Thread: Dust Extractor Question?

Harry72 and mic-d,
It seems that we three are the only players on this issue and I am grateful for your advice to date.

I bit the bullet and ordered the PFC's from Gregories today. I settled a property sale with a developer last week ,who I really thought would default on the contract, but he came good.

mic-d. I understand from your pics that the "chow hat" came with the pfc's as part of the kit. I note that your extractor has a deflector rim around the top to force the intake down. Harry72, I appreciate your advice re the requirement to have some sought of deflector to create the cyclone effect. Advice from Gregories is that for the amount I use the combo I could possible get away with doing nothing and just fit them. I am not sure that is an option.

The three option as I see it are:
1) Just fit the pfc's and do nothing:

2) Fit an 'onion ring" spiral fixed to the top of the inlet, with the end fitted to the underside of that inlet. Proposing light gal.sheet clipped to the hoop and stiffened on the inner circle with some hoop iron strap to brace it. This would give a central " hole of 200mm diameter for the air/dust to rise into the pfc.
Fitted to both hoops this still slightly larger in area than the inlet area of the motor's extractor.Do I just stop there? or;

3) ALSO fit the "chow hat" that will come with the pfc below that " onion ring fitting. This would seem to be terribly restrictive on the air flow and as Harry 72 puts a "flow killer".

Harry 72, I note your comment re the cyclone being a flow killer. Do you have a view that option will be sufficient seeing the set up will not be the same as that photographed by mic-d.

My new H&F single bag 2hp extractor with pfc has a "dish" setup similar to mic-d's, but wider with a 250mm hole in the centre. So there is obviously a deal of variation in design parameters depending on the manufacturer. The H&F dual hoop fitted without pfc's has the spiral type deflector fitted to both hoops.

I didn't check the design on the dual hooped H&F with pfc's, but I may have to go back and do that.

Retrofitting can be a bit of a pain but I will get there.

Any views or opinions??????????

PEN

2! For the deflector you need to make an upside down cone shape with its peak removed

The inlet comes in underneath the cone shape, the chips would have to make a very sharp turn to go up in the filter.

A cyclone creates a lot of friction at the cost of flow, it can be overcome by adding more cfm, which is ok for a small workshop. But once the shop expands and you dont have 3ph power your stuck to 3hp max, so once you add some big long runs of ducting your cfm is at a premium already. Im looking at running 2x 3hp fans for my new setup

I can't add much to the discussion apart from asking did you talk with the Gregory's dust engineer for his thoughts? He designed the set up I have, as he explained it to me, through lots of prototyping. Maybe he can assist.

Cheers
Michael

mic-d
Thanks to you and Harry72 for the reply.

Mic-d - Did you make the small inverted cone ring(yellow) at the top of the hoop above the "chow" hat or was it already there?

I would be interested to know before I ring Gregories.

PEN

Hi PEN, that ring, much like Harry has drawn in cross-section was already there on the Powermatic DC, in fact it is slightly larger as shipped. Gregory found that by cutting that down a bit, adding the vanes and the 'chow hat' that they arrived at very good cyclone generation and minimized the dust up in the pfc. When you buy the DC with PFC from Gregory all that installation work is done for you.

Oh I checked back at you DC photo which doesn't have it. Yes I think it is an important component you need to install. Gregory may be able to supply the shaped sheet metal for that component if sheet metal is not your thing

Cheers
Michael

mic-d

Off to see the steel fabricator very early tomorrow morning so he can make the "onion rings' as suggested by yourself and Harry 72.

You suggeted that yours had been modified and that can be seen in the picture. On my 2hp with pfc it has what I would call an "inverted cone with cut centre hole" as per Harry72's diagram. The outside diameter is 500mm and the centre hole is 250mm. The width of the cone side section is thus 125mm. It does not have the "chow hat fitting."

The top yellow ring on your machine is what I will be getting made. Can you let me know the approximate size of cone side section on yours as modified. It looks to be only about 60mm (scaled from the photo).

What I intend to do is fit this fitting first without the "chow hat". Try it and see how it works, before fitting the "chow hats". Step by step approach.

Harry72 - I gather from what you have said earlier that you would fit the onion ring and stop there- no "chow hat", because "a cyclone creates a lot of friction at the cost of flow". Am I correct in that assumption? If that is the case the cone side section would be 125mm with 250mm centre hole, or are you suggesting that cone side section could be say 75mm as long as there is something there to force the chips down?

