Dust extraction / cyclone pressure release valve

[MattRoberts]

That's a nice neat solution, thanks for sharing.

You do realise in that last pic you have the vac attached to the wrong port on the cyclone though right?

 

[AES]

Thanks Matt, yes, I did realise I'd connected it up wrong - AFTER I took the pic, naturally.

Don't know why the 1st part of my post appears twice, sorry. * NOW EDITED TO REMOVE ERONEOUS POST.
Neither do I know where the drawing & Legend has gone either - I thought I'd just posted it.

Here we go (again)!

 

[pike]

Very impressive AES! I am going to ignore this whole valve thing.. probably until something implodes...

Matt I'm certain he was just checking we were paying attention ;-)

 

[AES]

Now here's the Legend for the sketch:

A - Dark Green - Main Body(Geberit black plastic 75mm/50mm dia. rain water pipe reducer; 4 x
15+mm dia. equi-spaced holes in lower sides)
B - Yellow - Valve Stem, upper & lower (8mm nom. dia. Brass, drilled & tapped 6BA)
C - Brown - Valve Stem Bearing/Guide (15mm Sq. MS tube, approx. 3mm wall thickness)
D - Orange - Internal Seal Seat Disc (3mm ply, 50mm nom. dia.)
E - Purple - Rare Earth Magnet (8mm nom. dia; 3mm centre through hole)
F - Dark Blue - Valve Seal Seat Disc (3mm MS, 25mm nom. dia.)
G - Dotted - Valve Seal (approx. 3mm thick expanded PVC sheet packing material)
H - Light Green - Valve Head (19mm ply, 50mm nom. dia; coned to suit taper of inner Main Body)
J - Red - Lower Valve Guide (3mm hardboard, 50mm nom. dia; 4 x 15+mm dia equi-spaced
holes)
K - Light Blue - Manual Reset Knob (plastic or wooden disc to suit - spares box!)
L - Grey/Black - Valve Spring (8mm nom. ID x 6tpi, free length to suit)
M - Dashed/Grey - Upper & lower retaining bolts (6BA Brass)
N - Heavy Blue - Approx. line of dust bin lid on installation (NOTE: Body Retaining Ring omitted for
clarity)

Yes, I DO know I've broken all the basic rules of "Tech Drawing" ("Sorry, Mr. Johnstone, Sir"), but my excuse is that A) I was trying to make it clear at the small size we have for attachments, and B) I had nothing else better to do than think about bloody back ache!).

I stress that this sort of stuff is NOT my speciality, this was all "empirical" but it does work fine (now I've enlarged those holes in the body).

If anyone has any Q's I'll be pleased to help if I can.

AES

 

[pike]

Would a quick fix for the lazy be to make a inch wide hole and put some tape on it?

 

[MattRoberts]

Have updated my first post to highlight your alternative solution AES

 

[sunnybob]

if you arent clever enough to build that, its a spring loaded check valve fitted into swimming pool pipe line to prevent syphoning.

http://www.ebay.co.uk/itm/SWIMMING-POOL ... SwbqpTtyaC

 

[AES]

Thanks for the interest everyone.

@MattRoberts:

Thanks mate.

@sunnybob:

Yeah, looks like a possible solution. And if you added the "value" of my time making that valve, then mine probably cost a lot more than the 25 quid your swimming pool valve costs. Not so much "fun" though!

@pike:

You'd have to try the tape idea to see if it works OK (i.e. doesn't break the tape under normal ("unblocked") suction operation, but does break the tape when a hose gets blocked).

But just a point - I THINK that if your hole is one inch dia, that's roughly 3+ sq ins of unsupported tape surface area ("py" - 3.142 x 1 inch) times nominal sea level atmospheric pressure (14.7 psi), equals roughly 45 lbs force on the tape in normal operation. Seems to me the tape would need to be pretty thick/have good adhesion to stay in place when in normal operation. And of course when a blockage does occur and the tape did break/come unstuck, then the broken bits of tape would disappear into the dustbin. So you'd have to find another similar bit of tape and stick that on again after clearing the hose blockage.

But give it a go. Certainly quicker a cheaper than messing about with a valve like mine (even if it was good fun). Let us know if tape works please. I wouldn't be at all surprised if it does work ("KISS" and all that).

