CNC Ballscrew for knee

[Karl_T]

*NOTE* Repost from Camsoft forum of CNCzone.com. I'm the resident guru there. This is my 2013 winter project


One big weakness on a CNC knee mill is lack of travel in Z making it very hard to do toolchanges without moving the knee and losing your part 0 setting. This is my project to install a ballscrew in place of the acme hand screw and integrate it into my control.

First, I had to build two air cylinders to counter balance the weight of the knee. I found a couple scrap 3" air cylinders but had to do a complete refabrication to fit this application.

 

[Karl_T]

Then, i took an old scrap ball screw and made a ton o' parts to replace the Acme knee screw

 

[Karl_T]

Here's the completed installation

 

[Karl_T]

Then I had to write the code. Its actually pretty easy to do something like this in Camsoft. The pic is the code to do the tool change, read the tool settings and then reset the knee for that tool.


Here's a video of a short run and toolchange
https://www.youtube.com/watch?feature=player_embedded&v=e716JDh6Xs8