Sunday, July 10, 2011

Translating toolpaths with scriptop

I have committed a change to my git repo that lets me snap new coordinates anywhere on the drawing and then have my toolpaths generated relative to it. This becomes useful if I import a dxf file and the geometry isn't anywhere near where it needs to be for sensible fixture offsets. Here's an example:

Notice how the origin/datum is to the far left of the rectangular sketch. To make things a little easier, create a new coordinate system with 'Set Origin' (I like to use the 'Pick 1 Point' option).

Snap the new coordinate datum to the upper left corner of the sketch:

Create a 'ScriptOp' operation and copy/paste the new coordinate object into it. Then you can position the ScriptOp operation just before a regular machining operation,such as Profiling. When you post process, the gcode will be shifted by the distance that the new coordinate object is away from the original origin:

This is useful if you want to place your fixture offset in a familiar place. In the case of this sketch, the fixture offset (G54-G59) is placed in the upper left corner. I like to place a fixture offset on that corner because I touch off to the fixed back jaw of my vise and the left side of the part. There are always other ways of doing things, but that is a common one.

Note for my fellow git brothers: I changed,, and ScriptOp.cpp to make this happen :)

Saturday, July 9, 2011

Manual Tool Changer Carousel

My Bridgeport CNC mill uses 'Quick Switch 30' tooling. I like it for prototype work- it's easy to change out a tool by hand. All that's required is a spanner wrench at the spindle nose to loosen and tighten the knurled ring. It only takes a quarter turn to secure the tool in the taper. When I bought the mill, it came with a small aluminum plate that had 5 holes in it for holding tools, that could be clamped down to the table. This made it convenient to have 5 tools within reach while running programs. This is not enough for the programs that I am running nowadays. Right now, I have 29 Quick Switch 30 toolholders and I like to use the hell out of them during a program. Sometimes I have 8 different tools in a program.
I have been thinking about using an old Heathkit turntable platter that I have had in my stock pile (junk pile) for many years- to make a tool carousel. It's a substantial aluminum casting that's .20" thick in it's cross section and about 11" diameter. It looked like I could put 10 holes in it that would comfortably hold 10 QC 30 tools.
I ended up writing a program in HeeksCNC, using scriptop to bore holes with an end mill. It ended up being pretty slick- it descends in a helical motion and then spirals out with an even chip load on the tool. It was kind of fun to write and use.

Here's a link to my 'array_of_holes.heeks' file that was used for this project:

Friday, July 1, 2011

Creating a rectangle with radiused corners (fillets)

I am just copy pasting this in from a reply to a question on the heekscad user's list on google groups. This might be helpful to some.

Q: How do I create a rectangular cut-out, but with rounded

A: Doing a rectangle with fillets in heekscad is pretty easy- use the sketch toolbar and look for the icon that is square- the tooltip for this is 'Start drawing rectangles'. After you select this, a box with appear in the left hand column of HeeksCAD that is titled 'input'. There is an entry for 'radius'. It might not work for you on the first try, so fill it in with a radius value and attempt to draw your rectangle on the screen. If your rectangle doesn't have fillets, right click with the mouse 'stop drawing' and then try making the rectangle all over again- then your fillet/radius values should stick this time.