Thread: Help with dust collection on a crosscut sled

Not sure what you mean - do you mean mounting the guard and dust collection port on the sled itself so it moves with the sled?

If so, that is not the best way to collect the dust using an overhead guard.
The guard should stay in a fixed horizontal position above the blade and the best place for the collection port is above and just in front of the blade.
This is a particular nuisance for a sled and which is why I don't use one.

Instead I use a 600mm long solid mitre slide with the end near the blade only about 30 mm high and my guard has bristles on it so the wood and the end of the guard can pass through the bristles.
There are no bristles on the back of the guard.


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The above guard has excellent vision but is still not ideal because the dust port is not in the correct position
I will be remaking the guard again soon and below is the design I will be using
Notice how open the back of the guard is - this is to allow air to flow into the guard and grab the dust.

OHGplan.jpg

I mean a dust collector for a crosscut sled like this ...

Crosscut Sled with Dust Collection - by dtzeutschler @ LumberJocks.com ~ woodworking community

I'm OK with cutting timber on the surface of my table saw but at the moment I have to move my overhead dust extractor out the way to use my crosscut sled because of the front and back fences. Having a fixed overhead hood isn't possible because of those fences on the sled.

BTW I have ordered a shark guard Leeway Workshop, LLC as I really like the design. This will be great for all my cuts except thin strips and using my crosscut sled.

Originally Posted by barri

I mean a dust collector for a crosscut sled like this ...
Crosscut Sled with Dust Collection - by dtzeutschler @ LumberJocks.com ~ woodworking community
I'm OK with cutting timber on the surface of my table saw but at the moment I have to move my overhead dust extractor out the way to use my crosscut sled because of the front and back fences. Having a fixed overhead hood isn't possible because of those fences on the sled.

On the same lumberjocks link above he shows an overhead guard arrangement for use with a sled.
OHdustguard.jpg
The size of the ducting being used is less than satisfactory but I reckon it is a better solution than putting the dust port on the sled.
It also means you only need one guard.

BTW I have ordered a shark guard Leeway Workshop, LLC as I really like the design. This will be great for all my cuts except thin strips and using my crosscut sled.

The size of the dust collection port on those and all commercially available guards are too small to collect dust efficiently.

The trouble with that guard is that it limits the size of the timber than can be cut as the fence will hit the guard for wide stock so I guess compromises have to made, also the shark guard can be ordered with a choice of port width. Yes I know that 6" is optimal but I find 4" acceptable for my small workshop.

Originally Posted by barri

The trouble with that guard is that it limits the size of the timber than can be cut as the fence will hit the guard for wide stock . . . .

Provided the saw is not moved around such a guard can be suspended from a ceiling which means the stock width is limited by the shed walls.

also the shark guard can be ordered with a choice of port width. Yes I know that 6" is optimal but I find 4" acceptable for my small workshop.

Unfortunately it's a long way from even a 4"
The model on the left is the old model which shows the constriction of the port. The new one on the right is worse.
It matters little that the port is elongated as the smaller dimension dominates the flow.

SHKguard.jpg

Hi Barri,

Can I suggest that the important points are to locate the port just forward of your back fence, directly over the line of the blade and as high as the thiockest timber you would be cutting on the sled.

mount the port on a seven inch wide strip of perspex mounted between you front and back fence. Mount "walls" of perspex that can be adjusted up and down to the thicknes of your workpiece. If these walls are lowered down to rest upon the stock in the sled, this would creat a wind tummel passing over the blade the entire time it is in the cut.

Note that I said seven inches thick for the horizontal strip of perspex to mount the port because that would allow for six inch ducting. Since you are happy with four inches, you would do better not to make it that wide.

Airflow into the ducting would be drawn from the area under the perspex walls between the workpiece and the front fence. With a very wide workpiece this may not leave enough gap to allow enough airflow. If you want to do that often, you may wish to cut out a hole in the rear fence to allow more airflow.

If I understand what you are trying to achieve this should help

Cheers

Doug

Excellent Doug, an informative post. I think I know what you mean but I'd love a picture. Have you made one? The adjustment of the walls I haven't got my head around yet. Maybe a slot on the side moving up and down on a screw or equivalent attached to the top. I shouldn't have any problems with the roof and the dust port. I actually have 3 sleds. One for bevels (I make boxes), a panel sled which I can use for wide stock and my main crosscut sled. The bevel and panel sled can use a "normal" guard with a dust port

I am pretty sure that some time ago John Russell posted with his modified sled to cope with his overhead dust guard. Can't find it now but somebody can probably point you in the right direction.

Originally Posted by barri

I think I know what you mean but I'd love a picture. Have you made one?

I have not made mine yet Barri but it is on the list.

Originally Posted by barri

The adjustment of the walls I haven't got my head around yet. Maybe a slot on the side moving up and down on a screw or equivalent attached to the top. I shouldn't have any problems with the roof and the dust port.

I am envisiging elongated slots in the "walls". at least two and maybe up to four or five depending on the length and how flexible the perspex sheet needed is. I have some 10mm perspex that I may use for the top panel and if so could tap in some 6mm threaded rod and use wingnuts and washers to secure the perspex. My design is not set in concrete yet by any means.

Originally Posted by barri

I actually have 3 sleds. One for bevels (I make boxes), a panel sled which I can use for wide stock and my main crosscut sled. The bevel and panel sled can use a "normal" guard with a dust port

This concept would work well on the crosscut and panel sleds and could probably be adapted for bevel and mitre cutting too.

I would love to see what you produce Barri.

Cheers

Doug

I'll report back when I've made it (don't hold your breath) and I'll give a review of the shark guard when I get it particularly from a dust collection point of view. The guard that came with my table saw is dreadful, also I use a thin kerf blade and the shark guard comes with a thin kerf riving knife. I know I could make some of the guard setup but sometimes its nice to take the easy option.

OK finished it. Very rough with how I got the walls to move up and down but it does the job. I was amazed with how well it worked. When the DC is turned on, the walls are sucked in on a bit of an angle. After many cuts there was no visible dust on the sled. Very pleased.

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I really don't know why some pictures are upside down when they look fine on my computer

Originally Posted by barri

After many cuts there was no visible dust on the sled. Very pleased.

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Probably all fell onto the ceiling

Seriously though Barri, it looks nice.

I would be inclined to make some vent holes in the back fence inside the walls just to ensure enough air is getting in.

Cheers

Doug

That's a good idea because it is forming sort of a vacuum inside the guard even with the gap formed under the walls when timber is placed there.

Doug, how many holes should I put on the back fence and what size should they be?

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Got it! A little rotation through Paint worked
I've discovered that if your phone is around the wrong way ie camera button is on the right instead of the left then the photo will be upside down.

Originally Posted by barri

Doug, how many holes should I put on the back fence and what size should they be?

A couple of issues to be considered here.

One big hole is preferable to several little holes adding up to the same size. Small holes create more turbulence and wall friction slows the air more than it does in one big hole.

However, be careful in designing where the hole/s go so as to not compromise the strength of the sled.

Alternatively, if you left a gap of say 30 -50mm between the end of the perspex walls and the back fence you would probably achieve the same or similar result without compromising the integrity of the fence. The aim of course is to be making the area enclosed by the perspex a wind tunnel for its entire length.

Up to you Barri to go with that either way or anything else, but right now I would be shortening the perspex walls, but then again I have plenty of perspex to replace them if it does not work well.

Cheers

Doug