Thread: Moving the DC outside

Ah ha - thanks.

I would have done the same as you but I recently watched my mathless BIL having to do a similar thing joint with Al pipe and what he did was use a piece of cardboard formed into a cylinder and a pair of scissors - he just winged the first cut and then made adjustments until he had it - pretty quick really. Then he did the same and wrapped the cardboard around the Al pipe.

Sizing up the inside half of the unit so I can work out where to cut the hole in the window pane . I'll be able to move it closer to the window once the hole is there.

To avoid a 90 bend straight out of the impeller, I have turned the whole unit onto its side, but it's hanging off the original mounts. I am concerned that the motor bracket may sag over time and was thinking to address that by blocking up the motor with a short timber offcut underneath. Is that a good idea, or am I better off reverting to the original orientation and including the bend?

(I don't do metalwork, otherwise I would have fashioned a support bracket to connect straight off the motor casing.)

Looks fine to me but I would add 45º wooden braces on each side of the marine ply bracket.

Originally Posted by BobL

Looks fine to me but I would add 45º wooden braces on each side of the marine ply bracket.

Yes thanks, did that already with the steel brackets which incorporate a 45 brace. They are painted black so are hard to see in the photo.

If I remember correctly you can unbolt the housing from the motor and rotate it ninety degrees and bolt it back on. The motor will sit as it was made and the impellor outlet exits to the side instead of up. You need to remove the inlet, then the impeller to get access to the bolts in the end of the motor. When you put it back together you should seal the mating surfaces to prevent leaks.

Pete

I'd be putting a block /cradle under the motor. I'd think it would risk distortion in the blower housing otherwise.




Russ

Originally Posted by russ57

I'd be putting a block /cradle under the motor. I'd think it would risk distortion in the blower housing otherwise.
Russ

The motor and impeller are not hanging off the housing, instead they're attached to a sturdy (3mm thick ) steel bracket attached to the ply upright. If anything the blower housing is hanging off the motor but it does that as supplied in the original fitting and the housing is much lighter than the motor.

I lightened up the photo so the motor bracket could be more easily see.
inside2.jpg

Originally Posted by BobL

The motor and impeller are not hanging off the housing, instead they're attached to a sturdy (3mm thick ) steel bracket attached to the ply upright. If anything the blower housing is hanging off the motor but it does that as supplied in the original fitting and the housing is much lighter than the motor.

I lightened up the photo so the motor bracket could be more easily see.
inside2.jpg

I can see clearly now the dust has gone ...
Yep, that should be fine I reckon.
IMHO.


Russ

Up until now I've been working through the problem of getting the DC outside (or at least the leaky bag and filter half of it) but had a bit of a blind spot on the inside implications of doing that.

My working space is one half of a double garage, and my primary dust makers are a table saw and a router table. The router table is set into the extension wing of the table saw.

This means extending ducting into the middle of the room as the table saw can't be located against a wall.

An overhead route from the impeller to the TS would be 2m up then 3m directly across and 2.4m down, with four right angle bends (plus 2m from the impeller out the window to the bag) ... from reading this forum that sounds beyond the ability of a 2hp modified dusty?

If pressed, I could put up with the inconvenience of running ducting across the floor, even then it would be at least 4m horizontal ducting inside, with two 90's, and 2m more outside.

How much flow loss will I get from the extra length of 150mm PVC? Bob, you say try not to go over 3m with a 2hp dusty, but I can't see how else to get the DC outside and I understand that is the #1 thing to achieve.

Also does pipe going vertical cause more of a loss than going horizontal?

Originally Posted by Ian Dobson

How much flow loss will I get from the extra length of 150mm PVC? Bob, you say try not to go over 3m with a 2hp dusty, but I can't see how else to get the DC outside and I understand that is the #1 thing to achieve.

By "3m" I mean as short as possible.
It's not like that up to 3m its OK , and then at 3.1 m it drops of to "Not OK".
If you cannot keep the ducting runs under 3m then you have to live with it unless you go to a larger DC.
I usually recommend no more than 6m for a 3HP DC but my ducting run to my TS is 11m.

Unless the ducting ends with naked duct (i.e. not attached to a machine) attached to a BMH the biggest losses are always at the connection to a machine.
I would focus more on that than anything else.

Also does pipe going vertical cause more of a loss than going horizontal?

No real difference.

I have had some time to get back to the project today now that Christmas is over.

1. Removed the lower glass window pane and replace with acrylic/Perspex, with a corner removed and replaced with a ply panel with a 6" hole for the ducting.

2. Took to my shed wall with a jigsaw to make a 6" hole for the intake duct. I found a DWV 90 with a larger radius than the storm pipe. BobL I hope that's the type you were referring to.

3. Rather than continuing with my earlier idea of interfacing the 6" pipe directly with the bag/filter ring, I have switched to making a ply adaptor following Jonno's idea. Then I have made two 6" round pipe to rectangular transitions, to fit the impeller in the garage and the bag/filter ring in the DC shed. The idea here is that if I decide later on to put the impeller into the DC shed too (with a swag of additional soundproofing) then I can easily revert to the original DC mod design with the impeller and bag/filter directly coupled.

The next step is to get the external ductwork completed and flashed/sealed

At present I haven't even started on the 6" input side to the impeller, or ducting in the garage. I am trying to work one step at a time without totally disabling my DC for a long period in the process.

Test fit of the duct work. I still have to change over the bag/filter connection to the 'Jonno' adaptor.

I downloaded an iPhone DB meter and took some measurements.

Inside the garage ~46dBm with nothing turned on.
~85dbM with the impeller powered up and standing 1m from it.

Outside 1m away from the DC shed ~64dBM with nothing turned on. Our ducted A/C heat exchanger is about 3m from here and currently operating so it's noisier than usual.

With the DC on, I measure 85dBM standing 1m from the shed with the door open, and 78dbM if the door is closed. Currently I don't have any exhaust ports cut into the shed and there is considerable back pressure with the door closed.

I am surprised that the bag/filter is pretty much just as noisy as the motor/impeller.

Now to work on some sound reduction, or the neighbours wont be too impressed with my efforts. My shed is only 0.8m deep so there isn't a lot of room for thick absorbing batts. I could line it with thick MDF or chipboard and still have room to move to empty the bag and clean the filter.

To stop noise transmission, mass..
Line it with chipboard, mdf, carpet, lead sheet, concrete
A baffle around the air exit, at least, or better some sort of labyrinth, lined with noise absorbing material. Eg, carpet, acoustic batts, acoustic foam.




Russ

I would be looking at fitting a vibration isolating "baffle" between the pipe and opening through the Perspex window pane. Its amazing how the pane can act as an amplifier for low frequency noise and also transmit vibration to the aluminium frame.