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Cutting arcs for planter....

2K views 9 replies 9 participants last post by  tomsteve 
#1 · (Edited by Moderator)
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.
 
#2 ·
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.
 
#5 · (Edited by Moderator)

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#6 ·
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.
 
#8 ·
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.
 
#9 · (Edited by Moderator)
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.
 
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