The Hell Ya Beller Fun with hot, pointy, sharp, and caustic stuff.


A nifty work-around for HeeksCNC Kurve offset error

HeeksCNC can be finicky about profiles.  Often I've found that a sketch which should be easily profiled won't generate any gcode at all.  When I look in the console, I find an error like this

  File "/usr/lib/heekscnc/", line 247, in profile
    raise Exception, "couldn't offset kurve " + str(offset_curve)
Exception: couldn't offset kurve <area.Curve object at 0xb6f4bf2c>
It most often happens when profiling inside a closed sketch where the radii is close to the diameter of the cutter.  Sometimes I can get around it by changing from climb to conventional milling or vice versa.
Recently I was profiling several cutouts that were exact copies of one another just rotated around a central point.  Some of the cutouts would profile fine and others wouldn't  I emailed Dan Heeks the author of the software and he clued me in to a work-around.
It seems that the error is coming from the entry point.  By simply setting a new start point for the profile close to the middle of the longest span, the error magically disappears.
This won't work in every case, especially if the pocket is very close to the size of the cutter or made up of tight curves but for the most common cases it should work fine.  Thanks Dan!

Cutting the cube.

I designed a nested cube in HeeksCAD and thought it would be cool to try casting it.  First step is to cut a foam version of it.

Since my router is only a 3 axis machine, I can only do the pocketing operations on one side at a time.

With the pocket operations, it looks something like this:

The interesting challenge here is to find a way to hold the cube in a repeatable position so that I can perform the same set of operations on all six sides.

I was afraid that if I used double-face tape, the cube would be too fragile by the last face to easily remove it from the table.

The solution I came up with was to build a jig out of other pieces of foam taped to the table.  The jig is deep enough to hold the cube securely.  It's also tight enough to give a repeatable position.


Am I too proud…?

Designing the thing you want to make takes a lot time, thought, and expertise earned by trial and error.  Designing a way to actually make the thing is the same.  I'm amazed at how much effort and creativity I have to put into holding strategies.  So when it comes right down to it, am I too proud to screw the block right to the machine table?

Nope.  I'm not.


Arrow of Light – Getting Started

O.K.  It's time to get this project rolling.  I've already finished the design, now it's time to turn it into some plaques.   I'm going to be making nine plaques and each plaque is going to have numerous operations including

  • Pocketing the holes
  • Profiling the curved edges
  • Engraving the names and other information
  • Drilling the holes for the arrow holders
  • Drilling a keyhole for the wall hanger on the back

The first problem I have to solve is holding and alignment.  Since I'd like to do the same operation on all nine before moving to the next operation, I need to find a way to hold the stock material securely and repeatably.  Here's the solution I've come up with:  I'll attach a piece of MDF to the router table and pocket out a large area to exactly fit the stock.  The pocket will only be a 1/4" deep or so to keep the stock from sliding sideways with the force of the cutter.  Then I'll attach each piece of stock in the pocket with double-sided tape.

The other advantage of this is that I can cut the stock to the exact dimensions on the table saw and avoid having to profile the entire edge.  The only section that will have to be profiled is the two curved corners.  This will help speed up the machine time.

In the picture above, you can see the design for the 'jig pocket'.  The pocket has round corners to let the cutter move in.  Without that, the corners would be cut round at the radius of the cutter and wouldn't accommodate the square corners of the stock.