routercnc_MK3

[Boyan Silyavski]

This seems quite an upgrade to me. Plus more pleasing to the eye, call me crazy but that's quite important to me.

[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.
:

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!

[Boyan Silyavski]

Very nice idea with the dust shoe. if you use some advanced CAM you could control all tool paths so no problem will arise. It seems even with simpler CAM it should work ok.

By the way i have a very similar dust shoe setup, only thing is that it does not slide like yours. Biggest problem i have encountered is when something chips and stucks in the section between the spindle and the vacuum hose. But my dust shoe seems not so deep like yours. So your should work better. i believe this dust shoe design will work better with short brush

[EddyCurrent]

Nice looking dust shoe, I need to study it better when I get time. I liked this idea, don't know if it can be applied to your; https://www.youtube.com/watch?v=tBzoQw4du8E

[routercnc]

@Silyavski
I guess you mean CAM toolpath control to avoid any clamps? I have some low profile clamps so should be OK there.
With regard to adding brushes - yes I've considered that and with the lower plate being removable I can try different designs and use the best one for the job.

@Eddy,
Thanks for the link to the video. He does go on a bit! During cutting mine will behave a bit like that, but with the advantage of rising up out of the way when the cut is finished. His looked static from what I could tell.
Also, the lower plate on his is completely open, whereas mine is only open locally around the cutting bit so should give better extraction. I also think my magnetic removable plate means it is quick to get everything out of the way and change over to jobs which don't really need a dust shoe such as aluminium machining.

[EddyCurrent]

Eddy,
Thanks for the link to the video. He does go on a bit! During cutting mine will behave a bit like that, but with the advantage of rising up out of the way when the cut is finished. His looked static from what I could tell.
Also, the lower plate on his is completely open, whereas mine is only open locally around the cutting bit so should give better extraction. I also think my magnetic removable plate means it is quick to get everything out of the way and change over to jobs which don't really need a dust shoe such as aluminium machining.

The only aspect I was drawing your attention to was the piece of 4" flexible ducting around the spindle collet area

[routercnc]

I'd glossed over that but you are right - that is a good feature and would improve dust collection still further. I don't think I could fit 4" hose, but something smaller in diameter and just tall enough to make a seal with the spindle during cutting should work. I'll look into it . . .