Cyclonit
24-06-2014, 11:18 AM
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 (http://i.imgur.com/rklWUiG.png)
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
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 (http://i.imgur.com/rklWUiG.png)
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