What I Learned From My First 3D Carve

Jul 16

“Any fool can know. The point is to understand.”

― Albert Einstein

3D carves have always been daunting to me and felt far beyond my ability. I kept telling myself that only the pros that have been at this for years can do it well. Recently, I finally took a stab at my first attempt and am obsessed with the result! I learned a lot in the process and hope that I can help others take the leap into the world of 3D carving! Disclaimer: I am by no means an expert and all speeds and settings discussed are merely suggestions and not professional advice. Please adjust based on your machine, material, and depths!

To begin, my machine is the CNC4Newbie new carve and I use Aspire to create my toolpaths and UGS to send the code. I purchased this file from 3dwave.us. We also offer a lot of 3D content on our own site to our members! But this one was a special selection for my father-in-law’s birthday.

Setup

I selected a small piece of scrap cedar for my material. The reason I chose cedar is due to a post I saw recently that mentioned how well cedar carves and I had a nice thick 1” piece on hand (it also has made my shop smell fantastic!). The first step was sizing my surface in aspire. For this carve it was 14” tall by 5.5” wide by 1” tall. Next I imported my model which was imported far larger than the material I was working with. I left “lock xyz ratio” selected and first sized the height and width to maintain scale. Then I unchecked “lock xyz” and chose to size my depth to 0.75 inches (I will explain why below).

The next adjustment I made was adding “base height" to the model to make it thicker and sturdier. Cedar is so soft I didn’t want this breaking the second it got off the machine bed. By double clicking the name of the model it brings up the model properties menu. I adjusted the backing, adding 0.2” to the overall thickness which brought the total height of my model to 0.95 inches. The final step before selecting bits and toolpaths was outlining the model for my final profile cut path. This can be done using the “create vector boundary” tool shown in the image below.

Creating Profile Outline

Toolpaths

I asked and received a lot of suggestions for appropriate bits, toolpaths, speeds, plunge rates, etc. What I learned from that; there’s more than one right way to 3D carve. What some prefer others will prefer something entirely different and that’s perfectively fine. I did not have a large ball nose on hand for my roughing pass so as some had suggested I used my 1/4” endmill for roughing, and it worked great! I was also told my bit was too small but the detail I achieved in the end is so worth it to me! My parameters can be seen in the images below for each bit. After some discussion the general consensus is between 7-10% stepover for detailed passes to avoid lines and can be larger for rouging pass. It’s important with 3D carves to increase your plunge rate to speed up the carve time with some much vertical travel involved in these carves. The first past on the detailed carve will undergo the most stress, after that it is only carving a very little bit of the wall and base as it travels.

Other parameters for 3D carves include the area machine strategy (offset vs raster) and machine allowance. It was only after I completed the carve and noticed I still had lines - even with such a small bit and stepover - that someone told me I need to be using the raster option. Raster will move your bit left and right slowly moving down until you have a completed engraving as if it was printing. Offset, which I used in this engraving as it was defaulted to that setting, is moving the machine in a spiral outward from the middle until the image is done. Raster will result in cleaner engravings. If you look closely at my completed images you will see lines from using the offset option. The machining allowance is a virtual thickness which is added to the 3D model when the Roughing Toolpath is calculated. This ensures that the toolpath leaves some extra material on the roughed part. I set mine at 0.01 inches. If you are using wood that tends to splinter easily increase your allowance. Once all set preview your toolpaths to see how it looks!

End Results

I use UGS platform to send my code to my machine. I was so nervous to press start (anyone else get an adrenaline rush?) but once it started I was mesmerized watching it work. I got very little done over the two evenings watching while my machine carve this out. In total it took 7 hours to carve. This is a long time and I’m sure I will be able to speed this up by tweaking my settings and speeds. 0.5mm bit is small and is why it took as long as it did but the detail was worth it to me! I painted it matte black and after a day of drying sanded with 000 steel wool which gave it an almost metal like finish. My father-in-law will love it and I plan to mount it to a matching style rustic look flag.