Wow. I got by with PLA at 20% infill and 3 outer walls. Seems skookum enough for this application.
IMO, you’d likely be better off using a shop vac with both your Suckit and sander because it would have approximately an order of magnitude more static pressure (albeit at an order of less airflow) than your dust collector. Effective dust collection doesn’t require massive airflow if the dust doesn’t get disbursed into a large air volume. The height of Suckets on the Shapeokos are independent of the height of their routers, so their brushes can initially be adjusted to contact the workpiece and minimize/prevent such dispersion. If the bristles are long enough and soft enough to maintain full contact with the workpiece throughout the milling process, 137 CFM from a shop vac should be more than enough to support all sources of dust and airflow into the dust shoe. The order of magnitude higher suction of shop vacs means that they’ll be significantly more effective at chip/dust containment and removal than dust collectors. You can also get HEPA filters for your shop vac for much less cost than one for your dust collector (assuming that you have filters.) That’s the Festool way. But, “the proof is in the pudding” - so try it.
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I have found that PLA tends to get brittle in the western Washington humidity. Typically only on things that are 0.50" or thinner, but since I don’t want to have to reprint them because I pushed on it too hard and it broke, I figure I’ll use PETG. The part is thin enough (0.10" wall), that going from 25% to 100% infill with two perimeters only added a couple of hours, so why not?
Here’s the part showing how little the fill is (brick reddish-brown squiggly line) after two perimeters.
Here is the small amount of support for the start of the saddle.
And here it is with the time to print. In case anyone doesn’t want to squint, it is 1 day 21 hours 42 minutes.
I totally agree with you on both points, but I typically run my Suckit about 3/8" off the work piece since I am using such small bits, and working in a small area, I need to see if a bit breaks before it finished its 15 minute run. The 2.5" flex hose has such a huge pressure drop across it that given the max static pressure my DC fan can generate it is my limiting factor to the amount of air I can move. I have 6in rigid ducting to 4in rigid fittings to this 2.5in flex hose.
Bu upping to a 4in flex hose, I am decreasing the static pressure drop by (I can’t remember and I am not going to make up a number) something. I work in a environmental control lab, so I can hook up 5ft sections of 2.5in flex hose and 4in flex hose and measure the CFM vs static pressure using calibrated venturis.
I just know that the volume of air moved is tied to the square of the static pressure, so a small increase in pressure can lead to a large increase in volume moved.
As far as tying in a shop vac, I don’t have room in my shop for one, and to be quite honest, I think I am done using them for DC. I burned out two of them. They each lasted around a year. And they are loud. I went to a spindle and have my DC motor just on the other side of the wall of my shed so I can have a quiet(er) space to work. Even with earmuffs I was tired of the router and vacuum noise.
If anyone is interested, I will post the results of using 2.5in, 4in and maybe even 6in flex hose CFM vs static pressure and pressure drop. In my lab, I have 5, 10, 25, 75, 125 and 175HP VFD controlled fans, so I can definitely draw more than the average DC setup.
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Bill Pentz claims " The only way to capture the fine dust as it is made is to start with hoods that block the fast moving air streams. His dust problem was simple. His big new over arm blade guard was wide open in front so launched the dust off the tip of the saw blade right out under his guard. A 3450 RPM blade speed with a 10" diameter blade creates a 102 miles an hour air stream. His saw pulleys increase the blade speed closer to 4000 RPM so the blade tips launched the dust even faster. A typical dust collector or cyclone only moves air at about 40 miles an hour. With the hot rod oversized impeller on his cyclone, he was got 60 mile per hour air speed which had zero chance of capturing the well over 100 mile an hour dust stream. To effectively control the fine dust as it is made we must have hoods that mechanically block all the fast moving air streams or there is zero chance of effectively capturing the fine dust before it escapes collection."
Vacuum vs Dust Collector1.zip (327.4 KB)
As shown below CNC routers can also generate high speed dust streams. Fortunately they don’t produce very much of that dust, so shop or other vacuums are well suited for use with them.
