Zero the Z Axis

When you want to cut all the way through your material it is a good idea to zero your bit to the spoil board surface first before placing the material. Next using your control software raise the z axis up to the material thickness you programmed. Then reset your z axis to zero. This will ensure that you cut through the material and not into your table or spoil board. Material thickness is not always what it is supposed to be and many materials can be warped so zeroing to the surface of the material can be misleading and frustrating when you cut too deep or not all the way through.

If you are engraving or pocketing or cutting dados or rabbets etc. then you need to zero the z axis top the top of the material being cut.

CNC Dust Collection Hose Track

If your shop ceiling allows you might consider installing a length of Crowder track directly above your CNC table.

I use a Kent dust shoe which accepts 4" hose and hang the hose from the track hangers. The hose slides smoothly as the router cuts. Best solution I have found so far.

Using Pocket Toolpaths for small inside cutouts

Cutting small shapes using "Inside the line" toolpaths can prove to be problematic even with vacuum hold down. This type of routing comes into play when cutting intricate screens or grilles for example. 

The waste pieces often are picked up when the router moves to the next position and can be jammed into the bit and ruin the work piece. I have found that pocket cutting the entire inside shape leaves a clean interior as the small shapes are turned into dust. Also because pocket cuts start in the centre of the shape and work outward there is no entry or exit mark from the router bit.

CNC Air Drilling

CNC Air Drilling custom pegboard

Drilling multiple holes will definitely result in the heating of your bit and eventually burning the material being cut. Slowing the router speed to approx 2000 rpms can help but most routers can't be set this low. When I was doing the CNC work for Robocop 2014 I had to drill 80 sheets of MDF with 5/16" diameter holes and spacing very similar to pegboard. Each sheet had between 8,000 - 10,000 holes and this would have killed the spindle I was using.  By using an air powered drill with automatic oiler and a very large compressor the task became possible and I was able to cut through 4 sheets at a time. In this case a vacuum hold down would not have worked. I decided to drill hold down holes and used screws and flat washers to keep the 4 layers of MDF from lifting and binding when the drill bit lifted out of each drill hole. Mission accomplished!