Curved Inlet

[phil (admin)]

Wow, some of these builds are way over the top!

Love watching the progress.

Wait till I get my 3D printer!!

Says the guy that started the insanity!

[retired2]

Wow, some of these builds are way over the top!

Love watching the progress.

Wait till I get my 3D printer!!

Says the guy that started the insanity!

Thanks for the compliment, but I think we would have to go back a little farther in this evolution to find the winner of that award! :)

[Mike F]

I don't know who started it but all I can say is thank goodness the development was done by a guy savvy enough to put this forum together so that others may learn and help the development - thanks Phil.

some of these builds are way over the top!

I don't know about that, it's just the way I happen to work and know. You guys like manipulating wood, I like making moulds and plugs. In the end, both methods get the job done.

Retired2; I like your comment about the 3D printer because it so happens I have one on the way!

Bell mouth is now laid up - just waiting for the resin to cure before attaching the duct.

Mike

[phil (admin)]

Retired2; I like your comment about the 3D printer because it so happens I have one on the way!

I've thought a 3D printer may be a good way to make a tangential inlet that would fit standard 30 and 55-gallon drums.  I just wonder how long it may take one to be printed, and what kind of cost would be involved if we did develop some models that people could download and provide to a friend/business w/ a 3D printer.

Any idea?  Just for the sake of argument, take some of the curved inlets in this thread, how long do you guys think it would take to print something that size, and what kind of materials cost would you expect?

[Mike F]

Hi Phil; a 3D printer would be perfectly capable of printing the inlet, provided there was enough build height. The only problem might be the surface finish. If you take a look on any of the 3D forums you can see examples of builds and, dependent on layer thickness, the finished article always has a corrugated surface texture. Some people have devised ways of post processing the parts by dipping them in acetone, or appropriate solvent, to give a better surface finish. I would imagine that the inlet really needs to be as smooth as possible on the inner surface. Finer finishes are achievable by using smaller layer heights. The standard layer height appears to be around 0.2mm but 0.05 is doable though this would take four times longer to manufacture!

Material costs are around 28 dollars per kilo. My finished, glass inlet weighs 330g and is heavier than an equivalent plastic one would be. I reckon 250g should be doable which would make the costs around 7 dollars per inlet. Time to print? - not a clue at present but I dare say a question on one of the forums may well get an answer.

[phil (admin)]

Thanks for the details, Mike.  I might sign-up at one of the forums and do some more research.

There was also a local craigslist posting for a printer building camp.  Here:

http://milwaukee.craigslist.org/tls/4483878715.html

I thought it looked pretty interesting but didn't follow-up because I'm out of time.

[Mike F]

Beware!!!! It can become addictive, especially if you are into new technologies. I am a member of this forumhttps://groups.google.com/forum/#!forum/deltabot as the printer I am getting is called a Delta printer because of the way it works and this is the actual printer I have ordered via KickStarter though the production machine differs quite a bit from that in the video. https://www.kickstarter.com/projects/ttstam/openbeam-kossel-pro-a-new-type-of-3d-printer

[Mike F]

Nearly there and it's only taken one month! That's extremely good - for me.

Just have to use some silicone sealant to prevent leaks and I can soon be testing. Before I apply the silicone, I would like some feedback on the positioning of the baffle. In one of the 'Assembled' photos you can see the current position where I have placed the start of the shelf at the end of the inlet, tapered floor (where the two bits of polycarbonate meet). I have made the assumption that the air will still be travelling more or less parallel with the inlet, at this point, and will not have started to fall appreciably.

It will not be too big a job to remove the baffle and rotate it if necessary although this would mean breaking the silicone seal and re-applying it. I will go with whatever the consensus is, if there is one :)

Mike

Edit: Just remembered - I have to add the straighteners too.

[phil (admin)]

Given the height of the inlet above the baffle, the current relationship between inlet and baffle shown in your fourth picture may already be about spot-on.

[Mike F]

OK, that's good enough for me - thanks Phil.

I'll now get everything sealed up and see how it performs. Just about to laser cut the straighteners and get them installed too. Not yet sure if I have enough ducting and flexible tubing to complete the installation but if I have, I may just get it up and running tomorrow. Unfortunately, with all the machining of the plugs, I will have to dismantle and clean my filter bag again :( What a pain - still, hopefully, it may be the last time for quite some time :)

Mike

[Mike F]

OK, initial testing has been a little disappointing :( I managed to rig the separator up enough to do some testing without being connected to my machine ducting i.e. the inlet was not connected to anything. I had removed the filter and collection bags from my DC and ensured everything was clean. Without fitting the bags to the DC, I started the extractor to see what kind of suction I was getting at the inlet. All was good, it seemed to be as good as I ever had before. I then threw some larger dust particles (very small chips) into the inlet and watched them rotate and drop obediently into the bin - so far so good and I was getting quite excited.

I then tried a cupful of the finer dust my machine produces and was horrified to see quite a lot dispelled through the DC. Watching as it entered the chamber, I noticed that once the air dropped below the entry level, the speed dropped off dramatically and the dust made its way easily to the outlet without getting anywhere near the drop slot.

This is a 1.5H design and I am wondering whether a 1H would be better in that the air is constantly re-accelerated each time it passes the inlet. Failing that, in order to keep the air velocity up and the particles attached to the wall, maybe a tapered wall, below the inlet would be needed. Is this why the cyclone type separators are tapered? An alternative may be to add a shelf, at the inlet height and to raise the outlet to just above this height. At the moment, the outlet is about 50mm from the baffle, well into the slower air region.

One positive was that the bin liner does not get sucked up toward the baffle. My liner does not have a cage but is an excellent fit over the rim of the bin. (See photo) The baffle is also an excellent fit in the top of the bin, consequently no air can get between the bin and the liner and hence it stays in place.

I have now cleaned and washed my filter bag so the next lot of testing will have the bags attached and I will try raising the outlet before thinking about attaching an internal shelf. Any thoughts would be appreciated.

Mike

[jdon]

What a shame that such a beautiful build isn't working. :(

A couple of thoughts that come to mind, having pored over recent threads on this site:

Phil commented in one thread that for heights over 1H, the orientation of the drop slot might need to be changed vis-a-vis the intake port- he suggested the chalk method to trace the path.

Also, can you adjust the height of the bell mouth over the baffle- maybe lowering it a bit would reduce pass through.

Just thoughts from a newbie (in the process of building my own).

[Schreck]

I think raising the outlet & bellmouth should be your next move.  The velocity at the outlet is high, so you don't want that so close to the baffle where dust has slowed down. 
What do you have to lose?  Nice work, BTW.

[Mike F]

Jdon; I don't think the drop slot is too far out and you will have noticed that I have indeed changed the start position of the slot after Phil's suggestion. The height of the outlet is very easy to change and, I believe it needs to go higher, not lower. The testing was done at 50mm from the baffle which, I think, was Retired2's recommendation at 1/2D. However as my design is 1.5H, and the air below the inlet is moving much slower, I think it may be better positioned at 50mm above the bottom of the inlet. This will be my next move.

Schreck; thanks for the compliment - yes, moving the outlet up is going to be the easiest thing to try next.

The chalk test would be good if only I knew where to get hold of some :)

Mike

[jdon]

Mike-

Thanks for the clarifications- I'm always learning more from this site.

BTW, I don't know what type of chalk Phil has used, but I'm planning on using snap line chalk- it seems to be ground pretty fine, and dirt cheap.

Regards, John