This is a complicated process, but will help you think through problems you have when using your CNC machine.
Rule 1: Always think in simple terms 1st. Example, is my machine plugged in and is the voltage correct, before i rip all the controls out and start to rebuild the machine. Is bit tight in collet? Is the collet clean after every tool change(remove the collet from nut and clean with air / toothbrush, every use)? Did i bottom out the bit in the collet(not a good idea).
Don’t assume anything. Check the simple stuff first, and break down the steps in the most simplest terms.
Questions to ask:
Is this operator error?
Is the machine connected and operating as it should?
Do I understand what happened?
Do I understand why it happened?
These questions need to be asked when you have any kind of issue or problem. Stop, think and break it down. If you can’t answer the most basic questions, ask for help.
Now Time to break it down to categories.
- Using The Wrong Cutting Tools / Settings
Choosing the wrong cutting tool for the job may often result in poor quality finishes. This could be seen as rough edges, cutter marks on the surface, raised marks, or burn marks on the material’s edges or corners. Excessive tool wear (burning) may result.
Poor material finishes could be due to the type of tool used(upcut, downcut, compression) or improper feeds and speeds.
Using incorrect feeds and speeds, can cause burning of material or tool, breaking the tool, or machine damage. Learn to listen to the machine and watch the chips coming off the cutter. If you hear the tool whining loud, change speed and feeds. There are harmonics beyond just feed and speed charts. If you run too slow, or too high of rpm with low speed, you will see a fine dust come out, not a nice chip size. The chip loading that the manufacturers use, are based on number of flutes
This chip load is used to maximize the cutter efficiency, chip removal and cutter cooling.
Chip load is calculated using the following fomula:
Chip Load = Feed Rate (inches per minute) / (RPM x number of flutes). Example: Chip Load = 500 inches per minutes / (15,000 RPM x 2 flutes)
Chip Load = . 017″.
- Chip load per tooth is the appropriate amount of material that one cutting edge of the tool should remove in a single revolution. This is measured in Inches Per Tooth (IPT).
- Chip load per tool is the appropriate amount of material removed by all cutting edges on a tool in a single revolution. This is measured in Inches Per Revolution (IPR).
A chip load that is too large can pack up chips in the cutter, causing poor chip evacuation and eventual breakage. A chip load that is too small can cause rubbing, chatter, deflection, and a poor overall cutting action.
You might be limited by having a machine with a dewalt router, and then you are limited by the minimum speed the router can run, or having a machine that cannot move fast enough to support the minimum speed your router can run.
Tool Maintenance
Another issue is not viewing the tools properly as having a cutting life. Keeping track of your cutters and how many cutting hours they have, you can start to predict the lifespan of different tools depending on what materials you cut.
Clean tools is just as big an issue. Buildup collecting on the cutters, will shorten the life, and cause poor results.
Your tool has several flutes. The more work you do on the machine, the faster the bit wears out. With proper and consistent maintenance, you can reduce your maintenance costs, and keep your routing quality high.
- Remove Resin
Your router bit will likely have accumulated dust. Blow it off and remove built-up resin. Resin left on your CNC router bit eventually hardens, which reduces the bit’s cutting efficiency. Use alcohol and a toothbrush to clean the bit further. Resin will also build up on the inside of the collet and spindle and tool holder. Use a felt brush to clean it off. The outside taper of the collet and tool holder should also be cleaned, and brass brushes work best for this purpose. - Check Shanks and Nuts for Burrs
Shanks left unclean may prevent you from properly tightening the bit in the collet. And if that’s not tight, it’s easy to see how that could lead to big damage to your CNC router eventually. Use a brass brush to clean the shanks and insides of nuts, on every tool change. - Sharpen Your Router Bit
Only sharpen if you know what you are doing. Most bits can be easly damaged and very dangerous as the speeds that they run. - No Need to Oil
Do not oil your router bits to prevent rust. You only need to dry them well following the cleaning you’ve just done. - Store Your Router Bits Right
Don’t store your router bits in a drawer or box. They can get tossed around, which could lead to damage to their cutting edges. Make sure they can’t move about, wherever you choose to store them. - Change Router Bits Immediately
The moment you notice deterioration of the cutting edge or damage to a bit, change it out and remove the bit from your collection. There’s no need to risk any degradation to your cut quality.
I hope this will give you a starting point to troubleshoot bit use in your cnc router.