Cheers

AES

 

[pike]

AES, your valve is quality. I'm just thinking if there was a basic solution of hole and tape it might avoid implosions for people who haven't yet made one. Assuming the hole could be reused for the valve.

 

[AES]

"Quality", pike. Thanks for that, I like it.

I posted it because I thought that maybe someone else may like to do something similar, and as it does work OK now, and as the dimensions are all based on junk found in my various "scrap boxes" (apart from the valve body which I had to buy), it's pretty easy to adjust sizes to the contents of one's own "might come in useful one day" box/es.

BTW, when commenting on your idea for sticky tape over a 1 inch hole (above), I accidentally used py x dia for the area of the circle of unsupported tape. That's rot of course, (py x dia is for the circumference of a circle), I should have said py x rad squared. Makes a difference too, of course - instead of the 45 odd psi I posted, the proper number is nearer 11.5 psi. Sorry.

Have you tried the tape idea yet?

AES

 

[Graeme48]

Good morning all.
As a newbie, please forgive me for bumping an old post, but this is a subject of great confusion to me at the moment.

After a period of nearly 15 years with little to no woodworking, I am now at a stage where I can resurrect my primary interest of woodturning. Times have moved on since I last did this and health aspects are now more of a concern. Using a double garage as a workshop, I already have a wall mounted Fercell Fly chip extractor which still seems to work well and I will be using a powered respirator when I replace my now obsolete Racal.

I am thinking of installing a cyclone into the chip extraction system, to further reduce the fine particle dust that seeps through the filter on the chip extractor and have several 'silly' questions, which hours of Google time cannot answer simply.

1. Am I correct that the ducting goes from machine to cyclone to chip extractor?
2. Do the 'heavier' chips pass through the cyclone?
3. The existing ducting on the chip extractor is 100mm, so this obviously needs reducing down to the fitting on the cyclone - if I then use smaller diameter ducting between the cyclone and each machine (lathe, bandsaw, sander) will this reduce the efficiency?
4. Is there a practical limit to the extent of ducting between each machine and the cyclone/extractor setup - my workshop is approx 5m wide with machines on opposite walls, which also implies running ducting at ceiling level.

Thanks for any advice offered

 

[AES]

Hullo Graeme,

I'm by no means an expert on all this stuff, but like many here I'm dabbling - sometimes with some success!

I can't do better than direct you to an excellent "sticky" in this Forum by member siggy 7. Here's the link:

a-guide-to-dust-extraction-by-member-siggy-7-t102025.html

And if you want/need to go deeper than that (I found the above thread a GREAT help) then there's what seems to be the bible for wood workers, namely Bill Pentz's info, here:

http://billpentz.com/woodworking/cyclone/index.cfm

When you've got through that lot, you'll find lots of youtube videos on the practical aspects of making individual items like blast gates and cyclones, etc. Just use the youtube search function and look up "Dust Extraction".

I'm not a turner myself, but from the little I've seen, as a turner you have several concerns - "lightweight"/airborne dust - long spirals of shavings - smaller "chips n chunks". All need handling a bit differently.

HTH

 

[sunnybob]

Theres 10 years worth of reading on this subject, and at least a 100 different opinions, but to answer your questions as briefly as possible;
1. Am I correct that the ducting goes from machine to cyclone to chip extractor?
Yes, the flow is from the lathe to the side of the cyclone, then out the top of the cyclone to the extractor unit.

2. Do the 'heavier' chips pass through the cyclone?
Yes, and no. Normally, the chips will fall down the cyclone into the collector, but sometimes, if there are a LOT of chips, as in a thicknesser machine, sometimes they will go through the cyclone.


3. The existing ducting on the chip extractor is 100mm, so this obviously needs reducing down to the fitting on the cyclone - if I then use smaller diameter ducting between the cyclone and each machine (lathe, bandsaw, sander) will this reduce the efficiency?
Yes, and no, again. Depends on the bore of the cyclone pipe. If youre thinking of one of those 50 mm dust deputy things, then youre wasting your time and money because the 100 mm pipe will just suck everything straight through the cyclone. Dont ask how I know this, but I do have a 50 mm dust deputy for sale.
I now have a 62 mm cyclone made from an old 3/4 size traffic cone, and all my ducting and blast valves are 62 mm, and its quite acceptable performance when running one machine at a time. But I would like a bigger cyclone in the future.

