Coastal Enterprises, manufacturers of Precision Board HDU, is proud to host guest blogs written by some of the signage industry’s biggest movers and shakers, posted to the Precision Board Blog. This guest blog is written by Adam Carlson with CNC Tahoe. He talks about how a local sign company, Dollar Signs and Graphics, approached him to carve two large crosses with roses around them for a new sign they were making for a local church. They are fabricating the sign itself, but needed to outsource the creation of the two large 3D pieces to mount on the sign. The pieces are 24″ x 42″ and are carved out of 1″ thick PBLT-15 Precision Board HDU. Once Adam completes the carvings, they will be painted and installed on the sign.
A Q&A with Adam Carlson from CNC Tahoe…
How did you get selected to do the dimensional part of this sign?
I live in a small mountain community, but it is also a worldwide destination resort seeing millions of tourists every year. I have been doing CNC work for 5 years and some of my work as been seen and appreciated by locals and businesses alike. I know the owner of the sign company and he knew that I had the machinery and skills to get the job done. He contacted me and I ran a quick sample of the bottom 1/8 of the piece to show him how it would turn out.
Why use Precision Board for this sign?
Precision Board machines better than anything I cut on my CNC. It’s dimensionally stable and is voidless, also lightweight at the 15 lb. density. Because it is closed cell, HDU is waterproof and resistant to heat and cold, making it a perfect choice for all outdoor signage. Dollar Signs and Graphics uses Precision Board on a lot of their signs.
What density of Precision Board did you use for this project?
PBLT-15 Precision Board HDU was the density of choice, I did not make that choice though. The sign shop made that decision and I knew that I’d be able to work with it no problem as I’ve worked with the 15 pound density in the past.
You converted a 2D design into 3D. How did you do that?
I have limited skills in 3D conversion, so I had to outsource the 3D modeling to a professional. The original artwork was given to me by the sign shop who worked with the local church. I then contacted my guy to do the modeling.
What software do you use for your CNC?
For the CAD/CAM I use Vectric Aspire software. It’s great software and I’ve been using it for 6 years. Programming didn’t take too long for me as I’ve done quite a bit of 3D work and know the little things that can cause headaches, so I can avoid them.
What kind of CNC do you have?
I am using a Shopbot Buddy PRSalpha 48-12. Shopbot is a great company based out of Durham, NC and have great customer support and an amazing network of users. This piece maxes out my current work envelope but I am going to expand my table to a 4′ x 4′ sooner than later, it’s currently 4′ x 2′ x 11″.
What router bits did you use and did you need to use multiple bits?
I only use Amana tooling on my Shopbot, which I get through ToolsToday. The Spektra coated end mills last so much longer than just solid carbide and I can personally say that I’ve experienced way longer tool life. I also take care of my tooling and make sure to clean it with a non-caustic cleaner in a ultrasonic unit after each use. Seems like overkill, but I have yet to have a Spektra coated end mill wear out on me.
For this job, I used 2 different end mills. A 3D carving end mill and a straight end mill for the profile cutout. The 3D carving end mill is tool #46284-K from Amana and the profiling end mill is #46483-K.
Speeds and feeds settings for the routing of the Precision Board?
The settings for the 3D portion are: Feed Rate of 600 IPM and Plunge Rate of 420 IPM with a spindle speed of 13,000 RPM using a 10% stepover (.012″). Due to the acceleration/deceleration settings in my control software, there are limits to the machine actually reaching full speed while maintaining accuracy. I’m waiting on new pinions from Shopbot and I needed to get this job done. The sample I ran prior to the job had bad quality because of the worn pinions allowing the machine to slightly miss steps.
The settings for the 2D profile cut portion are: Feed Rate of 60 IPM and Plunge Rate of 45 IPM with a spindle speed of 18,000 RPM cutting at full depth in one pass. I was really conservative on this as I don’t have a full vacuum table and wanted to leave a skin on the bottom to hold it in place. Since PBLT-15 is lighter weight and less dense, I didn’t want to push it and have any chip out or chatter. Worked out perfect and only takes 5 minutes to clean up the “skinning” afterwards.
How long did it take to rout all the PB for this project?
Each piece took approximately 5 hours and 30 minutes for the 3D carving portion and the profile cutout took about 3 minutes. Going into the Shopbot Control software I’m able to adjust my ramping deceleration/acceleration speeds and distances, to maximize speed while not losing quality or having my machine wear prematurely. This is the largest 3D carving I’ve done in my 5 years machining but luckily it went smooth and the finished product came out clean.
Any tips or tricks you used for this project?
If you don’t have a vacuum setup, using the “skin” method during the profile cut will help keep your piece in place while allowing you to use a few screws to hold down the main board. Especially with PBLT-15, when you go to remove the skin, it comes off so easy you really only need to rub the edge with your fingers and the edge is clean and sharp, removing the .005″ of material that was holding it to the main board. Max out your feeds and speeds because as long as you have an accurate machine, PBLT-15 truly cuts like butter.
Coastal Enterprises is a 30-year old privately-owned company, located in California. Our manufacturing producst and processes are fully integrated in the United States, which has allowed us to avoid supply chain disruptions and maintain unparalleled market stability. For thirty years we have manufactured Precision Board, a high-density urethane tooling board used in many different applications including composite tooling, prototyping, thermoform tooling, pattern making, theming, dimensional signage and more. It is currently being used in many essential industries including aerospace, defense, transportation, energy and healthcare. You can get pricing, free samples, sign up for newsletters or contact us.