A recent question was asked by one of my customers “These two bits look the same, can I use them interchangeably?”. The customer was referring to a single o flute CNC bit for plastics and a single o flute CNC bit for aluminum and ACM. Even though both of these bits could cut the opposing material they are made for, the answer is “No!”.
Here’s why.
Single O flute CNC bits may look similar but they are created differently to optimally cut a specific material. Four main factors distinguish these apart from one another and are critical to the edge finish and tool life. If you’re looking for optimal edge finish, use the single o flute meant for that specific material.
- Helix Angle
- Cutting Geometry
- Polished Flutes
- Cutting Edge Sharpness
Before diving into each one of these, I will note that upcut bits are going to provide the best quality, effective chip evacuation, and remove more heat. A downcut bit is used more often when additional part hold-down is necessary. A downcut bit can cause rewelding of parts which is where a slight groove in the spoilboard can be helpful for chips to fall free.
(Acrylic/Wood/Assorted Plastics)
1. Helix Angle
The Helix angle of a tool is measured by the angle formed between the centerline of the tool and a straight line tangent along the cutting edge. The helix angle on a single o flute for plastics is going to be less than one made for aluminum. A “multi-purpose bit” is going to be somewhere in the middle. Please note that a multi-purpose bit will not cut plastics as well as a bit created to cut plastics nor cut aluminum as well as one created for aluminum. These are common for users operating a collet spindle in which they use one bit in order to save time. If you have tool holders and automatic tool changing, there is no need for an expensive bit that provides poor quality.
2. Cutting Geometry
The research and testing behind CNC tool cutting geometry was very important in deciding how to achieve high quality edge finishes. This is research that continuously improves which is why new tools flood the market every year. The way a CNC bit cuts into a material and then releases the material chip is important. Too large of flutes could tear material instead of cutting it. Too many flutes could cause an increase of heat. There are many geometry factors that require complete optimization for a tool to work properly. When it comes to single o flute CNC bits, this is exactly the case. The geometry of each has been optimized for recommended materials.
3. Polished Flutes
Polished flutes assist in providing a clean or smooth finish, especially when it comes to a material like Acrylic. The goal, when cutting acrylic, is often to achieve the best and most clear or see-through edge. A polished flute is best suitable to assist in this process because there are fewer tool edges that can cause inconsistencies. On the other hand, a polished flute is not necessary for cutting a material like aluminum. Aluminum is tough enough and doesn’t show tool marks as frequently.
4. Cutting Edge Sharpness
You may think that the goal for tooling would be to sharpen the cutting edge as sharp as it can get. The problem with that is that the edge will then become brittle and/or inconsistent which in turn can cause a shorter tool life and/or poor edge quality. Each single o flute has a sharpness that is best suitable for the material that is recommended.
All in all, single o flute CNC bits made to cut plastic should be used on plastic and the ones meant to cut aluminum/ACM should be used on aluminum/ACM. Again, I personally don’t recommend multi-purpose bits unless someone has a collet spindle, low quality standards, and time constraints. So, do not use single o flute CNC bits interchangeably unless you don’t care about edge quality and tool life. Your product will not look as good as it should and your bits won’t last as long as they could.
This is one of many articles to come, related to CNC routing on this website. We will also be sharing videos and updates on our social media pages. Stay up-to-date with Multicam Great Lakes by following us on LinkedIn, Facebook, and YouTube.
If you need any help cutting specific materials on your CNC Router or Knife Cutter, please call me at (616) 502-7277. I (Greg) manage the tooling department, where we are a distributor for CNC tooling. I work with some of the best tooling suppliers in the world, such as LMT Onsrud, X-Edge, Techniks, Whiteside, LMT Belin, Amana Tool, Emuge, and more. Feel free to check out our online webstore to see some of what we offer. Thanks for stopping by.
Greg Smolka
CNC Tooling Manager at Multicam Great Lakes
Here to help with tooling recommendations (bits, knives, collets, tool holders, cleaners and kits, torque stations, etc.) and cutting recommendations (feeds/speeds, tips/tricks, # of passes, etc.).