PEN

Originally Posted by PEN

mic-d

Off to see the steel fabricator very early tomorrow morning so he can make the "onion rings' as suggested by yourself and Harry 72.

You suggeted that yours had been modified and that can be seen in the picture. On my 2hp with pfc it has what I would call an "inverted cone with cut centre hole" as per Harry72's diagram. The outside diameter is 500mm and the centre hole is 250mm. The width of the cone side section is thus 125mm. It does not have the "chow hat fitting."

The top yellow ring on your machine is what I will be getting made. Can you let me know the approximate size of cone side section on yours as modified. It looks to be only about 60mm (scaled from the photo).

What I intend to do is fit this fitting first without the "chow hat". Try it and see how it works, before fitting the "chow hats". Step by step approach.

Harry72 - I gather from what you have said earlier that you would fit the onion ring and stop there- no "chow hat", because "a cyclone creates a lot of friction at the cost of flow". Am I correct in that assumption? If that is the case the cone side section would be 125mm with 250mm centre hole, or are you suggesting that cone side section could be say 75mm as long as there is something there to force the chips down?

PEN

Hi PEN,
Just measured it and you are spot on. 60mm.
The central cone is held by 3 or 4 vanes of sheet metal which directs the flow down into the dust bags. These are very important.

Cheers
Michael

Thanks mic-d,
I forgot to ask about the vanes!

Did you bend the fixing clip UP- lowers the height of the central cone away from the onion ring OR DOWN which raises the height of the central cone?

Did you set the vanes(full length) to point slightly down in the direction of the air flow?

Thanks heaps Michael

PEN

Originally Posted by PEN

Thanks mic-d,
I forgot to ask about the vanes!

Did you bend the fixing clip UP- lowers the height of the central cone away from the onion ring OR DOWN which raises the height of the central cone?

Did you set the vanes(full length) to point slightly down in the direction of the air flow?

Thanks heaps Michael

PEN

Okey dokey, been back out to have a second look at the vanes. The bracket and vane is all one component like a + shape. The narrow section bridges from the hoop across to the central cone (may actually all be cut from the one piece - don't want to go ferreting about inside it too much) The wider section makes the vane, the section into the wind is bent up, the lee section is bent down. Have a look back at the earlier photo, think it shows it OK.

Cheers
Michael

Hi PEN, I did up a rough schematic of how the flat sheet could be cut, need another 2 vanes of course. Hope this clarifies it a bit. The bracket/vane could be cut as a separate component.

Cheers
Michael

Originally Posted by PEN

Harry72 - I gather from what you have said earlier that you would fit the onion ring and stop there- no "chow hat", because "a cyclone creates a lot of friction at the cost of flow". Am I correct in that assumption? If that is the case the cone side section would be 125mm with 250mm centre hole, or are you suggesting that cone side section could be say 75mm as long as there is something there to force the chips down?

PEN

Just a flap directing the material down will work better than none, the only time you will get chips blowing upwards will be when the bag is full.
The cyclones Im referring to are the big ones like Mic's, not a insert.
I dont think a restriction the chow hat may present would make much difference to the cfm as its after the fan.

Looks like my guts after a nght on the p*ss

Jazza,Maybe the second post will be better.

Harry72 and mic-d,Thank you, everthing is very clear now.

Harry72, Understand your point now and thank you. No

mic-d - that fitting comes with the pfc kits and thank you for the measurement I asked for.

I will get the " onion rings" made over the next couple of days, and fit them along with the chow hats as per the photo.

I will post a photo when finished. It may take a couple of weekends to get there as I have a lot on at present.

Thanks guys very much for your patience and help. Top stuff.
Regards
PEN

Originally Posted by PEN

Jazza,Maybe the second post will be better.

Harry72 and mic-d,Thank you, everthing is very clear now.

Harry72, Understand your point now and thank you. No

mic-d - that fitting comes with the pfc kits and thank you for the measurement I asked for.

I will get the " onion rings" made over the next couple of days, and fit them along with the chow hats as per the photo.

I will post a photo when finished. It may take a couple of weekends to get there as I have a lot on at present.

Thanks guys very much for your patience and help. Top stuff.
Regards
PEN

No worries PEN. This fella Jazza has made another post on the subject. Ignore his concerns, it does not block up with any machined shavings. I have been successfully using this setup with a planer thicknesser with straight blades, since of course these still only produce tiny chips. As we both know, this has been designed by a dust engineer About the only thing that hooks up on it are long floaties made with a handplane. I sweep these up instead of putting them in the floor port

Cheers
Michael