Printing airlock parts for my dust collector

[ddmckee54]

Andy, now you're cookin' with gas! The airlock gearmotor is 20rpm at the output, which is kind of fast for airlock rotation. But I had it on hand so I'll try it.

I originally used a container sealed to the cyclone that the debris would fall into, but it was a hassle to check the level and/or empty. Hopefully this airlock will make it much easier to do both.

I'm debating whether I want to try and reuse some of my first dust collection system's ducting or not. I'm leaning towards not, as it was pretty much just cobbled together with whatever was easy and cheap - mostly HVAC sheetmetal fittings. I'll probably wind up just keeping the blast gates and junk the rest. As much as possible I'll try to do it right this time, the HVAC fittings tend to wreak havoc on your airflow.

Don

 

[ddmckee54]

After a very sad and unsuccessful attempt at making a wood adapter ring to bolt my airlock to the cyclone, I gave it up and 3D printed a ring. The wood ring was one of those I cut it off twice and it was still too short type of deals. It took about 6 hours to print the ring, and golly-gee - it fits. I'll bolt things together tonight and take a picture of the cyclone and airlock.

I've been looking at the existing ductwork that I have and thinking about using various plumbing fittings. I think I'll use a combination of the 4" sheet metal HVAC snap duct and 4" PVC sewer fittings.( Sweep Tees and Ells) The sweep fittings and have a more gradual bend radius than either the HVAC sheet metal fittings or the standard plumbing fittings. This and the higher CFM blower will help eliminate the dropout problem I was having on the original system.

There is some concern about using PVC in a dust collection system because of static buildup. This can be alleviated by either running a continuous ground wire on the inside of the duct, or simply running it along the outside of the duct. I am going to simply wire across the PVC fittings tying the sheet metal peices into one continous grounded duct. I've seen what happens to dust collectors that go boom and it ain't pretty.

Don

 

[ddmckee54]

OK, this is what the airlock looks like when it's bolted to the cyclone.

I'm waiting on a more reliable coupler than my printed version for the gearmoter. That's why I printed and installed the hand crank that you see on the left side of the airlock. I'll probably just leave the crank installed after I get the parts since it will give me a visual indicator that the airlock is running. The slow boat might have docked by the time I get all of the rest of the bits and bob assembled.

The DC blower will live under the cabinet that's behind the door. The 6" elbow on the right side of the cyclone is the cyclone's inlet. That's the only 6" duct that I've got, and it's 6" because that's what the cutting patterns in the plans were sized for. The 4" duct to the blower will come off the top of the cyclone and tuck into the corner between the wall and the cabinet behind the inlet duct. As you can see, I have yet to build and install that duct along with the final filter for the DC blower. For a home built cyclone, these things were amazingly effective, it removes probably 90-95% of the particulate from the sirstream before the it gets to the DC blower, the final filter gets the rest. Both my Dad and I used the dust collectors a lot, and there was only a small amount of fine dust in the final filters on both units.

Don

 

[awake]

Don, I am not seeing the picture.

 

[ddmckee54]

Andy:

That's because I did something stupid again, I forgot to put it in shared album. The images show up for me, but not you guys. Let's try this.

I'm going to attach the link to the pic in the shared album too.
Cyclone

 

[ddmckee54]

I saw that I had the pic's as attachments in my previous posts and that seemed to work, so I'll try it one more time.

Betcha it worked THAT time.

 

[awake]

Yes, that last one worked. Very cool! Now we need to see a video of it!

 

[ddmckee54]

Andy:

It's going to be awhile before a video is even a possibility. Right now the DC system is missing more parts than it actually has installed.

Over the weekend I worked on getting the DC fan modified, I wanted to roll the scroll housing 90° so that it discharges out the top instead of the side. I also started printing the bushings that will adapt the 4.05" OD sheetmetal duct to the 4.2" ID PVC sewer fittings. The last of the bushings are printing now.

Don

 

[awake]

Understood. I am enjoying seeing how you are using 3d printing on this project!

