Y-Axis Designs

[Cyclonit]

Hi,

I've started compiling different plans and ideas for my very own diy cnc build. There are a lot of things to consider and me being a perfectionist I don't like building something just to find out that I screwed up or could've done better. So, without further ado I decided to come here and ask some more experienced people for help.

My first concern is the y-sled:

I see two reasonable ways of positioning the ballscrew nut without adding any angled pieces to the y-sled. I want to avoid angled pieces because they would contribute slack and could thus (hypothetically) reduce accuracy.

These are the two different options I see including some pros and cons:

Option A: Ballscrew in between the linear rails
- requires spacers on linear guides to clear the nut
- less space for placing the z-axis rails

Option B: Ballscrew above the linear rails
+ thin sled
+ better clearance for the ballscrew (less dust)
- taller sled
- power transmission offset from the sled's center

Here a little image as visualization aid: LINK

You may notice I don't see any point in choosing option A over option B, most CNC mills I've seen so far however use option B. Thus I decided to start this thread and hopefully initiate a discussion about different designs. I'm a computer scientist, not a mechanical engineer, but if you happen to have any mathematical or more technical input, please go ahead.

Regards,
Cyclonit