Hi all,
I’m new to CNC woodworking so I was wondering if anyone could help me out selecting a set of bits that are a must have.
Thanks,
Coen
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Same case here, very new to all this. I would at least like to know what the standard is (size and quality-wise) for each material. Then there is a basis one can work with. And subsequently how smaller you’d go in size and what would be the compromise for that. If anyone has tested and has anything to share it would be pretty much appreciated.
I have some experience with conventional CNC, but I think the overall cutting speed one can obtain with a fixed frame CNC is not comparable to one you’d be able to obtain with the goliath.
That being said, you normally calculate a so called chip load. The chipload is the thing you use to determine the ratio between the rotation speed and the movement speed. The chipload is a material parameter of the thing you are trying to cut.
Chipload is one of those magical terms, that if you know it, a wealth of information is suddenly available on google.
To answer your question briefly:
generally speaking a smaller mill bit has to do more passes and may bend more easily if there is too much force applied to it. It also generally has to rotate faster, which may run into the limits of the router/spindle.
here is a table I found online:
Mind you, these are kind of magical values, and you can probably find some differences in the actual values.
Thanks for the table.
Interesting the mix between imperial and metric dimensions.
For the start I would suggest do not go deeper then the milling bit diameter for soft wood.
If you want to go faster then use so called SCHRUPPFRÄSER these do not generate a fine surface but eat a lot material, just add one additional pass with a normal bit to remove the last remaining 0.3mm and clean the edges.
As I have not recieved my Goliath I’m not able to tell
what forces during milling the machine can withstand. Therefore depht, speed and rotation speed may need to be adapted.
Yeah, I’m quite sure that these are different from what I’m used to in CNC machines. The behavior isn’t exactly the same. I’ve noticed that especially the first pass is very important. If that one is correct, the whole part is much more likely to come out nicely. I think this is because the toolbit has a path to follow and this sort of stabilizes the machine and removes small oscilations or inaccuracies.
Goliath is different from conventional CNC because it is relying on its own weight to avoid skidding. Goliath weighs less than 20 kg!
In a conventional CNC machine with a suspended motor, it is almost impossible to make a driving belt skid…
That is why Goliath’s feeding speed should take this fact into account.
It is already half a miracle that it cuts wood with a weight less than 20 kg.
Hello @phoenus
The fact that despite Goliath weighs less than 20kg it is able to cut wood without slipping is not a case.
We spent months trying to find the perfect balance between the torque of the motors, the power of the spindle, the wheel’s dimension, and the workpiece friction. Goliath works thanks to the correct balance of these elements. 
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