Roof skin advice/help needed

[Chris_Hamilton]

I posted something about this in the thread I started about wheeling alone. I trying to make a complete roof skin for a Datsun/Nissan 240Z. Partial patch isn't an option trying to do a complete skin. I have been trying to work through it and figure out issues that arise (best way for me to learn) and not ask for help but I do need some. Being that I can't wheel this alone and at the moment don't have the funds for Peter's hammer attachment I have been racking my brain as to how to do this. I remembered David Gardiner in his DVD demonstrated a way to make a low crown panel using a hammer and a steel table. Well I have a hammer and a steel table so I thought even though this is much larger I would give it a go. I've attached some pics at the bottom to help illustrate.
To summarize, I made a lot of profiles (42 I think) and still need to make a some more but I wanted to get started as I was sick of sanding MDF. So made my paper pattern off of my good car (I have two of them) and transferred it to my blank, 20 gauge, closest thing I can get in the US that is close to what was used on the car. I think 1mm was originally used but taking some measurements with my calipers of Z roof skin, I was getting readings of .030-.033 so perhaps they used 0.8mm originally. Marked out my pattern on the blank and proceeded to start hammering on the table. This went surprisingly well and all things considered did not take to awfully long (few hours) to start getting some shape into the panel. Stopped every so often to set it on my good roof and judge the shape. Got the panel to sit flat in the center (front to rear). Looking at the panel it was clearly telling (as with the paper pattern) that I had too much material at the center edges (side to side) of the panel. I proceeded to hammer some more trying to continue to raise the panel and was able to get it to sit down better and make more contact in the center-out to each side. (hope that makes sense)

So the panel was still showing too much material in the center edges so I figured it was time to shrink as being only 20 gauge I don't know how much stretching would be too much. This is where I started having trouble. The panel drops a lot as it reaches the edges (side to side) so I needed to do some long shrinks. Actually had some success doing long shrinks (one was over 12 inches long) but I probably stretched the area some making the long tucks. As such I started to lose control of the panel a little. That is where I am now. The shrinks were pretty good especially considering they were all 8-12 inches long but the panel isn't doing what I thought it would. It actually started going high in front (to the center) of the longest shrink. And because I'm stretching the panel too much while trying to make these tucks I don't think I'm seeing the full effect of the shrinking.

Is my thinking correct? The paper pattern showed that I would have to shrink at the sides and to a lesser extent at the front. So my thinking was to stretch the middle first get some shape into it and then start shrinking where my paper pattern told me too. Then planish and check the shape with my profiles and adjust according. Once everything looks good turn the edges (block them in?) Am I on the right track? Is it possible to make the skin this way? I've got to believe it is. Any advice on the correct way to proceed would be appreciated. Or how one would proceed using the stretching method that I have to use (table and hammer)?

[Chris_Hamilton]

More pics.

[Chris_Hamilton]

Last of them.

[neilb]

i don't see why you would have to put shrinks in 8-12 inches long.... if you wheel the centre of the panel in both directions but only short runs, you will raise the centre, then making progressively longer runs you will always have the centre higher than the surrounding area as it's got wheeled that little bit more at the beginning, don't forget to keep away from the edges. i'm sure peter will have a more descriptive way of explaining. we did this way making the door skins for my 356 and on a video peter did for a panel for the ferrari


thank you for posting your project chris, it's been a while since i saw a old z lol

[Chris_Hamilton]

Just to be clear Neal, unfortunately I don't have anyone to help wheel this. So I'm trying to do it an alternative way hence the hammer and steel table. Wish I did have someone to help with it. In the last pic (part is upside down) I posted you can see the shape it's taken on with the hammer on steel table method that Gardiner described in his video. Perhaps it's not possible, maybe Peter could tell me.

[MP&C]

Is my thinking correct? The paper pattern showed that I would have to shrink at the sides and to a lesser extent at the front.

The paper pattern shows there exists a difference between the two areas. Don't get locked into a this is a shrink or this is a stretch operation. Look at both, which makes more sense? Which do you have better tooling to accomplish, better skills to accomplish? My thoughts.... if a person only had a set of Lancaster style shrinker/stretchers for "tools" other than hand tools, IMO they have far too little throat to accomplish anything significant on a large panel like your roof skin. Tuck shrinking would be required. Or stretching the center of the panel would be required.. Which is more effective? Which does a better job in keeping the panel flat(ish) with less puckering? All things to consider.

Also, I know where there sits a power hammer you can use...

[Peter Tommasini]

Chris .....
.Am I to understand that you are trying to make the complete roof skin in one piece ? Well that is VERY VERY HARD even for two people, and it would be almost impossible for me to ex plane how to do it in one piece via the NET....... the only way that I could do that, is if I was there shaping and wheeling with you. YES I understand that it would be very nice and rewarding to be able to do that roof in one piece ,BUT sometime one can only do what one can do
So......
this is the way I would do it if I was on my own ......

