Ok, I have opened the doors on the ’49 Mercury. I know there have been countless questions on how-to-do-it, and just as many explanations, but I figure one more can’t possibly hurt. There are many ways to accomplish this, and this is just the technique I use most often. So here goes.
Now, before I go any further, I know there many ways to open doors….you can use thread and “melt” your way through the door jam (doesn’t work too well for me) You can buy two models and grind away the door on one body and cut the door out of the other body (not very cost efficient) and you can use knifes and saw blades to do it. I prefer the latter, but you are free to do it anyway you like.
I open the doors on just about every vehicle I build so I have become pretty proficient at it. I open resin bodies, regular styrene bodies, chopped tops and sectioned bodies so I have dealt with just about every obstacle there is….this though, was about as simple as it gets. The two main tools for this job are a “used” exact-o knife blade, and by used, I mean one that has lost its point and about 20% of its sharpness and the other is an exact-o saw blade. Both are shown here……
Now the trick is to start with a very light “hand”, meaning that you use very little pressure. With the back of the broken point knife you begin by lightly dragging it down the score line of the door. Use just enough pressure to insure that the blade stays in the score line but not so much that you lose control of the blade. If you are not sure, go slowly. When you get to a curved corner, stop. Do the straight lines first. And then go back and slowly work your way around the curved corner…it will take a little time, but your care will be rewarded in the end with a nice smooth rounded corner. Also, alternate from side to side.
I find that you want to have both doors, assuming this is a two door model, done at about the same time. Since you are handling the body quite a bit during the process, you don’t want to put too much pressure on any surface, also, and this applies to this build in particular, be very careful if the car is a convertible because there may only be a small amount of styrene (the lower rocker panel) holding the front of the car to the back of the car, once the door is removed. You can understand why I am saying to finish the doors, or in other words, have the doors ready to pop out at about the same time so that you do not put unnecessary tension on the rocker panels. Got it?
Ok, as I said before, the ’49 Mercury is a great car to start with, especially in this case, because you do not have to deal with the area above the windows which require a different technique to free up.
Alright, here is what I am talking about. Here is an older Fujimi Porsche that I have been working on and off for a while now.
I opened the doors, as you can see, but the point of this is I want you to look at the area around the window frame. Notice how delicate and thin the window frame is? That requires a slightly different technique to free up. The styrene in this area tends to be thinner and great care must be taken not to damage the window frame. For this kind of area, I use a very sharp knife, in fact a brand new blade and I work very slowly. I free up the window area before the door because you need to have a solid foundation for this to come free easily. You don’t want the door wiggling around as you are working on the tight space around the window. And once this is free, you can attack the door without worrying that the window area will be an issue later. Using the front of the new blade, I very carefully work through the styrene pushing the knife point through the scribed lines of the door into the styrene and then working the knife around the edge. I will not say it is easy, but obviously it is doable and I think it looks great to see the delicate door opened….I mean, many guys who are just starting out will marvel at this kind of work, so I think you should give it some consideration if you have any competency at all. Don’t be afraid of the tiny delicate window area, just work the new blade around the edge and surprisingly, it will come free without as much bother as you may think.
Back to the Mercury……
And, these doors do not have rounded corners, which make this job a snap. Here you can see the door removed from the car body.
to get to this point it is really easy, just increase the pressure on the blade as you draw it backwards through the door panel score marks. The saw blade comes in very handy at the ends of the door. Once you have scored the door seam all the way through so you can see daylight, you can insert the saw blade, assuming the door edge is a straight run and not curved (this one is straight) and slowly saw your way to the end of the door panel. The saw works especially well at the corners. Take, for instance, the lower front edge of the door in the picture above. Once you are through the door panel in the middle of the door, insert the blade, saw side down and slowly saw your way to the bottom front corner of the door. Stop at the bottom edge. Now insert the saw in the panel edge that runs along the bottom of the door, and again, assuming there is daylight through the door panel lower line, put the blade in, saw side facing forward and slowly saw your way to the front. Stop when you get to the intersection of the front lower edge and the front forward edge. That corner is now free from the body of the car. Just repeat the process all around and inside of an hour the doors will be free. Now don’t worry too much if your hand slips and you get a cut line in either the door panel or the body panel. Later, once the door is removed, lightly sand the area and apply a bit of putty. Once dry, sand it smooth and no one will be the wiser.
Once the doors are removed you will see that the edges are rough….not to worry, just sand both the door edges and the body edges smooth and straight. In most cases the gap will be fine as you will need a slightly bigger gap between the doors and body when it is unpainted. Remember, the primer and paint and clear top coat add to the edge of the door and the body, so you need to allow for that extra build up of paint. Plus, you will need to have a bit of a gap to allow the door and hinge to work properly later on. From experience I have found that you will need about a 16th of an inch all around the door and the body. Now if for some reason, you have really screwed up the panel and the gap is greater, that is very easy to fix. Cut a small piece of styrene using the appropriate thickness of styrene and glue it to the offending panel or door edge….I like Tena-X7r liquid glue for this because it melts the styrene and literally welds it to the panel. Once dry, sand it smooth to the body contours and the door gap will be restored. I have found situations where I had to do this a few times to get the gap right, I mean, glue multiple layers into the door jam and sand smooth and no one will ever know.
