CNC Dust Boot

[Brad Shipton]

The last large slab I surfaced I was literally using a shovel to pick chips off the floor. Part of the problem I fixed by adding a border to the sides of my machine I do not need access too. Next I thought I would do a bit of experimenting to see if I could improve the dust collection. Using the tips from many others I increased the size of the duct to the shoe. That coupled with improving the overhead piping helped some, but it still was not great. I decided to alter the basic shoe design I had to see if I could improve it. I am pretty much stuck fixing the basic shoe design because I cannot afford (or justify) the industrial solution to chips pictured below.

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The first dust shoe I built did not work any better. In the second version I added a small housing to the underside of the shoe to get the suction side closer to the cutter. The housing was sized so its bottom aligns with the bottom of the collet. This version worked a little better, but the air velocity near the cutter was still quite low. I tried extending the housing closer to the cutter, but it did not work much better for the 3" - 3 1/2" long cutters I use. I did find this design picks up more dust than my old shoe as the tool moved around the part, but that will be largely because of the increase in the size of the piping.

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The third shoe design was similar to the second, but I added a bellows to the bottom of the shoe. The height of the bellows is adjustable, and it has two springs that keep the bellows open. A friend referred to it as a dust pan. The air velocity is much greater at the cutter when the bellows is opened, and it does seem to collect more chips. When cutting full sheets without any large pockets it should be fine to let the bellows float on top of the stock like others one can find, but I already found it needs to be adjusted to be above the stock when cutting large pockets or partial sheets where it goes past the edge of the stock.
DUST-PORT-V03a -SM.jpgDUST-PORT-V03b.jpg

I am curious to hear any ideas others have to improve the shoe design. I have to cut out some sheets of plastic in the next few days so I am curious to see if it works much better. The last sheets of plastic led to far too much time vacuuming up chips.

[Bruce Page]

I'm a hobbyist with a small machine (24x36) but I have been thinking of adding an air nozzle inside my Kent boot to blow directly on the cutter. My thinking is it would get the chips & dust airborne so the DC could better pull them out. It looks like you have a nozzle right there above your boot.

[Brad Shipton]

I am a hobbiest for the most part, but take on jobs for people I work with now and again. I hope to be able to pay off this machine and then move up to something a bit heavier.

I do have an air nozzle. I did not find a single one all that effective. I found the air nozzle was most effective when it could blow directly into the groove behind the cutter and effectively lift the chips wedged in the bottom of the cut up so the DC could pick them up easily. A single nozzle works fine in one cut direction, but in the others it tends to just blow air on the cutter. I think for it to be effective four air nozzles might do a very good job, but that seemed cluttered and a nuisance to adjust so they would not get caught on something during a tool change. When I was looking at steel milling machines I found it was fairly common to have multiple coolant nozzles and I think that might be for a similar reason.

[Bruce Page]

Hmmm.. That gives me the idea to fabricate a hollow metal ring with 4 outlets pointing to the cutter tip. It could be permanently mounted and fed by a single air line.

[Brian Lamb]

Your machine uses interchangeable tool holders, CT30 or 40, why don't you get the special collet nuts that are venturi style, techniks makes some:

http://www.techniksusa.com/AirPRO/About_AirPRO.html

They are supposed to really help lift the chips up and get them into your dust collection piping.

[Brad Shipton]

I have looked at the airpro before and researched them on the woodweb. They are $900 a crack and they seem to work best with MDF or melamine since some have mentioned breaking theirs when chips get caught in them. Right now, it is mainly the cost. I have spent far too much lately.

[Brian Lamb]

I had no idea of the cost, that seems rather excessive at $900. Maybe a home brewed version?

[Brian Lamb]

I did some more looking, while the Techniks may be that expensive, I found some at CMT that are on sale a lot cheaper ($274):

https://www.scosarg.com/catalogsearc...dust+extractor

and another company called Klein that I haven't found pricing on, so with other options out there, maybe you can find one at a reasonable cost.

http://www.sistemiklein.com/en/produ...-tornado®.html

Found prices at Stiles ($495):

https://store.stilesmachinery.com/nu...pe-with-wrench

[Brad Shipton]

Thanks Brian. The tornado looks like a more cost effective option, and it spins up to 20,000rpm, so that would be fine. I sort of get why they are so expensive. It seems like it would take some machining to balance something like that so it can spin at 24000rpm. I see the tornado was mentioned on the woodweb. I might have to see what it will cost in my neck of the woods.

I toyed with the idea of adding a motor and some sort of impeller above the collet, but it got pretty complicated, pretty quickly. Building one of AirPro's myself is not something I would likely attempt. I know you could build it, but I do not have that machining skill.

I bet the Klein version will be pricey. I bought a magnetic tape from them years ago.

[Brian Lamb]

Hi Brad,

The Tornado mentioned in your link is the Blue Tornado dust collector, not this Tornado nut... The link I sent for Stiles shows the nut at $495... I would try the CMT version at $274 first....

If I had a CNC router, I would fire up the CNC mill and make a few of these things.... :-)

[Brad Shipton]

I see it is $274 now. It came up as British pounds earlier and I didn't look at that one much more. Here is a video for others: https://www.youtube.com/watch?v=rIN_5CUtPkg I am going to get a price from one of the companies I deal with. I noticed the Leuco option mentioned too in that woodweb link, but it looks even more pricey. https://www.youtube.com/watch?v=3ESHhXO-U5g

I would like a CNC milling machine, but I am not sure I would ever build anything other than jigs or machine improvements then.

[Brian Lamb]

That's the trap we fell into....

[Robert Bonenfant]

Hey Guys,

Ill attach a picture of my dust shoe below (It needs to be cleaned Lol) - It works great and it has lifter so it can be moved up and down for easy access. From what it sounds like you might want to look at the amount of suction from your dust collector. It might not have enough power to provide good dust collection, we had this trouble and upgraded to a 5 hp Laguna Cyclone and it made a huge difference (This vacuum is only connected to two cnc routers). What vacuum system are you running ?? Even if you have a 10 hp vacuum system you still have to ensure you are getting enough suction to the boot.

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[Brad Shipton]

I see you have an air cylinder on your boot. I do not have that, nor the solenoid that lifts it for the tool change operation. The machine I plan for next year will. That would solve much of the problem. I have a 5hp cyclone as well. All ports are closed when the CNC is running (one man shop). There is great pull right at the inlet from the boot (I can get all of my piping jumping by putting my hand over the port), but around the tool the air flow is not great. It is much better now with the extension, but that is just another thing to need to think about. I did order the CMT kinetic lifter Brian pointed out. A supplier in Canada offered it to me for the same price as in the US, but in CAN$. There was a special on the Airpro now too it turned out.

[Brian Lamb]

Curious to hear what you think of the nut when you try it out....