Door skin flanges

[Lizer]

What method are you using to get a really sharp edge on a door skin like the factory had?

I’ve read mixed reviews on the zipper tools.

I have a door skin hammer but I have to be careful because the dolly will put low spots on the front side of the door skin. I’ve done several skins and have never liked my technique or results. I can never get a crisp edge on it, it looks “bloated.”

 

[Chris_Hamilton]

All the old guys had were a hammer and dolly. You can get excellent results with just the hammer and dolly. It just require proper technique and practice. If you are getting dents (starting out everyone does) when using the dolly and hammer it's because you are letting it (dolly) bounce off the front part of the skin when the hammer strikes the fold area.. You need to keep it solid against the skin or position the dolly on the edge, kind of off the skin itself when turning the flange. Generally I will stay off the skin (holding the dolly tight on edge, cocked off the skin) till the final round of hammer blows around the skin. Usually it will take a minimum of 5-6 rounds of blows (each round being one pass around the skin). Creep up on it, use the dolly on edge, when almost finished hold the dolly flat then make your final pass with the hammer.

Reprofile your door skin hammer if needed. Most of the ones sold today have too much curve in them. A flatter one works better. Just slightly more curve/contour than the door/skin you are working on. Porter-Ferguson made a good door skin hammer. I got one from my mentor 30+ years ago and have been using it ever since. If you are using the Martin one, flatten it a bit on the long side and it will work better.

Try making some 90 degree pieces of scrap and then folding them over another flat piece. Practice is the key really. Once you get the feel of it you can do it without denting the skin and getting it nice and tight on the fold line. I don't know if what I said will help. Not a quick fix really but maybe some things to ponder.

 

[Chris_Hamilton]

A useful crutch is a hand held leather shot bag filled with birdshot. You can use that for your final passes and not transfer anything to the front of the skin.

 

[Lizer]

A useful crutch is a hand held leather shot bag filled with birdshot. You can use that for your final passes and not transfer anything to the front of the skin.

This is what I’ve been doing in place of a dolly. Though I like the trick of using the dolly on the edge of the skin.

 

[Big Dave]

If you have the door off the car, try laying it on a smooth table, move the door so the table becomes your dolly. Work around and continue to move the door as you go.
Obviously not ever door will be the right shape for this method.

 

[Glen440]

I'm a licensed collision repairer. I learned a trick from an older body man 25 years ago. He used a solid piece of wood. I would tape a 2x4 to a dolly and use the wood side. The dolly was for added weight. Would sometime tape 2 dollies together.

It's the dolly bouncing that makes the damage. I only use my doorskin hammer where I cannot use a normal body hammer. Usually the bottom and some curves.
You need to take your time bending. On newer cars the skins get panel bonded so it's a bit of a hurry to hammer and put on the car and hold its shape for the glue to dry. Some shells are weak

 

[D.A.T.]

Factory did not have any sharp folded edges--pictures show a typical F-150 door skin bent with the grain and against it. There is a nice radius to roll over and cinch tight against to the jam structure. Radius of 2 times thickness is often used. Mine looks and feels more like 3. Hammering a fold with the grain direction to a flattened edges is asking for cleaving and making a mess of it. One alternative is balancing stresses and work from a fixed point to free points and consider symmetry and the fact the sheet crystals form more easily across the grains than with the sheet's rolling direction.

 

[Chris_Hamilton]

You need to take your time bending. On newer cars the skins get panel bonded so it's a bit of a hurry to hammer and put on the car and hold its shape for the glue to dry. Some shells are weak

Yup. I don't miss the race to get the skin on when using panel bond on a 95 degree day in the summer. The 2x4 trick is a good one. I remember several older guys using them. Guy I learned much of this from showed me how to do it with the dolly on edge so that's how I've always done it. Good discussion.

Factory did not have any sharp folded edges--pictures show a typical F-150 door skin folded with the grain and against it. There is a nice radius to roll over and cinch tight against to the jam structure. Radius of 2 times thickness is often used. Mine looks and feels more like 3. Hammering a fold with the grain direction to a flattened edges is asking for cleaving and making a mess of it. One alternative is balancing stresses and work from a fixed point to free points and consider symmetry and the fact the sheet crystals form more easily across the grains than with the sheet's rolling direction.

The trick is to hammer on the inside edge of the fold not the outside edge. If you do that the radius takes care of itself.

 

[D.A.T.]

Yup. I don't miss the race to get the skin on when using panel bond on a 95 degree day in the summer. The 2x4 trick is a good one. I remember several older guys using them. Guy I learned much of this from showed me how to do it with the dolly on edge so that's how I've always done it. Good discussion.

The trick is to hammer on the inside edge of the fold not the outside edge. If you do that the radius takes care of itself.

That assumes a radius of some sort is still there and was not removed or altered in the door skin removal--if the OP is asking about getting "a really sharp edge" that implies not having something existing to tuck back around against with hammering on the inside to draw with and something stout enough to shrinkage against with spot welds attaching the skin to the jam to draw taut.

 

[Chris_Hamilton]

That assumes a radius of some sort is still there and was not removed or altered in the door skin removal--if the OP is asking about getting "a really sharp edge" that implies not having something existing to tuck back around against with hammering on the inside to draw with and something stout enough to shrinkage against with spot welds attaching the skin to the jam to draw taut.

