Need Help Upgrading My Dust Extractor.

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Delaney

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Hampshire
Hi all.

I'm looking for some help replacing my P&J dust extractor (3kw / 4hp). I can't stop it from leaking dust into my workshop. It's leaking from the hopper, where it mates with the main extractor body and I don't trust the filter system.

I've got about £3-4k to spend on a new system and have serval options. My preferred choice would be a Donaldson Down Flo, but then I wake up.

Your average Jet, Axminster, Laguna, iTech etc.. will not have enough power for my needs but my needs aren't that great per say. I only use one machine at a time, so I'm not 'industrial' but I do have some pretty big kit, which pushes me into the more 'extreme solutions' department.

My initial idea was cut the tower off my P&J, cut off the hopper shoot and cap both remaining holes. Then cut the end off the unit and connect a plywood box section with 4 cartridge filters. That system will then have its own bucket connected by gasketed clip ring. Something like this. (pic 3)

There are many revisions I can make to the design but that's the basic idea. My concern with this and why I haven't gone ahead, is the issue with the cartridge filters.
I ordered some custom ones from Cavendish but I think they are far too tightly pleated for wood processing. They say they will work but I can see them getting clogged in about 1 second. I also have different machines attached to the system.
1x Planer/Thicknesser
1x Bandsaw
1x Panel Saw
1x Wide Belt Sander

The m2 of the material of each cartridge is about 35 m2 (totaling 140m2) so huge amounts of nano coated, anti static real estate. Far too much actually.
The trick is how do I stop the bigger bits of material going into the filters and clogging them? I can add baffles but not sure how to do that. Perhaps one low cut panel going across the first two openings that causes the heavier particles to get stuck on and the lighter ones to flow over the top? That's kinda how they work but will need some fine tuning. That could be a horrendously fussy process, unless I get lucky.

Screenshot 2024-08-14 225830.jpg
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Screenshot 2024-08-14 231949.png



The second option is to buy a cyclone system. I've been researching them but they are difficult to get your head around. With a normal single stage positive system, usually more power means more suction, means better (ala Jeremy Clarkson). Cyclones are a very precisely controlled system with the exact size of ducting and amount of ducting. Even throttling some pipe runs to balance them at the cyclone.

I've done a LOT of research into flow rates, velocity, pascals and static pressure but being pretty thick, it's not natural for me to understand such things.
I'm aware that the system has to be set to your most greedy machine (including ducting).
In this case, that would be my Fleder Bandsaw, which has 2x 120 ports.
Felder rate the ports as follows

20.32 m p/s (4000 FPM)
814 m3 p/h (500 CFM)
917 Pa (3.7"w).

There are two of them which is as follows

20.32 m p/s (4000 FPM)
1628 m3 p/h (958 CFM)
1834 Pa (7.4"w)

This means that I need a motor/fan that can achieve 1,700 m3/ph (958 CFM) and a minimum of 1834 pascals (7.4 WC). This is all without ducting so if I use a calculator I can measure the required motor with ducting.

Using the Pentz calculator I add the ducting and cyclone into the equation.

Ducting 1.5 mtrs, 2 x 90 degree bends at 120mm, a Y shape 2 x 120, 1x 150mm, joining onto 3 mtrs of 150mm ducting into the cyclone.

This comes to:
Flow = 1628 m3/ph (958 CFM)
Pressure = 4869.5 Pa (16 WC)

The problem is, I'm having trouble finding a motor with a power curve that can keep up to Metric: 1628 m3/ph - 4869 Pa:
Imperial: I958 CFM - 16 WC.

Here is a power curve for a 5hp 4kw motor which should have more than enough power but @ 958 CFM (1628 m3/ph) , the WC is about 11 (2739) Pa), which is far too low.
I can lower the WC (Pa) by increasing the ducting to 180mm etc. but the ports on the Felder are still going to be 120mm. Ultimately the ports are too small, or the extractor to use on it, should have much more pressure over volume. So more like a supe'd up shop vac.

I don't want to have to buy two extractors if I can avoid it but a machine to power the extraction here, is going to be huge and very expensive to run.

If anyone can help, it would be much appreciated.
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I've been camping or I would have replied sooner.

The ClearVue cyclone with a 1950CFM rating has a 5hp motor using a 16" diameter, 6 blade backward inclined impeller and is meant to draw through 8" ducting. Their 1450CFM cyclones use a 15" impeller and a 6" duct. ClearVue is the Pentz designed cyclone so the one on his website will be in essence the same.

What size is the impeller in the DC you have now?

You can never have too much filter area. 😉

A couple other filter makers in the UK. Depending on your location venting directly outside after the Pentz cyclone produces no visible dust, so bypassing the filters in better weather is an option.

https://c-airfiltration.co.uk/dust-cartridge-filters/

djnuk.co.uk/ I don't know if the link still works as it blocks me out. Possibly because I'm out of the country.

If you are going to make your own cyclone and have trouble with sourcing the impeller I have the dimensions (pictures with a rule) of mine I could send you that could make your own. You would need to find the shaft taper lock weldable fitting to fit your motor.

Consider a 3 phase motor and use a FVD to power it. You'll be able to adjust the flow as needed and even overspeed slightly for more flow.

Pete
 
I've been camping or I would have replied sooner.

