How do I create a scalloped edge


I have SketchUp Make 2016 installed on Windows 10 and I’m trying to add a scalloped edge to a board.

In the above image I want the “D” option, e.g. sine wave.
My board is 96" long and 11" wide. The sine wave should repeat about every 12" and the distance between the max high and max low is 2" on the bottom edge. As in the image of sample edges I need to start and end on the max low point on the ends of the board.
Scalloped Board.skp (18.1 KB)
BTW I need the instructions for dummies. :slight_smile:


I just installed the Sine Wave extension but I cannot get it to do what I want. Obviously I don’t know how to use it :frowning:


So something like this?


Yep, exactly!, so how in the heck did you do it? Did you use my Scalloped board.skp file?


I did use your board file. Hang tight and I’ll see if I can show you how I did it.


Let’s see how this goes.Note, I am laying out the scallopws on the component but outside of its container. I do this to prevent modifying the component until I’m ready to do so. I think of this as similar to drawing the lines on the real board with a pencil. You aren’t committed until you take a sharp tool to the wood.

You could layout the larger arcs starting on the lower guideline but that makes the spacing a little different or the scallops shallower.

After moving the board component to above the ground plane and setting camera right so the solid blue axis points up, I used the the Tape Measure tool to measure in 1 in. from the end. The exact distance will be determined by the size of the scallops you’re after.

Using the 2-Point Arc tool, I drew an arc from the guidepoint. click and release at the guidepoint, move the cursor toward the right along the edge and type 10, Enter. then raise the bulge to the upper guideline and click again.

Use Move/Copy to copy the arc to the right 12 in.

Again, with the 2-Point Arc Tool, draw an arc between the first two using the intersections of the first two arcs with the lower guideline as endpoints. I moved the bulge to get the magenta arc which indicates it is tangent with the first two arcs.

Use the Eraser tool while you’re here to erase the unneeded ends of the larger arcs.

Use Move/Copy to copy the smaller arc to the left. Then erase the unneeded end of the left hand large arc.

Over at the right end of the scallop layout use the Line tool to draw a temporary line segment that meets the arc where the lower guideline hits it. This will divide the ar so you can erase it’s unneeded end. Then erase the temporary line segment.

You now have a scallop unit for copying.

Select the scallop unit and use Move/Copy to copy it down the board. Grab it by its left end and move the copy to the right end. Hit enter to set that distance.

Type xn where n is the number of additional copies you want. In this case I went for 4. It’s OK that it runs off the end of the board.

Next, select the entire scallop curve. Hit Edit>Cut or Ctrl-X to cut the curve to the clipboard.

Open the board component for editing. Hit Edit>Paste in place.

Use the Eraser tool to erase the curve where it runs off the ends of the board.

Use Push/Pull to get rid of the waste below the curve. Make sure you stop the Push/Pull operation at the back edge of the board.

There are other ways to layout the curve and you could basically do any of those edge treatments from your screen shot in a similar way.


If you have a reference image, you can always use it to trace the contour…


like wow, I have a LOT to learn.
I really like the idea of laying out the scallops on the component but outside of its container. As you suggest this does not commit the action and gives me time to make adjustments.
I’m trying to make my way through your excellent instructions but you are using several concepts that will require learning on my part which is OK but I’m in a time bind, could you also please attach the finished SKP file?
In the meantime I really want to utilize your instructions and repro them. I think I can apply this to several other things I’m trying to do or will be doing.
This was excellent!!!


I think you are reffering to @DaveR explanation, you should mark his answer as the solution…

Here’s the tracing model too.
trace.skp (146.9 KB)


Tracing is not required, you have all the info to lay out except the phase info to start curve where you please or you can make copy and move over to desired start

Check their help file if problems.


Ops yes I was referring to DaveR.
I’ve been trying to follow both instructions (Yours and DaveR) so far not much success but I have not given up. :slight_smile:


mac7595 - Sorry but I have no idea how you did the sine wave, plus it does not start or end correctly and the amplitude is twice what I need.


OK I’m immediately lost with the above statement. I broke the statement into two actions and have been trying to find the how. I’ve been searching the help and the forums and found a bunch of stuff but nothing seems to give me the knowledge I need. Sorry to be obtuse.

In my test file I’ve reoriented the board so the green axis points to the back, blue points up and red points to the right (is this what you mean by “After moving the board component to above the ground plane”. In the file I uploaded this was not the case.

Manually I’ve rotated the board so the blue line points up, I think it is straight up but not 100% sure. However I don’t think this is the action you performed when you stated “setting camera right so the solid blue axis points up”. I noticed in your image the board is not straight up on the end but yet it is on the blue line, thus I think I’m doing something wrong.

