Thread: Contractor saw dust extraction - do I need air ports

Some questions before answers.

What are your dusty specs?
How far away is it from the saw and what sort of ducting (size - material) connects it to the DC

I can't imagine how you could seal up around the motor mounts or the adjustment wheel swing hole. Mine throws a lot of dust out through the adjuster hole in front.

Got any pics?

Originally Posted by BobL

Some questions before answers.

What are your dusty specs?
How far away is it from the saw and what sort of ducting (size - material) connects it to the DC

2 hp dusty - standard DIY unit from Carbatec. The ducting is 4 inch flexible pipe. The dusty is only about 1.5metres from the tablesaw. There are no gates or joins or anything, just a straight pipe which I connect/reconnect to whatever machine I want to use.
cheers
Arron

Originally Posted by Fuzzie

I can't imagine how you could seal up around the motor mounts or the adjustment wheel swing hole. Mine throws a lot of dust out through the adjuster hole in front.

Got any pics?

To seal up the motor area.
Imagine a huge sock, made of fabric. In my case I used that rubber backed curtain material because its impervious to air - I think its called thermal somethingorother. One end of the sock is square, the same size as the rear of the cabinet, and has velcro sewn around the edge. The other side of the velcro goes on the cabinet, all around the edge.
The other end of the sock has two elasticised holes. One goes over the motor mount, while the other goes over the belt guard. The motor has to be removed to do this.
Any air gaps are sealed up with hot melt and hard foam rubber, depending on how much air flow you actually want (hence my original question).
Just make sure your 'sock' has enough spare fabric to allow swing to 45deg, but not so much that it gets sucked into the mechanism or outlet port.

The tilt adjustment wheel swing hole is sealed the same, smaller sock.

This is not an original idea. Commercial ones are available. I copied it off the web, but cant find the original picture. Perhaps someone else can.

Photos later today.

cheers
Arron

OK, here they are.
The sewing is rough, but they work.
Arron

I'll have to look into that idea for mine. Thanks.

Originally Posted by Arron

2 hp dusty - standard DIY unit from Carbatec. The ducting is 4 inch flexible pipe. The dusty is only about 1.5metres from the tablesaw. There are no gates or joins or anything, just a straight pipe which I connect/reconnect to whatever machine I want to use.
cheers
Arron

On such a set up, totally closing up the back of the saw cabinet like you have done will restrict the flow too much - how much to open it up by will a bit of trial and error. If you want to increase flow by drilling holes in the zero tolerance insert, remember that small holes are MUCH more restrictive to air flow than a 4" diam pipe so you will need a total number of holes that are at least the equivalent of double the cross sectional area of the 4" pipe. By all means drill some holes but if they are too big you risk the chance of timber being cut, catching on the holes - this cane be quite dangerous.

The most restrictive component in your system is actually the single 4" flexy which unfortunately will be hobbling your DC.
A 2HP DC is nominally rated at 1000 - 1200 CFM with no pipes, but connect even one 4" flexy to it and the DC cannot pull more than about 400 cfm through it.
I assume your DC has more than one port on it so to improve air flow in/around the saw consider connecting at least 2 ,4" flexies in some way or other to the saw. - one below and one above the saw to some sort of guard.

Here is a link to a top guard I made using a "dust picker" back in 2006. The coiled up flexy as shown in that post is OK on a 1HP DC but not a 2 or more HP.

4" ports and 4" pipe on 2 HP DCs really restrict the operation of these DC - just one 6" diam port allows for more air flow than 2 4" port and only marginally less than 3 4" ports.

I'm currently in the middle of installing ducting and twin bag 3HP DC. for the saw connections I'm planning 6" underneath and keeping the 4" above

I just pick up a magazine called (I think) Tune up your Tools from the newsagent. There is a good article on sealing a contractor and cabinet saw. If anyone is interested in the article happy to scan and post here.