Drawing/laying out large radii

[Dan Mitchell]

I'm considering a design for a couple end tables which incorporate large radius curves in the side aprons, ranging from 21" to 50". I've laid out curves like this before using a bent batten, but if I wanted to draw them exactly to the specified size, what would be the most practical & accurate way of doing this?

TIA

Dan

[Todd Hoppe]

Make a compass. Use a long stick, with a nail in one end, and a hole drilled in the other with a pencil or pen inserted. Space the nail and hole so that the distance between the nail point and tip of the pencil or pen is your radius. Put the nail through a spacer that equal to your apron thickness, and attach it to some sacrificial piece. I usually use scrap hardwood for the compass arm, and my workbench top, which is made of OSB to mount the compass.

Make sure that the ends of the apron are equidistant from the nail. Then just draw your curve.

[Mike Henderson]

Trammel points and a shop made beam. I can provide a picture if you need it.

Mike

[Bill Huber]

I had one of these, it worked very well. I have no idea what happened to it, I was looking for it awhile back and can not find it.



http://www.amazon.com/gp/product/B001E0HLKW/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B0015AQLRA&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1K5TPECMFBPKPVKZS41G

[Paul Atkins]

I just made a 20' long, 14' radius deck trim using a 16' 2 x 4 as a trammel. A little larger than your project, but same idea.

[Russ Hauser]

Go to eBay and search for Trammel Points. There are currently 19 listed. I use a set of vintage Starret points that have a pencil holder as well as a steel scribe point.

Russ

[Doug Shepard]

If you want an excuse to spend money, see
http://www.leevalley.com/wood/page.aspx?c=2&p=32629&cat=1,42936,42939

[Kent A Bathurst]

......... I was looking for it awhile back and can not find it...........



Heh-heh-heh........Bill - I've got more than just a couple items stored in that exact same place. I can't find them, but occasionally while looking, I find things I forgot I had.

Back on-topic: You can measure from the arc centerpoint, make 3-4-whatever tick marks, and put the batten back in play, and scribe your line. I've done this a few times. I admit I might have had a little error (<1/8"), but on that scale it can't be seen.

[David DeCristoforo]

The Lee Valley trammels are nice but if you get the Starretts...

http://www.toolsforworkingwood.com/indextool.mvc?prodid=ST-TP.XX

...you can use a stick instead of having to come up with a long metal rod. I have some very long beams that are made from 5/4 stock (for extra rigidity over long lengths) with the ends cut down to accept the trammels. And with the Starretts, you can still spend some money although not quite as much as you would for the LVs. It is noteworthy that this is one of the rare times when the "competitors equivalent" actually costs more than Starrett!

[Dan Mitchell]

Thanks for the suggestions. I guess I'll have to rig up a trammel setup. I was hoping there was some "quick & dirty" technique I wasn't aware of, but I guess not.

Dan

[John Coloccia]

A piece of string and a nail? If you don't want to nail into anything, a piece of tape works as well to hold the string. That's how I do it, anyway. If I had trammel points, I'd just loose them all the time.

[Dan Mitchell]

A piece of string and a nail? If you don't want to nail into anything, a piece of tape works as well to hold the string. That's how I do it, anyway. If I had trammel points, I'd just loose them all the time.

Certainly worth a try, given the cost of string. I could tie on a suitable washer, laying it flat on the surface, & pass the pencil point through that, so there'd be no issue with the pencil "tilting". Might actually try dental floss, since it doesn't stretch. Plus, I know where the floss is :D

Thanks for the idea, I'll give it a shot tomorrow!

[Rye Crane]

Dan,

Are you building those tables designed by Ted Brown and shown in Popular Woodworking Oct 07 (part I) Nov 07 (part II)? The radii sound very familar. I am building these right now and I used some of my Micro Fence Circle Jig for the set up.

All in all I think the long piece of wood as a compass beam with a nail in one end and a pencil on the other is the easiest solution.

If you are building these tables please let me know, in Ted Brown's notes he does not show the corressponding radius for the top of the bottom curved apron. I wonder how you solved this problem, and I would like to see your finished project. I ended up using a reciprocal of the larger radius that is it's neighbor.

Thanks,
Rye Crane
Pittsburg, Ca.

[Dan Mitchell]

Dan,

Are you building those tables designed by Ted Brown and shown in Popular Woodworking Oct 07 (part I) Nov 07 (part II)? The radii sound very familar. I am building these right now and I used some of my Micro Fence Circle Jig for the set up... Ted Brown's notes he does not show the corressponding radius for the top of the bottom curved apron. I wonder how you solved this problem, and I would like to see your finished project. I ended up using a reciprocal of the larger radius that is it's neighbor.

Thanks,
Rye Crane
Pittsburg, Ca.

Good pick up Rye, yeah, that's the project. I like the design, but the articles leave a lot to be desired in terms of detail. He also doesn't mention the radius of the curve at the ends of the tops either, and the "Cut List" on page 71 of part 2 isn't even for these tables! Apparently, it's just supposed to be "an example of a cut list", but why the heck he didn't use the list FOR THESE TABLES is really baffling. What I was planning to do regarding the radii you refer to is draw out patterns on poster board for the aprons with the lower radii which he does give, using the width specified (19" for the sides, 9.25" for the ends) as end points, then move the pencil/lengthen the radius upward the height he specifies (1.25") and draw the top arc.

Are you planning to incorporate the ebony dowel between the upper & lower apron pieces? If so, how were you planning to produce the hole in in the 2 pieces into which the dowel fits?

I haven't actually done any cutting yet, and I would also like to see your work, as it progresses!

Dan

[Jim Heffner]

Just make a beam compass from an old wooden yardstick. You can make it
as large or small as you want. Drill a hole on one end for a small nail (pivot
point) and another one for your pencil or other marking device at the proper
radii location and start laying it out!