| Author |
Message |
Bob (Bobb) (69.19.1.163)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 19, 2003 - 7:07 pm: | |
Got the skin off and windows out, a bit of rust here and there..
Going to reskin with 16 or 18 ga steel.. Was considering replacing all the structural members with square tubing ( between the stainless lower half, and the curved roof members)
Any suggestions? |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 19, 2003 - 9:09 pm: | |
In my conversion, I discovered some "Creative" re-framing in a wall.
I am using .120 wall box-tube, and 18ga sheetmetal.
16ga would be REAL heavy, I think.
There are a lot of other details, but this post would rapidly digress into war and peace.
Feel free to Email me off-list if you like.
Gary |
Dave Wheat (24.197.182.248)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 19, 2003 - 11:02 pm: | |
Bus Conversions magazine has done articles on reskinning and also articles which included replacing structural members. Lots of pictures and good info for your situation.
Dave |
Bob (Bobb) (69.19.1.163)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 19, 2003 - 11:29 pm: | |
Thanks Dave.. don't have access to that magazine. Have subscribed, but have not recieved a copy yet. Are the articles available online in some sort of archive?
Gary..
Will email you when I get a few things together! I like the idea of square tubing and welding the sheet metal to it.
Bob |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 20, 2003 - 12:22 pm: | |
Bob--
Don't weld the Sheet metal. It will crack like a spiderweb.
You have to rivet the skin to the skeleton.
Gary |
NEO/Russ (66.83.53.142)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 20, 2003 - 12:33 pm: | |
Gary,
My Neoplan, like most of the thousands of their intercity designs built over the years is a skeleton frame of about 1 1/2" square of about .125 wall (all metric, that's why "about").
The skin is a paintable galvanized sheet steel material about 18 gauge. It's spot welded on in about a million places. It doesn't have spiderweb cracks after hundreds of thousands of miles and one final run off road into a boulder in AZ. It's also got up to 1/8" bondo over many areas and that only cracks when I use my zip gun to peel skins to replace. What's the engineering theory that says Bob can't weld his MC, what's different? |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 20, 2003 - 1:06 pm: | |
That's interesting
In my Bird, there were some "Modifications" done to the skin. They welded it down. Everywhere there is a weld, there are cracks.
All of that skin is in the dumpster now though.
I suppose if you have evenly spaced plug welds, that would hold up. My background is structural, I'm still learning this lightweight sheetmetal stuff.
His MC-7 is a rivited construction bus (Isn't it), I was recommending that he stay with the manufacturer's construcion practices.
Gary |
Bob (Bobb) (69.19.1.163)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 21, 2003 - 12:16 am: | |
I would like to hear from others if they have experience with 18ga sheet metal welded to 1.5" tubing..
In peeling off the riveted aluminium skin, I have noticed a few stress cracks. Not the small spider type cracks, but the long ones going from rivet to rivet.
Perhaps a combination of welds in the periphery, and sikaflex bonding in the field would work well..
One other note: the stainless frame at floor level is 1.75". I thought of using 1.5" tubing, and a .25 thermal break (wood or plastic?)on the inside might be a good idea..
Any and all thoughts are appreciated. I especially like the boulder test, but hope I don't have to go that far. |
BrianMCI96A3 (65.40.145.6)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 21, 2003 - 12:31 am: | |
Gary's is right, we had one vehicle that had structural elements added to it (welded) and over the years I swear we welded re-welded and refabricated that machine a dozen times at least.
I firmly believe you could spot-weld an entire vehicle together and have it be structurally sound (how many millions of them are on the road now-a-days?) but mixing welds with rivets is asking for cracks. If the rest of your structure with rivets has some inherent flex to it, welds only toterate so much flexing before they will crack.
Brian |
Ted Elder (24.92.13.13)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 21, 2003 - 1:49 am: | |
Bob, If you're going to replace all those verticals,you might as well raise the roof. I replaced mine with 16ga cold rolled steel over 1.75 square tubing when I raised my roof. I riveted my skin on, since I was covering it with one long peice of fiberglass from R&M. The best looking finish I have seen on a bus was where a guy put a 1 peice steel skin on the whole side of an MC8, Bag doors up. He drilled holes and rosette welded it and then ground of each weld. A lot of work! Ted |
Ron Walker (Prevost82) (209.52.245.237)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 21, 2003 - 11:36 am: | |
Hi Bob, are you in B.C.? If you are I'm in Merrit. It sounds like I'm at the same stage as you are with my bus.... email me
Ron |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 21, 2003 - 9:53 pm: | |
I'm in the major reskinning pahse of my bird. I'm not looking forward to riveting all of the new panels. I wonder abut plugwelding the panels in now that you mention it.
Probably not, I'm going to have to buy some riveting tools and explain to my wife what "Bucking" is.
Gary |
Bob (Bobb) (69.19.1.163)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 21, 2003 - 10:50 pm: | |
You still need the rivet gun to replace some of the old rivets.
