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By Farmer Giles
#1265050
I've bought a Wadkin AGS 12 and I have found a permanent location for it in the shop, its not going to be on wheels, so it staying where it is. The saw came without a crown guard, the riving knife has been modified for sled work and would need to be replaced to mount a guard on the riving knife. I intend to make a sled for it so useful as it is. But I do want a blade guard.

From experience of my previous saw, I did remove the guard for trenching and other tasks, so rather than mess about with riving knife mounted guards, I'm thinking that one that drops down from above would be best. I have looked at the ones on an arm from Axminster et al, but given I have a steel beam directly above the saw, and the price of 400 quid and upwards, I thought I would make my own and drop it from the beam and include extraction.

I have a few ideas including a telescopic metal pipe that can be the structural element, rise and fall mechanism and extract but if anybody has done this before I'm not above plagiarism :)

Regards
Andy
By SammyQ
#1265056
Me too please. AGS 10, with a non-standard, 'flatter'guard.
I am also aware of roof mounted "Simpson"(??) guard and extraction point from a few years ago.
Sam.
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By Farmer Giles
#1265063
My first thoughts for a prototype are a 25mm box section frame hanging down from the roof beam, either welded or clamped. Then with one of these clamped to it with exhaust clamps, its a 35mm vacuum cleaner telescopic pipe with about 300mm of travel on it, more than necessary and costs about 6 quid.

tube.jpg


Then a guard not too dissimilar to this, maybe home made as the extract connector needs to be vertical rather than angled backwards.

guard.jpg


I would bolt a strap to the pipe and the front and possibly the back of the guard too for rigidity. The pipe would connect to the extract on the guard. The telescopic pipe would give you Z axis travel, and going beyond the prototype I may think about minor x/y axis adjustment in the design other than moving the saw table :)

On the extract side I need an adaptor that fits to my 100mm blast gate and has a 35mm or similar branch as the 100mm pipe is going to the extract port on the base of the saw. Axminster have one that bolts to the side of a machine, I used one on my router table, but I want an inline adapter, I shall have a look around, it may mean using a plumbing strap boss on a bit of straight pipe or 100mm Y junction and a reducer as I can't see an unequal tee or Y junction.

I don't know if the telescopic pipe will be rigid enough yet, I think I have one in the corner of the barn where old vacuums go to die, I shall take a look at the weekend.

Cheers
Andy
By MusicMan
#1265092
In your position I would do an overhead guard, and I also am considering the ShopNotes design.

Remember that dust extraction is not the only or even the major purpose of the guard. I regard the main purpose as protecting the operator against wood flying up. This can happen in ripping if the wood is highly stressed, moves during cutting and closes up on the back part of the blade. This is rare but if it happens, it happens at high speed with the force of two or three horses kicking! So the conclusion I draw is that the mounting/support for the guard has to be reasonably strong and rigid.
Some of the youtube ones with light wooden supports look a bit flimsy to me. That's also why I have not used one of the flimsy plastic ones.

In cross cutting this is pretty unlikely to happen, so using a sled with a riving knife and a relatively lightweight guard is OK. The protection it affords here is against putting your hand on the blade, and the plastic type is sufficient, but a built-in cover on the sled is best.

Keith
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By Farmer Giles
#1265096
Good points Keith. I think extending the box section down to the guard and using some aluminium I have for the guard may stiffen things up a bit. 20mm box slides inside 25mm box nicely if you get the right wall thickness so that could be the vertical adjustment. I would want to avoid the guard falling onto the blade so will think of a mechanism that can't rattle free and needs additional force to bring the guard down, not just gravity.

Cheers
Andy
By MusicMan
#1265122
Farmer Giles wrote:Good points Keith. I think extending the box section down to the guard and using some aluminium I have for the guard may stiffen things up a bit. 20mm box slides inside 25mm box nicely if you get the right wall thickness so that could be the vertical adjustment. I would want to avoid the guard falling onto the blade so will think of a mechanism that can't rattle free and needs additional force to bring the guard down, not just gravity.

Cheers
Andy



Yes that looks good and the box section should work. Once you know the total weight, a very neat way to counterbalance it is with a constant-force spring, (they work like a tape measure only stronger) e.g. https://www.leespring.com/uk_int_learn_ ... 20Products

I would get one set for just over the weight so that if you unclamp it, it will rise rather than fall (probably won't do either because of friction!). And a cam for a clamp would be good. Alternative counterweight would be just that, a counterweight on a cable running over a pulley(s). The weight could be some distance away from the saw.
By SammyQ
#1266771
This: https://www.youtube.com/watch?v=cxZOO_zcpNM is reminiscent of the one I saw.

N.B. "Overarm" vs "overhead" table saw dust guards bring two VERY different constructions....

Sam
By LancsRick
#1266853
Are you truly against mounting it on the riving knife? You could make construction very simple if it was, with a hose dropping from above to the guard, and just a length of stiff wire to hook the guard on when you wanted to lift it out of the way.
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By Farmer Giles
#1266901
The riving knife has been modified for sled work so no place to hang the guard. And the guard is missing. I could get another riving knife or make one but as I have a metal beam above the saw and need a guard, it seems to me that dropping one down from the ceiling is probably the way to go and combine location and extraction in one fell swoop :)

I'm still thinking about it while finishing off the roubo bench. I'm about to order some polycarbonate sheet for the guard, I need some for the sled anyway.

Cheers
Andy
By heimlaga
#1268044
I prefere to build the guard from 3 or 4 mm eluminium plate. It doesn't shatter like polycarbonate.

Here are the two overarm guards that I have built. One for the 400 mm blade on my Stenberg combination machine and one for my 600mm cirkular rip saw.
klingskydd2.JPG
Home made blade guard on Stenberg KEV 600 combination machine

klyvsåg38.JPG
Home made blade guard on Chemnitzer Werkzeugmaschinenfabrik cirkular rip saw
By MusicMan
#1268050
Polycarbonate is not easy to shatter, in fact it is made for shatterproof windows (Lexan). Perhaps you are thinking of Perspex (polyacrylate)? That said, your guards look robust and excellent!