Custom Deskproto strategy

Project history

  1. current posting
  2. next step: add command line arguments and extensively test the strategy
  3. Next project: subdivide rotary axis operations to keep toolpath-distance constant while getting near the center of rotation


I have two problems with CNC machining either wax, plastic or soft wood:
  1. I lack experience with how much surface finishing detail I need. So I want a finishing strategy that graducally gets finer (distance of parallel toolpathes) until I stop. Without however milling the same path serveral times (like every second path when I do a tpd=tool-diameter/4 and then a tpd=tool-diameter/8 parallel strategy or every 15th path if I do a tpd=tool-diameter/3 and then a tpd=tool-diameter/5 operation.)
  2. I cannot machine the same part of the surface for too long a time. It will eithrer melt (wax and plastic) or catch fire (wood). It needs time to cool down. Duering that time however, I can maching other parts of the geometry that are far away.


Since the existing toolpathes did not offer such a strategy, I came up with a small Java program.
You would start with a Deskptoro CAM project containing one (e.g. "parallel along X") or two (e.g. "parallel along X", then "parallel along Y" or "along A")  FINISHING passes.
These would be marked by adding "REPLICATE" to their names.

The program will then make copies of these operations with the starting point offset by toolpath-distance / 2.
After these it will add copied operations with the starting point offset by toolpath-distance / 4 of the original and the copied operations.
Then it will do the same with toolpath-distance / 8.

The result is a finishing strategy that gradually increases surface quality and can be paused and aborted at any time.
At the same time it does not operate on the same part of the geometry until it has worked on all other parts.
Thus giving the part time to cool down where a simple parallel-strategy with a smaller toolpath-distance would mill over the same place dozens of times, thus heating up the surface and either melting plastic or wax or setting soft wood on fire.


Updated mounts for CNC homing switches

Project history

  1. Previous project: 4th axis homing sensor
  2. ATC upgrade
  3. current posting
  4. next step
  5. Next project: designing a chain link tool library

A while ago I posted some simple, 3D printable mounts for homing switches on my Chinese CNC6040.
After upgrading to a smaller USOVO ATC (automatic tool changer) spindle, the Z-Endstop no longer fit.
Formerly it would push against the upper spindle mount but this spindle only needs a lower mount.
So I added a 3D printed helper part to my design.

TODO: Photos of the assembled parts will follow next weekend



Returning to my CNC

I haven't worked on my CNC mill for a while.
This weekend I'm planning to:

  • Attach cables to the (already mounted) X+Y+Z+A homing switches (Update: DONE)
  • Test homing (Update: small issue to fix with Z first)
  • Test my experimented M6 tool change macro for my Usovo ATC spindle. (manual tests worked out) (Depends on homing)

Later I need to:
  • Add an M6 exception for the 3d touch probe to be stored in a different location (because it's too large for the pneumatic tool-magazine)
  • Find a way to get 10V, so the PWM-output of my PLCM B1 breakout board can control the Usovo spindle via 0-10V PWM because it doesn't have RS485 like my old China-spindle+VFD.

Raspberry Pi stage intercom system

Project history

  1. No Previous project
  2. No old posting on project
  3. current posting
  4. next step
  5. Next project: add LTC time code output using the unused RasPi on-board soundcard

Because analog stage intercom systems are way too expensive for what they do,
I started building a Raspberry Pi + Mumble based digital intercom that can work with existing Network infrastructure.
The software is based on the TalkiePi Walkie Talkie project.