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Old 10-07-2019, 09:13 PM   #1
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Hat and C Channel

On a roof raise what thickness metal should be used for the "C" channel insert?
My hat channels are 16g. How much over lap should the "C" channel have?
CB, did I see you say "C" in 18g?
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Old 10-07-2019, 10:06 PM   #2
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On a roof raise what thickness metal should be used for the "C" channel insert?
My hat channels are 16g. How much over lap should the "C" channel have?
CB, did I see you say "C" in 18g?
14ga.
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Old 10-07-2019, 10:14 PM   #3
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Seems thin compared to a Crown but then again everything else seems thin.
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Old 10-07-2019, 10:23 PM   #4
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Seems thin compared to a Crown but then again everything else seems thin.
I don't see the point of building the ribbing out of steel thicker than 14 ga.
What's your crown made of?
Maybe that's why they need class 8 running gear?
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Old 10-07-2019, 10:27 PM   #5
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I don't see the point of building the ribbing out of steel thicker than 14 ga.
What's your crown made of?
Maybe that's why they need class 8 running gear?
Don't the coaches have fewer ribs? So they make up for it in thickness of the rib. Just guessing.
How much overlap is needed and does it change on the height of the raise, I wouldn't think so?
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Old 10-08-2019, 04:31 AM   #6
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It would seem to me that you need enough overlap to secure the ribs to the extension pieces. You *could* butt-end weld the pieces, with the strength of the weld being the weak point. Not suggesting this at all. It also depends on the fastening method used. Bolting the pieces together may require more overlap to get enough strength to bond the pieces in comparison to welding. You would have to make the engineering calculations if you want to be sure.
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Old 10-08-2019, 06:51 AM   #7
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I'd use square tubing, instead of channel. Overlap doesn't need to be much longer than the width of what you're welding. You want a little more than 100% of the sheer value of the stock material. If the outside surface of the hat channel (across the flange, around the back of the "C" part, and across the other flange) is 4 inches, a couple of 2" flare bevel welds along the open side, and one across the back of the C on the other side will be plenty. Or go with a little more overlap, and eliminate the weld across the back.
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Old 10-08-2019, 07:55 AM   #8
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Some of us need pictures. lol
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Old 10-08-2019, 08:16 AM   #9
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I'd use square tubing, instead of channel. Overlap doesn't need to be much longer than the width of what you're welding. You want a little more than 100% of the sheer value of the stock material. If the outside surface of the hat channel (across the flange, around the back of the "C" part, and across the other flange) is 4 inches, a couple of 2" flare bevel welds along the open side, and one across the back of the C on the other side will be plenty. Or go with a little more overlap, and eliminate the weld across the back.
There isn't square tubing to fit a good many buses.
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Old 10-08-2019, 10:19 AM   #10
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I did my raise by removing the rivets that secured the hat channels to the chair rail. I secured the new hat channel material to the chair rail where the original stuff had been, and I sized the overlap between the extension and the original to be the same height as the chair rail itself - something like 10 inches?. Lacking training in mechanical engineering, it made sense that if those original hat channels were secured to chair rail with so many inches of overlap then I could secure them to hat channel extensions with the same amount of overlap and same quantity and placement of rivets.
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Old 10-08-2019, 10:30 AM   #11
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Don't the coaches have fewer ribs? So they make up for it in thickness of the rib. Just guessing.
How much overlap is needed and does it change on the height of the raise, I wouldn't think so?
I can't speak to MCI or Prevost but me Eagle was built very different from our school buses.

There are no frame rails or hat channel.

With the skin off it looked kind of like a spider web of square tube.

We used similarly sized square tube to raise the roof.

On my Bluebird we used C channel formed from 1/8" material and overlapped 10" top and bottom. A little overkill but I have some peace of mind with the structure.
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Old 10-08-2019, 10:43 AM   #12
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I can't speak to MCI or Prevost but me Eagle was built very different from our school buses.

There are no frame rails or hat channel.

With the skin off it looked kind of like a spider web of square tube.

We used similarly sized square tube to raise the roof.

On my Bluebird we used C channel formed from 1/8" material and overlapped 10" top and bottom. A little overkill but I have some peace of mind with the structure.
Man, Steve- we ended up doing virtually the same roof raise!
I also had 10" overlap each side.
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Old 10-08-2019, 11:03 AM   #13
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Man, Steve- we ended up doing virtually the same roof raise!
I also had 10" overlap each side.
Great minds think alike
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Old 10-11-2019, 12:03 AM   #14
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I don't see the point of building the ribbing out of steel thicker than 14 ga.
What's your crown made of?
Maybe that's why they need class 8 running gear?
Seems a tad thicker than 1/8 (10 or 11 ga.).
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