Dust extraction for table saw..HVLP or LVHP??

[Julesbarn]

The DE on my table saw is non existent. I have a 2hp HVLP connected to the 100mm port at the bottom of the saw. All it does is stop the cabinet filling up with dust above the port!

On close inspection of the blade,arbor,trunnions,cogs and general assembly within, I'm pretty confident that I can make a kind of blade/hopper thingy that will move with the blade (lift and tilt), from either plastic or thin ply. By necessity, the arbor/bearing side of this will be very close (a few mm) to the blade. The other(outer?) side of the blade has plenty of room, so will allow for a dado stack with room to spare. I guess it will act like an upside down crown guard below the table,with a DE hose attached.

I pretty much never use the crown guard; so i want to attempt good DE from below. I have a great homemade cyclone/thein baffle seperator (LVHP) but don't know what would work best...

HVLP with 100mm hose,or...

LVHP with 50mm hose.

I'm hoping someone on here has successfully done this before

I await enlightenment...

Cheers,
Jules

 

[PAC1]

I pretty much never use the crown guard; so i want to attempt good DE from below. I have a great homemade cyclone/thein baffle seperator (LVHP) but don't know what would work best...
I await enlightenment...

Cheers,
Jules

Why?

 

[Julesbarn]

Hi pac..although that's not an answer to my query regarding DE, it's a fair question! I guess i seldom use a crown guard for the same reasons that others don't. It gets in the way,i can see what's going on better without one, and i can't use it anyway when using my crosscut sled,mitre sled,or any other jigs.

As DE is usually from below the blade (as well as at the crown guard ), i wanted to make it as efficient as possible from below, for those times when i can't, or don't want to, use the crown guard. I'm mainly seeking opinions (hopefully based on experience) on whether HVLP or LVHP would be best below (and close to) the blade.

Jules

 

[Steve Maskery]

Well in direct answer to your question, your best bet would be to have a proper internal shroud around the blade inside and have that hooked up to a high pressure system.
As to the wider point, I think you are taking unnecessary risks. Everyone thinks that it is not going to happen to them. We're smarter. We're not that careless. Not that stupid.
Everyone who has lost their fingers thought that. Until it was too late.
It's perfectly possible to use CC sleds and other jigs and have a guarded blade. I have a CC jig that is properly guarded. I have the world's best tenon jig and it is properly guarded. Yes, I remove the crown guard, but I replace it with something else that is suitable for the job.
I've been bitten twice by my TS in nearly 30 years. Never by the blade, thankfully. In both cases it was my fault.
But I would never be that stupid, would I?

 

[PAC1]

Interesting, I doubt the majority of UK professionals do not use a crown guard. There are times when removing the crown guard is necessary but not to use a crown guard as standard practice is just dangerous.
In answer to the question HVLP but you need to think where the air will come from especially if you use a zero clearance plate or sledge.

 

[Steve Maskery]

That's interesting PAC. Why do you say HVLP? HVLP is usually a 100mm port, and that port is usually on the cabinet, miles away from the action (it's like that on mine and is useless). I'd say you need good suction right where the sawdust is made and to me that means HPLV.
So either a shroud below of a crown or SUVA guard above, driven by a high pressure system. We are not producing loads of debris like a P/T does, are we?
What is your thinking?

 

[PAC1]

Steve the table saw usually needs a large volume of air movement to keep it clear of dust so I use HVLP under with a nozzle that is directly under the cut and a shop vac fitted to my SUVA. The problem with a tight fitting cover will be where the air will come from whether HVLP or HPLV.

 

[Steve Maskery]

Ah, OK, belt and braces
Good set up.
S

 

[Julesbarn]

Ok steve,you got me there! I have no excuses. Safety is paramount..just because i have used a table saw for 20 years,and chainsaws for 30 years,and never been 'bitten' by either, doesn't mean it wont happen one day.

Back to my question regarding under table DE, my thoughts are that LVHP with a smaller hose connected to a funnel/hopper arrangement, there is a risk of clogging by small slithers of wood etc, and,as pac says, with HVLP there needs to be sufficient air flowing IN...so zero clearance plates and sleds will restrict the flow just where you want it .
Steve,i bought a 2 hp HVLP blower for my TS and thicknesser,and realise it is only suited for the thicknesser. It does practically nothing for the TS dust. An easily removable (for unclogging) shroud/hopper connected to LVHP makes sense to me, but given what you say, perhaps there is no ideal solution if trying to extract just from below...unless...you had an incoming air supply that is specifically ducted to behind the blade, with your HVLP 100mm hose connected to a big hopper below the blade!? I guess I'm going to have to find the time to do some experimenting!

..and thanks again for the safety reminders. I love my fingers.

Cheers

Jules

 

[SkinnyB]

I made this shroud for my Wadkin as it came with no extraction. I use a 32mm hose with it connected to a cyclone and then my vacuum cleaner. It collects about 90-95% of dust. I find it really effective.
The direction that the majority of the saw dust is thrown goes straight down the hose. I do have a little problem with it getting blocked if small pieces of wood fall into it but easily retrievable.

Scroll down a little:
my-first-tablesaw-wadkin-ags-10-help-and-advice-wanted-t104090.html

 

[eoinsgaff]

First and most importantl step is to close all surplus air openings - this will direct all your extraction to the blade opening. The bottom of most saws is open, the spaces where the trunion adjustment exits the saw etc.

 

[Julesbarn]

Thanks skinnyB. Very interesting! When you say the shroud..do you mean under the blade or over? I'm guessing over,and the bottom cover is for guiding the dust up to your over blade DE/guard,and perhaps also preventing trunions,gears and cabinet in general getting covered in dust.

Eoinsgaff,.. I've blocked all entry of airflow around the saw best i can. Why all these saws,even supposedly fairly good quality ones like this xcalibur I've got, don't come with a half decent and intelligent DE set up without having to faff around loads, i really don't know.

Cheers

Jules