I’m trying to figure out how to mate two curved pieces together. I’ve seen it done on such things as fancy cutting boards. It seems to me I saw an article on this way back when in FWW, but danged if I can find it now. If anyone remembers seeing the article, let me know. I have all issues.
I gave it a try using a router with a template, but as I’m sure everyone but me knows, that doesn’t work because the diameter of the bit makes each of the two pieces a slightly different radius. The tighter the radius, the greater the error. Is there another way other than employing a math wizard and/or making a separate template for each of the two pieces?
What I’m trying to do is add onto the end of a maple countertop, but instead of an ugly/plain butt joint, thought I’d spiff it up with an S-curve and a couple of butterfly inlays.
If this turns out to be impossible, or beyond my reach, does anyone have other ideas how to add length to the top using something other than a butt joint? Thanks for any ideas.
Red Dog
Replies
You can do it with a router and a template, actually a router and two templates. The difference in the radius of the two templates must be equal to the diameter of the router bit you're using. For instance, a 1/4" router bit, a 1/2" template, and a 1" template will do it. Or, a 1/8" bit, 1/4" template, and a 1/2" template. Here's a picture of a patch I did in some wooden siding using the method. It will help show how it's done.
http://mywebpages.comcast.net/krumy/temporary/pictures/oval_template.JPG
Steve K
Yeah, I can't find it again either, which is really annoying, because I thought it was a really cool idea. IIRC, you cut one edge first and then use that edge to make the template for the second edge. I just sat here for 20 minutes trying to figure out how to do that, and couldn't come up with anything. Maybe that's enough of a hint to get you going. IIRC, it was a cover story, but I tried looking for it a couple of years ago and couldn't find it then either.
If you've only got one to do, you can saw to a rough fit and then mark and scrape for as close a match as you have patience for.
You can do it with one template, a flush-trim bit, and a second bit with a large-diameter pilot bearing. The flush-trim bit cuts one side of the joint. The large-diameter pilot bearing offsets the other bit by the diameter of the bit, so it cuts the other side of the joint. Large pilot bearings are available from router-bit companies like http://www.eagle-america.com.
Cool. So I was on the right track last night, I was just too fuzzed out to complete the thought.
I have a question, though, if you use the same template for both sides. When you cut the first side with the flush trim bit, if the bit drifts away from the template, it also drifts away from the workpiece, and you can make everything right by going back over that spot again. But when you cut the second side, the bit is between the template and the workpiece, and if it drifts away from the template it cuts into the workpiece, and there's no way to go back and make that right. Am I imagining this correctly?
Yes, you have it.
If this makes you nervous, you can use this technique to first make a second template, and then use that template with the flush-trim bit to cut the second side of the joint. With this extra step, if your router drifts in making the second template you've only screwed up some template material, not your expensive show lumber.
Is your method the same as explaned in the article in issue 75? If so, only one master template is needed but two working templates must be produced. If you have a procedure for only using one exact template, I'd certainly like to know it. Thanks.
There is another method for doing this that was explained in an earlier article than in the issue 75. I couldn't find it in my brief attempt. That method used router guide bushings. As I recall, top bearing bits weren't readily available then. I'm thinking this was about 1980 or so.
Sophie --
I don't know if my method is what is in FWW 75. Mine can be used to make two working templates, but I often just use the one.
Incidentally, the way I most often use this technique is to put solid-lumber edging on veneered table tops which have curved edges.
Here's a schematic diagram on my scheme:
Cutter is trapped in first scenario, a risky proposition to this woodworker.
FWW 75 story predicated on this never happening in the entire sequence.
Routerman --
Okay, I looked up FWW #75. At first glance, the author's approach looks pretty similar.
You're right, I've got a router bit trapped on one of my cuts. You'll notice that the FWW article has the same issue as the right work template is produced.
Here is a photo of a demilune cabinet with a veneer top and solid-lumber edging I made using this technique.
Thank you for the followup. I can see how this will work, but I don't know if I like it. If it works for you, great. You sound like you know what your'e doing.
FWW no. 75.
Has been reprinted in a compilation. Routers
You could use an inlay router set to make a template, then use flush trim bit on the mating peice.
Tom - What I do is cut a piece of 1/4" mdf in the shape that you want, but cut carefully and save the cut-off piece. You now have two templates- one for the counter and one for the piece you are going to add on. Simply screw or clamp the template to your work piece and and follow it with a bearing-guided straight bit in your router. It is so simple and gives perfect results every time, as long as you are careful. I use it all the time for adding mitered returns to the ends of stair treads that I make. Hope this makes sense. Reply back if you have any questions.
Mike
Can you do tight curves that way? Say 2" or 3" radius? Seems to me you'd have to have a zero thickness saw blade to make that work.
Yea, you can easily do curves that tight. The only limitation on radius is how tight you can cut the template, and the radius of your router bit. I cut my templates freehand with a real narrow fine-tooth blade for my bosch jigsaw. You may end up with a real small offset in the front/back edges of the pieces, probably 1/32 or so.
Mike
Thanx to everyone who has responded. I am in the middle of a hiatus from the project til next weekend when I will try out some of the ideas. Also, I'll dig out issue #75, which is in storage.
Red Dog
I used the process described above repeatedly a couple years ago when I was building an elliptical mahogany staircase. Since all the treads were curved, I made a curved joint between the tread and the returns by using this technique. As someone mentioned previously, I cut mating pieces of 1/4" hardboard first, and then used these to flush rout the mahogany pieces. With all the work and money that went into the mahogany treads, I didn't want to risk losing a piece if the router jumped on the second template. It is also much easier to cut through 1/4" hardboard with a router bit than 1" mahogany. Once the templates were cut, I traced them onto the pieces, used the bandsaw to cut close to the line, and then used a 1 1/8" pattern bit to trim to size. I have attached a photo I took during construction of one of these joints. Good luck, and let me know if you have any questions.
Craig
Craig, Nice looking tread. It sounds like you use the same method I do. How do you fasten your returns to the tread? Lately, I've been glueing the first inch or two of the front, and use pocket screws from underneath, then bullnosing them. They say you aren't supposed to glue them the entire way, but last winter, I looked at some Brazilian cherry treads I made about 5 years ago(glued along the entire edge) and they looked perfect yet. Maybe I was just lucky. :)
Do you happen to have any more pics of your staircase?
Mike
Mike,
I used biscuits and glue, which may have been a mistake if the expansion of the treads is significant. All the treads I have purchased seem to include glued returns so I probably didn't give it as much thought as I should have. So far, this has not been a problem, and the staircase has been installed for ~ 1 1/2 years. I will try to post some pictures of the staircase soon. Right now I'm just home for lunch from my real job (the one that pays the bills), so I don't have the time.
Craig
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