DIY Top iron bow corners!

Model T Ford Forum: Forum 2010: DIY Top iron bow corners!

I wish we had a categorized DIY or tips and tricks section that we could post stuff like this in so everyone could benefit.

I've been pulling my hair out trying to do the corners in my top bows for about a week. Tried steaming and bending strips of paneling, masonite, paint stirrers, etc and laminating them togetherfor the corners but it either turned out cracking or just plain not working right.

I also wanted a material like a treated wood or something rot resistant because in time tacks do rust out and leave entry ways into wood. Moisture always can be found on the underside of canvas/vinyl tops and in time will work it's magic. In the wood kit I got from Fordwood.com for my roadster the rear rail/tack strip was not wood but a black plastic sort of material that required you to heat and bend around the curve of the body. Once cooled and set it really is some super-duper tough stuff and made the back of the car pretty rigid with the added benefit that it will never rot out. I kinda got the idea to use plastic in the corners from that, now that I think of it; had it crossed my mind I would have used plastic lumber from Lowes or Home Depot for the bows themselves but I already cut some poplar for those. Oh well, next car

I found these lattice/moulding strips at Lowes in the specialty trim section (#7049 Lattice strip). They are extremely flexible, are pvc plastic and will not rot (they are advertised as no-rot lattice), and they will take a nail or tack superbly just like wood but with no risk of splitting.
They are almost the width needed but are oversized by a little less than 3/16" so you need to trim a strip from them. This is super easy with a straightedge and razor knife, just score the cut a few times and it breaks right off! You will only need three of them layered in each corner, the bottom two will go in easy but you may have to sand the outer one just a little to get it to slip inside the iron.

The cross section of the irons are square but with rounded corners as you know so this needs to be taken into consideration when you shape the top and bottom strip. The corners need to be sanded round on these two so they fit flush in the holes, if you do not it will be impossible to fit the last strip in. On mine I just kinda cut them down with the razor but if I had to do it again I would use my belt sander and make them more uniform. Oh well no ones gonna see them anyway

Also the front and middle irons are shorter than the other therefore there is quite a taper to them as you get down to the pivot point. For the strips on these bows you must sand or cut them to have a little taper on that end. The main bow (one that's attached to the car) there is not much of a taper and you do not need to consider shaping them.

Slide the bottom one in and curve it down into the socket. You need to leave 2-2.5" for the straight bow so if you don't have enough room, remove it and trim it to fit. Once fit with the right amount of space left for the bow remove it again and use it as a guide for the other 5 for that bow. The strip will butt up in the tapered part of the socket so make your adjustments on that end. Once done slide the center in and then for the last (outer) strip insert in from the backside of the socket (here is where you may need to sand a little because it may get tight) and then curve it by hand and insert it into the bottom part of the iron.

All you have to do now is bend the little keepers down and into the strip. I used a hammer and punch for this, the material is soft enough that you can sink it just below the surface for a nice clean fit. Also it helps to have a small C clamp to use for this to ensure the pack of strips is all the way down.

The middle bow is a little different because there is a rivet that goes longways through the iron for the pivot for the front bow but that is simply resolved by cutting your center strip short, it fits perfectly. Also you don't have to use glue between the strips, you can but I didn't. It may be a good idea however, mostly for the main bow because it is possible for the strips to work their way down deeper into the socket. I put a finish nail through the pack of strips to hold them together in this bow and retain the curve. The shorter bows do not requie this because they back up on the taper of the iron.

Hope y'all like! Just wanted to share this!

Materials: #7049 no-rot lattice strip. About $4.00 each and you will have extras. 3 required (for a roadster so a touring would prob need one more)

Tools: Hacksaw. Razor knife. Tape measure. Straightedge. Hammer. Small punch. Flat screwdriver. Sandpaper (or beltsander). Small C-clamp. Glue if desired.

Pics!!!!!

I only bought 2 strips so tomorrow I'm going back to Lowes to get the third. That will be for the middle bow, the one with the rivet, and I will better document the build with photos and post here.

Thanks Patrick...very informative & nice pics!
Floyd

Very nice! You didn't even have to get that side job mowing lawns since you managed to make them yourself.

HAHA! Indeed so Seth! Guess I'll save the grass cutting for gas money lol!

I'm about to start on the third bow now. I think I am going to sand down the wood and coat the bows in POR-15 and on the top of the bows where the top will touch the wood I think I will lay some fiberglass in with the POR-15 (you can use POR-15 as resin) to help stiffen the bow from warping and possibly provide an added moisture barrier.

I have heard that you can soak oak strips in anhydrous ammonia until they are saturated and that they will be quite flexible without steaming. When they dry out the become strong and hard again.

I have not tried it but it works and you can save a lot of time and money making your own top bows. The story I read stated that you don't even have to leach out the ammonia after bending.

