Z axis height calculation

Hi when designing your machine in cad and calculating z axis height do I measure from the bottom of the collet to the top of the spoil board or from the end of the drill bit to the top of the spoil board?

Also 200-250mm isn't too much is it?

Thank you

I would make the bottom position with the collet touching the spoil board. The top position would be the maximum material thickness + the longest tool you will use + another 20 mm or so.

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Originally Posted by Jim Dawson

I would make the bottom position with the collet touching the spoil board. The top position would be the maximum material thickness + the longest tool you will use + another 20 mm or so.

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Thank you

200 mm is a lot of travel.Do you really need it?The amount of flex in the machine increases as you increase the Z axis as does the possibility of the gantry flexing since the drive is normally imposed at the base.I suggest you draw the spindle and backplate with a tool in place to see what the limitations will be as you can't get too close to a vertical surface that extends further up than the length of the tool.