Dear woodworkers
We are trying to figure out how to bend a crown moulding in two planes at once. The best idea I have so far is to layout paper over the crown and cut it to shape. Then cut 1/4″ basswood to that shape so that there remains a bend in one plane only. The moulding is about 5″ wide by 48″ long and is in a kind of half-moon curve down and folds back on itself about 4″. Two thicknesses would be enough. I think 1/4″ can do it, but there’s always a risk of breakage. Anyone know another approach to this problem?
Thanks for any ideas on this.
Replies
Asymmetrical cross section woods will always flip to the easiest bending plane, so moldings normally don't bend too well. Crowns will usually flip onto their back.
Usually it is best to either bend, or saw the shape, then mill the molding pattern onto the wood, after you have the shape.
Think about trying this. glue two layers up to fit the curve of the plan view, and break the miters to fit the curve so the the glue lines are staggered like bricks overlap in each course. Try to make it come out larger than you need for the actual moulding. Then cut the rise that you need for the front elevation, keeping in mind that the part cut from the bottom of the curve can then be glued onto the top in several layers to make up a blank for the final blank that you shape.
That may be more than you are asking though. If you are just trying to figure out how to cut the curve that winds around a curve, with a changing pitch, yes you can attach a blank to a fixture that holds the blank to a given pitch. then with the curves drawn onto ####top flat plane piece, you can then saw to the line on the pattern, to get the shape with the rise / run, with the back and front cuts plumb. That is, if you have a band-saw with enough throat height.
Hi zav,
Profiles in wood are hard to bend. If this is not fine furniture and the twist or bend is not too severe, try soaking it for a week or so in water.Idid this once on some interior trim. It doesn't do a lot but for my application it was just enough. Kerf cutting doesn't work too well on profiles either but, if it's paint grade and can be filled, it might be just enough to get it to do what you want.
Paul
Hi Zav,
In guessing that this is either 38 degree or 45 degree crown, I think you will find that what you are trying to do is impossible.
What is usually done is that a curved blank is made at the correct back angle, then the piece is shaped with a large shaper cutter in a large shaper.
Please don't try this at home. I have done it with smaller crowns, but would never do it with something this large. You would need a large industrial shaper, a large industrial powerfeeder, & more know-how and experience than you have. This is dangerous if you don't know what you are doing.
My advice is to go to a custom woodworking shop and ask them to do it for you, if this is what you want.
There is one other option though. You could glue a curved blank and shape the crown by hand. This is the old fashioned way to do it and is actually a pretty good way. It takes a bit of elbow grease, but you won't need much heat in your shop the day you do it.
Hal
http://www.rivercitywoodworks.com
Does it have to be wood?
All the flexible moulding I ever installed as a finish carpenter was from ResinArt. A company that makes many common crown profiles and sells just flat stock in different widths and thicknesses for custom profiles.
It smells nasty when milling up, but can be worked to very tight radii. Especially if you heat it up.
It can also be stained as well.
Here is a link to their website.
http://www.flexmoulding.com/
J.P.
Edit: Unless you intend to carve the piece. As others have said you will need to make a blank and then most likely carve by hand.
http://www.jpkfinefurniture.com
Edited 3/27/2007 7:22 pm ET by JP
Dear Zav,
JP is dead on. I've used that flexible stuff for years and it works great. If the application is acceptable, then it is an excellent alternative.
Best,
John
This forum post is now archived. Commenting has been disabled