Arched Mullions

[Mark Bolton]

I have a customer asking for an office center and they are wanting glass doors with arched mullions. The material for the project is going to be local sourced so we would have to have a go at these.

We have done mullions but never arched wondering what others experiences are.

Thanks,
Mark

[Leo Graywacz]

It's been a while since I did and arched mullion. But when I did it I used laminations for the curved mullions. I was using Mahogony and tried to just cut them out. But the reverse grain always seemed to be a problem and I have chip out problem. So I used laminations to do the curves. The curves were made out of 1/16" strips, I used 11 of them to get my 11/16" that I needed. I know I have a picture somewhere, just can't seem to locate it.

Here is something I found on the internet that is more or less what I did. My window wasn't as big and was less wide proportionally so the lites were more rectangular than square like the image
http://www.collinscustommillworks.com/images/Radius_Window_w_fancy_grill.jpg

[Larry Rasmussen]

Or at least a similar topic. It's on the Woodmaster Tool site and on the home page there is a video by a customer, Gary Striegler or something similar. This isn't exactly mullions but he does do a great job describing the set up and goes through cutting the strips, making the jig and gluing up the curved window moulding. I just happen to stumble on this recently and thought that it was above average in presentation on the technique he uses for curved molding. Hopefully you will find it of use. www.woodmastertools.com (http://www.woodmastertools.com).

Regards,
Larry R
Seattle

[Logan William]

FYI those are actually muntins, not mullions. Mullions are what is used to join multiple windows together to form a mull, muntins are the wood or metal bars adhered to the glass to create the patterns.

[Peter Quinn]

Most important part.....charge appropriately, by which I mean a lot. I haven't done curved muntin bars but I have made some arch top half round storms, around a 24" radius, and I opted to use a router table to shape the curves. I was having trouble with tearout, didn't want to make bent laminations, so I used the router and climb cut the bad grain as necessary, I would not climb those cuts on a shaper. I used an amana bit that allowed me to take the rabbit cutter out out of the stack which makes for a lighter cut. I added the glass rabbits later.

I'd guess the approach depends on the radius of the curves you are working, and the finish. If it's stain grade they may not want bent laminations on a door that will be a focal point. For muntins there will be a good number of carriage jigs to make to get the small parts past a cutter, and you will almost certainly need to make extra parts as some will blow out. There is an old FWW article on making curved divided lite doors that is quite good, so search formthat if you have access to FWW for some good pictures. I can't seem to find the article presently.

[Peter Quinn]

Found it. Issue #108, FWW, October 1994, Jeff Greef, Curved cope and stick. Its a good article on making the necessary jigs for doing accurate curved windows and doors.

[Mark Bolton]

FYI those are actually muntins, not mullions. Mullions are what is used to join multiple windows together to form a mull, muntins are the wood or metal bars adhered to the glass to create the patterns.

Well, right or wrong many sources for doors refer to these cabinet doors as arched mullion. This customer specifically saw them in a Conestoga catalog but many suppliers seem to be getting it wrong...

Mark

[Neal Clayton]

I have a customer asking for an office center and they are wanting glass doors with arched mullions. The material for the project is going to be local sourced so we would have to have a go at these.

We have done mullions but never arched wondering what others experiences are.

Thanks,
Mark

this topic recently came up on a historic restoration site i frequent. diamond patterns in window sash specifically were quite popular in the early 20th/late 19th century, and they wind up with the same issues.

from my tinkering with this...see this thread (http://www.historichomeworks.com/forum/viewtopic.php?t=1578) with some pics and drawings.

1) the profile must be as shallow as possible. for square patterned muntins i like to use a door profile cutter to make the profiles stand out, but it won't work with muntins that intersect the rail/stile at an angle, or you lose a lot of the stick profile at the joint.

2) the traditional way, if that matters to you, is demonstrated in that thread linked above as well. a simple foot operated machine with a straight knife that matches the stick profile, that creates a sort of profiled mortise. i think this could be replicated by machining a way to attach a custom knife to a mortiser chuck, but haven't gotten around to doing that yet.

the profiled mortise works quite well for mass production, obviously, since there are no ends to cope, you could make muntins in bulk and they simply need to be fit whole into profiled mortises. it's another one of those examples of an older/simpler machine being much better for a specific purpose than modern power tools are ;). the machine is called a sash trimmer. in effect, it 's a foot pedal powered shaper.

alternatively, you could simply remove the tenons left by the cope cut, and dowel or nail the muntins in place. this isn't really a compromise, imo, there are lots of examples of muntins being nailed in place that have lasted for centuries (see the diamond light sash in the above linked thread, it was put together that way if you look at the pics).

there is one person over there who does custom work like this, i've talked to him about paint issues and he's quite helpful, you could give him a call and i'm sure he'd be happy to provide pointers (he does own and use the old sash trimmer machines).

http://www.smithrestorationsash.com/aboutus.html

[Frank Drew]

FYI those are actually muntins, not mullions. Mullions are what is used to join multiple windows together to form a mull, muntins are the wood or metal bars adhered to the glass to create the patterns. not really, at least not if by ''wood or metal bars adhered to the glass'' you mean those applied ''glazing bars'' [clip-ons, or plant-ons]; the terms mullion and muntin were in use long before cost-cutting builders began using plant-ons to imitate true divided light sash.

i've never seen the word mull used as you're suggesting; perhaps that's a regional usage.