I’m also having a problem laying out the scallops outside the container of the board. When I draw them they end up being placed on the board.


Sorry about that. When I first opened the SKP file, it shows the camera inverted and the solid blue axis pointing down, thusly:

I orbited the camera so the solid blue axis points up, like so:

Then I just moved the board up so it was sitting on the ground plane which is defined by the red and green axes.

Strictly speaking, you wouldn’t have to do that just to draw the scallops. I assumed you wanted the scallops on the bottom edge of the board, though. The axis orientation is important if you want to use the standard views and if the model is below the ground plane, shadows won’t be cast correctly.

Is the board already a component as it is in the file you attached? If so, it’s alright if the arcs lie on the board. They won’t affect the geometry of the board until after you paste them inside the component.


John did you ever take trig in school? I told how to set start point , you can array a number of 96" curves together and then move to any start point you want, the amp is what you stated in you write up and is shown at 2" or 4" peak to peak. You can make it any thing you want using the curve maker plugin . You do not have to draw any thing just use the curve maker plugin and input the values you want.
The real question is how are you going to cut the curves? I assume you do not have a large form mat printer. From your profile I assume you do not have 2016 PRO and using the make version you will have to tile print and then a glue of number of 8 x 11sheets together. I would make one template, cut out with band saw, sand with spindle sander to get nice template and then use a router and flush trim bit and you could make a bunch very quickly
For this case the scallop is H=Asin(2pi()/P * x) where A = amplitude ( 2" your spec max high , min is -2" or peak to peak is 4" but can be easily changed if you want 2"pp, P = period of sine wave (your spec 21" although the pic you show is 4 one half period over cycles 96 " or it should be 48")
Here is skp file and the inputs to create the curve, you can play with inputs and make what you want and yes I know it does not duplicate what you want that is for you to learnscallop A.skp (29.1 KB)
Note the curve comes in as component so you can move it around to your pleasure


DaveR, OK! Last night I ended up doing exactly what you just described. After I got the blue line pointing up I flipped the component along the axis (I’m not sure which) so the guides were along the front bottom (e.g. I could see the guides without rotating the board).

I then realized I had the guides on the board thus I then deleted them.

I made sure I was no longer selecting the board and created new guides that were NOT on the board surface but appeared to be on the surface, e.g the guides were outside the container. I really liked your idea of drawing the lines outside the container thus allowing me to modify the scallops without effecting the board.

I then followed your instructions to create the scallop line but the end of the scallop was not correctly positioned on the end of the board. I then selected the entire scalloped line and used FredoScale to pull the scalloped line so the line was correctly positioned on the end of the board. I’m not sure what you did in that your line ended in the correct position.

I then moved the line down so the bottom of the curve was positioned on the bottom edge of the board.

Now I follow your remaining instructions to get the line on the board. Then individually selected the sections of the scallop I wanted to remove used the Push/Pull tool to eliminate them.

Thus at this point I had success!
Now I need to print the scalloped section to scale so I can paste it on the board and cut the scallop. For this action I will use SnagIt to capture the scallop section print to PriPrinter. In PriPrinter I can scale the image to the correct size, select poster as my output, in the poster I then select just the sections that have the scallop and print. Now I can tape the pages together and past the long strip onto the board. There may be easier ways to create the print but this works for me and this I know how to do.

MUCH thanks for your help!!!


I think this is getting more complicated than it needs to be. Draw an arc to half the height you want. Make it a group. Move/ copy and slide it down past the first arch, rotate the second arch 180 degree and then move the end point to meet the start point between the two arcs. Select both arcs, move copy both connecting the new copy to the end of the first. Use the multiply function on the move copy (type x and the number of copies you want then enter). Select all the arcs and explode followed. Select all the arc geometry and scale up and down as well as left and right until you get the required result. Then place the geometry on a plane that will become your board and delete out the edges you want to get ride of. Worry about the geometry of the curve first then worry about the board.


Your method will result in both the concave and convex curves having the same radius which doesn’t match the scallops the OP was asking about. And if you want the same arc up and down, it doesn’t need to be that complicated. There’s no need to group the arc before copying and rotating it. The copy can be rotated immediately after copying so there’ll be no need to explode the groups.


I believe a sine wave would have a matching geometry above and below the center of the wave, however, the user can draw whatever geometry they are looking for, and copy it over as required.


A sine wave would have the same curve top and bottom but they wouldn’t be arcs. The scalloped curve in the OP’s original image is not a sine wave.