Suggestions for my Vacuum system please

[Realmseeker]

Hey folks,

I am finally going to try a build a dust collection system for my router. I am using a laminate trimmer on a gantry. It is a small foot print for the entire router, 36"x36" basically.

My plan as I am thinking so far is to use my 2hp shopvac, attach through a Thein seperator, and to a shoe I sort of done up in my head.

As my hours at work are cut down a bit, I am leaning towards using things from around the house that I have left over from random projects, or scrounged. I have seen a bunch of different ideas here and there and hoping to combine them.

I plan to use 2.5" abs pipe. Have a 90 degree elbow centred over the machine above the height of the gantry. A 2.5" flex hose going down to the shoe(to be described). I would then run pipe to the wall, horizontally along the wall about 3 feet, then straight down to the Thein seperator. It will be about 12' of abs and 2' of flex hose. The seperator will be mounted on a 5 gallon pail.

I'll included a SW file of what I think I plan to do for the shoe(made of MDF). I plan to use left over velcro and clear vinyl to enclose the shoe. And to clamp the shoe to the router by using bolts through the 'wings' on the shoe.

So I guess my questions are:
- My shopvac has a 2.5" opening, so only use 2.5" pipe right?
- Too long for a small shopvac like mine?
- I have seen some comment on the 90 degree turns are bad for CFM, should I use 45 degree turns?
- Better ideas for my shoe design? Where can I get those brushes I see you guys with, just use dollar store brooms? More space between the intake and the router?

Appreciate any comments as always. Please question me as you see fit.


Cheers,


Jordan

[Realmseeker]

Just adding a SS if you can't use soildworks

[analogman]

I have a machine a bit bigger than yours I use for cabinets, sheet aluminum and engraving. Part time work. 4-30hrs per month.

I have 12' of 2 1/2" flex hose to a dust deputy to a shop vac. It picks up very well. I have no need for anything bigger. What you are doing sounds like it will work fine - except - you may want a longer flex hose. 2' would never work for mine.

Make sure to have a ground wire in your system.

[analogman]

Here is my shoe. The brush was simply from a shop vac dust brush epoxied into the the shoe.

[Realmseeker]

Awesome looking shoe Analog. I am going to see what I can scrounge up. Thanks for the info. Tomorrow I hit home depot I hope.

I am thinking of changing the design a tad to try and channel the routers output a bit. Does yours block the cooling fan on the router or does it just not interfere?

[cyclestart]

Originally Posted by Realmseeker I am thinking of changing the design a tad to try and channel the routers output a bit. Does yours block the cooling fan on the router or does it just not interfere?

That's not a hardware store router. Water cooled spindle possibly ?

analogman
That dust boot is a really nice design and it must be nice to be able to verify (watch) the air flow. That spindle has a lot of extension from the body to the tool, more than many of us have to work with.
Do you have to drop the dust shoe for tool changes or is there a spindle lock not visible in the picture ?

[Dean448]

My current dust shoe is made out of 3/4" 7 ply from Depot strapped directly to OD of the router. I built 4 small brackets and simply band clamp the dust shoe to the router. I first tried bristles like everyone uses and quickly found that for shallow depths of cut they create sigificant force resulting in depth variation. I'm sure that angling then would help.

I fould that the name of game in dust collection is to try to collect all the fine stuff and contain as much of the large stuff as possible. So the 3/4" ply is cut to an oval shape and I simply attach strips of non rigid foam extending down to the tip of a typical router bit. The big stuff hits the foam and drops, the fine stuff is all pulled up inside of the foam. Since you can't see through this I simply set depth without the shoe, then go up 2" and insert the shoe, clamp the band and hit start. For what ever stays on the table you simply manually vacuum it up after a series of cuts.

[CarbonKevin]

I've posted this elsewhere, but I'll put it here, too, since it's relevant.

Consists of two sections. The upper section deflects airflow from the router out to the sides and rear. This is screwed to the underside of the router; it stays on during normal use. A flange (black) is attached to the top, to attach the vacuum hose. Neodymium magnets are epoxied into the 4 holes around the edges prior to installation.

The lower section is the skirted portion. Neodymium magnets are bonded to this section, as well. Brush bristles, vinyl, or other material is attached to the outer face to form the skirt.

This design solves the problem of the router's airflow disrupting the vacuum's suction. Also, using magnets to hold the skirted section in place makes for very easy removal for tool changes, visual positioning, etc. This also means you can have a variety of different skirt lengths on hand to suit different situations.

Update - I didn't design in access to the collet lock button. I'll sort that out shortly and report back.

[Realmseeker]

Here is a re-worked idea for mine based off what you guys have said. The grey part will be detachable by magnet or some such thing. The small hole is large enough for the nut on the spindle to go through, but with the cut out on the back should direct the router's blower out of the shoe.

The bottom of the yellow piece will line up with bottom edge of the router.

[CarbonKevin]

The air deflector in the latest design is a bit problematic.

By placing the deflector on the removable section of the shoe, any forces generated by the router's airflow will be acting upon it, as well.

That means the magnets holding that section in place will be subjected to the weight of the shoe, an dynamic forces generated by the brush/skirt contacting the cutting stock, PLUS whatever forces the airflow from the router through the deflector generate.

Here's the really fun part. Stop reading here if you don't find yourself aroused by fluid dynamics.

Depending on airflow and the design of your deflector, you may actually get a force that helps the magnets do their job.

Bernoulli's principle states that as fluid's speed increases, it's pressure decreases. IF you can accelerate the air coming out of he router as it's transitioning from vertical to horizontal, and the resulting pressure drop across that zone is lower than the pressure of the skirted suction zone below it (due to the vacuum source sucking up dust), your net result will be a force pushing the lower section of the dust shoe upward.

Will it make a noticeable difference? Impossible to say without doing some CFD testing. Would I rely on this to help hold things in place? Nope. Just as likely the system would give the opposite effect, and put more load on the magnets.

My first suggestion would be to get the deflector into the top section. Remember, the two sections don't need to have uniform thickness - the top section can be thin at the front, and get wider to accommodate the deflector, and the lower section can be thicker at the front, and thinner at the rear.

Either way you go, it does make sense to do a smooth transition from vertical to horizontal airflow - radius the transition. It will help airflow, which can only be a good thing, if only or the router's internal cooling.

And don't make my mistake - remember to allow access to the collet lock button!

[analogman]

Originally Posted by cyclestart ThaWater cooled spindle possibly ?

Yes, its one of the chinese spindles.

Originally Posted by cyclestart That dust boot is a really nice design and it must be nice to be able to verify (watch) the air flow. That spindle has a lot of extension from the body to the tool, more than many of us have to work with. Do you have to drop the dust shoe for tool changes or is there a spindle lock not visible in the picture ?

That is one of the drawbacks of this design, I have to unbolt the dust boot for tool changes. My work is semi-production and quite optimized, so its not a big deal.

I like the idea of CarbonKevin's magnets, that will make changing quite fast.

The other drawback is that the shoe does not follow the work, its at a fixed distance (most shoes are probably this way). I can manually adjust it up and down, but thats a pain. When cutting deep, it'd be nice to have the shoe float on the work surface.

[CarbonKevin]

I've been thinking about a "terrain following" dust shoe for awhile now...but haven't got any good ideas yet.

Anyone ever seen a good design for one of these anywhere?