I'm building an lead screw CNC that mounts to the wall and will fold out to a 15 degree angle for cutting (this is due to space). Should I be using Anti-Backlash Nut Block or Nut blocks for the x axis that would be moving up and down? Also, does the Anti-Backlash Nut Block slow down the overall speed? Thanks for the help!
Because there is still a resisting force against gravity as a result of the end mill moving through the material, I'd still go with anti-backlash nuts. If all you are cutting is foam, it won't make a difference, but even MDF could have the possibility of showing backlash.
If it is a design like the LEAD Machine using the OpenBuilds Cbeam gantry plates you can opt to go for 2 nut blocks. They go on the edges of the gantry plate and their positions are adjustable. They are more easily accessible to adjust as needed when they wear to take out the backlash. I just installed an anti backlash nut on the z axis of the lathe I am building last night and now that I see how difficult it will be to adjust in the future, I wish I would have gone with two nut blocks. If you want installation info the x axis starts here at 19:35.