[Bill ThompsonNM]

Interestingly-- when I looked up mullion in the online dictionary: vertical members separating panes jn a window and a second def. The radiating members between panes in a rose window. It wouldn't take too much of a stretch to view an arch as a segment of a rose window. . .

[Leo Graywacz]

I have always called the vertical top to bottom elements of the window as Mullions and the horizontal shorter pcs as muntons. Doesn't matter to me what the proper term is anymore. That is what they are to me.

[Mark Bolton]

I think the definition that he is likely referring to speaks to "a structural member" separating two windows. I guess it could get interesting when you speak with someone who would say that these members are, or were, in fact structural to the sash or something like that rather than just being there for esthetic's or to accommodate smaller pieces of glass which were more common at the time.

Coming from the homebuilding trade in the north east US we commonly refer to multiples of a window as a "mulled" unit.

I really dont care whether the application of the terminology is correct for this application but its an interesting conversation none the less. Haha.

Mark

[Logan William]

I'm coming from the background of window/door manufacturing for one of the larger companies, we "mull" units together and apply "muntins" to the glass. Within the use of mull there are multiple ways/methods/components used to physically mull the units together but (at least in our product) generally involves the use of an aluminum extrusion to fit into the accessory groove of the mating units exterior cladding(on an aluminum clad unit) as well as a combination of upper/lower plates, external and internal covers and a generous amount of sealant. The components used to mull the units together is determined by the builder/architect/codes for the area and what performance level the customer requires.

One of our other plants does make True Divided Light as well as a "simulated" version with factory applied muntins, not sure what they call it when doing the TDL's but we call the non TDL method muntins and muntining. To my knowledge the 5 largest window/door manufacturers use the same terminology, doesn't necessarily mean its correct or how its always been used though, just what is common and what I've learned!

[Peter Quinn]

All this window terminology brings me to the old sill/stool discussion. I can remember a building inspector talking about the "sill height from finished floor". I asked flippantly "Shouldn't you measure the sill height from the ground up, seeing as most of it is OUTSIDE the building and its pitched?" Its funny how little humor bureaucrats seem to have when you're poking them in the ribs. But the code book does specify a "sill height" from finished floor for egress, though I'm pretty sure they mean the stool.

Any way, most of the people I have spoken about this with, including many field carpenters, call that piece of trim at the bottom of a double hung above the apron that the casings die into a sill. But it is in fact called a stool. You can sit on a stool, you can't sit on a sill, its pitched to shed water, and its outside the building. Many of the modern factory made sash look stupid because they have done away with the stool, which had a real role to play on old windows. No place for the trim to go, you wind up doing some picture frame thing, ugghh.

I learned a mullion separates windows, a muntin separates panes of glass. Perhaps we could put in a call to the national fenestration council for an accepted definition of terms? And then we could define that thing at teh bottom of a door that the jamb legs land on, because I hear more and more people call it a sill, when I'm pretty sure its called a threshold in English?

[Craig Carpenter]

Is this project a trim added to the glass to give the appearance of separate pieces of glass? Is it header trim? A mullion to me is a simple piece of material that merely covers the joint created by mounting glass above a door, two windows or more stacked or side to side. If you're only wanting to create your own header trim, get your casing in place, stick a peice of 1/4" material big enough to cover your area, then simply back scribe your arch onto the material. Cut that out, sanding to your line, then using a decent set of calipers/compass, scribe your width. Route your edge of choice or input a center flute. Using an American Eagle futing guide. http://www.youtube.com/watch?v=l-T2E5dNNms


I hope this addresses your issue.

[Neal Clayton]

All this window terminology brings me to the old sill/stool discussion. I can remember a building inspector talking about the "sill height from finished floor". I asked flippantly "Shouldn't you measure the sill height from the ground up, seeing as most of it is OUTSIDE the building and its pitched?" Its funny how little humor bureaucrats seem to have when you're poking them in the ribs. But the code book does specify a "sill height" from finished floor for egress, though I'm pretty sure they mean the stool.

Any way, most of the people I have spoken about this with, including many field carpenters, call that piece of trim at the bottom of a double hung above the apron that the casings die into a sill. But it is in fact called a stool. You can sit on a stool, you can't sit on a sill, its pitched to shed water, and its outside the building. Many of the modern factory made sash look stupid because they have done away with the stool, which had a real role to play on old windows. No place for the trim to go, you wind up doing some picture frame thing, ugghh.

I learned a mullion separates windows, a muntin separates panes of glass. Perhaps we could put in a call to the national fenestration council for an accepted definition of terms? And then we could define that thing at teh bottom of a door that the jamb legs land on, because I hear more and more people call it a sill, when I'm pretty sure its called a threshold in English?

i have to be corrected on the sill/stool thing and i build those old style windows ;).

never heard a threshold called a sill though.

agree on the old window designs. if everyone could see one taken apart to see how well designed they are and how well they work, the cheapo window manufacturers would definitely lose some business.

and as for doing away with necessary parts, that's not even counting the houses they build these days in which they eliminate all of the casings too. and the stairs that eliminate railings, and the doorways without doors, and the cabinets without hardware, and anyone who has ever been suckered by a cheap builder or his realtor will tell you how all of those corner cuts are desirable for some reason....