I am a brand new CNCer. Just finished building a C-Beam Openbuild machine. I am using a Kress 1050 FME-1 spindle (with 5k, 7.7k, 12.5k, 16.5k, 21k and 24k rpm speed settings) and have a variety of 1/8 shank carbide endmills (1.5, 2, 3.125 mm cutting diameter) and some carbide v-bits for engraving. I was able to engrave the Openbuild logo and route it out from 1/8 plywood without breaking the machine or the bits, so that's good.

I am desperately trying to get a feel for depth of cut, rpm and feed rate. I have been using GWizard but some of the numbers seem scary. So, what I am trying to do is simple. I have a 300x300x12 mm spoiler board made out of MDF which I want to bore in an array pattern (in order to add threaded inserts for clamping purposes). Say an array of 8x8 5 mm holes evenly spaced across the piece. How do I go about choosing the right tool and DOC, RPM and FeedRate?

I created a tool path using Cut2D, and selected a 3.125 mm end mill for the job. However, I need to give it parameters. What are the best parameters for MDF. Finally, when using the GW calculator, I got the following values:

Material MDF
Tool 3.175 mm shank, 3.175 mm diameter 2 fluted spiral carbide end mill.
Depth of cut 4 mm
Rpm 21000
Feedrate 903 mm/min

Does this make sense? Seems very fast to me ( I am used to hand routing )... I would love some advice and help in advance rather than trying all kinds of variations and breaking lots of end mills Any rules of thumb? Also, once you have parameters that work, does one use them for all operations, ie, pockets, profiles etc?

Like I said, I am a newbie's newbie!! Apologies if these are silly questions. What would be the best forum discussion to join?

Many thanks in advance to all,