Alpha Dust Skirt Mods

[joelschuman]

I've not been satisfied with the new Alpha dust skirt. Admittedly it's a difficult design problem, but I think ShopBot can do better.

The flaws I found were:

1. The vinyl curtains are not stiff enough to withstand the draw of my middle-of-the-road 3HP Oneida dust collector. They get sucked into the mouth where they block the entering chips and cause frequent jams.

2. The shroud-to-vacuum arrangement with the crunched 3" hose is pretty cobby. There's way too much restriction and leakage, and again I experienced frequent blockages, especially when cutting brash wood that throws long splinters.

3. The blue painted metal bottom plate has bends that protrude into the air stream, causing unnecessary turbulence and restricting flow.

4. It's easy to unscrew the thumbscrew all the way off. There should be a positive stop that prevents that.

5. The aluminum channel mounting bracket arrangement, with its two allen screws, is terrible. I cut a wide range of thicknesses and need to adjust skirt depth often, so I'm chewing my T-rails badly. Accessing the allen screws often requires manually lowering the Z. Mounting the skirt bracket to the T-rail should be a tool-free operation.

I'm slowly taking care of these problems, starting with the first three. I cut the flanges off the bottom plate, replaced the vinyl curtains with stiff strip brushes, and fabricated a fiberglass connector that bolts to the skirt using the chopped bottom plate and takes a standard 4" dust hose. Pictures attached. I'd be glad to pass on the molds for the connector, if anyone else is interested in making their own.


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[harryball]

I too experience the same trouble with the dust skirt. I'd love to make a better one but it's been on my lower priority list. For much of my cutting I've tossed it to the side as I find it pretty useless with larger chips, the flat hose clogs up rapidly.

I like the way it looks, how do you use the mold?

Robert

[paco]

It look good Joel! Keep us post on any improvements.

I too would be curious to learn about the way you mold the fiber glass.

I'm currently considering something new too but haven't yet figure the best way to achiveve my goal which would be to free some room around the collet area...

[gabepari]

I'm thinking about mounting the skirt to the carriage, so that it doesn't move up and down with the z-axis. This way you don't need to adjust it for every tool change, just when you switch to a different material thickness (and even then, to go from 1/4" to 1/2" to 3/4", you don't really need to move the skirt for that small distance). But when going from a 1/8" straight cutter to a 3/8" compression or downspiral, you need to move the skirt quite a bit. Hopefully I can get it setup so that the collet will plunge far enough below the skirt on the tool change routine so that I never have to mess with the skirt again.

And what he said about the 3.5" flex coupling getting clogged, gotta be a better way.

Gabe Pari
www.socalteardrops.com (http://www.socalteardrops.com)

[ariel_tff]

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[paco]

Very inspiring! Can we see the upper fitting/coupler to the 4"? What are those side duct (red)?

[ariel_tff]

the red are pvc pipes "home depot" gutters? heated and reduced to about 1.5" T to fit betwen the spindle and the frame
I will take more pictures tomorrow

[joelschuman]

At my usual shop rate, it's probably a $1,000 connector, but I'm sure you all understand.

I modeled it with Rhino, mostly to get a fair transition. I carved the transition piece on the 'Bot; the others were straightforward table- and bandsaw. Before gluing/screwing the pieces together I cut each section in half to make a parting line and reassembled. Then fill and smooth with Bondo. Took the halves apart and added flanges.


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I layed it up with cheap boatyard polyester resin and 2 layers of 6 oz. glass cloth. I skipped making a mold and made the part right off the plug because I cared more about the inside then the outside. Quicker, too. Popped 'em off, tacked 'em together with 5 min epoxy, and put strips of glass over the seams.


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[paco]

Ariel, I'm looking forward to those pictures. Thanks!

Joel, nicely done! What's the mold material?

[phil_o]

Gabe,
I mounted the dust skirt bracket so that it is independent of the Z- axis. It's much easier to change the bits.
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[joelschuman]

Paco,

The 'Bot-carved transition and the round section are poplar. The long bottom section is MDF with 1/8" Baltic birch plywood strip to build up the center ridge. Poplar, MDF, Baltic, HalfLife body filler, Icing surface filler, and Clawlock catalyzed primer are about all I need for most mold work.

The transition carve was done quickly, leaving .015" scallops. I do a lot of mold and foundry work requiring good accuracy but not high precision, and my most efficient method is to carve with a 1/2" roundnose leaving relatively large scallops: the tops .005" proud of the final surface. Then I fill the scallops with body filler using the scallop ridges as guides. Since the poplar ridges absorb more primer than filler, the width of the poplar lines gives good visual feedback, allowing an accurate final shaping between coats. I tried a new release agent on this, and you can see from the pics it didn't work well. Part should leave form clean as a whistle.

[scottcox]

Here's what I did with my Alpha. Dubbed the Dust Collector Boot Lifter, I built it because I was SICK of hassling with the set screws.

I had to move things around a bit and drill a couple of holes on my z-axis, but I didn't want to do any welding on my z-axis parts, so I built it to be totally removeable.

After using it several times, I see room for plenty of improvement, but overall it functions as expected. It does add a couple of pounds to the moving Z-plate, so I may try to find some aluminum all-thread to reduce the weight further.

Comments are welcome. I would like to see what everyone else is doing and then incorporate all the best ideas into a single adaptive solution.



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[matt_p]

Scott,
that's by far the best solution to the problem I have seen so far. Great Job!
Why didn't I think of that? So simple yet perfect!
I hope you don't mind if I adapt that for myself.
Thanks

[joelschuman]

Scott,
Please tell us what other improvements you'd make in addition to weight reduction. This looks like a winner, and could be my next step toward dust skirt Nirvana.

[scottcox]

Thanks for the comments. Please do use this idea, then share your experiences. I would do 3 things different were I to do this again.

1. Use aluminum for the all-thread.
2. Make the crank handle quickly removable.
3. Use a smaller diameter all-thread. I don't think that the 5/8" was neccessary but I had it already so I used it.

[scottcox]

Make that 4 things....

4. Use a lock nut to keep the handle from drifting/rotating while carving! :-0

[ariel_tff]

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