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Midday Gun 10-12-2019 02:31

Curved wooden mouldings - how to?
 
2 Attachment(s)
My boat has a few different areas in which it has curved mouldings / capping / trim to finish off the edges of the plywood.

These are now looking a bit tired and I want to have a crack at making my own, but I'm not sure on the process, looking at them they seem to have a glue line so maybe they are laminated and glued?

I've also added some webs as part of a project to move the chainplates & these need capping as well.

Anyone had a crack at this before?
Some photos as an example of what I mean

Help / tips much appreciated, thanks.

danstanford 10-12-2019 02:53

Re: Curved wooden mouldings - how to?
 
It depends on the wood and the radius of the bend, but the vast majority of trims like that are thin strips of wood glued together after being clamped around a form. I think this is the best solution for your situation.
For tight rad's you can also laminate thicker material to cover the whole shape and then cut the shape you want from the rectangular block. The final situation for smaller profiles is steaming until more pliable then clamping around a form.
Lots of work no matter which one.

Reefmagnet 10-12-2019 03:39

Re: Curved wooden mouldings - how to?
 
If the lengths are short (as in, say, between chainplate knees) straight pieces of wood can be used because no one will ever notice it isn't curved.

Or for a gradual curve, is place the widest dimension along the curve and screw from the opposite side to get it to conform to shape.

Another option is to use plastic edging strips. These can actually look quite decent in some situations.


To get more technical, there is steam bending or just cutting the curved profile from a winder section of material, and scarfing the joining pieces together to create a long run of curve. If you can sand once in place, the piece of wood will look like a single continuous piece when done.

funjohnson 10-12-2019 04:31

Re: Curved wooden mouldings - how to?
 
Quote:

Originally Posted by Midday Gun (Post 3033002)
My boat has a few different areas in which it has curved mouldings / capping / trim to finish off the edges of the plywood.

These are now looking a bit tired and I want to have a crack at making my own, but I'm not sure on the process, looking at them they seem to have a glue line so maybe they are laminated and glued?

I've also added some webs as part of a project to move the chainplates & these need capping as well.

Anyone had a crack at this before?
Some photos as an example of what I mean

Help / tips much appreciated, thanks.

For the curved knee you've shown, you'll need to laminate thin veneer strips together to build-up the thickness desired. We had 17 strips for one section just to get the radius and thickness needed to match the rest of the otherwise generic trim on our Sabre 34 (very similar to what you've shown). I've counted as many as 40 layers for 2" door trim on a Lord Nelson 41.. so at least you don't have to do that :thumb:

Make the profile uniform square or rectangle and then cut the recess to slip over the bulkhead with a router table.

We used resorcinol resin glue in suboptimal conditions the first time I tried this process (in Guatemala's humidity). When I released the clamps, in rapid succession I got slapped in the face with 10 strips of wood. Apparently the glue never cured :banghead: Good luck :biggrin:

Matt

capt jgw 10-12-2019 05:21

Re: Curved wooden mouldings - how to?
 
I have some curved trim pieces in my boat that are cut out of large pieces of regular timber. They look good but must have made a rediculous amount of waste. In an expensive would like teak this is a pretty dumb way to do it. I would laminate several thin strips to make the parts. Cut one strip maybe 1/4 thick and see if it will make the bend and trim it thinner till it does. Then cut the rest and clamp in place. Make the parts a little oversize so you can trim off the rough edges. Use epoxy, the glue lines will be pretty colorless and hard to see.

gonesail 10-12-2019 06:09

Re: Curved wooden mouldings - how to?
 
for the teak caps you could steam bend the wood to fit the curve. probably need to be screwed and glued to the plywood.

leboyd 10-12-2019 06:21

Re: Curved wooden mouldings - how to?
 
You may want to watch some of the last few videos on YouTube on the Sail Life channel. He just did some similar pieces and the videos are very good.

Midday Gun 10-12-2019 06:49

Re: Curved wooden mouldings - how to?
 
Thanks for all the tips & advice, as I suspected, it sounds like an awful lot of work.

I don't have the ability to steam bits so most likely I'll try the gluing thing strips method as has been described.

