Seeking Info on bow front divided light door

[Peter Quinn]

I may have a job upcoming requiring bow front divided light french entry door pairs, maybe panels and glass too. Anyone ever run across any good links to methods of work for this type of thing? I have a few old theory books but can't find much in the way of real practical applications using modern machines. I'm a researcher by nature, I have some experience with many aspects of this type of work by would love to see somebody that has put the whole method together. Feel free to pm me if a link can't be posted publicly. I have searched several other forums an am coming up with very limited info save one good blog on radius front cabinets, nothing regarding radius front sash or entries. Thanks.

[Mel Fulks]

The old ones I have seen are always veneer over segments for rails . Never seen a bowed French door, the first thing I would find out us if the GLASS has to be bowed. I saw a bowed sash made with sticking circular but rabbet was cut straight for standard flat glass.

[Kevin Jenness]

Complicated prospect for sure. I haven't done such a thing, though I have made some bow front frame and panel cabinet doors. Essentially the same setup as flat with a concave side up cradle to hold the rails for tenoning/coping. If the radius is small enough you might get away with flat stiles. On 18" radius 2 1/4" wide stiles I milled them flat, ran them with a bevel on the moulded edge and a small shim under the side away from the spindle, then blended the curve in with hand tools. The rails were bent laminations. The stiles I suppose could be also, or moulded with convex and concave cutters.

As far as references, the best one I have is Peter Collings' "Curved Work in Carpentry and Joinery", but it doesn't have much to say about machine work. I would suggest you post your question at Woodweb's Architectural Woodworking forum. Perhaps one of the old salts there would respond.

As Mel says, curved or straight glass will make a considerable difference in setups. I daresay it would be easier to mill curved rabbets than straight on curved sash bars, but harder and more expensive to get the glass made accurately, especially if insulated units.

Good luck with it. Be sure to charge plenty.

[Jamie Buxton]

Curved glass (it is called bent glass in the glass world) will be a big issue. It is possible to get glass custom-bent to a specific radius, but it is quite expensive. AFAIK, custom-bent insulated glass doesn't happen.

[david brum]

Peter, if you get the job, I sincerely hope you'll take lots of photos and share them. It sounds like a challenge, for sure. I'd love to see how you work out the joinery for the mullions.

[Peter Quinn]

I'll have to inquire about the glass, interesting consideration, I'm just the mechanic on this one (potentially), I could jig up to set flat panes in a curved frame, that will make the glass stop more interesting to fit! I've only had a brief initial conversation about the work, having never done it I'd like to be as mentally prepared as possible should it happen. I've heard of people using flat stiles on a bowed door and just making them fit, but this is an exterior door in a cold climate with weather seal requirements, or at least I imagine thats a requirement. Having flat stiles would present problems where door meets rabbited jamb head and sill even if the slightly segmented aesthetic were acceptable. I could see having knives made for a Hussey that match the average radius of the whole set to get pretty close, or CNC outsourcing the blanks, possibly machining stave core blanks and veneering those to minimize sanding? Or making a router jig like a giant guitar knock radius jig, one concave and one convex?

I have the Collings book, lots of great methods for doing layout, particularly on curve on curve work, but very little on the nuts and bolts of how to do anything. I poked around at wood web hoping somebody had tackled this prior, and I'll guess somebody there has, but no discussion of it. Maybe time for an inquiry.

[Peter Quinn]

Peter, if you get the job, I sincerely hope you'll take lots of photos and share them. It sounds like a challenge, for sure. I'd love to see how you work out the joinery for the mullions.

