Best way to draw curved lines?

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Forum topic by richardwootton posted 01-25-2013 08:57 PM 3805 views 0 times favorited 18 replies Add to Favorites Watch
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1699 posts in 1978 days

01-25-2013 08:57 PM

I’ve decided to cut the aprons for my table project with a curve that tapers from about 4” at each end to roughly 2” in the middle. The only problem that I have is that I don’t know the best way to accurately draw the cut lines onto the stock. I’ve included a picture of my rough design so ya’ll can see what I am talking about in case I didn’t explain it very well. Thanks for your input!

-- Richard, Hot Springs, Ar -- Galoot In Training

18 replies so far

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1699 posts in 1978 days

#1 posted 01-25-2013 08:57 PM

And of course the image is sideways!

-- Richard, Hot Springs, Ar -- Galoot In Training

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721 posts in 2887 days

#2 posted 01-25-2013 09:05 PM

Tracing paper with carbon sheets underneath. Of course you need to reference the drawing correctly onto workpiece.

Alternatively you could take measurements along the curve from your drawing,(assuming it is full scale) and transfer
those to your piece and use a french curve to connect the transfered measment tics.

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472 posts in 3002 days

#3 posted 01-25-2013 09:06 PM

Probably the easiest would be with tramel points. You can make your own with something like a yard stick or other stick, pencil and nail. woodcraft has a cheap set. Looks like 103” radius with your numbers

-- "If you think you can do a thing or think you can't do a thing, you're right". Henry Ford

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3599 posts in 2510 days

#4 posted 01-25-2013 09:07 PM


-- Improvise.... Adapt...... Overcome!

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19623 posts in 2698 days

#5 posted 01-25-2013 09:13 PM

Three finish nails and a 48” rule. A nail towards both ends and a nail in the center of the curve. Place the rule on the inside of the two outter nails and on the outside of the center nail. Any thin stip of wood could replace the rule.

-- Randy-- I may not be good...but I am slow! If good things come to those who wait.... Why is procrastination a bad thing?

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2202 posts in 3181 days

#6 posted 01-25-2013 09:20 PM

Put two nails on the ends and one on the middle. Bend a dowel or thin board between the nails..that will give you your curves.

Edit…or you could do it Randy’s way. :) Great minds think alike.

-- jay,

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418 posts in 2439 days

#7 posted 01-25-2013 09:21 PM

1. obtain a strip of knot free wood about 1/8 inch by 3/4 inch wide
2. on a sacrificial piece of wood knock in a nail beyond each end of the curve.
3. knock in a nail at the center of the curve at the desired radius
4. place the stick below the two ends and above the center nail.
5. draw a fine line along the stick in the radius you have formed
6. cut, trim, sand then use as a pattern.

-- ... Never Apologise For Being Right ...

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3123 posts in 3550 days

#8 posted 01-25-2013 09:21 PM

It’s hard to tell if what you want is an arc of a circle. I’ve used this technique for large-radius arcs:

EDIT: Wow, lots of similar responses at almost the same time!

-- “Big man, pig man, ha ha, charade you are.” ― R. Waters

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400 posts in 2714 days

#9 posted 01-25-2013 09:41 PM

Another solution would be to do what I did -

I created a drawing with an arc in a mini CAD program. I then sent the completed drawing to Fedex Kinko’s and had it printed on a plotter in actual size. Picked it up next day, took it home, cut it out, spray glued it to my work piece. Follow the line on my BS.

Total cost – under $20.

-- "It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so." - Mark Twain

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1699 posts in 1978 days

#10 posted 01-25-2013 10:01 PM

Wow that was quick, and pretty consistent across the board! Ok, here’s a follow up question: I can’t decide if I want to create the same arc on the side aprons like I did on the front. Here’s a picture of what I’d drawn up, but just can’t settle on it.

-- Richard, Hot Springs, Ar -- Galoot In Training

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5702 posts in 2836 days

#11 posted 01-25-2013 10:04 PM

I don’t like to use three points for marking out curves. They usually are not fair curves that way. I simply use a thin hardwood strip held at each end, and draw a line.
I have tried plastics and synthetic materials, but I like a thin strip of hardwood best.

I would make an arch on all sides.

Richard your CAD post – man, I thought I was OCD.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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1029 posts in 2945 days

#12 posted 01-25-2013 10:08 PM

Adapted from Scott Phillips (American Woodshop)

Get a strip of bendable wood longer that the curve you are cutting, maybe 1/8×1”. Drill a hole near each end of the strip and in the center. Take another piece of scrap, maybe 1.5 wide and longer than the radius of the curve you need. Cut a set of kerfs in it across the width. Jamb, epoxy, threaded insert, or some other way a machine screw that is placed through the center hole and has a nut holding the screw to the strip into the top of the radius scrap.

Tie a piece of non stretching string to the end holes. Pull the string and lay into one of the kerfs to bend the strip. The machine screw allows the strip to bend smoothly without having the radius scrap get in the way of the bend.

Kinda looks and acts like a crossbow.

This is, of course, reusable for any other similar task, just change which kerf the string goes in.

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4757 posts in 2374 days

#13 posted 01-25-2013 10:10 PM

Just take a spline that is a couple inches longer than 48”. Cut a notch in both ends and run a doubled piece of masonry twine between them. Insert a small wedge of wood in the middle of the two strings and start twisting (Spanish windlass) until you get the desired shape curve.

-- Bondo Gaposis

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1699 posts in 1978 days

#14 posted 01-25-2013 10:11 PM

Hahaha! Thanks Pinto! I may be a little OCD . . . but more than anything I don’t want to get everything cut, and dry fit only to realize I would have liked it better another way. I’ve already glued my table top only to re-rip it because I changed my mind about a design issue.

-- Richard, Hot Springs, Ar -- Galoot In Training

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8207 posts in 2600 days

#15 posted 01-25-2013 11:04 PM

Make a couple of templates and have at it.

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