A great question I was recently asked prompted me to write this post. When are your power carving burrs really worn out? That is a simple, yet, widely variable answer, and one that I will try to answer here. There are a few factors to consider.
Does The Material Being Carved Affect The Burr?
Yes, depending on the material you are carving the burr you are using may or may not be worn out. Some woods burn much easier than others. For instance, Poplar burns really easily even with brand new burrs. Each wood has different properties, and will let you know if your burrs are sharp enough.
The tell tale sign is that the carbide burr will burn the wood even after it has just been cleaned.
MDF is an interesting material because I can carve a lot with the same burrs without any burning. These same burrs that carve MDF just fine will burn on Poplar and burnish on Walnut. It really is dependent on the material.
Of course having sharp burrs is important, and the sharper the burr the less strain it puts on the turbine of the high-speed engraver and less torque on other tools.
The easiest way to tell if a carbide burr has worn out is by how much it burns the material you are carving.
Schedule Replacing Power Carving Burrs
I would not carve indefinitely with the same burrs. Depending on how much I carve I would set up some schedule that would allow me to swap out burrs on a regular basis. (This is most important when the carbide burrs are really small, such as with the high-speed engraver.)
You can find uses for many “worn out” burrs. They can last you a long time, but when your finished carving really depends on presenting the best quality you can complete using new burrs will always give you the cleanest most professional results. (Especially true with 1/16″ high-speed engraver burrs.)
The Larger The Power Carving Burr
The larger the carbide the longer its life will be. If you are carving with a flex shaft machine or micro carver, and your burrs are bigger they will last much longer than the smaller burrs.
I use Saburr-Tooth carbide burrs with my flex-shaft and micro carver. Some of these burrs I have had for about 7 years, and they are still doing a great job for me. I do not use them as often as my high-speed engraver burrs, but they still have lasted a very long time.
Is There A Specific Number Of Carvings That Can Be Completed Before The Power Carving Burr Is Worn Out?
There are too many variables that influence when a burr is worn out. Everything from the initial sharpness of the burr, how durable the burr is, what scale of carving you are working on, and even what type of material is being carved. There is no set number of carvings that will tell you when your burr is worn out.
You will just have to pay attention to each burr, and replace it when it is time.
Diamond Burrs Are Different
Diamond burrs are a bit different. As they wear out they become smaller. If, for instance, a round diamond is one size when it is new, and gets smaller over time replace it with the size you need, but keep using the old one where it fits in your carving process.
I will use diamond burrs until the shaft in the center is sticking out, and I cannot get the cuts I am looking for from them.
I hope that this gives you some guidelines to help you determine if it is time to replace some of your burrs.
Be safe, have fun, and enjoy all your power carving experiences.