 

[ddmckee54]

I managed to complete the surgery on the DC fan frame yesterday. I reused most of the fan's tube frame, but I did have to cut off one side. I thought I could just roll the housing 90° with no problem, I forgot that the housing was a scroll so the radius increased as I rolled it. That's why I had to cut off one side, but I actually got the fan bolted to the wall. I coulldn't resist a test run of the fan to see how noisy it was, it's actually fairly quiet.

I printed the last of the adapter rings for the 4" PVC fittings yesterday and got them all glued into the fittings. I also printed another mounting flange yesterday, should be the last one I have to print. This one's a 4" flange that will bolt the fan inlet ducting to the cyclone's air discharge at the top of the cyclone. I didn't manage to remember to take a picture of any of it though, I'll get that tonight.

Tonight I'll start on the installation of the fan inlet ducting. That duct will be about 6' long and it's only got to make three 90° bends between the top of the cyclone and the fan inlet.... Piece o' cake. I've just got to remember to wear gloves when working with that sheetmetal, the cut ends are like razor blades - I've got the boo-boo to prove it.

Don

 

[awake]

Don, your last post mentioned gluing, and got me wondering: What filament are you using for these parts, and what glue are you using to attach to PVC?

 

[ddmckee54]

I'm just using standard PVC cement, the plan isn't to get a chemical bond betweeh the two parts. Instead I believe that by using the PVC cement to soften the PVC and then pressing the printed adapters into the fittings, the softened PVC will mechanically bond to the nooks and crannies of the printed parts. Seems to work, because I can't budge the adapters in the fittings once the PVC glue is dry.

If you're wondering about gluing PLA, I did find a flavor of Weldon glue that works on PLA. I can't remember if it's Weldon #3 or #16, I think it's #3. But if you Google solvent bonding PLA you should find references to it. It's for acrylic parts but I guess PLA is close enough chemically to an acrylic that it works on the PLA. One thing I did find was that the Weldon tended to bleach the color out of one of the PLA'a that I used it on. I still got a fusion bond between the parts, but the filament in the bonded area turned white.

In this case I'm not really trying to bond the parts, just get a tight seal to stop air leaks. I'll either tape or caulk the rest of the joints. I used clear acrylic caulk last time and it wokded pretty well. A little TOO well, I've found that I can't get the joints apart in the sections I'm trying to salvage without destroying one side or the other. I've given up on trying to salvage the fittings and now I'm just trying to salvage the pieces of ducting.

As promised, I took a couple of pictures last night of what I've got accomplished to this point. This is a shot of the DC fan mounted to the wall. The house was built in the 1890's and the brick is kind of soft so instead of anchors into the brick, I've got threaded rod running through the entire wall, I don't think this stuff will go anywhere. Above the fan is where the DC final filter box will live.

The next shot is another view of the fan with a better angle on the type of fittings I'll use and their and adapters. Left to right it's a long radius 90°, a long radius 45°, and a sweep tee. I've also got a piece of the 4" snap duct shoved into the tee.

The next shot shows where the DC fan inlet duct will live, behind the 6" 90° in the corner between the wall and the cabinet.

I guess I've got a hook and several screws that will need to go away before that can happen.

Don

 

[awake]

Very cool. What is the red substance on the PVC fittings? That doesn't look like a PVC cement to me, but I'm drawing a blank on what else it might be ... ?

 

[ddmckee54]

Andy:

The PVC cement is the orange stuff that you can see in a couple of the fittings. The red bands are the 3D printed adapters, I guess it'd probably be more accurate to call them bushings. They adapt the PVC fitting from the 4.2" ID of the fitting to the 4.05"(ish) OD of the sheetmetal snap duct.

The ducts aren't exactly what you'd call round, or consistent - they varied from under 3.9" to about 4.1". I figured that 4.05" was probably close enough since it was supposed to be 4" duct, and it turns out that it was.