Now I'm getting cold feet about the sheet metal. I think bonding is better than riveting, and now maybe better than welding.
I'm so confused.. their must be an expert out there.. anyone care to scan some old copies of magazine articles on skinning a bus? |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 21, 2003 - 11:00 pm: | |
All of my research dictates maintain the original construction methods. So rivets.
When you say "Rivet Gun"---do you mean an air hammer or a "Pop-Rivet" gun?
I have a bunch of stainless "Pop"-style rivets and am thinking about using them. They are real heavy round-head ones. On the other hand, they leave a hole in the middle. the originals are "Bucked" meaning that you need someong to hold a bucking iron on the finish side of the rivet while someone uses an air-hammer on the inside.
I haven't finally decided which way to go.
Gary |
john marbury (Jmarbury) (65.100.118.72)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 22, 2003 - 12:56 am: | |
Gary.
I think you got that backwards, the air hammer is placed on the rivet head ( with a mandrel that is made to fit that particular rivet) the bucking bar is held against the end of the rivet shaft on the inside.
John |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 22, 2003 - 3:40 am: | |
Really?
Intiutively it seems the opposite. Good thing I subscribe to this list.
Still sounds like something my wife will hate.
Gary |
Jim Ashworth (Jimnh) (172.165.88.147)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 22, 2003 - 6:43 am: | |
Rivets should be air hammered on the inside with the bucking tool on the outside. One slip of the air hammer will leave unrepairable damage to the rivet head or skin if used outside. On the inside, the steel rib protects from this kind of mistake. Bucked rivets are cheaper, stronger and take no longer than pop rivets to install. They are watertight and need no finishing to fill the hole.
Jim |
john marbury (Jmarbury) (65.100.118.72)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 22, 2003 - 9:14 am: | |
Maybe I'm mistaken, but an aircraft mechanic helped me do my skins and he used the air hammer on the outside. I was on the inside with the buking bar, Try it the other way and see how it works. If you Use the bucking bar on the rounded rivet head, you will flatten the head. The only rivets that got messed up a little were some that had a different head than the mandrel I was using.
The revit head and the mandrel must match.
John |
Sam Sperbeck (206.230.105.230)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 22, 2003 - 11:30 am: | |
Hi John,
You are right that the air hammer is used on the outside of the bus (head of the rivet). In aircraft there are rivets in many locations where it would be impossible to get to with a rivet gun on the inside, but a specially shaped bucking bar will fit. I think if you use the rivet gun on the inside you will not get the rivets properly tight anyway, and may end up with a gap between the head and the surface of the metal. Logic tells me you want to drive the rivet in not out.
Thanks, Sam Sperbeck
La Crescent,MN |
Jim Ashworth (Jimnh) (172.174.196.225)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 22, 2003 - 12:08 pm: | |
I was just going from the way MCI does it. From the inside, with a lot of damage to the rivet end from the air hammer. I did it the same way on my MC-8 and had no paint chipping off the rivets in 10 years and 100,000 miles. My pop-riveted Prevost has several with chipping paint around them. I can understand that on aircraft it probably is important to hammer on the outside, but for a bus, one mistake, on a polished panel, for instance, and it's junk. 'Course its the same for a plane when it gets dented. But I'm not paying for another panel when I can safely hammer on the inside end of the rivet and get it tight at the same time. My bucking tool is a 12" piece of 2" diameter steel which holds the mandrel. It doesn't move off the skin with the air hammer impacts.
Jim |
Tom Connolly (Tomconnolly) (64.58.196.218)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 22, 2003 - 12:45 pm: | |
The panels are aligned by placing a tapered punch in the holes and then held in place with cleco's. The rivets come in several harnesses and many diameters and lengths in 1/64 inch increments.
The rivets are driven (set) from the outside and an assortment of bucking tools are used to apply pressure on the inside of the rivet.
It's a 2 person job, you need good ear protection and a good air hammer (not a $25 model) after you learn to work together (yelling "ready", "good", "more", "next") you can go quite fast.
It takes 1-2 seconds to set the rivet, You must have the correct size and shape driver for each size rivet, the drivers that I have are a set, the different size ends screw into the shaft making changing sizes a snap. Also a special drill that aligns and centers itself is used to remove rivets as properly set rivets expand and still hold if the head is sheared off.
Tom |
Sa m Sperbeck (206.230.105.230)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 22, 2003 - 4:19 pm: | |
Hi Jim,
If your method works "perfectly", is there such a thing as "perfectly wrong"? LOL |
FAST FRED (63.234.23.183)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 23, 2003 - 6:08 am: | |
An additional tool to purchase for using structural rivets , is a gadget that shers them to the exact leinth you need. Sometimes the single skin goes to a frame , sometimes 2 skins get attached. The rivet will be different .
Aircraft Spruce , or one of the other suppliers can set you up with an inexpensive gun and the rest of the goodies.No need for "the best" unless your going to compete with Boeing, and do a few hundred a year.
FAST FRED |