routercnc_MK3

[routercnc]

Before you ask - no I still haven't measured the stiffness of the new machine! But I have managed to make progress on the semi-automatic dust shoe system, and as you can see it is making nice cuts in aluminium.

The bits assembled on the bench. Used 12mm stainless rod and linear bearings for the rise and fall bits.
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I posted ages ago about the concept in another post, but made more sense to tack it on the end of this. To re-cap,

Bit changes
The dust shoe has a removable lower section, held on by magnets plus located by the ends of the support rods. This is to allow easy bit changes. It also allows a variety of dust shoes to be fitted depending upon the job.

Semi-automatic height adjustment
It is attached to the Y axis, not the Z axis, so it does not simply rise and fall with the cutter. Instead there are 2 adjustable knobs, one to control the maximum raised position, and one to control the maximum lowered position.

Initially at the home (or raised Z position) the dust shoe is held up by the lower adjustment tab, which rides on top of the spindle body. When the cutter drops down the dust shoe drops with it.

As the cutter approaches the cutting position the upper knob and stop-collar prevent the dust shoe falling any further, being set to be just above the top of the workpiece (say 2mm). During cutting, even deep plunging, the dust shoe is always at 2mm above the workpiece irrespective of cutting depth as the spindle moves independantly of the dust shoe. This should make it good at collecting dust, and avoid the problem of crushed brushes or brushes being sucked into the extractor or cut with the cutter etc.

When the cut is finished the Z axis raises up and at some point collects the dust shoe tab which raises the dust shoe as well. It is then ready for a bit change, or the next cut.

Here are the parts fitted to the machine:


Here is a close up showing the 2 adjustors for the max and min height adjustors.


Still have to cut a short length of 100mm duct to fit between the lower part and the fixed part, plus add the 100mm duct from the extractor machine, but you should get the idea. All sounds OK in theory so will let you know if it actually works!