Ive been trying to cut out some dinosaur letters on a growth chart, but cant keep the fine details ( teeth, hands and feet) to not tear off. I made several test cuts on plywood and found that was part of the issue, plywood just isnt stable enough for finer detail. Ive been using a 30° v bit running at 22000 rpm per manufacturers recommendations at a feedrate of 35iph
But before i go and try this on nicer lumber, is it better to reduce the feadrate and rpms when trying to cut those fine details or doesnt it really matter if your machine is stable enough.
A good heavy coat of sealer on the wood before cutting will help bind the fibers in the grain together & prevent chipping.
RPM is a function of SFM (Surface Feet per Minute), the velocity that the cutting edge travels through the material, and the diameter of the tool.
For each tool type, tool material, coating, part material, cutting strategy combination there is an optimum range for SFM.
This doesn’t change based on the level of detail.
I think of this as the “Resolution of the Material”.
Examples:
High Resolution
Maple
Walnut
Assorted other Hardwoods with tight grain structure.
Higher ply count plywood: as mentioned by @WillAdams above
Composites like Richlite and other compressed materials.
Hardened Epoxy
Hard plastics
Metals
Low Resolution Materials
Pine
MDF
Plywood with a low number of plys.
Soft Plastics - HDPE
Cork
Oak can also fall into this category due to it’s wide grain structure.
Some Strategies that may help:
As mentioned, stabilizers. You’re basically coating a Low Resolution material in High Resolution material.
Shallower and slower cuts could preserve delicate features.
Use of smaller cutters to reduce cutting forces
Experience and testing are key. With experience you’ll be able to test a design in MDF, see features that have collapsed and know whether to expect those same features to hold up when you switch to a different medium, like a hardwood. There is no substitute for the experience and knowledge of previous projects.
