I thought I'd post a few pictures I took today while fitting my top bows and explain how I did it. This is the third set of bows I have fit. I am far from being an expert but I am pleased with my results. Hopefully I can save someone from making the errors I made on my first set!
The first thing to remember is you NEVER fit anything on your top or upholstery when you are in a rush. Do not set any firm schedule that you will feel you must meet; that is setting you up for disapointment and potentially expensive mistakes! The best you can do is set soft target dates, and if the weather isn't warm enough for the top material or if something doesn't measure as you expect let your date slip. Few things look worse then a poorly fitting top.
If you're fitting new bows your also fitting a new top, so you have a perfect opportunity to fit them together. You need to get the dimensions your bows should be set for. There is a diagram in the Ford Service Guide that is good for most years, but if you have an early car it's more difficult. I bought my top and upholstery from the J. V. Group. They are the only provider I could find with leather interior kits for the early cars, and I wanted to buy everything from one vendor. Vince included a sheet with the dimensions for my year. Most measurements are from the center of the pivot point for the particular bow / socket. These are only a starting point!
I used a drawing program called Visio, but graph paper and a ruler will work fine for this. Using the dimensions you obtain, make a drawing to scale so you can see what the top silhouette will look like. You can then see if the difference in height appears to have the expected result. For example, the third bow (the vertical one by the rear seat) is the tallest point of the top. In your drawing be sure to include the windshield so you can see how the front bow will sit in relation to it. This is really important; when I did this the profile looked wrong and I called Vince. He checked his drawing and found there was a typo.
Once you know how far the 'flat' part of the bow needs to be from the pivot point you need to know where to cut them and how long the taper needs to be. Measure each socket carefully from the center of it's pivot point to the edge of the metal tube. Also measure how deep each socket is. I found up to 1/8" difference in length from side to side, and up to 1/2" difference on the depth of the sockets. The new sockets are filled with resin so, while they are close, there is a difference.
Once you have these measurements you take the overall desired height of a bow, subtract the length of the socket (this gives you the point you need to begin the taper), then add the depth of the socket to get the point you will trim the bow.
Mark each bow well! Mark what bow position it is, drivers side, passenger side, and use arrows to show the direction to the front. Also mark the centerline of each bow.
Use a framing square and pencil to mark the taper point and cutting point on each bow. You may need to adjust this point, so don't cut the bow yet! Measure across the 'outside' of the bow from the place each taper will start.
Lay out some blankets on a nice, flat surface. You need an area large enough fr your top panel to open up on. Spread the top panel out flat, and measure the overall length of the panel. Compare this to what you need (the sum of the spacing of each bow) and see how much extra there is. My panel was 5-6" longer then needed. Split the difference and, using pieces of masking tape, mark the aproximate place each bow will be. Mark each side of the panel. Now measure the width of the top panel at each bow location.
Compare the measurement taken across the outside of each bow to the width of the panel at each bow location. You should have about 2" - 2 1/2" difference, which will allow the top panel to come about 1" down over the metal part of the socket. When I did this I found that my 3rd bow had 1 1/2" more then my second bow, so I moved my taper-start and cut mark on each side of the 3rd bow 3/4" to take up the difference.
I used excel and made a simple spreadsheet with all of the bow lengths, socket depths and desired bow heights. You can easily do it on paper if you write neater then I do...
A word of caution.... now that you have everything marked, slowly and carefully double check everything you just did. If you make a mistake and cut a bow too short it's expensive. If you hurry you can snap off a taper... that's expensive too! Don't ask how I know.....
You can use a spoke shave or draw knife to make your tapers, but I prefer an air grinder, rat tail file and wrasp. Go slow, try the socket often and remove a little wood at a time. The grinder will remove a lot of wood quickly! As a reference, it took my 3 hours to fit my bows this afternoon, including setup and cleanup. My measurements and marking was already done; this was just carefully cutting and fitting the bows. Allow yourself at least 1/2 day and take your time!
Here are some pictures I took today.I'll post some more pictures as I fit the top.
Good luck with your project!
Here are the tools I use
I mark my bows a lot
This is marked with cutting and taper points
The scrap is cut off and ready to taper
The bow is shaped
This socket is fit!
The set is mounted on the car
Thanks for the timely post. I am about to do the top on my '15 touring. Why did you put a grove in the taper area of the bow? Keep adding to this thread so we can see the entire process beginning to end. Thanks again.
If you look inside the open end of your socket you'll see there is a 'rolled edge' seam. The sockets are made from flat stock, not tubing, so it has to be seamed.
I will post more tonight or tomorrow. Good luck!!!!
Excellent work,and how you did it!
I did my '15 T touring a year or so ago and I know how much work it really is,and how important it is to pay attention to every detail.You are absolutely correct about not getting in a hurry!
Mine took a little longer,as it was very first time I ever did this type of work.I was very pleased with my results and followed your methods practically the same way.
Please keep posting more info and pics as you progress.
Are you doing a '13 or a '14?
Hi Darren. This is a 1911. Previously I did a '15 roadster (did not come out well!) and a '15 touring (came out nice). I'll keep you posted!
One recommendation for anyone buying a set of bows; stick with steam bent oak or hickory bows. I understand that laminated materials can be stronger then solid materials, but that is not what I've found with the laminated bows readily available. I snapped the taper off one 2 weeks ago after I finished fitting it, and I wasn't beating on it. I've never had a problem with any steam bent bow. I asked a couple of friends who are pretty serious woodworkers what they thought and their opinion was the material used was too soft. Basically it looks like a number of layers of 1/8" luan plywood and had very little strength. If you look at structural laminated beams they are multiple layers of solid material, not layers of plywood.
This is just my opinion and I'm sure others will disagree.
That is a very nice job you are doing on your 1911. I have made a few tops for early cars and will be willing to share what I have learned with you. I authored an article that appeared in the July-August 2007 issue of the Horseless Carriage Gazette on setting up the top sockets and bows for a top. The article parallels much of what you have mentioned. The only suggestion I have on your bows is you might want to put a slightly larger radius on the edges of the front and rear bows where the top material rests on them to minimize wear and give those edges a softer appearance.
I agree with you that the laminated bows that are made from 1/8" door skin stock are not very strong and are a poor choice to use.
Ones that are properly laminated using strips of solid stock and the correct glue are very strong and stay very stable.
Sometimes the steam-bent bows will change shape as they stress-relieve. Ones that have been clamped in "drying" fixtures for a long time will do better.
Let me know if I can help,
I've got my original 1909 bows in pieces at the moment. Mine have a split sleeve inside which lines up either side of the folded seam, so reinforcing the socket and avoiding the need to groove the bow. Also the centre doesn't have modern resin but wood. The photo is bit blurred but I think you'll get the idea.
For anyone going to Chickasha who's interested, my brother will have sets of pre-1918 top bows made from laminated ash to the exact dimensions called for in the Ford drawings. He even has the little beveled strips that go on the rear bows, missing in most restorations, and the front bows have the different radius called for. Stop by NF 9 & 10.