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Table Saw Dust Extractor and Guard (prototype)(large)

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CHJ

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Objective:
1. To make an overhead dust extraction hood and blade guard that did not restrict blade cutting depth or table surface.
2. To make it as low budget as possible without compromising on effectiveness.

Design criteria:
1. Hood open mouth size to be the minimum required to contain saw blade not engaged in cutting when in vertical and 45 deg. modes (to maximise air movement)
2. To be as unobtrusive as possible in use whilst achieving dust removal and guarding hands from inadvertent contact with rotating blade.

Materials used:
1.[/b 10mm Beech stock. salvaged from old furniture draw. (Hood Top & Back)
2.[/b 10mm Pine stock .salvaged from old furniture draw. (Hood sloping sides)
3.[/b Acrylic sheet from “that will come in handy” bin. (Hood front)
4.[/b 50 mm X 2M rainwater pipe purchased from DIY store (~£3.50)
5.[/b A few small wood screws and some nuts and coach bolts from workshop stock bins.
6.[/b Oddments of wood for support clamp from the off cut bin.



Component parts of hood made from beech, pine, acrylic sheet and 50 mm rainwater pipe.

Hole in Hood back panel cut with 54 mm hole saw and eased out to form tight fit on pipe. (Pipe is actually 55 mm external)


Extraction pipe secured to Beech top with two small through bolts and nuts, as this is an essential factor in holding hood in place I wanted easily visible proof that fixing was sound (wood screws could work out without being obvious)


The finished Hood assembly, screwed together, I was intending to glue and screw but have omitted the glue for the moment as it would appear to be rigid enough without.
Red insulation tape trimming added to bottom edge to increase visibility and demark danger zone.

The means of providing the vertical support seems to be the biggest challenge, I initially wanted to just fit the end of the horizontal extraction tube with a 90 deg. bend and continue the extraction down vertically below the table.
First problem with this was that my selected 50 mm rainwater pipe system does not have 90 deg. bends, and further thoughts about the length of the horizontal tube resulted in the obvious need for limited adjustment of the distance from edge of table anyway.
The problem of how to achieve this adjustment and provide adequate clamping kept resulting in a somewhat cumbersome setup.

After a few experiments I decided to go with the minimalist approach to the 90 deg. transition shown below, only time and usage will prove whether the method and strength are adequate.


This was achieved by deforming the vertical pipe with suitable clamps and cutting a 54 mm hole though, this was subsequently opened out just sufficiently to allow the 55 mm horizontal pipe to pass through but still retain some distortion to provide a natural grip.




Due to my limited floor space and the fact that I rarely need to have an overhang of sheet stock on the left hand edge of my table I decided to secure the down pipe support to the edge of the table, because the table is cast aluminium and non to thick, I have carried the wood support block assembly under the table to reduce the leverage on the edge flange.


A little easing of the clamp hole with some coarse sandpaper and the fitting of a couple of coach bolts and a wing nut off a scrapped lawnmower handle securing the Beech strap achieve height adjustment and a means of swiveling the hood out of the way for jig use.


To cut the hole in the support block I used the 54 mm hole saw, removing waste core material in stages with a chisel to facilitate the depth needed.


A tip for cutting plastic piping somewhere near square without digging out the mitre block or saw, clamp it to a block of wood to act as a saw guide.




The finished article on saw and ready to go (except for hose linkup to tee piece at rear of machine.)
 

Bean

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Chas
The guard looks good, can I ask wether the setup is rigid enough to withstand a kickback or a sheet dropping off the end of the table :?:
I know that plastic pipe can be very rigid, I once saw a set of book shelves made from it :?
Its not meant to be a criticism just an inquiry

Bean
 

CHJ

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Bean":2odtb7ej said:
Chas
The guard looks good, can I ask wether the setup is rigid enough to withstand a kickback or a sheet dropping off the end of the table :?:
I know that plastic pipe can be very rigid, I once saw a set of book shelves made from it :?
Its not meant to be a criticism just an inquiry

Bean
It is only an estimate on my part (I don't intend to create a kickback to try it out) but I would think it would certainly slow an object down enough in a vertical direction whilst it cleared the blade. I am relying on the Riving Knife to keep the blade away from any wood slot being cut and always take care with small off-cuts lying around the rear of the blade.

It will certainly not withstand regular abuse as a catch-all for recalcitrant stock. I did think about that happening, more from the point of the hood rebounding downwards into the blade but came to the conclusion that most times the height of the fence will prevent this. (I am considering a "rest" attached to the top of the fence as an option)
 

Chris Knight

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Chas,

That looks as though it will do a good job of collecting dust and keeping your fingers clear of the blade. Thanks for posting the sequence of pictures, I always like to see how things have been done.
 

seaco

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Very nicely done Chas you have put alot of work in that article, I presume that it will just swing away when you need to do trenching etc?
 

CHJ

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seaco":3sj4ghoo said:
I presume that it will just swing away when you need to do trenching etc?
Yes, no problems there.

On first assembley it seems a bit of a restriction/access limitation over the table, first impressions are that it would be 'in the way' in practice it's proving OK to date.

If I had the luxury of a fixed location for the saw I would have preferred an overhead solution for the suction pipe.
 
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