I got this email from I presime a lurker here whoi is too shy to jump in and get his feet wet. I don’t normally respond to too many private requersts – partly because I would be all night long answeringh all of them and partly because I believe strongly in the mastermind principle that our combined experience and wisdom is multiplied when joined together to the point that we all learn together and the advice dispensed is better.
This particular info request is an interesting topic and i know that I haven’t got all the answers on this, only the way that I do it…
so here is the most of the text…
“I have been asked to rebuild a railing on top of a portico which has rotted due to exposure to the elements over the past 100 years. The existing rail has a 7.5 foot radius and is essentially a 1/2 circle tying in at each end to the house. My question to you is how would one go about getting the bevel on the top of a curved railing to shed water. The rail cap it to be fabricated from a series of 2 x 12 sections. I am at a loss and have seen photos of similar things that you have built. If you have any suggestions it would be greatly appreciated.”
I’ll make my answer in the next post
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first, I don't like to fabricate these things in short sections jointed together. I have seen and replaced several that were done that way and find them unsatisfactory. It is a way to work with basic handtools though, one can make up a a pattern piece and then chunk them out with a jigsaw and grind smooth on the cut edges ganging them together with clamps and use a belt sander.
but they tend to shrink/swell with moisture unevenly. That can look wierd in certain light that amplifies the irregularities and it can stress teh joints where the sections meet.
I prefer to rip and plane strips that will bend to the radius needed, and gig up a form to clamnp and glue them into that radius. Then I can easily run the full chunk through the planner to smooth it.
Thwe top profile depends on what sort of pattern it is and the width of the railing. Some can be done with a large swing router bit and guide, going at it slow and careful. A plain old bevel top as suggested here is something I can do on my portable panner too. I have a gig I use for all my railing tops that puts about a 7° bevel on. It is a bed for the planner that I clamp in. I wax it with a product called Slippit. This bed sits on the metal bed of the planner at seven degrees so that whatever runs through on it will have seven degree cuts taken off the top side. The trick is to have steady hands on both guys guiding and holding such a cumbersome piece.
An easier way to handle this would be in my Williams and Hussey molder, which is set up to be able to run elliptical and curved work, If I had the right cutters made for the desrired bevel. Maybe I should do that for the next one...
most of these I have done have had a curve of more like 10' to 12' radius. Fypon has certain radii railings as standard stock pieces and they will make anything, but the price gets pretty stiff for a one off that they have to build a form for.
Now, I'm sure somebody else must have other ideas.
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Taunton University of Knowledge FHB Campus at Breaktime.
where ...
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Another way would be to build the arch out of layered segments, laying them like brick work. The top could be beveled with a hand plane and a beltsander. You can get in pretty tight places with a block plane held on a skew. If the radius is too tight on the inside, a draw shave or spoke shave could be used. Edge shaping could be done with a router before the bevel is done. Much of the work in shaping could be done on a shaper or router table using guide pins, as is typical for circular work. Another way would be to shape straight stock and resaw it into thin strips and bend them around a form. This is an approach that is often used for circular stair work. You can buy bending rails which are resawn as I described. When making your own, you have to plan for the saw kerf loss. Complimentary form blocks are used to keep the pieces lined up for the profile.Beat it to fit / Paint it to match
Piffin
I don't find this particularly complicated but some of that depends on the width of the rail.
Got that info?
I've built many a radius rail, I've done it both ways, bent up laminates and sections, I don't find either to be superior to the other as long as care is taken when you segment the pieces. Lapping will go a long way to keep the pieces from pulling/separating.
For a radius of 7-8' I would probably do it with laminates because that's easy enough to make a jig for.
I'm sure you mentioned exterior? If so I would glue it with resorcinol glue, maybe epoxy. Either or. The new titebond III is supposed to be OK. Assuming that the rail will be painted.
You could put the chamfer on the top with a router with out to much trouble, make a jig to hold the router and swing it around as though you were shaping it.
Unless I was going to do this a lot and like you had the W&H I think the router would be the best option. Maybe you could modify a set of knives to cut the chamfer to the angle that you need. I guess I cant assume that the person in question has a W&H though.
If you had access to a shaper with the proper knives you could do it on that, make a sled that the rail can ride through the knives and cut the chamfer.
A lot of ways to do this one.
Doug
Ya know Doug, I think the first one of these I did was about ten years ago and it is still fine - with Titebond II on good grained well dried PT. Ripped the strips 3/8" and palined. I never have glued strips that were already profiled as mentioned, but have heard of the for crown or detailed curved molding.
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Piffin
I've glued those already profiled rails a couple times, it sure makes the job easy. They have notch's, sort of a key way so that they stay aligned. Its almost like cheating. :)
We bought ours already cut and profiled so that made the whole thing relatively easy.
For the situation that you introduced I think that simply cutting strips of whatever wood you chose and gluing them up in a jig, then using a router with a jig to run the profile/chamfer on the top.
It will require some effort to make sure the router jig is set up accurately but that's kind of a given on anything. Seems to be the way to go with the least amount of tooling.
Someone else mentioned to cut the chamfer by hand and that's certainly do-able. You could rough cut it with a power plane and clean up with a good sharp hand plane.
Doug
I have to build a couple of sections of curved rail in the next several weeks. Still haven't decided how to do it. The material is clear WRC 2-1/4" x 6" beveled both ways from center, clear finish. I need two pieces with an 8 foot radius and each about 5 feet long. The rest of the cap is straight sections and I don't think I want to switch to laminations for this part. I will probably edge-glue a couple of pieces for the necessary width, cut the radius... and then think some more about how to do the bevels. I'll probably end up with a trammel arm and a beveled base for the router, and then some elbow-greased sandpaper for the finish.
In paint grade it would definitely be a lamination of strips with the bevel cut into their tops... a nice slow glue (epoxy, probably) and a whole lotta clamps.
Most lumber yards carry bending rail and straight rail for staircases. They are all the same profile, it is just the bending rail, is the straight rail cut up with a bandsaw in 16th inch segments, to facilitate bending. They are a tad thicker than the straight counterparts to accomodate the loss of width due to the kerf.One makes a template of the curve using plywood and attaching "L" shaped brackets screwed into the template every foot or so. The brackets act as a jig to hold the rail in place while you bend it, and a firm location for clamps to be set.Fine Homebuilding had an article on this subject about 3 years ago, which was excellent. I would strongly urge the reader to use Taunton's Index and find and download the article. It has suppliers listed. too.Regards,
Boris"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934