The following shows how my central vacuum’s 1" input, which can provide 13568 FPM (154 MPH) airflow at 74 CFM, compares to other vacuums and dust collectors.
Since my central vacuum uses two of the motors shown below in series, it has 12.38 in-WG more static pressure (suction) than the 48.62 in-WG pressure drop in the ductwork.
Here’s how Clear Vue Cyclone dust collectors perform (likely without filters).
But, I’d be very interested in whatever measurements you make.
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Well you should have that conversation with @cgallery who will be able to discuss the finer points of dust control.
"Well you should have that conversation with @cgallery who will be able to discuss the finer points of dust control."
Works for me - do I need to do something to make that happen?
Thanks for the info. That’s some good stuff. I fell down a rabbit hole looking at what you posted and then looking at other info related to it and have come to the conclusion that I may know a bit about airflow, but I know almost nothing about dust collection. And it seems the more I learn, the more I find there is to learn. 
I guess I’m going to have to find a way to keep my Suckit down against the wood. And maybe add on a gate on the back side where the slot is for the bit to pass through. No two ways about it - decreasing the pressure drop at the hose / increasing the airflow by going up to a 4in hose is NOT going to do what I was hoping it would do after reading the articles you posted.
I guess I’ll have to find a small USB camera to tuck in there to watch what’s going on inside the Suckit.
I am still going to finish and print the 4in dust shoe just because I have already started it.
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Me too!!
“I guess I’m going to have to find a way to keep my Suckit down against the wood. .” That’s my take on it, but I’m certainly no expert.
“maybe add on a gate on the back side where the slot is for the bit to pass through” The latest Suckits have that.
“I guess I’ll have to find a small USB camera to tuck in there to watch what’s going on inside the Suckit.” Great idea - record the video for replay to see when things go good/bad?
“I am still going to finish and print the 4in dust shoe just because I have already started it.” Another good idea - “the proof is in the pudding”.
IMO, if you can keep the Suckit down against the workpiece, your dust collector should do a good job with either 2.5", 4", or 6" connections if you keep the other blast gates closed. Try it?
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This 100+ MPH dust stream created by the blade is fairly low CFM. And any dust able to achieve and maintain that sort of velocity isn’t respirable (they’re larger chips that hit the floor fairly quickly). The finest stuff won’t get very far before the DC grabs it.
Forget most of the scare tactics of BP, in my opinion most everything was proven absolutely false once hobby shop owners were able to get inexpensive particle counters.
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Keep in mind duty cycle with these.
Usually dust collectors have a higher duty cycle than shop vacs.
Don’t want to burn up a motor.
Those prints look awesome!
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Was I completely off base in thinking a 4" tube from my dust collector to my router’s dust boot w/ an enlarged opening (and a higher volume of air being moved than a 2" opening w/ a 2.5" tube) would be beneficial in capturing more of the fine dust? Providing that the brush on said dust boot is in contact with my work piece.
Yup! A 1/8" kerf blade cutting 4" thick MDF at 100 IPM generates 50/(12X12X12) = 0.0289 CFM of sawdust and requires about 1.5 hp. That’s why vacuums, which offer hundreds of CFM (vs the thousands of dust collectors) are more than the adequate if dispersion of the dust/chips is properly controlled. Rather than use power to produce unnecessary airflow (analogous to current) at low pressure (analogous to voltage), vacuums use the power to produce higher pressures at reduced (but still overkill) airflows. That increased pressure is useful in overcoming the pressure drop in the ductwork. That’s part of the “magic” of Festool.
“And any dust able to achieve and maintain that sort of velocity isn’t respirable (they’re larger chips that hit the floor fairly quickly). The finest stuff won’t get very far before the DC grabs it.” If something isn’t used to block the dust/chips from the top of the sawblade in a table saw, a cloud of dust quickly appears near/around the operator. The dust collector can’t do anything about that. Gravity eventually causes the heavier particles to fall out of dust cloud but has negligible effect on the lightest (most harmful) ones.
