Z-Plunge advice sought...

Hello all,

I'm in the latter stages of my mini-mill design - just looking to finalise the placement of the Z-Axis on the frame.

Have a look at the attached diagram - you can see that my Z has a plunge of 150mm. In the diagram the plunge bottoms out with the spindle touching the machine bed - probably not something that you'd want to see in the real world - so my question is: how much clearance would you recommend leaving between the spindle at it's bottom-most position and the machine bed? I know that this is one of those questions where the answer is influenced by further factors (machine use etc.) but is there a good clearance distance to start with?

Attachment 10776

Thanks for any advice you can offer!

Wal.

The closest you want it to the bed is close enough to leave room for the shortest cutter and thinnest material. The nearest I can think of would be milling PCBs - so maybe 10mm. Realistically you can generally just put a spacer between if you can't get the spindle close enough, so I wouldn't worry too much.

If you put the spindle mounts closer together, you can slide the spindle up and down in the mounts and it becomes a moot point...

>If you put the spindle mounts closer together, you can slide the spindle up and down in the mounts and it becomes a moot point...

Yep, true enough - I've included 4 sets of holes for the spindle brackets so that should give me a fair bit of room for manoeuvre - just wanted to be sure that I wasn't missing something obvious!

Cheers Jonathan.

Wal.

I just have holes in back plate for adjustabilty so between these and sliding spindle up and down brackets makes finding the best or ideal position easy.

Like this (Only showing 1 brackets but there's two) Attachment 10777 If mostly cutting thin material then the holes at the bottom are the Ideal position has the distance from lower Spindle main Body to collet is a constant overhang so here the Z axis is extended the least it needs to be.
Spare holes can be used for other things like holding air or Vacuum shoes/pipes etc.