Coves on a table saw

Question about how you do this?

Keith Newton

Did you use a saw blade at 90º to the table and slowly raise it up to just nibble away until you get the depth your after?

Re: Question about how you do this?

Bill Houghton, Sebastopol, CA

I'm not Bill Tindall, but you can find lots of information online by googling "making coves on a table saw." Every how-to-use-a-table-saw book I've seen addresses the question, too.

Answer coming soon and it won't be found on UTube

Bill Tindall, E.Tn.

At the Headley shop I learned to make crown molding a way I have never seen described before. It is trivial to target, then set up to make, any depth and width of cove and any ratio of height to width of the installed crown. The crown is made from 4/4 show lumber backed by secondary wood. Your question has motivated me to get this description written up.

Teaser:

After wasting out the cove, scraping and sanding it you are 4 saw cuts from a crown, shown in the picture. What is shown is the crown that will top the corner cupboard I am building.

Re: Coves on a table saw

John in NM

Done this several times, quick and easy. Did you use your 8" blade? That one looks smaller than what I could do with a 10", but its been a while.

Another interesting effect is tilting the blade and then angle wasting the way you did. I've not played with that one much though.

You didnt answer my question

Keith Newton

Did you use a saw blade at 90* or tilted, or dado, or some other shaper head?

Re: You didnt answer my question

John K Jordan

I always used a crosscut saw blade at 90-deg to the table surface and made numerous small passes. I used a radial arm saw instead of a table saw which I think is easier because the head can be easily rotated relative to the fence.

JKJ

Re: Coves on a table saw

William Duffield

CMT makes a special blade for this function that leaves a much smoother surface finish.

https://aboloxtools.com/cmt-orange-tools-235-006-07-cove-cutterhead-5-8-bore

However, I can't see most amateur and small pro shops justifying the expense of this blade vs. the time saved sanding, unless you were making many many feet of cove.

Re: You didnt answer my question

Bruce, a MN Galoot

I have used both crosscut and rip blades to make coves and have gotten much better results with a rip blade. I have no idea why.

Not Bill, but

Bruce, a MN Galoot

That’s the way I did it, maybe 1/8” - 3/16” at a time. Your saw will tell you if it’s too much. It doesn’t take many passes to get the depth or profile you want. A shallower cut fed slowly will give a better finish. Then I scrape with a gooseneck scraper, followed by finish sanding.

Re: You didnt answer my question *LINK*

Lee Schierer in McKean, PA

Here is a link to a video on how to cut coves. If you use a blade with raker teeth you get a smoother finish.

Lee


WWJ Cove Cutting

Table saw molder head, can't remember which

william, your on the right track

Keith Newton

While I don’t have that cutter, many years ago, I found that grinding a thumbnail arc on the 3 straight knives of my Sears Craftsman molding head, then tilting the arbor on the table saw creates a more efficient cutting angle that can easily take about half inch of depth per pass, plus it leaves a cleaner surface than any saw tooth, so it saves a lot of time sanding.

Of course, only taking a 1/16 or less for the final pass will give a cleaner surface than the initial heavy cuts.

Re: william, your on the right track

Barry Irby

I have done this many times. If you play around with it you can get an amazing variety of shapes. Symmetrical and asymmetrical. Tilt the blade and change the angle. I used a Forrest WWII. I liked doing it on the TS, but have done it on the RAS. The I liked the TS is it was unlikely to have the piece jump and get an excessive cut. If the piece jumped it just took a lighter cut and you could run it again to clean it up. If it jumped on the RAS, it created a divot.

Once you are finished getting the shape run it again without changing the setting and pressing hard, It will clean up nicely and take very little scraping and sanding.

I raised the blade about a 1/16" on each pass. If the blade is leaning into the cut you can raise it more.

There is more fiddling and set up than it takes to cut the actual material. Practice on a scrap.

I never used my Sears cutter setup for this.

Re: william, your on the right track

William Duffield

When I bought my DeWalt radial arm saw about 40 years ago, the seller tossed the Sears molding cutterhead into the deal. I've used it a couple of times on a tablesaw (but it won't work with my SawStop), but the admonition, "If it doesn't feel safe, find another way to do it" keeps running through my head every time I consider using it with the RAS, so I've never even tried it.

