My most satisfying and, I dare say, favorite hobby is subtractive manufacturing on the CNC. I am by no means a professional, but I take great pleasure in the process of designing something and working through the process of setting it up in CAD and CAM, then watching it become a real thing on the machine. I know that most CNC owners will talk about how cliche is is to make signs but it’s something cheap to produce and is always appreciated by the recipient. My friend wanted to buy a sign online for the front of her house with the street number and showed my girlfriend what she was planning to order. It was fairly pricey and not the best quality for an exterior decoration. (Sidebar: I love seeing people sell handmade items on Facebook Marketplace and Etsy, but it drives me nuts when they use materials that just won’t hold up to the abuse of being out in the weather. Please make sure you are asking about the materials used and researching whether they are going to hold up to what you are exposing them to.) My Lovely S.O. decided to volunteer my time and tools to make something a little heartier.
The first thing people should know about me is that I like to support small software developers and open-source projects (read as: I am incredibly cheap when it comes to buying software), so for 2D and 2.5D designs I use Inkscape and for CAM I use Estlcam. These are both excellent pieces of software and I fully recommend them to anyone trying to find a cheap alternative to getting into CNC. I was using Autodesk Fusion360 for 3D design but due to recent changes in their hobbyist license I’m currently in search of a new option in that arena. Inkscape is 100% free and open source and serves as a very capable replacement for Adobe Illustrator. It has a great community of users that have detailed tutorials for every feature (Check out Logos by Nick on his website or on YouTube, he’s got some of the most detailed tutorials that I’ve found). EstlCAM is a free to use CAM software with a quirk, as you use the software more and more, there is an ever-extending timed wait to save or load files. The license to get rid of the timer is a mere $60 and totally worth the money if you are totally impatient like me.
But back to the original topic… I decided on 3/4-inch whitewood ply from the big blue box store for this sign, mostly because it’s of adequate quality for a painted sign and it’s cheap enough to give away without crying over the price later. Due to the surge in number of HGTV star wannabes during the COVID Pandemic, there’s not a lot of cheap materials available in my area. Box store Plywood was a good point to settle on for quality and price.
My process started at the computer in Inkscape. I generally work up 3-4 designs and stare at them for hours until I narrow it down to 2 that don’t completely suck before presenting those to the boss to make a final decision before refining the design. I think it was a total of 10 minutes from concept to presentation, maybe another 10-15 minutes to refine and get final approvals from the Front Office. I always try to design in 1:1 scale to make the jump from Design to CAM seamless. At this point I save the design to DXF 14 in Inkscape and open it in EstlCAM to start creating tool paths.
Inkscape Design
I don’t trust my Marlin based CNC controller to stop for tool changes so I generally break my tool paths up into separate files. This particular project used 2 bits, a 60 degree V bit to chamfer edges and vcarve the digits and a 1/8″ straight bit to cut the pockets and outlines. Literally 10 minutes of programming paths , verifying correct depth of cut, feeds, and speeds, and writing down the order of files to run and what bit they require. Carving/Chamfering took approximately 40 minutes at a conservative 2000mm per second speed and 2.5mm depth of cut , and cutting out the part took 12 minutes at 2000mm/sec and 2mm DOC. The speed and DOC for both programs could have been increased to shorten these times but I was testing after making some software changes and wanted to make sure I had time to smash the Emergency Stop if necessary.
Overall, this project took about an hour and a half from design to completion. I did take a few extra minutes to apply a couple coats of shellac to protect the sign until painted. Painting, as always, is someone else’s problem… I hate it so much!
6.8.21 – Our friend was nice enough to send over a picture of the painted sign.
