Hi pavlo,

Well I have given allot of thinking, after the z axis is complete I will have about 170mm of travel. When you look at the different length cutters and so on it’s really best to have about 100mm of travel so you can accommodate different lengths, you also need to think about how far the collet holder will hang out of the bottom.

The other main reason is that the supported rail is only fixed at 150mm intervals, so yes we could cut the rails/travel down but then we would also need to machine the rails with new fixing points (drill, tap).

Given the choice of + 70mm extra vs. the work and loss of cutting everything down I went for having extra travel.

If I was to bring the lengths down I would be wasting money on the Rail, Ball screws and time spent building. I went with a pre machined ball screw for this z axis and that is 400mm long, the design I have gone with allows me to keep the full length of the ball screw and the rails, now if at any point I need to machine a tall part I also have the travel to do so.

Its better to have it, then not. Even if you may never use it !