Dust extraction from mitre saw

[AndyP]

Jonathan mentioned elsewhere that he used a baby’s shade tent behind his mitre saw for dust collection.
I am not normally one to bang on about Festool kit but I have to say that the extraction on the Kapex mitre saw does not need anything other than a vac hose attached.



I used a piece of old dyson flexi-hose to link to the numatic shop vac.

[youtubessl]7b7-YrHt2yU[/youtubessl]

https://www.youtube.com/watch?v=7b7-YrHt2yU&t=11s

 

[TrimTheKing]

Does that really pick everything up Andy? I bought a Bosch to replace my 20 year old, less than £100 Performance Power B&Q special, that had served me very well indeed but was starting to fail and I used some money my Mum left me when she died to treat myself.

The extraction on that isn't bad at all, but the mouth of the extraction, as with almost all saws, moves forwards with the blade meaning if I'm cutting a wide board then the extraction port is closer to me than the exit slot underneath the board, meaning a lot of that dust escapes into the air until I'm far enough back in the cut for the suction to take effect. I will be looking at that more closely when I get the saw into its proper position and probably putting either additional sucking devices in place or some kind of cowl, but I can't see how yours will be any different.

 

[Windows]

I’ve used the Bosch GCM 8 SJL (which has dust extraction at both the blade and the stand) and the Festool KS60. The Festool has noticeably better dust extraction than the Bosch (using stock blades in both cases and the same vacuum for extraction). The dust extraction on the Festool is really good. My personal experience is that some dust still escapes the Festool even if it’s night and day compared to the dust released by the Bosch.

 

[TrimTheKing]

Here’s what I’m talking about, a wide board across the marked area means the dust extraction is above the board but the dust will come out where marked. This is the bit where mine falls down and I can’t see from this pic how the Festool is any different.

Obviously I might be missing something.

 

[Windows]

The KS60 extraction port moves with the blade. The blade ejects dust up and forward approximately in the direction of the port. The precise direction of the dust stream isn’t particularly dependent on the width of the board, but is dependent on the depth of the cut. (Shallower cuts mean less upward projection. There’s vids on YouTube showing this. ). I couldn’t tell you the technical reasons why the Festool is so much better than the Bosch for dust extraction, but institutionally Festool doesn’t accept poor dust collection in their machines and you can notice the difference instantly in the machines I mentioned without needing any special equipment to see it.

 

[Windows]

To understand where the dust goes, the primary direction is along the tangent of the circle of the blade at the point the blade exits the top edge of the wood. Shallow cuts project dust almost horizontally and deeper cuts move the direction of the dust flow upwards. (Assuming no turbulence which may be where the Bosch is going wrong).

 

[Doug71]

Nice video here showing a Kapex and how the cutting technique makes a big difference to dust extraction.

https://www.youtube.com/watch?v=tbnQ0T-ccjA&t=1s

 

[AndyP]

Just before I had to rush out I took some before and after shots of the dust left after making a cut in a bit of 6 X 2 .I'll post them later on

 

[AJB Temple]

Andy is right, dust collection is much better from the Festool. I have had a Bosch GCM12 for several years. Using it currently actually to as I am making stud interior lining walls in our entire living area. I have it connected to a Festool trade large vac (superb Vac) and the dust collection is abysmal.

I know you can put it in a tent etc, but mine is on the Bosch wheeled stand and is used all over the place during my house rebuild and renovation. The stand is crucial because the saw is really heavy. Accurate saw and very tough. The sawdust sprays out all over the place well before it gets to the collection chute, and usually ends up on and behind the saw. If you use the supplied bag instead of the vacuum, the collection hood clogs in no time. Still a very good saw indeed. Mine has been dropped twice (stand unbalanced going through doorways) and remains dead on accurate. It's bomb proof.