Back in 1964, scientists at the New York State College of Forestry at Syracuse discovered that ammonia would soften the matrix bonds in wood, with both anhydrous ammonia and compressed gaseous ammonia used in varying degrees of success. The scientists found that ammonia breaks down the hydrogen bonds within cell walls. This allows molecular movement when subjected to tensile or compressive forces. Once the ammonia evaporates from the wood, new bonds are made creating a permanent set.

Unlike with steam and hot water bending treatments, no stresses or strains are bent into the wood when using cold ammonia. The new shape is like other kiln or air dried wood. It is ready to be machined, glued and finished.


Several experiments with anhydrous ammonia in pressurized vessels have been highly successful. Pressure vessels are used because the anhydrous ammonia vaporizes and dissipates at atmospheric pressures and temperatures above -28F.

However, processing in pressure vessels has several drawbacks, especially for special, or low production activities. Personnel must be trained and certified to compress and use pressure vessels. Pumps, vessels large enough to hold various sizes of wood lengths and recovery systems are expensive.

Anhydrous ammonia is kept in a pressurized tank to keep it liquid. It is highly corrosive to aluminum, brass and copper, and presents considerable health hazards. Iron or steel must be used anywhere ammonia vapor or liquid contacts metal. It can cause frost burns and serious damage to the nose, lungs and eyes.

Alternate Experiment

For short runs or one-of-a-kind special designs, a simple soak tank can be used. [ILLUSTRATION FOR PHOTO 1 OMITTED]. Standard filling fittings used for charging anhydrous ammonia can be welded to a steel tank/pipe. Since this is not a pressure vessel, a filler pipe should be extended to within 50mm of the bottom to reduce spillage and boiling of the liquid ammonia during fill.

The tank should be slowly filled with anhydrous ammonia in an open area or field. A vent pipe on the lid of a pipe tank allows fumes to be directed away from the operator during filling. Remember, ammonia evaporates at room temperature. The colder it is outside during this operation, the slower the anhydrous ammonia vaporizes. During hot weather, vaporization will be more rapid. It may be necessary to refill the tank in order to keep the wood covered at all times.

Wood specimens should be soaked in the ammonia for about five or more minutes per millimeter of thickness. It may be necessary to use iron weights to keep the buoyant wood pieces submerged. At least 90 minutes soak time are required for 18mm thickness. Additional soaking time is required for 18mm thickness. Additional soaking time may be required for some species or denser woods. In any bending process, the stock should be as straight grained and free from knots or grain figure as possible.

Results of using a "soak" chemical method were quite successful. Wooden strips approximately 6mm by 600mm were covered for about 35 minutes. The anhydrous ammonia was then drained onto the ground and allowed to evaporate. Specimens could be bent within one hour after removal from the soak tank. Red oak, American cherry, western cedar, Philippine mahogany and American black walnut were easily bent in a variety of jigs and by freehand. [ILLUSTRATION FOR PHOTO 2 OMITTED].

Allow bent pieces to "de-gas" for 48 hours in a well-ventilated room before removal from bending jigs. Bending jigs can be as simple as a "peg mold." [ILLUSTRATION FOR PHOTO 3 OMITTED] A 6mm American cherry dowel was simply bent around a coffee can and held in place with hand clamps. The result is a cherry spiral or spring. [ILLUSTRATION FOR PHOTO 4 OMITTED].

The most common bending failure resulted from a buckling or wrinkling in the fiber walls caused by compressive failure on the concave side. Walnut and oak were reluctant to bend as sharply as birch, cedar and Philippine mahogany. Some oak and walnut specimens broke from tension failures on the convex side. Wood can be stretched only about 2 percent in tension, but more than 30 percent in compression.

You can expect color changes in all specimens. Many of the walnut specimens lost much of their color. These results were actually positive because all specimens took stain and finish very evenly. Light colored species absorbed color from darker species.

One contractor used a soak tank on-site to bend previously milled 18mm thick oak strips. The softened pieces were simply attached to a box frame for the bar and overhead shadow box/glass holder. The bar was then finished and hardware installed. [ILLUSTRATION FOR PHOTO 5 OMITTED].

In another example, the contractor used the wall as a forming jig. Previously milled oak was soaked for more than two hours and then simply nailed to the wall. Sanding and finishing was completed in place. [ILLUSTRATION FOR PHOTO 6 OMITTED].

To summarize, use of anhydrous ammonia will make wood thermoplastic enough to be bent. Heat treating specimens may aid in the bending process. Working in a cold climate will slow the evaporation of ammonia but reduce some of the plasticizing effects.

If you want more information, here is the link.

http://www.thefreelibrary.com/Anhydrous+ammonia+helps+bend+wood.-a020133971

Awesome Frank! I have a set of early bows that actually have the straight part and curve as one piece then insert into the irons. I don't know what year they are but I have some oak strips I cut for them and I will use this to curve them!