Ok, the doors are off the car, the edges are smooth and the gaps are uniform and acceptable. Next comes a little part of the process that is easy, very important, but most often overlooked when doors are opened. Look at the last picture and then at this picture.
The styrene is always too thick (and resin is usually worse) to be accurate to scale. Usually, that is not an issue because you don’t see the edges, but when the doors get opened, the door edges are very visible. This is easy to fix……notice the door edge on the left side of this picture that is the edge that is on the outer side and visible when the door is open. Notice that I have used my Dremel tool with a sanding drum to grind away the excess styrene and to thin out the door edge. You must be careful not to over do it and grind through the door so take your time and only grind away small layers at a time. You will find, once you finish this and give it a light sanding to smooth it out, that the thickness of the door panel edge looks far more to scale. You will be surprised at how much that little bit adds to the realism of your model.
The next step is to get the inner door jams set. This is the flange that will stick out in the door opening and stop the door from closing “into” the car. In other words, this keeps the door flush with the body panels when the door is shut. I make these from small strips of .015 styrene. I cut them bigger then necessary and glue them in with Tena-X7r. I run a strip along the bottom and then up the side of the inner body panel where the door closes to the body, or the latch side, if you will.
In this picture you can see the driver side jams in place…..like I said they will be trimmed to the proper size later.
On the right side of the door you see my universal hinge. I call it a universal hinge because it works equally well on old style cars as it does on newer cars. I will explain.
Now again, just like how to cut out a door, there are many ways to hinge a door. Over the years, I have used many styles, but always return to this style because it is easy to make, flexible to use and works perfectly in just about every instance.
Older cars, say up through the 1960’s had doors that opened “out”. That means that the doors hinged out when opened which means that front edge of the door is outside of the panel just forward of the door. On late model cars, the doors open inward, which means the leading edge of the door, opens into the car. I have seen and heard many complaints over the years here that someone has the wrong style door hinge and the door is not operating the way the real vehicle door operates. This style hinge works both ways so it is easy to get it “right”. Now, you can see that the hinge is made of brass rod and aluminum tubes. I use K & S Engineering pieces for this. The brass rod is stock #1602, .32 rod and the aluminum is stock #1008 1/16 X .014 tubing. The rod costs around $1.49 for 5 pieces and the tube is around $1.69 for 3 tubes, so you see it is not expensive at all. I will show you how to mount this hinge later so you can have either style door opening. Back to the hinge construction……
The first step is to measure the maximum distance you can make the hinge. More often than not that distance is roughly ½ of an inch….in this case that space where the hinge will fit is slightly less than that so I made them accordingly.
Let’s assume here that we have ½ inch to fit into. Step one, cut two (for two doors) length of tube to this size. I always make the cut a little bit less than the size needed to compensate for the outside brass half loop on either side of the aluminum tubing. I simply roll the knife blade over the tube applying gentle pressure cutting the section free. 
There is a reason for doing it this way and not just using a cutter. A cutter will crimp and distort the end and we need both ends of the tube to be round and have a completely clear opening. Once one is finished, use it as a size guide to do the second tube, that way both hinges will be a uniform size. Now you may find that the end you cut has some excess material in the opening….not a problem just use the knife point, inserted into the opening, in a twisting motion and the material will be cut free. Now for the fun part, you need to form the hinge from the brass rod. Basically the hinge has two curved humps connected through the aluminum tube with two “wings” or attachment rods that slide into two more aluminum tubes. The first step is to determine how long you need to make the attachment rods. On my Mercury I have limited space because of the front wheel well opening. So you need to measure this space, but again, in the typical installation, ½ inch rod is fine….so for demonstration purpose, I will go with that length here. Take small pliers and grip the rod about ½ inch from the end and with your hand bend it to about an 80 degree bend. 
Then slide the pliers up away from the bend a few millimeters and begin to make a series of small bends as you see in the picture. 
Work your way around the bend until you have about a 170 degree bend. 
This does not have to be perfect, but you want it as smooth and uniform as possible. Once that is done, grip the “hump” as shown here so that the pliers are parallel to the rod wing…..in other words, form a straight line with the edge of the pliers and the rod extension. http://farm8.staticflickr.com/7028/6661360351_0fb98b15b7.jpg Now with your hand, give the rod a 90 degree bend as shown here. http://farm8.staticflickr.com/7001/6661363629_c7a48d8696.jpgOnce the bend is complete, and looks like this, http://farm8.staticflickr.com/7175/6661366841_2e11c2bb95.jpg Now take one of the aluminum tubes that we cut before and slide it down the long end of the rod. http://farm8.staticflickr.com/7154/6661370889_8395f08c75.jpg When it is in place, it should look like this. It should be snug to the bend in the rod. Next grip the rod with the pliers just about one millimeter down from the opposite end of the aluminum tube. http://farm8.staticflickr.com/7173/6661375487_96a3c09204.jpgWe want to make the other bend, to mimic the first 170 degree bend and we want just enough place, or space, between the second bend and the tube so that the hinge will move freely inside of the aluminum tube but not so loose that it can move. So make a 90 degree bend to this side, again, mimicking the angle of the first side.
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when you strip away the excess unnecessary frills and shinny things and stuff, the underlying metal is just perfect in the raw, so to speak, soft, round and sensual. Anyway, here the main chop is made to the windshield frame showing the lowered height. 