The ClearVue cyclone with a 1950CFM rating has a 5hp motor using a 16" diameter, 6 blade backward inclined impeller and is meant to draw through 8" ducting. Their 1450CFM cyclones use a 15" impeller and a 6" duct. ClearVue is the Pentz designed cyclone so the one on his website will be in essence the same.

What size is the impeller in the DC you have now?

You can never have too much filter area. 😉

A couple other filter makers in the UK. Depending on your location venting directly outside after the Pentz cyclone produces no visible dust, so bypassing the filters in better weather is an option.

https://c-airfiltration.co.uk/dust-cartridge-filters/

djnuk.co.uk/ I don't know if the link still works as it blocks me out. Possibly because I'm out of the country.

If you are going to make your own cyclone and have trouble with sourcing the impeller I have the dimensions (pictures with a rule) of mine I could send you that could make your own. You would need to find the shaft taper lock weldable fitting to fit your motor.

Consider a 3 phase motor and use a FVD to power it. You'll be able to adjust the flow as needed and even overspeed slightly for more flow.

Pete
Thanks Pete

After a few weeks of researching into cyclones, I’ve decided the best (and cheapest) way forward for now is to convert my P&J and see if I can get away with it.

Here is an example of the design I've come up with. It’s all a bit Heath Robinson but ’should’ work if I can get the internal baffles working properly to filter off the heavy stuff before hitting the filters.

I’m picking up the square to round metal section this morning from a local manufacturer. The 100 ltr steel drum arrives this afternoon. I;ve got all the MDF/Ply wood, made the boxes and cut the holes for the filters. I just need to cut the main inlet hole in the base of the box that sits on the old extractor.

D6D3F1C6-3B2A-49BF-BF75-39A8AEF9708C.JPG


The only tricky bit is getting someone round to weld some metal sheeting into the P&J section. One sheet to block off the old shoot and some to block off the outer perimeter of the internal space in the old P&J. This is to help guide the air flow out of the old extractor section and into the box ontop. It's also needed to stop dust building up in the corners.

I’ll connect the two boxes using a rubber gasket and toggle latches. I’m hoping the second box will be on castors and I can just wheel it into place and latch it onto the top box of the extractor.




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Little question about the filters. Are they meant to flow the air from the outside in or inside out like the hobby machines? Reason for asking is most industrial filters are meant to flow from the outside in so if they have layers to the fabric and the first one sheds the dust a little easier than the last. Looks like you are setting it up to flow from inside to out.

Unless you are making a Thein baffle I'm not familiar with any kind of baffling to separate dust so eagerly await pictures of what you are doing and how well it works.

Pete
 
Hey Pete

The filters are designed for a positive flow system, so air from the inside out. Much like a normal filter on a 2 stage. The nano coating is on the inside.
Negetive systems are imo a much better deign such as the Donaldson Down flo etc.. but they are very expensive and very big.
Someone was selling a used Donaldson but the bin was so small, i’d be emptying it every few hours.

The Donaldson baffles ‘encourage’ larger bits of dust to fall downward before hitting the filters. It’s literally a sheet of metal that the air has to climb over. It’s their best effort to make the system more effective without introducing a cyclone or other
They do have pulse cleaning though (which should really be called blast cleaning) to help keep the filters efficient during operation.

My system is not ideal and the filters may get overwhelmed although there is 140 m2 of filter material.
I’m going to direct the air flow from the impeller up towards the roof of the mounted box, then down again, to the exit shoot. If I can allow the heavier dust to fall out of the air stream through velocity, the lighter dust will then find it’s way up into the filters.

I’ll mount a camera inside to see how it all works internally.

I’m hoping since I use 1 machine at a time and only for an hour or so per day, if that, that they should remain at top efficiency for a few days before needing cleaning with an air hose. Or as our American friends prefer, a leaf blower.

As if they need an excuse to use one :)
 
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Thanks. The plant I used to work in had Donaldson Torit downdraft sanding tables and booths that were used for metal sanding. I'm well familiar with the pulses during the cleaning cycle. Sounds like shotguns being fired every few minutes. The office staff whined about it so they restricted it to the end of shifts.

Pete
 
Right! Quick update on the DIY dust extractor. After spending about £1,500 and 3 weeks of work, I've decided to stop the madness and purchase either a used twin bin unit from 'Wood Waste Control’ or have them make me a cyclone and fan system, which at least then allows me to use some of the filters I bought.
The issue with my system, is that under 3kw there is just too much air flow coming in to the main housing and thus the bits, are going strtaight up into the filters. I could remedy this but have run out of heart. I’m not a dust extractor manufacturer and I need to get back to what I should be doing.

Wood Waste Control are an interesting company. They primarily manufacture ducting and dust extractors, whilst having their fingers in many pies in that sector. I have visited their workshop in High Wycombe and they have their own plasma cutting machines. If you need something made and assembleed out of sheet metal, they will do it for you, if you provide the drawings (as to be expected). The shoot I had them make me was well made, they made it in 24 hours and it cost about £230 which I thought was good value.

Hopefully they’ll make it two for two, with this extractor.

Generally a very handy company to know. I can imagine getting them to make me all sorts of stuff for machine prototyping because they cut, weld and bend. Plus being base in the south east, they are very handy for people in that area, which usually has no industry left.

Here’e their site.

https://www.woodwastecontrol.co.uk/
 
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