4. Is there a practical limit to the extent of ducting between each machine and the cyclone/extractor setup - my workshop is approx 5m wide with machines on opposite walls, which also implies running ducting at ceiling level.
Yes. the further the pipework travels, the less flow you get. Every metre, every fitting and every turn slows the flow. Work out the most direct route across the workshop, even if that is a diagonal. Use as few elbows as possible, preferably long sweeping bends. Dont use T joins, they are the worst for restricting flow. If you have to, use Y branches and put a blast gate as close as poss to each machine.

 

[Graeme48]

Thanks to SunnyBob and AES for the replies, it looks like I have more reading to do but some excellent source material to start with.

 

[dtecting]

Hello First time with pictures Hope it works.
Have used this valve on my cyclone with no problems
https://www.dropbox.com/sh/peqm83fes5w7pg6/AABG96fkZar_2sJU8aIsrbsCa?dl=0

 

[sunnybob]

I'm not completely convinced about release valves on smaller systems.

If the pipework blocks, the noise change is so dramatic (even with the extractor in an enclosure) that you hear it straight away.
Unless you are completely isolated with music headphones of course, which i really dont like and wont use. But it would need a big extractor to collapse any pipework, and the pipe would have to be blocked for a fair old time before the motor got too hot and gave up.

I made a slight modification to my 63 mm plastic blast gates that actually help stop a problem like this. I cut the very corners off at the end of the slide housing for a completely different reason. The blast gates kept getting jammed with dust forced into the slide runner every time the slide was opened and closed till in the end the blade would not fully close and it was a real pig to clear them out. I cut the corners off so that the slide now just pushes the dust all the way out the ends instead of blocking. An unexpected extra bonus of this was when the pipe did block, the valves all gave out with a piercing whistle which nobody could ignore.

 

[AES]

The only reason I made my "auto valve" is because I found out in testing that there was enough suction to start collapsing the wall of a SS dustbin bought especially as a collector - admittedly only a cheapo from the local DIY place though.

By the time I reacted to the changed noise (sunnybob is quite right, it's easy to hear the changed note) the wall of the dustbin had already started to fold up. OK, not a serious problem, and easy to get (most!) of the denting out of the wall, but still!

Also my "extractor" (it's a Kaercher wet/dry shop vac) also has an auto valve built in, but as said, during testing, I found the dustbin wall started to collapse before the valve on the vac released the pressure from me deliberately blocking the pipe.

Perhaps I should add that my "system" is very simple, no blast gates or fixed piping such as sunnybob describes. Just the fleX hose that came with the vac, some "solid" PVC pipe between the vac and the single cyclone, and only 1 tool in use on DE at a time. So I thought making a valve worth it. But that's just me.

 

[sunnybob]

are you sure that dustbin was steel, and not aluminium foil? :shock:

were you doing destruction testing? I cant think of a situation that would completely block the pipe to that extent.
Last week while using the hose to vacuum the floor and bench of the workshop I accidentally sucked up a pair of black vinyl disposable gloves. They made a huge whooshing noise and I could hear them go down the hose, through the blast gate, turn right at the T, and all the way round the cyclone, before I could get to the wall mounted off switch. I found them past the cyclone inside the extractor bin when I cleaned out. But even that didnt block the pipe completely.

 

[AES]

Well the bin isn't ali foil, and the label in the shop said it's SS, but it IS rather thin I grant you (like most such things, the "strength" comes from the wire "hoop" at the top and the corrugated sides - plus the bottom of course). But my simple test was simply to put my hand over the end of the flex hose - within a second or 2 of being covered the sides of the bin started to fold inwards.

From that I concluded a "safety valve" was necessary, so I made one and fitted it.

 

[MattRoberts]

You're more likely to get a bin collapse from an LVHP system (shop vac) than an HVLP system (chip extractor).

I have a thick walled plastic 30L container under my LVHP cyclone system, and it collapses easily without a pressure relief valve.