It's a lot more comfortable to pull out my hollows and rounds, a sticking board and my copy of Matt Bickford's "Moldings in Practice" and quietly make some shavings. Note that I usually take a mixed approach, roughing out the curve with a dado blade on the tablesaw and finishing up with the moulding planes. A lot of days, I find it difficult to wrap my mind around the conic sections, so simply drawing the desired profile on the end of the board using circle and ellipse templates or a French curve is a lot less exhausting than fiddling with blade diameter, blade height, fence angle and blade tilt.

Safety

Bill Tindall, E.Tn.

A half inch cut is going to produce a lot of force on the stock being milled. Not a problem for someone experienced and prepared for this situation. However, not a route I would encourage someone to take the first time they made a cove. 5 min to do it in 1/32 increments. 1 min to do with aggressive molder cuts. Important difference at $100/hr shop time I suppose.

The 4' molding I recently made took no more than 5 min to scrap away the teeth marks from the cross cut blade I used.

I am not certain I could use the geometrical way to calculate the fence angle with the cutter you describe. This time saver would trump by far saw tooth-mark removal.

Re: Safety/Question

Barry Irby

For Bill and William and anyone else with experience.

Would it better for the angled rail you run the piece against on the TS to be in front of the blade? That way the blade is thrusting the piece against the rail. Just a thought.

PS, Bill I have the same feather board magnetic gadgets you show on your TS. They had drifted out of my mind but am using them more lately. Good on the jointer for holding a tall piece against the fence.

Resolving force components

Bill Tindall, E.Tn.

You will see in Picture 5 of the above description that a force component from the blade is indeed pushing against the fence while the other force component is resisting advance of the wood.....just the situation one wants to have. (there is another force component pushing up on the wood. A light cut makes this force easy to resist with hand pressure on the wood. )

Re: Safety/Question

William Duffield

For starters, reference picture 5 in Bill's second thread on this subject, linked to here:

What Bill says is correct.

Since I only have one Grip-Tite, for insurance, I use a second rail against the other (leading) edge of the molding. The disadvantages of my method are that it takes longer to set up, and if the edges of the molding are not exactly parallel and both edges relatively smooth, it can jam part way through the cut, or get loose.

This method can also be applied to forming the concave half of the faces of ogee bracket feet.

My bad, ....

Barry Irby

My disgraphic brain turned it around.

That is indeed the way it should be. With the rail in front of the blade.

Re: My bad, ....

William Duffield

No, not bad. The first couple of times you do it, it's real easy to get confused. You're running around the saw, trying to get clamps on one or even two fences, your rip fence (a normal point of reference) is off the saw, you're fiddling with blade height, blade tilt, fence angles, trying to remember trigonometry you haven't used since eleventh grade, etc. If you look at Bill's set-up picture, it's not even clear which is the front and the back of the saw. Bill's got it set up on the port tack, but a starboard tack works just as well. Yoou're worried about where to stand and where to push and which way the molding is going to fly if the saw decides to kick it back. Just make sure you've had a couple cups of coffee, take your time and think it through. It gets a lot easier after the first pass.

Another observation: The L-fence that Bill shows in his picture is very, very useful on a table saw.

Re: My bad, ....

Barry Irby

Went back and looked at Bill's picture again and now I realize he is doing it opposite had of the way I did it. He is feed from the port side and I fed from starboard. On my saw, the blade leans toward the right. Somehow I thought it better to have the teeth lean into the cut. Whatever I did worked nicely.

I will say again, this takes a lot longer to set up than to do if you are making molding for a single piece of furniture. Even if you take a 1/32 on each pass, it only take a few passes and each pass takes less than a minute.

And, let me add, there is a danger in this. It "seems" the saw blade just appears, like magic, out from under the piece at the end of each pass. If you are concentrating on holding the end of the piece down it would be easy to get a finger into the blade. Use good push sticks and blocks and It might be a good idea to put some kind of vivid marker over the blade. Maybe a stick fastened to the rail over the blade.

(Bill, your router table is on the opposite end of your saw from mine. That's just wrong!)

set up time ....

Bill Tindall, E.Tn.

I will say again, this takes a lot longer to set up than to do

If you tell me how wide and deep the cove is to be, the following occurs:

Crank up blade to target height

measure width of projected blade

calculate cosine of the fraction

set fence to this angle

lower blade

push through first pass

I'll leave you to calculate how long these steps take. The point of the above post was to show how quick set up can be.

I demoed making a crown for the club in my shop. Including discussion, questions, passing around examples, etc it was an hour program

What is this Cosine you speak of????

study the crown molding post..PIC4