Well he said sharp edge like the factory did. So I assumed he wants a factory like edge/radius. Staying off the lower 1/4-1/3 of the edge will give you that radius. You need to get close to the edge but not too close. If you don't get close enough you get the bulbous look Lizer was complaining about.

Sometimes though you have to lightly finish on the edge but that is dependent on the vehicle and manufacturer. Porsche used narrow flanges so they often need hammering right up to the edge. Domestic stuff all used relatively wide flanges so staying off that last bit was important. Modern stuff is different. Most modern skins have fairly narrow flanges. But the principle is still the same stay off the bottom 1/4- 1/3 until you've turned it 90% even if you eventually have to finish/ flatten it some. Plus hitting the edge too hard will stretch it and worsen the bulbous look. Lots of light hits are what's required. Flattening too much in addition to looking strange will close up the gap between panels. In the older days with cars with fairly wide gaps that wasn't a big issue, on modern stuff it can be an issue.

Just what I've observed over the years. Getting good at putting skins on and making time on them takes doing quite a few of them. Most of us didn't like doing skins because it was hard to make time on them. Panel bonded modern ones are worse with the extra labor involved.

 

[MJM]

Couple of good tech tips in this video.........

 

[Lizer]

Chris is right, I want it to look factory. This is on a 70 F250 by the way.

 

[D.A.T.]

Chris is right, I want it to look factory. This is on a 70 F250 by the way.

If you are going to do your pinch welds with a decent kVA rated resistance spot welder--then warping the bottom flange after the skin is folded over is not likely a problem with a sharp folded edge. If you plan to do TIG or MIG spot welds to replicate--it is real easy to bow the folded flange welding the bottom if the sides are folded over tight as well and you start randomly welding without a "fixed to free" sequence. The door skin cover on the door structure acts as a torsion box and can easily bend outward at the bottom from one sided arc welding. Once together and stout--the deeper resistance of the door side jams make working the bottom bow out difficult. You can also twist the door from these one-sided arc spot welds that add filler metal and you may not see it until the weatherstripping has uneven contact with where it is supposed to mate in the opening and you run out of adjustment. The presenter in the video was proud of "with no body work" but did no one-sided MIG or TIG spot welding either.

 

[Chris_Hamilton]

If you are going to do your pinch welds with a decent kVA rated resistance spot welder--then warping the bottom flange after the skin is folded over is not likely a problem with a sharp folded edge. If you plan to do TIG or MIG spot welds to replicate--it is real easy to bow the folded flange welding the bottom if the sides are folded over tight as well and you start randomly welding without a "fixed to free" sequence. The door skin cover on the door structure acts as a torsion box and can easily bend outward at the bottom from one sided arc welding. Once together and stout--the deeper resistance of the door side jams make working the bottom bow out difficult. You can also twist the door from these one-sided arc spot welds that add filler metal and you may not see it until the weatherstripping has uneven contact with where it is supposed to mate in the opening and you run out of adjustment. The presenter in the video was proud of "with no body work" but did no one-sided MIG or TIG spot welding either.

Well all I can say is what I have written in this thread is how I have done them over the last 30 years with satisfactory results. Most of the time (almost never) those skins with spot welds never get put back on the replacement skin/door at any Shop. No real need in most cases. I've never seen any ill effects from not putting a spot weld back on a door skin. The only place it may be necessary would be at the top on certain doors where the skin was attached by 2 sided spot welds. Honestly that was the only time I would weld and most of the places I worked at over the years never used the one sided spot welder like a Lenco. If the Shop had it, it was usually in the corner collecting dust. I've worked at some really good Shops and I can't ever recall anyone doing one sided spot welds ever on a skin. IIRC from my I-CAR training even I-CAR said it wasn't necessary. I've never seen a skin move around after hemming it in.

If something (older stuff) I'm doing did need a weld nowadays, I would much prefer using panel bond in that location. If one were doing a really concours type resto then making the effort to replicate the one sided spot welds would be wise. IMO though spot welds on a skin were really overkill by the OEM's.

 

[Chris_Hamilton]

Hardest thing for me to replicate on a skin was the factory seam sealer. I've never been able to make a seam sealed skin look exactly like what the OEM did. Even with the new 2 part seam sealers. Very hard to do, at least for me.

@Lizer Another thought. If you are getting the bulbous look, like Glen said above try using a regular body hammer (slightly crowned face) to finish the fold. You need a hammer that matches the curve of the inner part of the skin/door. Too flat will leave coining marks. Work it over with the doorskin hammer to about 90%,, then lightly finish along the whole of the flange with the regular hammer. Some places you may not be able to use a regular body hammer. Stay off that last bit closest to the edge. Probably less than a 1/4 of the width. Doing that will flatten out the bulbousness and get it matching the other door(s). If you need it sharper then work to the edge carefully.. Do only as much as necessary to get it to match the other door. Hope that's understandable, something like this is hard to put into words exactly, at least for me.

 

[Chris_Hamilton]

This is the Porter Ferguson hammer I mentioned earlier. I've been very careful to take care of it over the last 3 decades. I think of my friend Clyde everytime I use it.