for tons of materials. Using the settings in the manual I ran a bunch of different tests.
I made some laser setting cards based on a friends design from Rice University. My goal was to list and visualize the recommened settings found in the manual. To engraving I varied the fill instead of the power and speed. This allows the machine to adjust dynamically.
For my projects I wanted to used cardboard and settings for cardbord are not in the manual. The closest material was matbord so I started there.
The setting made a clean cut but as you can see on the left cardboard shape the laser didn’t cut all the way through.
I adjusted the speed down to 15% and raised the power to 50%. This made a clean cut without burning the material.
One of the important factors about pre-fit projects is that the fit needs to be consistantly snug. To do this the kerf has to be accomodated for. The kerf is the portion on the material the laser burns away.
To calculate the kerf I cut three rectangles that were one, two, and three inches wide.
Once cut with the settings discribed above I measured the rectangles with calipers. They all consistantly read .016” smaller than the design. Since there is a kerf on both sides of each rectangle .016” is divided by 2 to determine the kerf of a single line cut by the laser.
Epilog 40 watt Kerf of cardboard cut at 15% speed and 50% power is .008”.
Parametric Design for Laser Cutter¶
I took this parametric challenge as an oportunity to dig deeper into SOLIDWORKS. This allows my work flow to be consistant.
Below I opened the program to start modeling I thought it would be helpful to figure out the logic of the model on paper. I’m really proud that I able to drive the model with just 4 variables.
The SOLIDWORKS Equations tool makes parametric design really nice. The global variable can be entered by navigating to TOOLS/EQUATIONS
The four variable I sketched on paper were entered into as Global Variables and given names that I would recognize down the road.
Once the global variables are defined any sketch can use them. When adding a dimension simply type “=” before the variable and it will show all the global variables in a dropdown.
Once a dimension is driven by a variable the red E symbol will appear to indicate the equation.
The Boss-Extrude feature can also be defined by variables.
Here you can see the by adjusting the repeat variable I can change the number of slots.
SOLIDWORKS & Laser Cutting¶
To cut the SOLIDWORKS files on the laser cutter I updated the vaiables, after measuring the carboard thickness, and saved the file as a DXF file. To ensure that the model was saved from the correct angle, with straight lines, I selected EXPORT/FACES. Then, I clicked on the face of the model that would be cut on the laser.
Once the check markis clisked a pop-up windows opens and shows how the file is being exported.
When the file is opened into Corel Draw the selected ENGLISH(inch) as the unit to import. Then cut the files on the laser using the setting listed above.