“Forget most of the scare tactics of BP, in my opinion most everything was proven absolutely false once hobby shop owners were able to get inexpensive particle counters.” Got references?
Only if the dust is able to to achieve what I call escape velocity, quickly getting beyond the envelope of evacuation. The finest dust likes to meander, it doesn’t shoot in a straight line very long. Meanwhile, a 400-CFM hood is evacuating a 9’ sphere of air every single minute, or a sphere approx. 4.3’ every single second. So unless the respirable dust can make it past this point, it is likely going to get collected.
Even if some DOES briefly get beyond that point, make-up air will likely bring it back to the hood in short order.
I don’t have links for the Dylos particle counter buy threads, you can likely google them. They’re from some time ago, maybe 2008 I guess. If you go back to before this point in time on many of the woodworking forums, you can find lots of concerned woodworkers that were told their shops had never-settling fine dust that would eventually be their undoing. My recollection is that maybe eighty or so people got Dylos meters in the first go, and they all pretty much reported that the Dylos showed their shop air was cleaner than the air in the rest of their homes, or even outside.
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Isn’t the 400 CFM hood in the saw’s cabinet (under the saw table)? How does that have any effect on the top of the saw table? 
You only need bright lights (like sunshine) to see the dust cloud and how it disperses. Too bad you can’t see how much (and what types) of it gets inhaled by the operator and others in the shop. But at least they can sometimes smell it, cough it up, and/or have an allergic/toxic reaction to it later! 
When the saw is cutting, dust is brought by the teeth to below the surface of the table. On many saws these days (my inexpensive Ryobi included) there is a shroud around the blade. Some dust is ultimately carried back out of the shroud and to the top of the saw again, but with the DC running that air is rather quickly evacuated to below the saw where the hose attaches.
A demonstration I’ve done for people in my own shop, when I still allowed visitors and they were here in the winter evening when it was dark, was to take a few passes on the edge of a board w/o the DC running. Then we’d turn off the lights and turn on the DC, and I’d hand them a flashlight. They could see the dust-laden air moving towards every opening on the table saw.
Even more spectacular, when I had it, was the drum sander. That was dust cloud creator, but the same result. The air around the tool was evacuated, carrying the dust with it.
That’s a good argument for HF Spindles instead of routers too! (Or purchase with credit cards that extend manufacturers’ warrantees.)
“Those prints look awesome!” Thanks, but tables are just standard Excel stuff and the chart came from Clear Vue.
very true. i’ve heard and experienced typical shop vacs to fail moreso than i’ve seen routers.
believe it to be due to the necessary upkeep nature of a shop vac. if it is run with a clogged hose, dirty filter, completely filled bags/canisters it’ll experience excessive strain on the system. non normal working conditions if you will. low duty cycle + long run time + one of the mentioned items above = 
whereas a router tends to work at normal conditions most of the time and is easily visible if something is a miss.
oh, and i was referring to the 3d prints by @MadHatter. sorry for the confusion.
Wouldn’t it be nice if that was sufficient!
“On many saws these days (my inexpensive Ryobi included) there is a shroud around the blade.” Safely is their primary intended purpose (though most users remove them), but they also somewhat control dust dispersion above the workpiece. Here’s a video on how to get it to do a better job, or buy a SharkGuard. More to the point here is - lower the Suckit brushes to the workpiece!
“They could see the dust-laden air moving towards every opening on the table saw.” I’ve blocked all of the unnecessary/counterproductive openings in my table saw and bandsaw cabinets. That improved dust collection considerably.
“Even more spectacular, when I had it, was the drum sander. That was dust cloud creator, but the same result. The air around the tool was evacuated, carrying the dust with it.” The higher airflows that dust collectors provide can help control dust cloud generation/dispersion when more efficient and effective techniques can’t be employed.
Your partial quote of my message misrepresents what I said.
I’m not here to argue with anyone.