Dust foot, / zund / questions

[fozzyber]

I have been looking at dust foots / feets?
I have seen many designs and configurations for the shopbot.
All have been large, I was looking at the zund cnc's and they all have real small
dust foots, like somewhere in the 2 inch range, and they seem to work really well. There is a video out there:
http://www.youtube.com/watch?v=OCRpXRLWDf0
of a zund cutting 1/2" plexi and picking up all most everything. all with a 1.5in hose. how is this possible? This seems so much different from what everyone else is doing here. Has anyone played around with using this type of setup?
and yes I know the zund is a $200k system. but how do they get such good dust collection?

The only thing I can think of is they are limiting the collection area and thus boosting the airspeed of the vacuum getting great DC.

what am I missing here?
could this be a possible adaption to be made to a shopbot better DC all run on a shopvac?

[Brady Watson]

They use very high RPM spindles on those machines. Typically in the 60,000-100,000 RPM range. Lighter chiploads, smaller cutter diameters and smaller chips all contribute to easier to pick up.

-B

[fozzyber]

Brady,
OK understood, high RPM and light chip load, but they are cutting the same stuff I want to cut, (imagine that with me being a sign shop;).)
Are you telling me as long as I keep my chip load light this type of setup could work? I'm not trying to be contradictory but most of the stuff I've been cutting and most of the stuff I've seen coming off a router is light chip load, at least compared to a planer or lathe. I have my bot in the warehouse, no more than 30 ft from my large printer, 72" large format UV printer, I NEED to keep dust under control. This just seem like a good solution, If I just need to play with it , fine, I'm just looking for some downfalls to avoid before I do.

Jerry

[bleeth]

Jerry:
To add to Brady's post (he is correct in what he says) The big boys also will have a very strong vacuum, not the usual botters vacuum of a few HP. They are moving some strong CFM and using hose that won't collapse under the pressure. You don't have much to lose by experimenting though so give it a try and tell us how it works.

[fozzyber]

Test 1 shows alot of promise,
The air velocity is high and even with the back half of the skirting gone it was collecting all the dust of fine acrylic w/ a shop vac.
From the looks of this it is doing a few things, first, keeping the router exhaust away, and keep the air speed up.
The main problem of this design is the 1 1/2" of space need for the hose / pipe... if you used a standard design / style foot but kept it small might work as well.

I think the main thing is to keep the amount of skirting as small as possible.

[Brady Watson]

Yes...Higher vacuum suction, combined with decent CFM will result in better pickup - However, you may be playing games with filters clogging with the high suction and velocity with that setup. This is why dust collectors are high CFM with relatively low suction, and large surface area filters.

Sucking up dust with a ShopVac on a CNC is certainly nothing new for those of us starting out 10 yrs ago with the dust foot made for a ShopVac. Clogged filters made the dust foot next to worthless (MDF? Dust Collection? LOL!!!), and it wasn't until the new design that moves up & down with the Z axis, that the dust foot was made to work with a dust collector and 4" hose.

As long as you are just cutting plastics and non-wood materials, you should be fine. Don't expect ANY dust collection system to suck up 100% of homogeneous wood materials like MDF...as I am sure you already know!

-B

[fozzyber]

Brady I agree with you, MDF is a mf, I made a 2nd prototype, it is a scaled down version of what others are running now, it works well, so for.
But just like 10 years a ago with shop vacs clogging filters, there are now cyclones for all types of systems.
I have a delta 1.5 hp DC with 1 micron penn state ind, bags, I surfaced a 3x4 mdf board and my bags were plugged, so many things need to be addressed.
like adding a cyclone to extend filter changes.

My hopewith this project is to create a better leaner meaner foot that can be used with out a mega 220v DC.

think of what I want to do as I'm inventing the pressure washer to clean the house while every one else is using a fire hose.

one advantage I can see so far with the smaller foot is that you don't lose vacuum as quick as you get close to an edge.

let the newbie fool beat his head for a bit.......;)

[bleeth]

Well done Jerry.
Nothing like a working model to get the questions answered the right way!

The little trash can lid cyclones actually help quite a bit. There are also larger glalvanized ones available. I got one a while back for under 200. It is designed for 6" pipe and a larger DC than a shop vac.
The smaller mesh that some companies offer as an option on their DC's actually reduce vacuum and many who have bought them have noted how easily they get clogged.
There is also a guy who sells lightweight acrylic cyclones that were designed for smaller motors. The whole rig doesn't take up much room and can be enclosed in a closet as long as there is sufficient airflow through a filtered dorade vent. Keeps the noise down that way. I think he has an e-bay store.

[phil_o]

Keeping your filters from getting clogged is a big part of an efficient dust collecting system.
I've built a few separators based on the design discussed in this forum. As you can see from posts by people who have built them the separators they work well. http://www.cgallery.com/smf/index.php?board=1.0

[fozzyber]

I just found the thein style and it looks verry good or at lease interesting.
Looks cheap to build as well....

The bags I have for my DC are good ones, they have better filtration than stock and more flow. but after the mdf thing, not so much, but what filter does.
Hence the cyclone.

[HelicopterJohn]

Hi Jerry,

I just sent you a PM.

John