[bwiab]

Hello Peeps... thanks for all your help so far. I've been prototyping a couple of cabinets on my new Avid Pro 12060. I added a vacuum holddown using the Hurricane Vacuum. It works great. The first cabinet I cut out of 3/4" mdf with (2) sided alder veneer. I destroyed a brand new 3/8" compression bit on that first run. I noticed the saw dust packed into the cut lines. I don't remember my nesting but the pieces were about 1-2" apart... So the only void was the 3/8" gap left by the thru cut. I did the thru cuts on one pass. I didn't notice that the bit had been damaged until after the cutting was complete. Most of the thru cut lines were packed with saw dust. I assumed my dust collection was not up to the task.

I have a 3hp motor (supposedly) Reliant is the brand - can't seem to find much on it... maybe Korean from a while back. any ways - I have a 6" pvc line coming into my garage. The duct collection is outside the garage wall. The 6" line tees to (2) 4" flex lines. One was for my machine and the other was going to be to connect other tools. Well after cutting the first cabinet I assumed that I would need both 4" lines to the dust boot and was prepared to hold one and follow the machine for the 2nd cabinet prototype until I could build a new dust shoe with 2" 4" ports on it.

I cut my second cabinet prototype today and cut it out of 3/4" melamine on particle board. the 3/8" compression bit cut amazingly well and the edge was awesome. I only did one test cut and as I ran the 2nd 4" vacuum dust collection line next to the machine, the saw dust didn't budge. After the machine returned to 0,0, I tried to remove the saw dust again and still would barely budge. I'm wondering if the vacuum hold down was too strong for the dust collection. The dust seemed to pack in there and not want to move. Any ideas? Stronger dust collection or something else? I was thinking of running a 6" line to the dust boot and then just forking off with two 4" lines at the z axis. But I'm not sure that would even do anything.

Here's some photos.

This is after I removed the cut piece. the hold down was still engaged and I tried vacuuming with my 2nd 4" line. The dust still would not move. FWIW - I measured about 315 cfm 1" from the nozzle of the 4" line. At the nozzle - my simple meter maxes out at 600 cfm so there is some decent air movement... but maybe not enough?

Attachment 478340

Here's after the cut. You can see the dust packed in there. But I also trimmed the material completely around the outside edge and there is almost no dust there?

Attachment 478342

Not my machine - but same brand/model...

Attachment 478344

Any ideas?

[routalot]

The geometry of compression cutters is such that the dust is forced to the middle of the board and compacted.You found this out.In addition,the suction that holds the board down is a lot more powerful than the average extractor.Which means at the end of each sheet you will be having to clean a lot of dust from the spoilboard or the next sheet won't hold down.It is a pain and I have thirty or so sheets to cut today with the same obstacle to overcome.

[bwiab]

Thanks routalot... that makes sense. A little bit of extra clean up doesn't bother me as much as my bit that exploded. I've been cutting with a whiteside 3/8" Compression bit. (HC4122).

the first cabinet I cut I ran it at 20,000 RPM at 200IPM with a chip load of .005... maybe that was a little to high on the RPMs? The up cut piece of the bit partially broke off. That was cutting thru 3/4" mdf with a veneer.

the 2nd cabinet I cut I ran it at 14000 RPM at 150 IPM with a chip load of .0054,,, I didn't understand the saw dust so that was a concern (thanks for that insight!) I only cut about 108" of travel and the bit was warm to the touch... this was cutting thru 3/4" melamine. Maybe warm is ok? Maybe I need to ramp it up to 200/250 IPM?

Thanks again!