How do I make this cutting board curved joint?

[Alan Lightstone]

Desafortunadamente, mi español no es muy bueno, así que no pude entender lo que estaba diciendo. Pena.

But basically, he used an inlay to solve the geometry problem with the two pieces, as well as the rough cut from a bandsaw. Interesting other steps, all with a handheld router. I used a router table. Did not want to risk tilting the router and ruining the board. I did use a handheld router to round the corners, although with a corner jig.

I wonder what woods he used. The darker word was quite pretty. Quite nice work.

[Alan Schaffter]

Matching curves for cutting boards- The reason the pieces won't mate and you can't successfully use almost all of the techniques suggested in this thread is simple geometry. You especially can't use the technique where you route curved kerf partially through the boards, bandsaw down the middle of the keft, and flush trim the waste. It just won't work. Likewise you can't use the cut piece and router with bearing bit- the same thing happens.

Let's see if I can do this- I don't have privileges any more so can't see other's pics, but hopefully you can see mine.

In the following SketchUp drawings I used an exaggerated curve and simulated a 3/8" wide kerf to make a near triangular shaped piece and mating piece- not quite the worst case but close! As expected, the perpendicular distance between all points on opposite sides of the kerf is 3/8" and as the pieces are brought together at the apex they meet after moving 3/8." However you are not moving the other angled surfaces perpendicular to t tje surface of the angle, you are moving them obliquely so the angled segments will never both meet. Remember this a a worst case scenario. The shallower the curve the closer the curves will get, but unless both surfaces are flat and parallel (horizontal in my drawing) they will never mate perfectly.

board.jpg

board2.jpg

board3.jpg

Someone mentioned the Bondo method to make complementary templates- I concur. I used that technique to quickly make templates before, e.g. use that to a template to cut the opening in the top of my router table that matched the radius of the corners of the router mounting plate. It is quick and easy and doesn't require a lot of precision: Draw the desired pattern on template #1. Bandsaw, file, and sand for a smooth, pleasing profile. Trace the profile onto stock for template #2 and cut it out with a bandsaw- it just has to be close, not precise. Remove any high spots so they roughly mate. Then cover the edge of template #1 with thin plastic tape. Mix and spread Bondo onto the mating edge of template #2. Force and clamp the templates together. Once the Bondo has hardened, clean excess Bondo from the top and bottom faces of template #2 and you will have two templates that mate perfectly and can be used with a flush trim router bit to make mating pieces of cutting board.

Can everyone see the drawings? I can't. My apologies to Glenn if his post demonstrated the same principles.

[Mike King]

Matching curves for cutting boards- The reason the pieces won't mate and you can't successfully use almost all of the techniques suggested in this thread is simple geometry. You especially can't use the technique where you route curved kerf partially through the boards, bandsaw down the middle of the keft, and flush trim the waste. It just won't work. Likewise you can't use the cut piece and router with bearing bit- the same thing happens.

Let's see if I can do this- I don't have privileges any more so can't see other's pics, but hopefully you can see mine.

In the following SketchUp drawings I used an exaggerated curve and simulated a 3/8" wide kerf to make a near triangular shaped piece and mating piece- not quite the worst case but close! As expected, the perpendicular distance between all points on opposite sides of the kerf is 3/8" and as the pieces are brought together at the apex they meet after moving 3/8." However you are not moving the other angled surfaces perpendicular to t tje surface of the angle, you are moving them obliquely so the angled segments will never both meet. Remember this a a worst case scenario. The shallower the curve the closer the curves will get, but unless both surfaces are flat and parallel (horizontal in my drawing) they will never mate perfectly.

board.jpg

board2.jpg

board3.jpg

Someone mentioned the Bondo method to make complementary templates- I concur. I used that technique to quickly make templates before, e.g. use that to a template to cut the opening in the top of my router table that matched the radius of the corners of the router mounting plate. It is quick and easy and doesn't require a lot of precision: Draw the desired pattern on template #1. Bandsaw, file, and sand for a smooth, pleasing profile. Trace the profile onto stock for template #2 and cut it out with a bandsaw- it just has to be close, not precise. Remove any high spots so they roughly mate. Then cover the edge of template #1 with thin plastic tape. Mix and spread Bondo onto the mating edge of template #2. Force and clamp the templates together. Once the Bondo has hardened, clean excess Bondo from the top and bottom faces of template #2 and you will have two templates that mate perfectly and can be used with a flush trim router bit to make mating pieces of cutting board.

Can everyone see the drawings? I can't. My apologies to Glenn if his post demonstrated the same principles.

thats the issue. And that issue is solved exactly with the bushing method Mark showed above (challenging requiring a metal lathe) or the simpler process of buying the Whiteside guide and bushing I referenced far earlier in this thread or, for that matter, using the concepts Mark showed and different sized bearings on pattern routing bits.

[mreza Salav]

Looks like some people still don't believe (or think) there is a simple way to get "perfect" fitting curves using the method I described. No bushing is needed, just two different bearing sizes (e.g. if you are using a 1/2" router bit you'd need a 1" bearing). People do these things all the time. how do you make matching rail/stile pieces on curved rails then?

[Alan Lightstone]

Looks like some people still don't believe (or think) there is a simple way to get "perfect" fitting curves using the method I described. No bushing is needed, just two different bearing sizes (e.g. if you are using a 1/2" router bit you'd need a 1" bearing). People do these things all the time. how do you make matching rail/stile pieces on curved rails then?

Mreza:

This is one of the reasons I suggested that people put their methods to a test. By making a board using their technique and posting pictures of it. And videos of those would be better still. I can't be the only one who tried to make curved matching pieces. And yes, an inlay looks so much simpler to accomplish.

I used Michael Clark's methods, which should have worked perfectly, but I still had a bit of a gap. Then using the Bondo method to create a perfectly matching pattern, I was able to make perfectly mated pieces and a nice cutting board.

[mreza Salav]

Perhaps you didn't read my earlier posts. I have used this method I described several times and it does give perfect matching pieces. So I speak from experience.
I think even the bed whose picture is in my avatar and a few other beds I made had curved rails that needed to be mated with the Stiles.
I am out camping for several days and can't take pictures or videos but am willing to explain the method in more details.

[Rod Sheridan]

Hi, make a pattern then use a 1/4” straight bit to cut maybe 1/4” deep. In something to use as template.

Now saw the board in half, then trim flush on the router or shaper.
Now you have 2 templates that will fit….Rod.

[mreza Salav]

Hi, make a pattern then use a 1/4” straight bit to cut maybe 1/4” deep. In something to use as template.

Now saw the board in half, then trim flush on the router or shaper.
Now you have 2 templates that will fit….Rod.

That won't fit tight Rod. The two curves have a radius difference of 1/4".
You need to compensate that on one of them with a bearing 1/4" bigger.

[Mark Hennebury]

If it's the way that i read it, it wont fit, but then i am only guessing at what you mean. why not do a sketch so we know what you are talking about.

Hi, make a pattern then use a 1/4” straight bit to cut maybe 1/4” deep. In something to use as template.

Now saw the board in half, then trim flush on the router or shaper.
Now you have 2 templates that will fit….Rod.