Dust collection and riving knife on table saw

[chataigner]

I thought this topic looked a bit lonely, so here's a contribution :

I have long been very frustrated by the above blade dust collection arrangement on my TS. The dust chute was supported by the riving knife, and to make this possible, the knife is quite a bit taller than the blade, so you have to take the knife off to use a crosscut sled etc. Taking it off involved undoing the two allen screws holding the insert, cranking the blade to the top of its travel to get at the bolts, undoing two bolts, removing the knife, then tightening the bolts back up so they dont wobble loose and fall into the sawdust etc etc. Needless to say, with all that hassle and the fact that I use a crosscut sled a lot, most of the time the riving knife sat in a drawer - not good...

The cure was spotted on-line : an overhead support for the dust chute which will enable me to cut down the riving knife to the same height as the blade. (It's not yet done so not shown in this pic).

The dust chute support is a wooden channel fixed to a joist above with a slider running in it that is clamped to the desired height with a toggle clamp. That also means it can be taken off completely if required. It's slightly to the right of the blade with the old dust chute temporarily screwed to it, that will allow tall work pieces such as cutting raised panels to pass to the left of the channel. Next job is a new dust chute in perspex for better visibility. I've also turned the old one around so that the vac is concentrated at the front where most of the dust seems to be thrown by the blade.

For the moment, the dust extraction tube still runs to the back of the TS where it meets up with the tube from below the table, but clearly it would be better to link it straight into the overhead tube to the extractor - as soon as Axi can supply some parts I'll change it over.

Dust collection seems very good, a little better than before, and I can leave the riving knife in place for almost all jobs !

 

[kirkpoore1]

Looks good, as long as you never move the saw. Since I assume your DC pipe came up to beam before adding the guard mount you aren't losing any maneuvering space. Do you get a lot of chips off the top of the blade? My saw dumps very little off the top, but that may be because I only use a rip blade with very deep gullets.

Kirk

 

[AndyP]

David how did you reduce down from 4" on your flexi hose to the tiny port on the top of the yellow plastic cover. I have a kity 419 withe the same cover

 

[chataigner]

David how did you reduce down from 4" on your flexi hose to the tiny port on the top of the yellow plastic cover. I have a kity 419 withe the same cover

The "plumbing" for the dust collection is all in 100mm rigid pipe except for the one flexible that you see in this shot. The small flexi from the top of the saw goes into a hole made with a hole saw in the side of the 100mm rigid pipe and is expoxied in.

 

[Wizard9999]

Searching via Google for images of overhead table saw dust collection this popped up! Looks like it was the very first post in this section of TWH2. I wondered if it was still in use?

Ultimately I think I will have to look at making something myself, unless anyone knows of commercially available crown guards with a 100 or 125mm dust hose connection. They all seem to be a lot smaller.

Terry.

 

[chataigner]

Yes, very much so, the only change being that I've now taken the hose from the blade guard up to the 100mm tube above the saw and added a blast gate. Works exactly the same, but the hose is more out of the way.

...oh yes, and I've added a diagonal brace to the guide for the guard, it was tending to move off line if it got a clout from a large work piece.

 

[Rod]

I use a separate vac for the crown guard - it's a cheapo one from B&Q ( similar to the Aldi/Lidl ones).
It extracts from a 20mm pipe up to the vacs 40mm? one and works really well. I use a remote controller to switch it on.
A 100mm hose dangling over the saw table will be a bit intrusive I think?

Rod

 

[Wizard9999]

As far as I can understand going down to anything less than 100mm when coming of a chip extractor (HVLP) reduces the airflow to such an extent that it is not really dealing with the duct. My ducting runs directly over the top of my tablesaw's blade (I am on lunch break from installation, pictures later I hope), so it seems too good an opportunity to miss. What I need to ensure is more that I can deal with times when the tablesaw is rolled back against the wall, say for bigger assemblies, so the dust outlet is not left dangling. That is something I have yet to bottom out as I am solving this type of thing on the fly rather than having a grand plan worked out in advance.

If it proves too much of a compromise I could just cap off the outlet and connect a vacuum up, but then I would need to work out how to get the hose to the top of the blade. I guess if there were one perfect answer everyone would use it, the fact that there are a range of approaches suggests it is just aout different weighting on different compromises by different people.

Terry.

 

[tracerman]

David , Mark , Terry and a gentleman , its great isnt it ? I've wasted more time , been at my most imaginative , and gained most satisfaction whilst thinking up/executing and re-vamping problems of dust extraction than anything else . Sadly I never had a table saw , only an RS but the search for perfection is never far away . Terry - your last paragraph just about sums it up .
Steve

 

[Rod]

On my machine (a Deft ) there's very little dust emanating from the guard - most gets extracted from underneath from the main body of the saw.
I think you worry too much?

Rod

 

[chataigner]

Rod, interesting comment. I've never understod why, but my TS seems to throw most of the dust in front of the blade. A good part is of course below the table, but quite a bit above and the top cover is really essential for a decent level of collection.

The collector below the table pulls the dust to the rear of the saw, but it's not as effective as I'd like - a big heap of dust builds up on the floor under the TS - much too much for my liking.

 

[Wizard9999]

I have to say I have never had any dust extraction 'over the top' and I always end up with a fair pile of dust in front of the table saw at my feet when I use it. Now it is possible it is coming from underneath and through the opening where the rise and fall handle moves if the blade angle is changed. Problem is that having butchered my chip extractor I can't now test it so I can't really tell.

Over and above the extraction I do like the idea of a guard that is not mounted on the riving knife, that way If I want to I will be able to modify the riving knife to allow me to keep it on even when I am not making through cuts.

Terry.

 

[tracerman]

Guys , sorry if I sounded flippant earlier , actually dust extraction is of course the most important issue in the workshop .
Didn't I see , on this forum (?) somebody had made up a hood out of Perspex so that he could see what was happening to the dust inside the hood ?. It seemed to work well if I recall ....

Steve

 

[Wizard9999]

Steve

Not sure about others but I didn't read the comment as flippant. Yes, for life of me can't remember who but it had some high speed photo images that informed a curving design and extraction from the front if I recall correctly.

Terry.

 

[Rod]

My saw's guard has transparent sides with metal top:

And the "main chamber" is pretty well sealed and retains most of the dust.

Rod

 

[AndyP]

Guys , sorry if I sounded flippant earlier , actually dust extraction is of course the most important issue in the workshop .
Didn't I see , on this forum (?) somebody had made up a hood out of Perspex so that he could see what was happening to the dust inside the hood ?. It seemed to work well if I recall ....

Steve

It was our Robert
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