Cutting arcs for planter....

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Forum topic by AAANDRRREW posted 04-30-2015 01:48 PM 783 views 0 times favorited 9 replies Add to Favorites Watch
View AAANDRRREW's profile


210 posts in 1369 days

04-30-2015 01:48 PM

So, I’m making 2 of the cedar outdoor planter holders for mothers day (the plans from Kreg). I have the planters almost done except for the top lids. They are either 1×6 or 2×6 (can’t remember offhand). They sit on top of the 4 upright walls. The plans give me the measurements of the arc and say to freehand it or use a flexible ruler – anyone have any good tips on doing this? Not sure what a flexible ruler even is – didn’t see one at menards or HD.

Also, once I cut these out with my jigsaw it says to sand them to get a nice curve – what kind of sander should I use? All I have is a 5” RO and 18” belt sander.

9 replies so far

View Kazooman's profile


1236 posts in 2149 days

#1 posted 04-30-2015 02:03 PM

You don’t need a ruler, just some sort of flexible material. A strip of plexiglass or thin maple or something like that. One simple way to go is to put a hole near each end and run a string through the holes. Tie it off at one end and then flex the piece into the curve you want (judged by eye) and tie off the other end. You can then use the curve to mark your layout line for the cut. You need to be sure that the material you use bends evenly along the entire length to give a symmetrical curve and not some lopsided arc. You can test this by drawing the arc on a piece of paper and flipping the tool end for end. If the tool and the mark line up you are good to go.

I would start with the belt sander (go easy!) and finish up by hand.

View Yonak's profile


986 posts in 1718 days

#2 posted 04-30-2015 02:04 PM

Andrew, would a 5 gal. pail bottom be too big ? .. would a paint can be too small ?

You might be better off using a file on this. Be sure to secure the planter well as you shape it.

View SirIrb's profile


1239 posts in 1427 days

#3 posted 04-30-2015 02:08 PM

Make a 1/4 X 1/2 board out of a good straight grained wood. Cut slots in the side. Add a string. tie one end well and the other end is tied off when the desired rad is reached.

Got that one out of By Hand And Eye. Buy the book.

EDIT: Just saw Kazooman’s post. What he said.

-- Don't blame me, I voted for no one.

View a1Jim's profile


117328 posts in 3774 days

#4 posted 04-30-2015 02:15 PM

You can make a simple bow that’s made from a thin piece of flexible wood.

Like this

and then after drawing it out cut it out with a band saw or jig saw,you then can smooth it out with a oscillating spindle sander or a simple round sander that fits in a drill press or cordless drill.

-- wood crafting & woodworking classes

View Richard H's profile

Richard H

489 posts in 1877 days

#5 posted 04-30-2015 02:50 PM

a1Jim covers the tools pretty well. You can also use a piece of sandpaper attached to a 1/8” thick piece of wood used as a flexible sanding strip if you want to do it by hand.

This might be obvious but to get a symmetric curve mark in from the two edges a equal amount than find the center point between them and mark up the height you want the curve so you have two ends and a high center point to adjust the draw bow to.

View gfadvm's profile


14940 posts in 2887 days

#6 posted 05-01-2015 12:25 AM

Those strip/string “bows” are called fairing sticks and they work great. I find that using MDF, Plaxiglass, metal works best as they have no grain and bend in a more uniform arc.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View jerryminer's profile


944 posts in 1638 days

#7 posted 05-01-2015 07:12 AM

If you’re making several of these, you might want to make a template out of—say—1/4” mdf or plywood. Then you only have to sand to a fair curve ONCE—-on the template. Use a router with the template after roughing out the curves with a bandsaw or jigsaw.

Tip: when I do these, I cut the arc pretty carefully and use a piece of the off-cut as a sanding block and sand the template by hand with the custom sanding block. (Using thin stock for the template means less effort in sanding—-also why I like mdf over plywood). This avoids the dips that can occur with a spindle sander.

-- Jerry, making sawdust professionally since 1976

View tomsteve's profile


869 posts in 1416 days

#8 posted 05-01-2015 01:08 PM

For sanding the radius, what I’ve done on something similar is cut a piece from the scrap about 8’ long to use as a sanding block. Since I also do some auto body work I have rolls of sticky back sandpaper that work good, but I think sheet sandpaper with some spray adhesive on the back might work good,too. Might not even need the spray adhesive.Might even be able to make the sanding block the right length so one of your sanding belts slides over it.
I found using a sanding block makes for a smooth, continuous radius.

View tomsteve's profile


869 posts in 1416 days

#9 posted 05-01-2015 01:09 PM

Whoops…. I think it might be easier of the block was about 8” rather than 8’.

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