Float precision for Ultra-Precision applications

Context:
I want to use Linuxcnc for a Ultra-Precision machine.
For that i need Linuxcnc to tell my drives (via Ethercat) the waypoints with high resolution.
I can get 0.5 nanometer resolution out of the Ethercat bus with the 32bit Integer format at the travels that i need. Which is sufficient.

Now as for my question:
From what i gather the path planner and everything works in single-precision floats.
Doing the math on that at 10mm and 500mm positions tells me the resolution between bits of the float number is not enough.
10mm/2^24=0.59nm
500mm/2^24 = 29.80nm

I dont want to waste that much precision in my control for no reason (plus having to convert to the scaled integer value).

Is there a way to change that to double precision floats (64bit) without having to rewrite the whole control?
Also feel free to tell me that my math is wrong^^

Leo
 

Wow so you're aiming for sub lithographic accuracy, you got any pictures of your machine ?
How you handling temperature, a dedicated controlled room ?
I guess this is a retro fit ?

The feature size is still well above a nanometer, but the edge precision and positioning precision have been well below a nanometer for many years.

The numbers quoted for various generations, such as TSMC's 4 nm are pure fiction; merely a label. Real dimensions have not been used as generation names for more than 20 years.

(I spent my career in state-of-the-art lithography. Now I use LinuxCNC to build model steam engines.)

Gene

.5nm, isn't that just a bit smaller than 4 gold atoms ?

With the radius of a gold atom being about 0.135nm ?

Hi,

Precision of the entire machine and resolution of commands are two very very different things.

The setup and build of the machine itself are not the topic of this discussion. Please keep it that way.

PLEASE stay on topic.

Thank you

Sorry sir, didn't know you were the boss of what could and couldn't be discussed, I'll crawl back into my hole

Yeah but someone starts a topic mentioning half a nanometre it's going to raise some interest. It's getting around to the level of the CMM NIST has in the US.
Precision is interesting whether it's a machinist hitting tenths on a manual lathe, a grader operator nailing a sub roadbed to the millimetre, the construction of the bridge over the harbour in the capital of my state or the work of Brunel in the 1800s.