View Full Version : z axis servo on main ball screw or down feed handle

10-29-2004, 01:37 PM
I posted this in a unrelated thread but I figured it would get more hits seperate.

I looked at a retro www simplycnc com did on the type of mill I have which is an X-3

They put the Z-axis control on the down feed handle instead of the z-axis lead screw. The maximum travel of the down feed handle is 3 3/8" while the maximum travel on the z-axis lead screw is 9 "

What is everyones opinion on this? Would it make more sense to just stick with tradition and keep the servo on the screw to get the 9 inch travel or is the point irrelevent because there are no 9 inch long end mills to begin with.

I dont have plans for machining anything over 3 inches thick at this time and it would save me tons of time in mounting a servo on the down feed handle instead of installing a ball screw in the z and mounting a servo.

10-29-2004, 05:10 PM
I have a round column mill/drill so moving the head up and down is out to begin with.
But having said that I chose to add a timing pulley on the micro feed shaft rather than making the necessary fixture to add a ball screw feed. Read it was much simpler and easier to do.
Also consider that if you move the whole head, you will need a heavier motor to move all that mass and depending on how tight your verticle ways are, you may intoduce additional "slop" in the movement.

Just my .015 worth.


10-29-2004, 09:49 PM
Hello, one advantage of driving the entire head is you can lock the spindle in it's uppermost travel. That may reduce spindle run out/flex due to the reduced overhang on the bearings. Just as with milling on a conventional knee mill, I will move the knee instead of the quill.

Another less important advantage is the concealment of the driving parts verses having them hung off the front of the head.

Bubba pointed out the advantages to driving the spindle down feed. There are tradeoffs to both. JRouche

10-29-2004, 10:19 PM
that little over 3 inches isnt nearly enough to change tools, especially an r8 collet or end mill holder. You would have to move the entire head then loose your Z offset.


10-29-2004, 10:38 PM
you could move away from the part X AND Y and maybe get the tool out.

10-29-2004, 11:25 PM
Thats a good point. I think ill stick with my original plan. Seems like the easy way out is full of problems