Molding around an arched exterior door - Woodworking Talk

wkharden · 06-04-2009, 08:48 PM

I want to replace some rotted brick molding around an arched exterior door. Can I just buy brick molding at the home center and bend it? I was going to soak it in water and then build a jig with pegs that will allow me to bend it to the shape I need. Any ideas?

woodnthings · 06-04-2009, 09:38 PM

I have a friend who makes custom arch top doors up to 48" wide and 10" tall who uses a large shaper cutter and a no of templates of the arch to accomplish this. It's a matter of building up straight lengths of wood joined or spliced to form a large enough piece to bandsaw out the rough arch and then shape the contours of the individual moldings usually in a 3 stage glue up. This is not an easy task. And he gots a lot of money for his work. It's beautiful. If you can get by with flat surfaces cut on the bandsaw and then run a vertical profile cutter with a rub bushing in a router to achive your molding that would be an easier way. You'd still have to build up the segments to achieve that arch. Maybe others have another approach?

bill
BTW the brick mold at the HD is just a cheap grade of wood finger joined to make it look like one piece,and any soaking will destroy the joints and it really won't bend anyway.

skymaster · 06-06-2009, 07:30 PM

If you can find out the mfg of the door, contact them.

cabinetman · 06-06-2009, 09:19 PM

A very common method mentioned by woodnthings uses straight pieces wide enough to get the curve to lay out within them. First draw out the pattern on 3/4" MDF or particle board and cut out and smooth the edges. Then cut straight pieces of wood that will fit on the pattern allowing for enough lengths to do scarfed/half lap joinery. The shorter the pieces are the less likely it will be noticable that they are straight.

After the joinery is machined lay the pattern on the pieces as they lay to form the curve and draw out the curve. The individual pieces can now be cut close to the line with a band saw or a jig saw. Once the glue up is done, the whole section can be fixed to the pattern and both outside and inside edges can be trimmed to the pattern with a flush trim router bit.

Another method for making the curve is to rip thin strips long enough to make it around the whole outside length of the same type of pattern as above, with enough to end up straight to be joined to whatever is below. For small tight radii, 1/8" will bend easily. For larger curves, 1/4" or thicker may be able to make it without stressing. Do a test piece against the outside of the pattern to see how thick you can go.

Lay waxed paper on the outside edge, and lay the first piece against the waxed paper, and to that one you can clamp up a few at a time. You can use TB III, or if you need more time you can use UF glue (urea formaldehyde) glue, like "Plastic Resin Glue" from Dap. Doing a glue up this way will yield a continuously curved grain pattern. But keep in mind that you can have very tight glue lines and the grain may be defined as to its segments. This works out to be a very predictable lamination with no springback, like steaming or soaking may allow.

scribbles · 06-07-2009, 02:16 PM

Quote:

Originally Posted by cabinetman

A very common method mentioned by woodnthings uses straight pieces wide enough to get the curve to lay out within them. First draw out the pattern on 3/4" MDF or particle board and cut out and smooth the edges. Then cut straight pieces of wood that will fit on the pattern allowing for enough lengths to do scarfed/half lap joinery. The shorter the pieces are the less likely it will be noticable that they are straight.

After the joinery is machined lay the pattern on the pieces as they lay to form the curve and draw out the curve. The individual pieces can now be cut close to the line with a band saw or a jig saw. Once the glue up is done, the whole section can be fixed to the pattern and both outside and inside edges can be trimmed to the pattern with a flush trim router bit.

Another method for making the curve is to rip thin strips long enough to make it around the whole outside length of the same type of pattern as above, with enough to end up straight to be joined to whatever is below. For small tight radii, 1/8" will bend easily. For larger curves, 1/4" or thicker may be able to make it without stressing. Do a test piece against the outside of the pattern to see how thick you can go.

Lay waxed paper on the outside edge, and lay the first piece against the waxed paper, and to that one you can clamp up a few at a time. You can use TB III, or if you need more time you can use UF glue (urea formaldehyde) glue, like "Plastic Resin Glue" from Dap. Doing a glue up this way will yield a continuously curved grain pattern. But keep in mind that you can have very tight glue lines and the grain may be defined as to its segments. This works out to be a very predictable lamination with no springback, like steaming or soaking may allow.

Great advice these are the two methods I use, as a qualifier I generally use the 1/8" laminate method if the door has transitions between straight and curved, and I use the stack and cut method for continuous curves.

TheRecklessOne · 06-07-2009, 06:24 PM

In my head it seems like I've used vinyl brick moulding before...If they really do make vinyl brick moulding and I'm almost positive they do you may be able to bend it using a heat gun to warm it up. It works for vinyl tile...Just a suggestion...GOOD LUCK!

KC

ponch37300 · 06-08-2009, 11:28 PM

They do make vinyl brick molding but I'm not sure that you could get a nice smooth curve by using heat to bend it. It's relatively cheap so it might be worth a try.

Cookn · 06-09-2009, 05:02 AM

If you are going to paint the moulding, you might want to check with a millwork supply and see if they have bendable brick mould. It is available and makes the job quite easy. I've used bendable moulding on a few things, and it's OK if you are going to paint.

Bob156235 · 06-10-2009, 01:16 PM

It's easy. Use exterior 3/4" and 1/2" ply's.

Set up a radius arm for your router to arc the cuts using a simple dato bit to cut the 3/4" and 1/2 ply arcs. Change to a flat bottomed v, or 45 degree bit for the "steps" in the 1/2" ply then glue it over the 3/4" ply. Matching brick molding is an easy profile to match - or to come reasonably close, especially in this "up, out of the way" application.

After you cut it and laminate the two ply's, dilute yellow (exterior) glue and brush it on the laminated edges (to seal them). When dry, prime and paint.

woodnthings · 06-10-2009, 05:01 PM

[quote=Bob156235;83871]It's easy. Use exterior 3/4" and 1/2" ply's.

Set up a radius arm for your router to arc the cuts using a simple dato bit to cut the 3/4" and 1/2 ply arcs. Change to a flat bottomed v, or 45 degree bit for the "steps" in the 1/2" ply then glue it over the 3/4" ply. Matching brick molding is an easy profile to match - or to come reasonably close, especially in this "up, out of the way" application.

Why not use MDF, no grain, no tearout, no gaps or missing sections. Paints well and will rout well, but make lots of DUST!

bill

cabinetman · 06-10-2009, 06:54 PM

Give yer brains a rest, he hasn't been back in 6 days.