Waste Board location

Hey Jerry,

the Z travel on the Z-16 slider is 133 mm (5.24″).

Here you can see that the Z assembly can be mounted in three heights:

With this, the distance between the machine bed (without wasteboard) and the lower end of the Z assembly is adjustable from 104 mm (4 3/32″) to 138 mm (5 7/16″):

Where the collet and your bit end is, is not defined as you can clamp your spindle more or less high into the milling motor mount. This means that even if you mount the Z assembly in the highest position, this does not forcibly mean that your bit’s end will be able to use the entire travel. This would only be the case if in the highest Z position, your bit’s lower end is exactly at the level of the lower end of the Z assembly. Usually you would not clamp your spindle slid that low into the mount or use such a long bit because you would add unnecessary leverage force which leads to more deflection under load which could increase chatter. Unfortunately the Onefinity milling motor mount, unlike on other machines (see also here, here and here), does not protrude downwards beyond the lower end of the Z assembly.

For these reasons, some people replaced the Onefinity Z assembly by a Universal Z assembly. How such a Z assembly/spindle slider could look like is shown below, see also RoverCNC Z assembly or Sorotec Z-Axis DIY-Kit “Alu-Line”


The problem with a wasteboard is that since it’s intended to be wasted, i.e. replaced from time to time, it would not be wise to mount the machine’s feet on top of it.

One thing to consider is if you know that you will only use workpieces of lower height, is that it would be a disadvantage to mount the Z assembly in the highest position, because you would have to slide your spindle much more downwards into the motor mount in all cases where you happen to work on a low workpiece. Usually you don’t use the entire Z travel in a project. So for most stability and least leverage forces and thus deflection and chatter, it is the best to mount the Z assembly in a height which accomodates your usual workpiece height. Industrial machines of gantry-type sometimes have the possibility to alter the height of entire X axis with an additional W axis (as shown here), which would avoid these problems since they can better accomodate to a varying workpiece height.

A solution for being able to work on workpieces higher than 138 mm could also be not to attach the machine on a table top, but on a U-shaped base, this way gaining more room for high workpieces (or for a larger rotary axis). A wasteboard could then be mounted at a desired height. e.g with the possibility to fix a “flying” machine bed with the wasteboard at different heights.

Another way could be to use an open frame as base as shown here or here.