I've built this machine 100 different times in my head!!!

[Bart]

Hi,

I don't want to hijack this post but i have a similar design and I'd like to use your experience.

I've designed the frame etc. in inventor and from the simulation i get deflections smaller than 0,015 mm with the force of 500N excreted on a tip of an end mill. Thus, the design seems to be sturdy and good enough but I'm waiting for any suggestions.

My questions...

1. Chinese spindle - which one to chose
There is plenty of different looking spindles on ebay and even more sellers so I'm not sure where to buy and more importantly which model. Which one do you have or which one you know is safe to buy.

2. how to avoid two motors.
I tried couple designs of frames to hold one ballnut for one ballscrew in the center under the table but it's hard to get small deflection without making it very heavy. Do you have some ideas how to solve it without 2 ballscrews and motors on each side?
How is the solution, with line that winds up on a rotating drum, called?

3. what's the free play on a linear rail's open bearings?
Is there any free play on them, how much do they flex?
Also I saw couple times that max speed for linear rail bearings is 5 m/s. What happens above that speed and how does it affect service life.

4. whats the advantage of linear guidways over supported rails?
They would cost me at least 2 times more. I've read the spec and according to it they don't deflect almost at all. What are the other advantages and are there any disadvantaged besides the price?


5. End supports for ballscrew.
I saw a design where instead of end supports fixed to the gantry or frame there where bearings directly fixed to gantry/frame. It seams that it might be stiffer and cheaper. What do you think of it?

Kind Regards
Bart