Bosch was bought because I needed the larger capacity when I built my outbuildings. Preferred the Festool 120, but the blade was too small. Despite that I bought an ex display (unused) Kapex 120 three years ago and in some respects it is superior. Much better for both left and right hand use (Bosch v. awkward to use left handed), dust collection actually works and the tilt mechanism is more accurate and far easier to use than the Bosch. The only snag with it was .....motor failed after three months. 6 weeks later saw came back from Festool with a new motor. That motor lasted 11 days. Refund followed. 'twas a shame as the saw design is great. Festool should buy motors from Mafelll.....

 

[AndyP]

Mine is the baby Kapex of course the KS 60.

Before






And after








This is the only mitre saw I have ever used so can’t make comparisons but there is certainly no need for a tent like device behind the saw to cupture dust.

The dust vac is a twin speed Numatic NVQ (Q=Quite) and is run from one of those take off gang sockets, so as soon as the saw is switched on the vac fires up.

 

[AJB Temple]

Neat. Very good saw that Andy.

Up in the workshop I still have my first ever mitre saw. Bought it 30 years ago. 8" Elu. Still works fine and the dust extraction is good as it has three hose points at the tool, feeding one at the extractor. Just kept for old times sake. Built two kitchens and two utility rooms with it a long time ago :lol: Swiss made I think and probably will last forever.

 

[Doug]

Nice video here showing a Kapex and how the cutting technique makes a big difference to dust extraction.

https://www.youtube.com/watch?v=tbnQ0T-ccjA&t=1s

I’ve found the same as the chap in the video when using my battery Metabo chopsaw on site, it’s quite staggering how much cleaner it is when doing a sliding cut towards the fence.

 

[AJB Temple]

Interesting video. Thanks for posting. :text-goodpost:

I just tried it out on the big Bosch. The methods may make a difference on the Festool, and they do on the Bosch too, but not as much. I am cutting shed loads of softwood for stud anyway.

Used in chop mode, quite a lot of sawdust goes straight under the boot. Some people extend the boot to help with this, but it becomes a nuisance when the blade is angled left or right.

In gradual depth cuts sliding forward, it a) takes longer and b) makes hardly any difference to dust.

In trenching mode (limited depth, with work away from the fence and directly under the blade axle, this produces the most dust of all and the shop vac at full whack gets maybe 50%. I've done about 300 such cuts today to get round big pipes. I usually do it in chop mode with the depth adjuster in use (gives a trench with blade radius obvs - but much quicker than sliding mode to get level trench and less risk of break out being chucked around).

In full sliding mode front to back (you wouldn't go the other way as it pulls the work off the fence) this is the most effective for dust collection and only a bit slower than chop cuts.

But ...whatever, I still need to vacuum the tool and all around it at the end of the day. 'Tis what it is.

 

[Doug71]

Nice video here showing a Kapex and how the cutting technique makes a big difference to dust extraction.

https://www.youtube.com/watch?v=tbnQ0T-ccjA&t=1s

I’ve found the same as the chap in the video when using my battery Metabo chopsaw on site, it’s quite staggering how much cleaner it is when doing a sliding cut towards the fence.

That's good to know, I do wonder how much of the bad reputation that mitre saws have is because people just use them like a chop saw.

The Kapex is very good regarding dust collection but once you start making certain bevelled or compound cuts it does seem to drop off a bit.

Bosch was bought because I needed the larger capacity when I built my outbuildings. Preferred the Festool 120, but the blade was too small. Despite that I bought an ex display (unused) Kapex 120 three years ago and in some respects it is superior. Much better for both left and right hand use (Bosch v. awkward to use left handed), dust collection actually works and the tilt mechanism is more accurate and far easier to use than the Bosch. The only snag with it was .....motor failed after three months. 6 weeks later saw came back from Festool with a new motor. That motor lasted 11 days. Refund followed. 'twas a shame as the saw design is great. Festool should buy motors from Mafelll.....

I thought they sorted the Kapex motor thing a few years ago? Mines had a few in it's 11 year life but the last one did last 7 years, that one was replaced a couple of months ago, the saw was making a horrible grating sound so I sent it off to Festool. Turned out my Kapex needed a new "gearbox" and they replaced the motor at the same time, I don't know if they have to do that or if it was just looking tired but fingers crossed it should be good for a few more years now.