That part I'm pretty clear on, the verticals will be flat, no need to radius those, I'm told the top is straight, not arched thankfully, the horizontal bars can be done on a sliding shaper with a cope set and a carriage clamped to the sliding table to hold the work at the correct angle, run maybe a 1/2" stub tenon, very much like traditional sash bars in that sense. Whats baffling me is how to take a traditional straight threshold section and turn it into a radius. Maybe on a hussey, with glue ups, or a plunge router and trammel then lots of belt sanding? I'm seeing that taking more hours than I care to think about. The other tricky parts is making all this bowed horizontal bars, profiling them, then taking out the rabbits accurately, and making the stops. I assume the convex side faces out, haven't seen plans yet. I'm guessing its a few months out, if I get the work I'll definitely try to document construction.

[Jamie Buxton]

Remember: curves cost money. You have a whole shop full of machines that make lumber flat and square, but making lumber curved means templates and special setups and such. It can be done, but it just costs a bunch more time than you might think.

[Sam Murdoch]

I have used this company several times for bent glass work - http://www.standardbent.com
If you give them an accurate drawing of the curve or all the dimensions and the correct radius they will give you good product.

My inclination would certainly be to build to the curve. Depending on the radius (and if you own a bandsaw) you might be able to take the rails from thick stock without the need to laminate. I prefer this because it eliminates any spring back issues. Easy enough to make the horizontal muntins from sawn stock too. Depending on the profile you will need to do some fancy shaper/jig/bearing work but that goes without saying for this type of project.

[Larry Edgerton]

I made a pair to replace a failed attempt by another company years ago. I made the styles out of solid wood. I ground a pair of convex, and a pair of concave knives to fit my Porter Jointer that had tables that could be slid back to allow profiled knives. I used a powerfeed on a custom sled that rode outside the knives to shape the two sides of the styles. The rails I used 1/8" laminations glued together on a form using West System. I used West here because that is where the other doors failed, radius changed over time I suppose due to glue creep, but I am just guessing on that. There was no springback with this ply size on a 2" thick door. These had full bent glass so no mullions so I did not have to deal with that. They are still there and it has been twenty years. Hope this helps.

I believe these were a 12' radius just for reference. Tighter would have required a different strategy.

Larry

[Peter Quinn]

Sam, thanks for that glass link, I'll pass that up the chain if it becomes my work.

Larry, mind my asking how did you handle the threshold? We usually do an adjustable gasket at the bottom of the door, a flat the thickness of the door starts the sill, then a 5/16" vertical drop for water dam, then a 5-10 degree pitch drop to the exterior depending on exposure and wall thickness. But I have no idea how to gasket the bottom on a curve, the stuff I've used only does straights, and actually making a wooden sill with typical profile in curve has challenges, big curved jig on a router trammel and lots of passes? Followed by a jack plane? I'm left scratching head and butt at the same time on that one. If this happens I'm pushing for west systems on this. Did you thicken it or just wet it out as it comes out of the pumps?

[Larry Edgerton]

Brushseals from Conservation Technologies located out in your neighborhood. I use their tubeseals on most doors. Google Conservation Technologies and weatherstrip and it will pop right up.

I made the sill and and head jamb with a 3 1/4hp router on a heavy trammel. I custom ground a HS steel bit for the rain ledge and put a hook in the door bottom so that the brush seal sealed vertically and a tube seal in the door bottom sealed against the threshold. These were inswing french doors so I could do the double seal to combat the winds off of the lake.

I used the West system straight, just like I like my scotch.........

[Peter Quinn]

First third is out the door, so much time pressure I didn't take a single photo...not even of the finished product! Spent probably 120 man hours making jigs. Lots and lots and lots of jigs and fixtures. Turns out it is 9 french pairs, curved glass, SDL grills (which have proven to be more difficult than TDL IMO), transoms. I'm in the middle of the second phase, took a few pics so I can remember the process. Scary stuff!

[Mel Fulks]

Agree on that grill thing, with true divided there is a way to hold it together. We will look forward to more photos.

[Bill Orbine]

I'm already envision buying a few auto/truck windshields.... that is if you could find the proper curve. Maybe these windshield replacement companies will have a bunch cheep. It's a thought.