Don

 

[awake]

Ah, got it. You had talked about adapting the one to the other, but in my head I was thinking you had printed up a whole separate fitting. Far more efficient to print up the "bushing" instead! (Let's see - how long would it take to print half-a-dozen ~4" diameter, 6" long 22.5°, 45°, or 90° sweep fittings?? Yeah, might be a wee bit slower than printing up a half-dozen bushings!)

 

[ddmckee54]

Actually it was a few more than that, so far I've printed 16 bushings. There's three 45's at 2 bushes per fitting, two 90's at 2 bushes per fitting, and two tees at 3 bushes per fitting. That just counts the main line, the branch that will go to the CNC router, and the branch that will go to the drill press/1" belt sander/bandsaw. I'm installing the sweep tee that will eventually go to the branch line for the tablesaw and radial arm saw. But I'll just cap it off until I figure out a good way of getting things hooked up. I haven't got a good picture in my head yet of how I want to hook things up.

Although I'm seriously considering just selling the radial arm, since I rarely use it for anything other than a horizontal storage location. The sliding miter saw will do just about everthing the radial arm does, and in less space.

Edit: i just realized that it MIGHT not hurt to put a coupling or two in there someplace in the DC lines. Just in case I have to take part of it out to work on something else. I DO have to dodge around the sewer line to the downstairs bathroom after all. That line is just visible in above the DC cyclone in one of the previous posts.

 

[awake]

Although I'm seriously considering just selling the radial arm, since I rarely use it for anything other than a horizontal storage location. The sliding miter saw will do just about everthing the radial arm does, and in less space.

In my experience, the best way to establish the essential need for any tool is to get rid of it.

 

[ddmckee54]

Yeah, that's one of the reasons why it's still sitting in my shop.... That and the fact that I can use the same dado blade set on both it and the tablesaw.

Don

 

[ddmckee54]

I got some more done over the weekend, along with a lot more yardwork than I had planned on doing. I've got an old black locust tree behind my garage and sometime during the high winds we had over the last 1-1/2 weeks it dropped a 4" limb in my yard. After the derecho last year I had an evergreen tree that was leaning towards my house taken down and the dead limbs in the locust trimmed. I've still got to get that limb hauled to the compost pile, I just picked up the pieces and threw them to the side so I could get the lawn mowed.

I was looking at the ceiling in the shop, plottin & coniving how I was going to fit the DC ducts in place, when I had a brain-fart. I realized that if I moved the radial arm from its' location on the West wall, to in front of the chimney on the North wall, it would make it MUCH easier to cut longer pieces of wood. The door is on the East wall and if needed a long piece could just stick out through the door. This new location means the table-saw and the radial-arm saw can share the same DC branch, and I'll just plug in whichever saw I'm using.

I did get one piece of 4" duct hung temporarily in place. I lined it up with the inlet to the DC but I've got to move it at least an inch or two to the West, as it currently interferes with the gas-line to the water heater.

I'm gonna hafta move 2 of the shop lights too, but that's no big deal. I had already planned on moving one of them to a location more or less directly over where the CNC router will live. Right now I'm thinking whoever the genius was that thought this was a good location for the DC should have his head examined. Oh well, it'll be nice when it's done.

One of my couplings for the DC airlock rotor shaft was delivered. This one is a solid 5mm x 8mm coupling, I couldn't get a 6mm x 8mm coupling on this side of the pond. So I went with a 5 x 8 and just bored the 5mm out to 6mm-(ish). I didn't have a 6mm drill, 0.236" & change, but I did have a new 15/64" drill that was 0.234" & change. Turns out that was close-enough, because the coupling fits the gearmotor shaft like a glove. The 6mm x 8mm flex coupling that I ordered, before I realized that it had to come from China, is still on the slow-boat. It's not due to get here for another 2-4 weeks, and it may very well just go on the shelf when it gets here..

Don

 

[ddmckee54]

No progress for a while, gas water heater doesn't. Been working on getting it heating again, parts on order.