Take a pattern of one of the OUTER KENT RAILS, make sure to be wide enough to miss the INNER KENT RAIL so you can tack and weld it to the center of the roof, and yet to have the weld on the most bulbous shape possible , with that pattern you be able to make L H / and R H SIDES of the outer KENT RAILS .
When you are making them ,......... make them one after another use profiles or sweeps to make sure that they are the same . Then go ahead and pattern the front KENT RAIL ,then the REAR KENT RAIL . Once the rear and front outer are done ..... clamp with appropriate vice clips the 4 Kent rails ....MEANING ...L H / R H + FRONT AND REAR , by that time if all KENT RAILS are clamped in and adjusted , check if all the INNER EDGES... blend together with a sweep..... (they can be 1 or two mm ONLY up or down to each other ....If not take one at the time out and re adjust till they are OK ............SO you will be checking LEFT to RIGHT and BACK to FRONT. ...OK....... by now you will see the the center of the roof is NOT QUITE SO BIG So ...you would possibly need someone to wheel the center with you.... (by memory the center piece should only be about 1 Meter by one Meter given and take ? By using a profile gauge or sweep you should be able to shape the center piece to the right shape. Once that is done put the center piece on top of all KENT RAILS check the flow etc etc ...if you are not happy with the flow ...just keep touch up all panels till it looks OK . By this time the center of the roof should over lap the outer KENT RAILS by about 15 / 20 mm if that is the case ? Pre drill the outer edge of the center roof panel and use self tapping screws to stitch all together (MAKE SURE NOT TO PUSH DOWN TOO HARD OR YOU COULD CHANGE THE NOW BLENDING SHAPE BETWEEN THE OUTER KENT RAILS AND THE CENTER OF THE ROOF, ALWAYS CHECK FOR THE BLEND BETWEEN THE SHAPES...... once that is done scribe the cutting and welding line BUT be sure NOT to cut the corners SQUARE . have some kind of radius on all the corners, once all that is done your welds line should be AWAY from the inner KENT RAILS so it will be possible for you to tack and planish. When the job is all welded together concentrate your planishing only close to the welds ( just to fix any distortion. Once that is done ... you can undo the clamps on the KENT RAILS and POP the whole roof off, by this time it should be all nice and stiff AND ...you can either (with a helper ) with light pressure wheel the welds out OR.... hammer and dolly all surface and metalfinish them . I would use 1 mm sheet steel (if possible but .9 would OK as well .

When all this is done and you are happy with the finish , prepare all surfaces and spot weld the OUTER KENT RAILS to THE INNER all the way around .

LET'S NOW TALK ABOUT TABLE AND HAMMER....

YES that can be done BUT it would take a long time to shape the center of the roof .... So if you are on your own ...AS MENTION , the center of the roof should only be about 1 Meter by one Meter ..SO try to wheeled on your own and get some shape up , then file finish the piece prior to put it all together

This is the only way (short of been there with you ) that I can help you ... it's possible to do it this way as a one man job ,...... as mention before one can do only what one can do

Simply say to your self ...I am going to do this no matter what ...you will be OK....Not to mention the expertise you are going to achieve for future jobs
Peter T.

PS
Doing the rook skin this way would only need little shrinking on the KENT RAILS as most of the work would stretching them to achieve the shape

the fact that you got the center too high is because of the tuck shrinks ( TOO LONG ) ..so shape the KENT RAILS and shrink only when necessary( about half way up before the center of the radius you should be able to do it with the Lancaster machine

[Chris_Hamilton]

Peter, thank you for taking the time to write this and trying to help me. Really means a lot. I will re-read this several times and "attempt" to put your advice into practice.

If I understand right "kent rails" are the inner bracing panels on the roof? Outer kent rail would be the outer part of the roof panel...yes? Never heard that term before which is why I ask. Use the de-skinned car (inner kent rails) to help form it and hold it, correct? Not actually form on the car but using it as a guide and a "buck" of sorts. Correct? And form the front and rear flanged areas separately? Is that what you refer to as the front and rear kent rail? Sorry for the questions, trying to understand as I've never heard that term before.

If i have some additional questions I'll post them here (hopefully you won't mind too much), along with my progress. And yes I am going to do this no matter what. Thank you for that bit of encouragement as well.

Robert thank you for the offer. I wish you were closer. I do plan on getting up there and visiting, but life keeps getting in the way.

[Peter Tommasini]

Peter, thank you for taking the time to write this and trying to help me. Really means a lot. I will re-read this several times and "attempt" to put your advice into practice.

