Reply
 
Thread Tools Display Modes
 
Old 08-18-2020, 01:52 PM   #1
New Member
 
Join Date: Mar 2019
Posts: 6
Weld or rivets?

I'm about to start my conversation and will raise my roof. I'm a welder by trade and I am wondering why not weld the skins on instead of using 2000 rivets? Thanks for any information or opinions.
Denis is offline   Reply With Quote
Old 08-18-2020, 02:21 PM   #2
Bus Geek
 
o1marc's Avatar
 
Join Date: Dec 2017
Location: Dawsonville, Ga.
Posts: 9,364
Year: 1999
Coachwork: Genesis
Chassis: International
Engine: DT466/3060
Rated Cap: 77
That is certainly an option for a cleaner finish.
__________________
I Thank God That He Gifted Me with Common Sense
o1marc is offline   Reply With Quote
Old 08-18-2020, 06:26 PM   #3
Mini-Skoolie
 
Join Date: Mar 2020
Location: Tacoma, WA
Posts: 55
Year: 2004
Coachwork: International
Chassis: RE300
Engine: DT466E
Rated Cap: 76
Quote:
Originally Posted by Denis View Post
I'm a welder by trade and I am wondering why not weld the skins on instead of using 2000 rivets?
I think rivets are used in bus construction because it is more cost effective to train someone to rivet rather than weld. I'd imagine in your case, since the labor is "free" welding would be the better way to go.

I would have considered welding some of my stuff, however I'm not comfortable enough with it so used rivet nuts and rivets instead.

Someone please correct me if I'm wrong, but wouldn't welding be technically a stronger joint anyway?
jjaj823 is offline   Reply With Quote
Old 08-18-2020, 06:56 PM   #4
Bus Geek
 
Join Date: Sep 2015
Posts: 3,528
Year: 2002
Coachwork: Thomas Built Bus
Chassis: Freightliner FS65
Engine: Caterpillar 3126E Diesel
Rated Cap: 71 Passenger- 30,000 lbs.
If welding-only is done, how would you keep the sheet metal from moving in relation to the hat channels while driving down the road?


I am curious how a welder would tackle this. I like to weld, but short of drilling holes through which to weld to the hat channel (in effect like a rivet would be doing) or with arc welding, simply make a bunch of through-welds to tack in the sheet metal how would you do it?
Native is offline   Reply With Quote
Old 08-18-2020, 07:02 PM   #5
Bus Geek
 
o1marc's Avatar
 
Join Date: Dec 2017
Location: Dawsonville, Ga.
Posts: 9,364
Year: 1999
Coachwork: Genesis
Chassis: International
Engine: DT466/3060
Rated Cap: 77
Quote:
Originally Posted by Native View Post
If welding-only is done, how would you keep the sheet metal from moving in relation to the hat channels while driving down the road?


I am curious how a welder would tackle this. I like to weld, but short of drilling holes through which to weld to the hat channel (in effect like a rivet would be doing) or with arc welding, simply make a bunch of through-welds to tack in the sheet metal how would you do it?
I would rosebud weld the skin to the old rivet holes in the hat channel, it would be much more solid than rivets alone. Some of my skins are welded inside to the edge of the hat channel.
__________________
I Thank God That He Gifted Me with Common Sense
o1marc is offline   Reply With Quote
Old 08-18-2020, 08:54 PM   #6
Bus Geek
 
Join Date: Sep 2015
Posts: 3,528
Year: 2002
Coachwork: Thomas Built Bus
Chassis: Freightliner FS65
Engine: Caterpillar 3126E Diesel
Rated Cap: 71 Passenger- 30,000 lbs.
Quote:
Originally Posted by o1marc View Post
I would rosebud weld the skin to the old rivet holes in the hat channel, it would be much more solid than rivets alone. Some of my skins are welded inside to the edge of the hat channel.
I have heard of a rosebud tip, but never used one. Is a rosebud weld a weld done with a rosebud tip?
Native is offline   Reply With Quote
Old 09-30-2020, 06:52 PM   #7
Mini-Skoolie
 
Join Date: Jun 2020
Location: Ohio
Posts: 39
Year: 2003
Coachwork: Bluebird
Chassis: All American
Engine: Cummins 8.3
My brother is an aeronautical engineer and when i told him my plans for the roof raise he wanted to know why i was even welding the hat channel. In airplanes they rivet EVERYTHING. He says their main issue is stress fractures in the weld which at any altitude isn't ideal but a much bigger problem at 20,000 feet in a pressurized cabin. The follow-up he had was "with enough rivets you can squeeze any metal tight enough it's impossible for water to get through". So his two reasons are stress cracks and waterproofing, the second of which is one I'm willing to take a little more seriously than the first as an issue in my bus.
aswallie is offline   Reply With Quote
Old 09-30-2020, 08:21 PM   #8
Skoolie
 
Join Date: Aug 2020
Location: Mesa, AZ
Posts: 191
Year: 2003
Coachwork: Blue Bird All American
Engine: 8.3 Cummins
Rated Cap: 2 adults and two pigeons
Thats very true about welding, but if you do not put down a continuous bead along the hat channel and square tube (Added inner support) you can prevent hardening the steel where it will crack. On a bus, once it's all paneled together, there really isn't much movement or shouldn't be any for our intended uses.
__________________
--Simon


