Adding encoder to stepper motor and adding a buffer to Stepper Motor controll

Hey I am quite in the beginning of building my first CNC. But I had some ideas I wanted to implement on it. Maybe someone could point me to existing projects and or give me feedback on it. My plan is to put LINUX CNC on a RPI and controll the motors from there.

So first I heard that it is a problem that Linux like most OS is not a realtime OS and due to this the motors have to run slower as the Controll signal for the motors is not guaranteed to be exact. Hope this is understable. So my idea was to put a barebone Mikrocontroller in between the Motordriver and my RPI controll unit. The purpose of the Mikrocontroller would simply be to function as a buffer which can handle precise Signal generation better.

Second idea was concerning my stepper motors. I heard that it is the problem when they run faster that they can loose steps. To tackle this I had the idea to build an encoder which keeps track of the steps. And to get feedback of motor position. So basically creating a closed loop setup. I have some simple encoders at home which could fullfill the purpose. But they are only 128 steps per revolution. So I thought maybe I could build my own Encoder by printing out a black and white stripe which goes around the coupling of the motor and read it out with a laser and a light sensor. Assuming that the black stripes consume enough laser light and the white reflect enough.

But these are just some ideas as I really don't know much about CNC untill now. I would be happy to get some feedback.

Thanks a lot
Felix

Hey
yes you are right using a desktop pc is definitly the better solution.

For the encoder do I really need 4 times the resolution. I think the best option is to have the exact same amount of pulses per revolution.

But i don't want to invent the wheel new. I just was hoping to find some projects I could contribute in.

What is the problem with 4X resolution? The encoder counter hardware needs to detect all 4 state transitions of the quadrature signal anyway to detect direction, so why not use it?

But, unless your encoders have very low resolution, and you move quite slowly, you do need hardware encoder counters to not miss counts.

Jon

Oh now I understand what he said. Just didn't understandin the first place. It's an idea! But I realized that they are also mechanical so they won't stand the amount of revolutions which is needed on a cnc. So can't use it. I really would like to try out more of encoders. But I guess it's not worth it. Found stepper motor for round 130 euro including encoder. And without 20 Euro less.

[update]

any knowledge about this one. Would be an option.
www.renishaw.com/en/new-am4096-12-bit-ma...-encoder-chip--10829

thx. But I think it's too small for my CNC. I will ask