Cove Cutting on Table Saw

[wcndave]

I've seen so many videos now of people cutting interesting things on TS. I don't think I'll go as far as Izzy Swan making a ball on a table saw, however I've now seen Izzy, Wood Whisperer, Steve Ramsey and many others cutting coves on the TS.

Yes, they're all yanks right.

So I was wondering if there was any definitive treatise on this from the more safety minded population that typically inhabits our green and fertile shores.

With a good fence at an angle, and downward featherboards, slowly raising the blade, it looks like it can be made pretty safe.

What does anyone think?

Dave
(running for shelter)

 

[Steve Maskery]

Dave, I have done this in the past. It doesn't give a very good finish (perhaps a different blade would have done so) so there is quite a bit of sanding to do. But it does work, in so far as cutting the actual shape. But bear in mind that the blade and bearings are not designed to take sideways pressure, which is what this method requires.

It's best done with two fences rather than just one, but the biggest problem is guarding. Not so much an issue when actually cutting, the blade is completely covered. but the big danger point is at the end of the cut when you hands are over the blade. It's scary, IIRC.

I have occasionally thought about making the ultimate cove-cutting TS setup, but I do the job so rarely it's easier to just take loads of blind cuts and spend half an hour with a gooseneck scraper.

 

[Tortion-Stephen]

Completely agree with Steve's points (no shock there, if I live to be 1000 I will never have that kind of knowledge or ability)

I saw Matthias Wandel on youtube did a few videos about tooth shape and how the standard ATB blade left a rather rough finish, he suggested if you were going to do a lot of coving then perhaps re-grind the teeth (his experiment with doing it freehand was a touch too hit and miss) though I think he also more or less decided that as he did it so infrequently it really wasn't worth special consideration.

 

[wcndave]

Thanks, if Steve did it, then it must be possible to do it safe ;-)

I am happy with having to sand, Steve Ramsey cut a sanding block from polysterene to match. Also could scrape.

Was just thinking I have no tool that could cut wide elliptical profiles like this.

I think i would use a special push stick with a lip at the back, or possibly hot clue a handle on top of the board being cut.

Regarding the blade, I would take lots of very light passes so as not to stress it, and for safety. Steve (R) had his blade tilted to 45deg away from the cut. Did you try this? I can't figure out if that simply creates a different shape, or has some other benefit.

 

[Steve Maskery]

I'm pretty sure that when I did it I was not working in a safe manner! I've not always been the goody-two-shoes my online persona might depict...

Altering the angle of the blade alters the shape of the curve, not just the height and span. For example, you can end up with the curve steeper on one side than on the other, and the crest is not in the centre, but offset to one side.

 

[wcndave]

I think you'd get that effect with a straight blade, the only way to avoid would be to pass the wood over at right angles. I could be wrong. Tilting the blade would increase the effect, so I'm only unsure of something different now, thanks

 

[Steve Maskery]

No, Dave, if the blade is vertical you get an elliptical curve, symmetrical about the crest. If you past the wood over at 90 deg to normal, you would get a circular profile.

 

[wcndave]

No, Dave, if the blade is vertical you get an elliptical curve, symmetrical about the crest. If you past the wood over at 90 deg to normal, you would get a circular profile.

That's what I said!

Given you get ellipse on vertical (straight), I wondered what point there was to tilting, however now I see that it increases the ellipse.

Reading you again though, are you sure it's symmetrical with straight blade? If you sight down at say 45deg, the crest is closer to the back of the blade...

I did 3 A-levels in maths, but it's long in the past to work this out... I dread when I get asked to help with my son's homework. To make matters worse it will all be in German!