Controlling Dado Blowout

[TReischl]

I am cutting dadoes in hard maple (dadoes are cuts across the grain) on parts already cut to size. Using the pocketing or profile tool will cause blowout on at least two corners of the dado. This has nothing to do with the software.

After some thinking the idea came to "roll around" those corners. Here is the technique I use:

Notice that the start points for the vectors are all outside of the part boundary. Also note they extend into the material by a little more than the RADIUS of the cutter.

After cutting 24 dadoes with this technique and 0 blowouts I am happy as a clam. Also tried it on really brittle spruce. I got one very small chip out in a batch of 12 slots.

Creating these vectors is not a big challenge. The easiest way to do it in Aspire that I have found is to just draw two new vectors over the existing ones, pop a fillet of about .005 between them and then offset them. (I actually do it in Corel but also tried it in Aspire to make sure)

When pathing, make sure to set the Tool Path to ON, not right or left.

You could also draw the vectors right on the part vectors and then use right or left to follow them around. If you use this method you must put a very small radius on that corner or the tool will not roll around, it will go past then plunge into the material splintering as it goes!

The parts for this technique to be successful have to be fairly accurate. Undersize by a little bit is ok, but if they are oversize by more than the small radius used to create them marks will be on the edge of the part. So the message is: set this up for the largest part you expect to process.

[Fleming]

Excellent idea! Thanks for sharing that.