Z travel design

[Tom]

Thinking (hypothetically) about travel on Z axis for a (hypothetical) next machine. I'm trying to base the required Z travel around some logic. My 1st machine was a guess (ended up being 127mm).

I'd appreciate some thoughts / constructive criticism on the attached sketch. Does this define all possible "uses" of Z travel? I'd like to get a good summary together so that I (and the forum) can mix and match the required elements to come up with a design.

No auto toolchanger? Just shorten the length of the "toolholder" to the length of tool which is engaged in the collet. That type of thinking.

[Ross77]

basically looks ok, collet size and tool length will vary quite a bit tho. I think thats why mills have extra travel on the column so you can set the optimum work height and tool spacing. A fixed gantry will always be a compromise.

Im looking at keeping the z travel reasonable(75 to 100mm) to reduce the cantilever and then either a deep bed and pack the work up to it, or be able to move the gantry beam up and down depending on the work piece. it means a little extra work but I will save on the motor, rails and ball screw. for the z axis. thats my logic any way

I think your diagram would look good in an excel sheet and then use pick lists for collet and tool size which would auto enter in the dims space, then add up the max travel :o)