OK! Here is the last set so I am now finished with my top irons.
To be clear, after experimenting with wood I specifically did not want to use wood for these corners.
The reason is for the durability and strength this material gives. Of all the woods I tried before...even if they curved right...when you drove a tack or nail into them they would split. Sometimes the split was small, sometimes big. That is the problem with a material with a grain. On either side of the tack would be a very little crack which when no doubt when the top is up and humidity or any little leak allows moisture in between the top material and bow and into the wood itself. This pvc material allows nothing in, WILL NOT ROT, and GRIPS THE TACK 360 DEGREES. I could barely dislodge the tacks after being driven completley in.

Pretty nifty stuff! It may not be what Henry put in there but I feel as restorers, preservers of pieces of history, we should make use of such materials to prevent further deterioration of the final specimen.

Below are the pics in order of assembly. This is the center bow and for this assembly I used the beltsander to curve the material and provide for a more cleaner and professional look.

I HAVE UPLOADED THE PICS TO MY PHOTOBUCKET ALBUM. THE FORUM UPLOADER SAYS THE PICS ARE TOO LARGE SO CLICK THE LINK TO VIEW THE PICTURES. IF THEY DO NOT SHOW FOR YOU OR YOU HAVE ANY TOUBLE PLEASE POST HERE OR MESSAGE ME AND I WILL FORWARD THE PICS TO YOUR EMAIL.

Iron clamped in vice. If you haven't already you should coat the insides of the iron with POR-15 prior to this. My irons are protected with POR-15 both in and out and the outsides have a topcoat of Rustoleum satin black.
http://img.photobucket.com/albums/v425/EZFEED/My%20vehicles/1119101521-00.jpg
Here is the cross rivet for the front bow pivot. You will have to cut one short for this.
http://img.photobucket.com/albums/v425/EZFEED/My%20vehicles/1119101521-01.jpg
The two outer slats must be long enough to protrude past this attaching point for the side curtain fasteners so the screws or nails will have something to bite into.
http://img.photobucket.com/albums/v425/EZFEED/My%20vehicles/1119101522-00.jpg
The three sections of lattice material.
http://img.photobucket.com/albums/v425/EZFEED/My%20vehicles/1119101523-00.jpg

Here is the pack of three sanded to fit. Only the top and bottom need to be sanded, not the center.
http://img.photobucket.com/albums/v425/EZFEED/My%20vehicles/1119101530-00.jpg
Slide the bottom in first and under the rivet.
http://img.photobucket.com/albums/v425/EZFEED/My%20vehicles/1119101532-00.jpg
Next slide the center in and butt it up to the rivet.
http://img.photobucket.com/albums/v425/EZFEED/My%20vehicles/1119101532-01.jpg
Now this last one you need to put in the socket first...
http://img.photobucket.com/albums/v425/EZFEED/My%20vehicles/1119101532-02.jpg

...and then put a small clamp on it right in front of the socket mouth. Once clamped the pack won't shift on you and you can bend and feed it into the backside of the top of the iron.
http://img.photobucket.com/albums/v425/EZFEED/My%20vehicles/1119101533-01.jpg
Once done go ahead and crimp the tabs down. I use a punch and drive them down flush with the surface of the strip. Also do this one first then move up, I found that the strips like to walk back if you don't. Reposition the clamp in the middle of the bend when you do the next set of tabs to ensure the pack is sitting tight against the bottom of the iron.
http://img.photobucket.com/albums/v425/EZFEED/My%20vehicles/1119101546-00.jpg
Done deal!!!
http://img.photobucket.com/albums/v425/EZFEED/My%20vehicles/1119101548-00.jpg
See how the material backs up the holes for the side curtain fastener. You don't have to taper the strips at all either, just cut them square and drive them down in, when the end of the long strips gets here they start to compress in the taper of the iron and actually stop about half an inch past the holes which is plenty.
http://img.photobucket.com/albums/v425/EZFEED/My%20vehicles/1119101548-01.jpg

Hope this is usefull to y'all!!!!

Total material cost is about $15 and it only takes a couple hours to do the whole top (3 bows for roadster).

Lowes does sell plastic lumber. There is a board that is almost the perfect thickness of the straight bows but it's only sold in a 10' length (go figure ) and is about 15" wide which would make a whole bunch of bows.
I would think that would make a most excellent bow that would never warp and never rot!

Just got a small section of the 1 inch thick plastic lumber today! Somebody had cut it and discarded the unused section!

I think I am going to cut it into sections for running board blocks since it's about enough to just do that and these would be totally impervious to rot. Anyone want to try it out????

The plastic works great!!!

Problem with composite material is heat and expantion, composite siding tends to sag between nailing. Lasts like the devel though! You can always prop the middle of your top up on a hot day in the deep south!

The plastic wood works great for other projes cts also. I was wondering on using 1 inch material to replace the wood on the top of the body as a tac strip. I have bought 3, 4 and 6 inch material in 8 foot lengths and scored the back about every 5/8 inch and then bent it for the trim inside my 1/2 round windows in our house. Did not want rectangular so the 1/2 round on top really adds to it. Took just a little experimenting but it works well and I think a little experimenting on a T will show more uses. Would not want it for floorboards as it flexes to easy.