Any tips on metal skin at roof-raise transition?

[cdrobbins77]

I've got a conventional School bus that I did a 14 and 1/2 inch roof raise on. Got all the sheet metal up on the sides. I got to the point where I was ready to attempt the roof transition, I had a sheet of 20 gauge galvanized but the compound curve was just too much for my limited metalworking skills. Even with trying to do multiple pieces around the tightest part of the curve it's still just wasn't working for me. Does anyone have any tips or tricks? I would prefer to stick with metal but I'm not entirely opposed to learning how to fiberglass if that's my best option.

[BlackJohn]

Pics of the section in question, the framing?


John

[EastCoastCB]

Originally Posted by cdrobbins77

I've got a conventional School bus that I did a 14 and 1/2 inch roof raise on. Got all the sheet metal up on the sides. I got to the point where I was ready to attempt the roof transition, I had a sheet of 20 gauge galvanized but the compound curve was just too much for my limited metalworking skills. Even with trying to do multiple pieces around the tightest part of the curve it's still just wasn't working for me. Does anyone have any tips or tricks? I would prefer to stick with metal but I'm not entirely opposed to learning how to fiberglass if that's my best option.

I used the thickest plate steel I could work with. In this case it was 18ga.
Carefully using a large piece of poster board I made a template.
Then I cut the steel very carefully until it looked and fit perfectly.





That's the late, great Eddie Sampson at work^ RIP brother!

[o1marc]

Yep, ratchet straps to pull it into shape.

[cdrobbins77]

Originally Posted by BlackJohn

Pics of the section in question, the framing?


John

Only pics i have of that section. i have since removed all the rivets and the small 3" section of roof skin on the upper portion, all the rivets on the lower roof section, and welded on angle pieces to each transition tube steel

[cdrobbins77]

pics of the bus

[banman]

Originally Posted by cdrobbins77

I've got a conventional School bus that I did a 14 and 1/2 inch roof raise on. Got all the sheet metal up on the sides. I got to the point where I was ready to attempt the roof transition, I had a sheet of 20 gauge galvanized but the compound curve was just too much for my limited metalworking skills. Even with trying to do multiple pieces around the tightest part of the curve it's still just wasn't working for me. Does anyone have any tips or tricks? I would prefer to stick with metal but I'm not entirely opposed to learning how to fiberglass if that's my best option.

search "metal working english wheel"
Probably not the tooling you wanna invest in but maybe available at a makers space?

Make a form from plywood scraps to match the contour of the transition shape you want. 1½" thick or so, cut with a saber saw, put the form in a vice and slowly gently start hammering your metal to conform to the bend of the profile. You want to keep working it till it mostly lies in place how you want it so you're not "fighting it" in place when you fasten it. If it's installed under a lot of tension from just be clamped and forced into place it will always be putting undue stress on the fasteners and probably be more prone to leaking and "oil canning" ...
Take your time and have fun with this process -- feel how the metal is 'plastic' as you move it.

[EastCoastCB]

If you start at the sides, you can make it out of 3 pieces and it should come out looking good if you're careful and take your time. Allow for a bit of overlap where the top comes over the sides.
Bending isn't much of an issue just use some light ratchet straps. Tack it all down with a mig.

[o1marc]

It takes 100's of hours to become proficient on an English wheel to shape into the design you want. Not something I would recommend to a noob to the process.

[shaymcquaid]

Originally Posted by o1marc

It takes 100's of hours to become proficient on an English wheel to shape into the design you want. Not something I would recommend to a noob to the process.

Amen. The English wheel is not for the novice.

[banman]

Originally Posted by shaymcquaid

Amen. The English wheel is not for the novice.

Agreed, but...
One must begin at the beginning... (the Tao of Po)

...and the OP asked how does one form metal?

[wrenchtech]

Equally important as the English wheel is the planishing hammer and other tools for shrinking or stretching sheet metal. None of which I am proficient with, but a guy can dream and plan for the future.

This series from YouTube is an excellent place to start building sheet metal shaping skills with simple hand tools.

https://m.youtube.com/watch?v=7mEKuOR-93U

When you’re ready to graduate to larger stationary tools there are many dealers.
https://www.trick-tools.com/tools/Planishing-Hammer

[wrenchtech]

I’m kind of surprised too, that I have not seen anyone tackling any of these panel making projects with composite construction, i.e. fiberglass and the many substrates, like marine plywood, shaped foam, or even balsa wood, that can be used with polyester and epoxy resin’s.

[PNW_Steve]

Originally Posted by wrenchtech

I’m kind of surprised too, that I have not seen anyone tackling any of these panel making projects with composite construction, i.e. fiberglass and the many substrates, like marine plywood, shaped foam, or even balsa wood, that can be used with polyester and epoxy resin’s.

I have had my fingers in a handful of boatbuilding projects including hulls built from foam sheets, fiberglass and epoxy resin. The foam was shaped to conform with the male mold and then covered with fiberglass using epoxy resin. Finally the hull was removed from the forms and fiberglassed on the inside.

The result was an extremely tough hull.

I can see that working for the roof transition. The only place that I would be concerned with is the mating surfaces where fiberglass meets metal. I don't know if it would present a challenge or not.

[EastCoastCB]

Originally Posted by shaymcquaid

Amen. The English wheel is not for the novice.

Its supposedly a very tough tool to master.

[EastCoastCB]

Originally Posted by wrenchtech

I’m kind of surprised too, that I have not seen anyone tackling any of these panel making projects with composite construction, i.e. fiberglass and the many substrates, like marine plywood, shaped foam, or even balsa wood, that can be used with polyester and epoxy resin’s.

Stu did and regretted it.

[wrenchtech]

Originally Posted by EastCoastCB

Stu did and regretted it.

I’d like to hear more about that.

[wrenchtech]

Originally Posted by PNW_Steve

... I can see that working for the roof transition. The only place that I would be concerned with is the mating surfaces where fiberglass meets metal. I don't know if it would present a challenge or not.

It seems like people have been bonding composite parts to metal car bodies for quite some time with great success. Usually it’s not recommended for structural components but rather for cosmetic stuff like wheel flares. The Singer Porsche 911 resto-mod make extensive use of composites, Replacing roof skins, hoods, deck lids with carbon fiber pieces, some of which must be structural (the roof skin at least).

[kidharris]

Originally Posted by EastCoastCB

I used the thickest plate steel I could work with. In this case it was 18ga.
Carefully using a large piece of poster board I made a template.
Then I cut the steel very carefully until it looked and fit perfectly.

I believe 18 ga. is refered to as sheet, not plate.
Terrible instructions, but the transition looks really good.

[EastCoastCB]

Originally Posted by kidharris

I believe 18 ga. is refered to as sheet, not plate.
Terrible instructions, but the transition looks really good.

How are they such terrible instructions?
Plate, sheet.... semantics. Anyone ordering the steel knows what 18ga hot rolled or cold rolled is.
If OP wants to ask about any "instructions" I'm all ears.