Without having to discuss off the topic things like the target machine base, x, y & z layout and gantries I would like knowledgeable feedback on a B/C Spindle head design.
The objectives are:


  • Lightweight (target weight including servos and spindle <= 20kg)
  • The cost within reach of a home CNC'er / Targeted at individuals and not corporates
  • HF spindle 2 to 3 kW.
  • Soft metals, wood, etc.
  • Low manufacturing cost and as much as possible off the shelf parts.


Apparently, nothing meeting any of the above criteria on the market.

With the following 2 main components,


  1. 1 x Teknomotor - 5160 DA
  2. 2 x Harmonic Drives - FHA-17C Actuators


I came up with this:



I posted the actuator and spindle to GrabCAD if anyone want to check the dimensions.

https://grabcad.com/library/fha-17c-actuators-1
https://grabcad.com/library/teknomot...0-da-spindle-1

Weight 20kg (brackets, 2 x motors and spindle). This is the 2.2kW version of the 5160 DA. There are also a 3kW one, of wich the height is 20mm taller (but can be modified to be shorter)

This Technomotor spindle was the shortest one I could get (without having to go to Jaeger or stuff that cost the price of a farm)
It has ER25 collets on both sides. I opt to remove one just above the black end cap. (Does someone maybe have a photo of such a spindle to show the inside. Where is the bearing, inside the black collar or inside the square aluminium squirrel cage?

The B and C drivers are harmonic drives FHA-17C. There pricing is high, but within reach. Not sure about which gearing, but several options.
In addition, even though the spindle and C bracket can hang of the harmonic drives, I included a support shaft right through the harmonic drives hollow to support the opposite side. I use off the shelf FK15 blocks here. (Also fixed (not floating), with two angular contact bearings)

Here are my questions:


  1. You think the design are sturdy enough for materials listed in objectives?
  2. What about breaks. Will it be needed. Can Harmonic Drive Inc. FHA-17-C be ordered with breaks, or is it only the more expensive harmonic drives (like SHA20, not sure with ones now), that have the break option?
  3. Why your thoughts on why there are not such products on the market?


In advance, thanks for the relevant feedback.
Guss