Table saw Crown Guard angle.

[MikeJhn]

Guys what is the ideal approach angle for the front of a crown guard, at present I have the side's angled at 45degs and wondered if its worth lowering a bit more, the alternative is to put a counterbalance weight at the rear attached to the top arm to help lift the guard, any suggestions? what is the angle of the guard on your table? any problems? anyone with a counterbalance weighted guard and have any comments?

All comments appreciated.

Mike

 

[Peter Sefton]

Not used this style of guard before but my one suggestion would be to merge between the the 45 degrees and the flat bottom with a curve to ease the timber in.

Cheers Peter

 

[MikeJhn]

Thanks Peter that will be done to prevent catching the edge after the guard has lifted and the workpiece is transitioning to the underside, my thoughts are the first point of contact of any vertical faced piece of timber will be the angled face, that angle will determine how easily the guard will lift, hence my question what angle do others have on their guard and does it lift as the workpiece is pushed into it.

Looking at the Axminster after market guard: http://www.axminster.co.uk/axminster-in ... kit-508229 it looks to be below 45 degrees, anyone have one and can confirm?

And the really expensive one has a wheel on the front, but a handle on the top to lift it manually: http://www.axminster.co.uk/axminster-ov ... kit-211562 any one got one of these and can confirm that the wheel allows the guard to lift without manual assistance.

This would all be much easier if I had access to my workshop, but I am away from it until late May, so the thought process goes on. #-o

Mike

 

[SteveF]

Hi Mike
have you got the room for a skate wheel in between the front
and maybe a skate bearing at the back
once you get half way through the cut will the base of guard just scratch the workpiece?

Steve

 

[MikeJhn]

Steve

Great idea, wheels, front and back slightly below the bottom surface will lift the guard above the workpiece help the transition and prevent any scratching.

This will eventually look like a combination of both the Axminster guards.

Mike

 

[MikeJhn]

Just thought of one potential problem with the wheels as a lead in, the front wheel would block the view of the workpiece and blade, one of the outstanding things about a Polycarbonate guard is that you can see the blade and workpiece through it, I will have to try it to see how much it obscures the view, perhaps two Polycarbonate wheels on the outside of the guard, but that would restrict the width of cut on the fence side, hmmm think on.

A carefully set up cantilever weight on the upper parallel arms would allow the guard to lift whilst reducing the pressure on the workpiece and so minimising any scratching, may still be the favoured idea.

But what angle to eventually make the lead in is still in question, can some of you guys put a protractor on your saw guard and give me an idea of what different manufacturers think is the optimum?

Thanks in anticipation.

Mike

 

[MikeJhn]

But what angle to eventually make the lead in is still in question, can some of you guys put a protractor on your saw guard and give me an idea of what different manufacturers think is the optimum?

Thanks in anticipation.

Mike

Anyone?

Mike

 

[Noel]

I've an old Penn State guard. Just measured the angle for you and it's 46 degrees with a soft curve on the bottom edge.. Don't use it too often but when I do I just set it to suit the thickness of the timber.

https://www.pennstateind.com/store/TSGUARD.html

Could maybe set it so that it rises with the counter balance once the leading edge hits it but happy enough to just lift it. Although might give it a try, if it works that is.

 

[MikeJhn]

Thanks Noel, you are the only answer so far, the present side piece's are cut at 45 degrees without being finished off or closed in, just need a few more angle's from other manufacturers to see how many think what the optimum angle is?

I personally think that the counterbalance weight is the way forward and will experiment with that idea as soon as I get back to the workshop, but meanwhile please any other interested guys or gals let me know what your lead in angle is on your crown guard?

Mike

 

[no idea]

I've got an Axminster PS315 and the lead in angle is 45 degrees with a slight curve to the horizontal. Something to take into account though is the effective lead in angle (from the horizontal) decreases as the blade is raised because the guard is mounted on the riving knife. This makes it easy for any material thickness to raise the guard just by pushing into the guard even if the pivot screw is tight (to the point where the guard will stay in a raised position).

There is a photograph of the guard in the instruction manual for the saw on the Axminster site if it helps.

 

[MikeJhn]

Thanks no idea, 45 degrees or thereabouts seems to be the angle that most manufacturers think is ideal, my guard is on parallel arms so the angle does not change when the guard is lifted, thanks for mentioning that, its another factor that makes the counterbalance more of a viable modification.

Mike

 

[LancsRick]

Related to us slightly off topic possibly - why is the vacuum pickup at the front of the blade and not the rear please?

 

[MikeJhn]

I have seen from some high speed photo's that the dust and debris from the secondary cut are carried forward in the gullet of the blade to the front of the guard, it is only after the blade has reached its azimuth that the debris is ejected forward.

Mike

 

[PAC1]

Mike
I agree that dust does get thrown forward, but given the volume I tend to think it is from the gullet not clearing in the first place.
Two suggestions the dust collection should be slightly further back so it is catching the dust whereas your current design the dust will hit the wall of the guard before it is sucked up.
Second a skirt on the left hand side of the guard is very useful. It stops dust coming out of the side when trimming up material to final size. Check out the SUVA guard for an example

 

[MikeJhn]

PAC1

Thanks for your input, on my previous guard which was the same/similar configuration the dust extraction was as near 100% as makes no difference, I have 2000m3/hr suction on the underside of the table which tends to make the volume of dust above the table very small, I feel most of the gullet is cleared underneath.

The skirt on one side or even both sides is a good idea and one I will take on board if the need arrises.

Previous guard.

Mike

 

[Noel]

Hi Mike, if you get a chance try experimenting with brushes on the sides and rear edge, I've used draught excluder material in the past and does improve dust collection.
With regard to vacuum position years ago the rear face was the preferred position but I've noticed central and front are becoming more common. With your version front seems to make sense because of the curved dust path from the rear. Interesting.
Have you a larger picture showing the boom?

 

[MikeJhn]

Only pic I have to hand is of the components laid out on the floor, basically aluminium scaffold tubes and galvanized fittings. It would have been nice to have the aluminium scaffold tube bent at right angles to avoid the top fitting, but the tube came out with corrugations that I feel would compromise the flow through it and would not allow easy clearing if any blockage that may occur.

The collector :http://www.axminster.co.uk/big-mouth-dust-hood-200114 below the table is attached to 100mm drainage pipe that terminates at the side of the table in this connection: http://www.axminster.co.uk/axminster-du ... 0mm-502568 the boom has a flexible tube similar to the one attached to the guard into the adaptor.

Mike

 

[n0legs]

It would have been nice to have the aluminium scaffold tube bent at right angles to avoid the top fitting, but the tube came out with corrugations
Mike

Did you try filling the pipe with sand Mike?
Old school but works very well.

 

[MikeJhn]

The problem is the thickness of the aluminium tube it will not compress sufficiently on the inside of the radius without crimping, tried sand and opening up the radius all to no avail, managed to get a steel scaffold tube bent OK, but its so heavy the cantilever made it unstable, still I have a perfectly operating system now so have stopped looking for a solution to a problem that does not exist anymore.

Mike
505 11/05

 

[MikeJhn]

45 deg angle is fine, the guard lifts over the stock without a problem.

Mike