Bending 16mm quadrant

[pooka]

Hi all,
I am currently re-glazing an internal door with a single piece of laminated glass, with 16mm quadrant (rounded over) to hold the new glass in place. The top of the opening in the door is curved. The top section of the door was grooved to accept the previous glass (previous glass was 12 small panes set into a wooden framework), but I removed the curved wooden "lip" in each side as they didn't match the quadrant which will act as the new beading.

I had hoped to bend some quadrant to match the curve, but this is proving more difficult than I expected. The length of the quadrant is 665mm, and at the highest point in the curve the wood has to move/bend by 45mm. In my ignorance, I have hoped that the curve might be gentle enough that clamping pressure would be enough to bend the quadrant, but no joy (it will snap if I try). I have been trying this with pine quadrant, but I also have hardwood quadrant (not sure what the wood is though) if that might prove easier to bend.

I could make a steam-bending box like those that I have read about, I guess, but I'd prefer to get this door finished sooner rather than later (I also don't have a suitable kettle). So, my question is, is there any way to bend this quadrant to shape without a proper steam-bending set-up?

Perhaps my best alternative is to simply cut out a curved piece from a larger piece of wood, but I don't have a roundover router bit that matches the quadrant, so I'll end up having to round the newly cut piece by hand and I am not sure how close a match to the existing quadrant I'll be able to get. Is this my best alternative though, in the absence of proper steam-bending kit?

Thanks for any advice.

 

[StevieB]

How about trying to soak the quadrant in hot water? I used to plank model ships using this method - soaked for about 10mins in hot water run in the bath. Not sure if it will work for 16mm but maybe worth a try.

Steve.

 

[RogerS]

I'm not an expert but couldn't you make up some sort of simple jig using a piece of scrap MDF and a series of holes and pegs that gradually bent the quadrant to the curve that you need. Possibly dampen it (hot water bath?) then bend as much as possible and peg. Leave for a couple of days. then repeat but peg into a hole giving a tighter radius?

 

[pooka]

Soaking it might work. I have used wet newspapers in the past to get a warp out of a full length door, but I wasn't sure if it would be enough to allow me to bend the quadrant as much as I need.

One problem is that I no longer have a bath (replacing it with a shower seemed like a good idea a the time...) so I have nothing to soak the quadrant in - I may just wrap it in wet paper, or towels, in the shower tray and pour hot water over it. It is certainly worth a try. Thanks.

Roger, using an MDF jig is a good idea, but it will take me longer than I'd like (I happen to have picked the coldest weather for ages to remove the door from our living room and expose the room to draughts :roll: ). At that stage I'd probably just give making a curved section by hand a go.

 

[Scrit]

I could make a steam-bending box like those that I have read about....

Yes, but it will only work on hardwoods, not softwoods - and even then not all (e.g. poplar isn't good for steaming). To check suitability see "World Woods in Colour" by W. A. Lincoln or post the speciaes here and I'll look it up for you.

Perhaps my best alternative is to simply cut out a curved piece from a larger piece of wood, but I don't have a roundover router bit that matches the quadrant....

That's probably your best bet, but shaping it can be done using a scratch stock. I think there's one either on Alf or BugBear's web sites. Start by planing/thicknessing then band sawing to size and square off using a router and template with a guide bearing cutter (or alternatively router/trammel bar) before forming the edge with a scratch stock. Before you start to form the edge the stock must be a true square cross section

Scrit

 

[JFC]

If the door is going to be painted you could also try cutting slots in the back and then soaking the slots can be filled if part of them show on the face of the timber .

 

[pooka]

Thanks for the tips. I'll give them a go these evening. Otherwise it'll be the painstaking process of cutting out curved pieces and shaping them (one step forward, two steps back! ).

 

[Chris Knight]

Laminating thin strips is another way of creating curves..

 

[pooka]

I tried wrapping some of my pine quadrant in wet towels last night, pouring on more water every few minutes (sometimes I miss having a bath available for properly soaking long stuff!). After 40 minutes or so, I tried bending it, and it snapped. Oh well.

40 minutes of that type of soaking is obviously far from enough. Impatience got the better of me though, so I cut out a curved piece from a pine plank, followed by quite of bit of spokeshave-ing. Shaving a roundover on a curved piece of pine is "interesting". It worked out okay though - a layer of paint might show up all sorts of blemishes, mind you, but in its bare form it is a close enough match to the quadrant to do the job (and draughts coming through where the door should be hanging are a great incentive to just get the job done!).

If nothing else, at least this issue has forced me to practice cutting curves on the bandsaw, and to practice using my spokeshaves, so every cold and draughty cloud has a silver lining.

Thanks again.

 

[StevieB]

Just a thought for next time, but 16mm quadrant will fit into 22mm copper pipe - why not cap one end, fill it with hot water and let it stand for as long as you need (insulate as necessary). For larger pieces 40mm plastic pipe or even drainpipe should be fine.

Steve.

 

[Scrit]

The only problem with trying to bend pine is that it's, well, pine. It's one of the timbers generally regarded as unsuitable for steam bending, whereas beech, for example, is excellent. That's why OI suggested looking-up the characteristics of a wood before using it in a new situation. Beg, borrow or requast for Xmas a copy of Edlin's book and you'll save a LOT of exasperation

Scrit

 

[SketchUp Guru]

Although I can't remember where I've seen this recently, there was a magazine article showing how to make curved quadrant (we call it glass stop in the US). rather than bending it, it was sawn. The inside arc was cut and profiled. Then the external radius was cut. It would seem that this would be a better way to go about it.

An alternative that comes to mind is to saw thin veneer-like strips and do a glued, laminated arch. If you make a form to match the arch in the door, you could glue the laminations to the form with a layer of brown paper in between. This would allow the quadrant to be removed after cleaning up the top and bottom faces as well as adding the profile.

You could also put packing tape on the iside face to the form and later stick the raw quadrant back on the form for profiling.

 

[Steve Maskery]

If you cut from the solid, I suggest you cut the inside curve first and profile it. When you are satisfied that it is right, bandsaw the other curve using a single-point fence.

That's how I did some tight maple cock-beading in this table (except I did the outside curve first, of course):

Cheers
Steve

 

[Chris Knight]

Steve,
Nice table! How did you create the curved apron if I may ask?

 

[Steve Maskery]

Chris, thank you.
It is made up of 3mm ply pressed on a former.
The veneer grain was running off badly, so I cut it into 3 to straighten it up. The joint-lines are covered by the legs.

Cheers
Steve

 

[pooka]

StevieB: Good idea re the pipe. I'll bear that in mind for the future.

Scrit: I had a look at the hardwood quadrant, but I couldn't figure out what it was and the label doesn't say either. Its colour is a little like iroko in some places, like teak in others. All in all, for this job I think that trying to bend any of it is going to cost me further grey hairs.

Dave R, Steve: Thanks for that advice. It makes a lot of sense and I think I'll take that approach with the next curved pieces I have to tackle (I have two more doors, of the same style, to do eventually). Oh, and very nice table Steve!

 

[SketchUp Guru]

Steve, that's a loverly table. I want to touch it.

My brother did a similar table in the Arts and Crafts style. He used a piece of 3/4" oak and a piece of 1/4" oak for the apron. He kerfed the thicker piece and then laminated the thinner one on the inside of the curve to hide the kerfs. That worked well for him. He even calculated the spacing, depth and number of kerfs so that they would just close up when the piece was bent.

 

[Scrit]

Its colour is a little like iroko in some places, like teak in others....

Possibly red meranti? Used a lot for mouldings from Indonesia/Malaysia.

Scrit