I'll also try and standardise all my curve radii so that I can make one jig to do all or at least most of them. Cheers.

billknny 10-12-2019 07:30

Re: Curved wooden mouldings - how to?
 
youtube video,

If you go to this at 26:25 or so, you'll see how a high end boatbuilder does it in their shop. Nothing magic, you can do it at home.

Sorry about the technical quality of the video, it's really old and a VHS transfer. I am sure you can find a more "how-to" video once you know what you are looking for...

wingssail 10-12-2019 07:34

Re: Curved wooden mouldings - how to?
 
1 Attachment(s)
The quickest and (I think) easiest is to cut the moldings from a solid piece of timber. Obtain 1 or more planks, in your case probably 1" thick. I have dark stained mahogany but teak is used in most boats.

Make templates and cut the sections carefully. Make them slightly longer because fitting will require some trimming. Sand to smooth, perfect, shapes.

Use a router to cut a groove in the back.

There will be wastage.

Screw in place and plug the screw holes.

Finish.

Sand crab 10-12-2019 08:48

Re: Curved wooden mouldings - how to?
 
I'm a retired contractor, builder, carpenter etc. I've done this and it is complicated even for professionals. I've built those really nice curved stair rails that you see in the high end homes. The rails come in packs which include the outside molded parts and the laminated strips to build up the width. I have also made my own when there was a time issue due to shipping. Here's some tips.
1.You will need 3 times as many clamps as you have and then you still won't have enough.:biggrin:
2. Making a really good jig will take almost as much time as making the piece.
3. The wood also has a nasty habit of wanting to spring back so will lose (sometimes) some of it's curve.
4. One tip to make it easier and cheaper is to just use regular yellow wood glue because these parts aren't going to get wet and they will have a seal coat on them anyway.
5. Freestyling this with a router is not advisable. A router table is a must.

or

6. When assembling the laminate cut smaller strips for the radius where it will meet the panel. this way you will already have a channel already built in to the molding. If you do it this way then you can just carefully hand sand the profile. Do not use any type of powered sander or you will f*#k it up. The good part is there will be no need for a router, bits or table. :thumb:

Boatwright 10-12-2019 09:28

Re: Curved wooden mouldings - how to?
 
Pro tip:

1) Laminate or steam bend stock to a rectangular cross section.

2) Prepare a template out of thin material such as 1/8" tempered masonite.

3) Attach template to stock

4) Use pattern following router bits of the needed profile on a router table.

You can produce very accurate curved moldings, including complex shapes, using this method.

Exctyengr 10-12-2019 09:35

Re: Curved wooden mouldings - how to?
 
This is a big, complex but fun project. You will need to laminate multiple layers of thin strips around a mold or a form.. Best to use a steam box but I have friends who simply soaked the wood in water for an extended period of time, like a week and then gently bent it around the form. Use a wood that lends itself to bent shapes. Ash, Oak are good choices. I have not tried it with teak but I suspect mahogany having an open grain might work. There are online sources for more information on steam bending. Once you have made your form and laminated your strips and the glue has cured, you will have to sand and shape the finished product. A drum sander is best, I would be careful of using a thickness planer. We used the drum sander at the local community college. Shape the curve with a table router (DO NOT TRY USING A HAND ROUTER FOR THIS, unless your insurance is paid up.
All that said, have you considered simply refinishing what you have and using straight wood for the chain plates?
Good luck, send photos if you proceed

dadster3 10-12-2019 09:48

Re: Curved wooden mouldings - how to?
 
Steaming and laminating are the most common ways to make new curved work. Since you already have the curved pieces, perhaps you could remove them and use them for a pattern to cut new ones. If you use plywood you will want to cover the cut edge. I'm not a fan of the glue on edging. My preference is to use a thin strip of solid wood maybe 1/8" thick or less glued and nailed to the edge.

Luckyknot 10-12-2019 09:55

Re: Curved wooden mouldings - how to?
 
I just got a Rockler steam generator that comes with the generator and hardware to make a steam box. It was $80 on Amazon. Haven't used it yet but I'm hopeful. Maybe something you could look in to. Pretty compact. Also saw a youtube video about a shipwright using a plastic bag as the steam box to bend pieces directly in place.


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