If I understand right "kent rails" are the inner bracing panels on the roof? Outer kent rail would be the outer part of the roof panel...yes? Never heard that term before which is why I ask. Use the de-skinned car (inner kent rails) to help form it and hold it, correct? Not actually form on the car but using it as a guide and a "buck" of sorts. Correct? And form the front and rear flanged areas separately? Is that what you refer to as the front and rear kent rail? Sorry for the questions, trying to understand as I've never heard that term before.

If i have some additional questions I'll post them here (hopefully you won't mind too much), along with my progress. And yes I am going to do this no matter what. Thank you for that bit of encouragement as well.

Robert thank you for the offer. I wish you were closer. I do plan on getting up there and visiting, but life keeps getting in the way.
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I do not know what the Kent rails are called in the US ......? It's a English term for those panels for cars of the 50's / 60's /70 up to early 80's

The side INNER kent rails are situated under the roof lining, they hold the bows for your roof lining, the front INNER kent rail is where the rear vision mirror is screwed on to ,and so are the sun visors ,they are spot welded at the bottom together with the upper door frame opening creating a flange about 15 /16 mm wide and that is where the door rubber seal and the door lacing are fitted
They INNER kent rails are welded in a bit of a angle creating a box section between the upper door frame panel and outer roof skin and the kent rails them self, usually there is a gap about 4/5/6 mm only between the roof skin and the top of kent rails, THAT IS WHY when making a roof panel the weld must be away from there to gain access and planishing the weld out between the OUTER kent rail and the center of the roof

The OUTER kent rails are simply the 2 sides +,back and front of the roof skin it self

if you where to take the roof skin right off you will see that the 4 INNER kent rails are spot welded together create a ''FRAME '' for the skin and hold the top of the car all together , or how you put it........ ( INNER BRACING PANEL ON THE ROOF)
So on most cars .....looking from the out side, the INNER kent rail + the top of the door frame opening + the roof skin are spot welded together at the edges to create the 2 outer GUTTERS
Cheers
Peter T.

[cliffrod]

Really good thread. Please keep us posted on what works and doesn't work for you, Chris. Anything that helps people like us who always work alone is much appreciated.

Thanks for the extra clarification, Peter-I didn't find "Kent rail" in the AU translator...

[skintkarter]

Cant Rails I think - drip rails, turret rails?

[Moving molecules .]

2 People and many hours.... light/ med pressure wheeling..... using No. 17 Sweep left to right/ No. 16 Front to back and a few home made profile Gauges.... blocking on front edge .
Tig butt welded in . Big job.

like Pete says you need to get to the welded line on the inside to Finish.

on this car I pushed the boat out and got it 98.5 /99 % a invisible repair. .... for Instagramer Jason GTI.👍

Its not easy....😳

we can help you.....👍👍

[neilb]

Just to be clear Neal, unfortunately I don't have anyone to help wheel this. So I'm trying to do it an alternative way hence the hammer and steel table. Wish I did have someone to help with it. In the last pic (part is upside down) I posted you can see the shape it's taken on with the hammer on steel table method that Gardiner described in his video. Perhaps it's not possible, maybe Peter could tell me.

yes sorry Chris, i missed that.... doing anything alone is a pain in the derriere especially when it's quite large

just thinking about it now, would it be possible to put a bend in the sheet down the sides (cant rail's) and a slight bend across the front to give the panel some support so you could wheel it? you would have to keep taking these bends out though to lay it on the old roof, or reduce the bends radius. keeping it mind that when taking out some of the edge bends it will add shape to the radius across the panel. i know the largest panel i was able to wheel on my own was just over a metre long by 800mm wide (39 inch x 31inch) this had lots of shape in it at the end but was a pain at the start. i put a slight bend through it to get some rigidity in the panel then eventually moved the return to where it needed to be.

if you have some profile gauges of the roof you could do it on the table but it will take some time, and wrist and elbow ache will probably happen several times lol

[Peter Tommasini]

Really good thread. Please keep us posted on what works and doesn't work for you, Chris. Anything that helps people like us who always work alone is much appreciated.

Thanks for the extra clarification, Peter-I didn't find "Kent rail" in the AU translator...

You are probably right.... I most probably spelled wrong ! After checking ..I did spell it wrong !
Peter T,

[Peter Tommasini]

2 People and many hours.... light/ med pressure wheeling..... using No. 17 Sweep left to right/ No. 16 Front to back and a few home made profile Gauges.... blocking on front edge .
Tig butt welded in . Big job.

like Pete says you need to get to the welded line on the inside to Finish.

on this car I pushed the boat out and got it 98.5 /99 % a invisible repair. .... for Instagramer Jason GTI.👍

Its not easy....😳

we can help you.....👍👍

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Nice to see that someone does the job the right way..... WELL DONE !!!!!

Peter T.

[Chris_Hamilton]

Thanks for all the replies Gents. I will post my progress soon in this thread.