Found my Bus at AAAbus in Phx!
Bus'n it is offline   Reply With Quote
Old 09-30-2020, 08:49 PM   #9
Bus Geek
 
musigenesis's Avatar
 
Join Date: Jan 2019
Location: Philadelphia
Posts: 4,054
Year: 2003
Coachwork: International
Chassis: CE 300
Engine: DT466e
Rated Cap: 65C-43A
Quote:
Originally Posted by aswallie View Post
My brother is an aeronautical engineer and when i told him my plans for the roof raise he wanted to know why i was even welding the hat channel. In airplanes they rivet EVERYTHING. He says their main issue is stress fractures in the weld which at any altitude isn't ideal but a much bigger problem at 20,000 feet in a pressurized cabin. The follow-up he had was "with enough rivets you can squeeze any metal tight enough it's impossible for water to get through". So his two reasons are stress cracks and waterproofing, the second of which is one I'm willing to take a little more seriously than the first as an issue in my bus.
Pressurization/depressurization cycles aren't really a big thing in school buses. A better thing to look at than how high-altitude airplanes are constructed is how ground vehicles are typically modified: when a load-bearing beam needs to be extended, an extension is welded and/or bolted on. This is exactly what is done in a typical skoolie roof raise, which also naturally involves the extension of load-bearing beams. I don't know that I've ever seen anyone rivet the rib extensions in place - it would certainly involve a lot more work than welding.

As far as riveting, that is typically the method used to attach new sheet metal to the newly-extended ribs. I have seen people claim that something like this can be made intrinsically watertight just from the riveting, but I've never been able to achieve that myself using my Harbor Freight riveter. All the stuff I've riveted on my bus has been with seam sealer, including around the holes that the rivets go into.
__________________
Rusty 87 build thread
musigenesis is offline   Reply With Quote
Old 09-30-2020, 08:56 PM   #10
Mini-Skoolie
 
Join Date: Jun 2020
Location: Ohio
Posts: 39
Year: 2003
Coachwork: Bluebird
Chassis: All American
Engine: Cummins 8.3
Quote:
Originally Posted by musigenesis View Post
Pressurization/depressurization cycles aren't really a big thing in school buses. A better thing to look at than how high-altitude airplanes are constructed is how ground vehicles are typically modified: when a load-bearing beam needs to be extended, an extension is welded and/or bolted on. This is exactly what is done in a typical skoolie roof raise, which also naturally involves the extension of load-bearing beams. I don't know that I've ever seen anyone rivet the rib extensions in place - it would certainly involve a lot more work than welding.



As far as riveting, that is typically the method used to attach new sheet metal to the newly-extended ribs. I have seen people claim that something like this can be made intrinsically watertight just from the riveting, but I've never been able to achieve that myself using my Harbor Freight riveter. All the stuff I've riveted on my bus has been with seam sealer, including around the holes that the rivets go into.
I explained the general relaxed nature of our build compared to the construction of something like a 747. He told me to get the mil depts of all my materials and he'd get me the max load level per rivet or something lol.

I've not seen a roof raise done with rivets but I've seen them done with bolts and lock nuts. Personally I'll chance the vibrations on a weld over a lock nut, but that's just me.

For the record, i plan on welding my roof raise, despite my brother's suggestions. I do believe him on the waterproofing but i think your almost need the rivets touching for them to be THAT affective at waterproofing. I've tapped into my bus air lines and I've got 110psibi planned on running a rivet gun with, hopefully that smoothes the process out a bit.
aswallie is offline   Reply With Quote
Old 10-01-2020, 06:24 AM   #11
Mini-Skoolie
 
Join Date: Sep 2020
Location: Central PA
Posts: 24
Year: 2002
Chassis: AmTran RE
Engine: T444E
Quote:
Originally Posted by aswallie View Post
My brother is an aeronautical engineer and when i told him my plans for the roof raise he wanted to know why i was even welding the hat channel. In airplanes they rivet EVERYTHING. He says their main issue is stress fractures in the weld which at any altitude isn't ideal but a much bigger problem at 20,000 feet in a pressurized cabin. The follow-up he had was "with enough rivets you can squeeze any metal tight enough it's impossible for water to get through". So his two reasons are stress cracks and waterproofing, the second of which is one I'm willing to take a little more seriously than the first as an issue in my bus.
Keep in mind that many airplanes are made of mainly aluminum. Different animal than mild steel in a bus. Aluminum, when not pre-heated or welded incorrectly, can crack along the "toes" of the weld where the filler meets the parent material. TIG welding as opposed to spool gun with MIG helps decrease the chance of this happening but it takes considerably more time. Additionally, removing a damaged aircraft panel thats been riveted on is much easier than cutting/grinding away welds.
RamRod4 is offline   Reply With Quote
Old 10-01-2020, 12:08 PM   #12
Mini-Skoolie
 
Join Date: Jun 2019
Location: Troy, Montana
Posts: 28
Year: 1988
Coachwork: Bluebird
Chassis: international s1800
Engine: dt466
Rated Cap: 10 windows
welding lap joints in sheet metal between structural members might result in problematic warpage.
obrien creek farm is offline   Reply With Quote
Old 10-01-2020, 01:30 PM   #13
New Member
 
Join Date: Mar 2019
Posts: 6
Well I'm 95% done the welding the sheets on. Just the corners to deal with. I used 4 full brand new 4x 8 sheets on one side. That was nice to work with. The other side I reused the interior roof panels. ******* disaster to work with. They are slightly bent in places making it impossible to weld in place nice and straight. Had to make a relief cut in one to get rid of a "wave". But I am resusing material from the bus and saving around 500$. As for rivets versus welding topic. I feel rivets allow for some movement as welds are ridged. I feel like I will hear some tack welds pop while I am on the road. But the real welds should be solid. I feel like i would use new sheets all round if I did it again.
Denis is offline   Reply With Quote
Reply

Tags
rivets, roof raise, welding

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 07:25 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
×