21 Hull #136...Restoration...Started

[Blue_Heron]

Terry,
I've been kicking around some ideas for a wood windshield frame. I want to use simple joinery that can be made using just a table saw and router and still be strong enough that the corners will take a beating without coming apart. I still have to mock up a corner joint to test my idea. Maybe I can do that between now and Thanksgiving and we can look at it if you're able to stop by on the way home. The part I haven't completely figured out is how to make operable sashes like the original Seafari windshield has.

Dave

[Islandtrader]

Sounds like a plan.

Here is some information I got off a wooden boat forum.


I'd think something around an inch thick x 1 1/16 or 1/8th wide, would be minimum.

Depending on your skill level, box joint corners with bronze or stainless screws in the corners to lock them would be nice. Alternately, the same size stock with a glazing groove in the center could be used, and edge screw the corners ( the stock would be just mitered corners, like a picture frame). You could set the glass in a glazing rabbet, but, the amount of space left for a retaining stop would be so small that you would be lucky to get 1-2 years on them.

The thinnest laminated glass that I can get I think, is 7/32" thick. A rubber boot around the edge would secure the glass in the frame ( if using a groove). Possibly could bed the glass in the groove with either butyl rubber caulk or maybe an elastomeric caulking ( careful with those, the squeeze out won't take stain ).

Wood frame windshields can look pretty nice, but they can't be overly bulky. Don't want the "home made look ".

Then to answer your other question on sashes, here is what Thompson boats did for there opening.

[Mikem8560]

Looks good !

[Blue_Heron]

Terry,
I haven't settled on glass thickness or type yet, so I haven't figured out how beefy my frame needs to be. What were the original glass windshields, laminated or tempered? How thick? Maybe I'll model it after automotive application and go laminated in front and tempered on the sides. I haven't done my research yet, so I'm just thinking out loud.

My thinking on the frame joints is to cut a glazing groove in the frames and then use a combination butt/mortise and tenon joint at the corners. The glazing groove in one piece also serves as a mortice and you cut a tenon on the other piece that mates with the groove. Then hold the joint together with a SS screw or two. There are still some assembly issues I need to think through, but that's where I am now.
Dave

[Islandtrader]

"My thinking on the frame joints is to cut a glazing groove in the frames and then use a combination butt/mortise and tenon joint at the corners."

I was leaning to butt and biscuit joining...not unlike mortise and tenon.

Let me know what you find out on the glass. If you go to plexi things change because of weight.

[Blue_Heron]

Originally Posted by Islandtrader

I was leaning to butt and biscuit joining...not unlike mortise and tenon.

Let me know what you find out on the glass. If you go to plexi things change because of weight.

Yes. A biscuit joint wold do the trick. There are several reasons I'm leaning toward a mortise and tenon:

* Allows me to cut a glazing groove in all my stock before I cut it to length.

* The tenon fills the glazing groove at the end of the adjoining piece, so there's no gap showing at the joints.

* Minimizes the potential for movement in a joint that is mechanically fastened, not glued. I want to be able to take the frame apart again if I have to replace a broken pane.

I called my contact at a local glass company I've worked with. He thought my idea of using laminated glass for the windshield and tempered for the side panels was a safe one. Laminated is about $13/sf, tempered is about $7. Pretty big difference in cost, but I don't want to be picking little bits of glass out of my eyes if I hit an albatross at 40 mph.

Tempered would be 1/4". Laminated would be slightly thicker, like .31 inch instead of .25". The grooves for both types of sashes could be cut the same width and the difference made up in sealant. He recommended a Silicone sealant, but I told him I'm planning to coat my frame in epoxy, so it will be like bonding to plastic. If you're planning on glazing before coating the frame, the sealant type might be different.

Now that you've got me thinking about it again, I may run some wood through the table saw to mock up a joint and see how it looks and functions.

Dave

[Blue_Heron]

Terry,
I came home from work this afternoon and mocked up a couple joints, one acute angle and one obtuse, to show what I'm talking about. These were made with a table saw, power miter, wood chisel and drill.

Obtuse angle prep:



Acute angle prep:



Obtuse angle assembled:



Acute Angle assembled:



The whole thing:



And the glazing groove. Obviously, screw placement is critical:



I made the glazing groove 5/16" wide by 3/8"deep. It should probably be a little deeper. The stock I used was 3/4" x 1 1/2". I think that's going to be big enough. The joints were pretty strong. Add some glass and sealant, and I think they'll do nicely.

Dave

[floorboy]

If that was just a quick one when you take your time and do one it should look terrific.

[Islandtrader]

As they say a picture is worth a thousand words...When you were talking M&T I just could not make the connection. I was so use to looking at the Thompson windshield that I could not understand the glass channel. Now I see what you were talking about.
The Thompson laid in the glass more like a picture frame there would be advantages to both installations...hopefully we can discuss in a few weeks.

[Blue_Heron]

Originally Posted by Islandtrader

The Thompson laid in the glass more like a picture frame there would be advantages to both installations...hopefully we can discuss in a few weeks.

Yep. My first ideas used a frame with an applied glazing stop like you're talking about. Any way I drew it it looked either too bulky or too weak.

The frame with the glazing groove is strong enough, but presents some logistical issues with sequence of assembly and installation. For instance, If one fixed pane breaks sometime down the road, can you disassemble the frame enough to replace the glass without taking the whole frame apart or removing it from the boat?

I was hoping to conceal most of the fasteners, but that may be problematic. Virtually all of the glass panels taper towards the top. The front panels are trapezoids, the side panels are triangular. So how do you replace a broken pane without taking at least one side frame off. But the side frame is attached to the side frame of the adjoining pane, so the process dominoes. It might be possible to sequence installation to solve that initially, but I want to be able to make repairs without starting from scratch. Still have to solve that before I'm ready to move ahead with this design.

Dave