| Author | Message | ||
| DavidInWilmNC Rating: |
I'm getting ready to skin over some windows on my MC-8. I've heard of people using either butyl tape or Sikaflex for this. In particular, I'm not sure what to use where the aluminum will contact the steel frame. I don't plan on using rivets. I'd rather use a thicker alum. and have smooth sides. Also, what's a good source for the adhesive of choice? Thanks | ||
| TWODOGS (Twodogs)
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no rivets.....???.............. | ||
| Rich International Bus & Parts
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SikaFlex 252 either White or Black & 210t or 206gnp Primer. Will hold your panels on the side of you MC-8. No worries about the paint chiping around the rivet heads, No worries about your panels "oil canning" (wrinkling), no worries about electrolosis corrosion. Easy choice for me. Rich 800-468-5287 | ||
| John that newguy Rating: N/A |
"G.E." Butyl in the tube, not ribbon, between overlapping edges. Sikaflex may be the greatest thing since sliced bread, but I wouldn't trust that alone to hold outside panels to the side of your bus. There's a tremendous amount of flexing as you drive down the road, plus a gross amount of heat and cold that expands and contracts everything. If there's any chance of moisture behind the panels (with or without freezing), or insufficient initial adhering of the glue, you'd be in for problems. Even the most costly commercially made motor homes suffer delamination.. The advantage of a bus, is the aircraft styled manufacture; the substantial amount of rivets, holding it together. (just my opinion, of cuz) | ||
| TWODOGS (Twodogs)
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no rivets....so....the bus mfg. must be wrong all these years.... | ||
| Jim Ashworth (Jimnh)
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I have used Sikaflex in several applications and wonder how you are going to hold the panel to the ribs so the Sikaflex can be squished out and be evenly spread over the entire length of several ribs at the same time. Maybe if you had a clamped template that formed the panel to each rib it would work. Sikaflex is strong enough to do the job of holding the panel in place but remember that the skin on an MCI is as much a structural part of the body as the ribs and other framing. When you do something on a bus, your entire focus is on that and not the big picture. Although the use of rivets will seem to stand out like a sore thumb, they will eventually dissapear when the bus is painted and finished. Nobody will object to them since they blend in with the thousands of other rivets already in place on the rest of the bus. Go for rivets, bucking rivets. Not pop rivets. That way you will not only retain the original design strength of the bus but improve on it. A properly set bucked rivet will not chip paint off around it. A pop rivet is much more likely to do that. Whatever you decide to do with mounting the window covering, pre-bend the aluminum to match the curve just under the rain gutter. It's difficult to make it conform to the curvature of the side without doing that. Jim | ||
| Rich International Bus & Parts
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Prevost uses little to no rivets on the outside of there new XLII & H-3 coaches. All of the large panels on the outside (stainless, aluminum, fiberglass) are all held on with Sika. All of the New MCI coaches also use Sika Flex to hold the outer skins on. New Technology..........I remember that people were confused by the micro-wave oven when it first came out. I hear people that make statements that Sika Flex cannot hold panels on coaches & you "just need to use rivets" But ask them what Sika Flex's Tensile Strength is? or Elongation at Break? or Lap Shear Strength? or Service Temperature? Those same people will give you the most confused look....... I was a non-believer at first until It was proven to me, but I gave it a chance. Just like every major coach manufacturer & converter. Come to my seminar at Rickreall or give me a call & we can talk about it. Sure rivets are good, we sell hundreds of thousands every year. But the advantages of Sika Flex are incredible. Rich 800-468-5287 | ||
| Rich International Bus & Parts
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Electric fans??? so all the bus mfg must have been wrong all these years...........Kidding Two Dogs. | ||
| TWODOGS (Twodogs)
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rich.....jump into the millenium ...glue structural stuff....best for "BUSINESS" if you don't get into this...what does your car have ,elec. or belt driven fan... | ||
| RJ Long (Rjlong)
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"All of the New MCI coaches also use Sika Flex to hold the outer skins on." I guess that explains all the duct tape holding various panels together on Greyhound's G4500 models. Did you know that lots of Hound drivers now carry duct tape in their travel bags, just to fix these MCIs when a panel splits or falls off between maintenance depots. Talk about a bus that's a piece of junk. . . FWIW | ||
| DavidInWilmNC Rating: N/A |
I'm sure some of the panels are structural, but I doubt the ones covering 15 feet on each side are. After all, there was once windows there. We're not talking about the alum. that's below the windows and above the stainless. There will be square steel tubes (framing) in the window openings; those will be structural. I guess I wasn't entirely accurate when I said 'no rivets'. It will be riveted at the top, bottom, and each end. These riveted areas will be covered and won't be seen. Of course, when this MC-8 was built, adhesives weren't anywhere as good as they are now. FWIW, many higher-end rv's use Sikaflex... Newmar uses it on their Dutch Stars. Thanks for the info. By the way, what did happen with those electric fans? | ||
| Jim Bob Rating: N/A |
Dogs, ALL of my cars use a belt driven fan. "Peanut roasters" (front wheel drive) cars use electric fans cause it was cheaper than anything else. And Dave, the highest end RV ("plastic bus") is not as strong as the cheapest real bus. You won't find many million mile RVs. (Bluebird & Newell are real buses.) Let the remarks begin! | ||
| John that newguy Rating: N/A |
Re: "I guess I wasn't entirely accurate when I said 'no rivets'. It will be riveted at the top, bottom, and each end. " Actually, that's the type of installation that Sika recommends. (Download Sikaflex info here) You'll still have the problem of flexing and twisting. According to Sika, no more than 12% of the width of the "gap" can be tolerated. My personal fears of a poor initial application causing later de-lamination need not concern you, of course... But with a perfect application, and assuming the stuff will stick forever... How difficult will it be to replace a panel, when the time comes? It's easy to drill out rivets, but getting that apart would be like digging wires and plumbing out of foam insulation... (Just more of my ramblings... don't mind me..) | ||
| Dale Waller Rating: N/A |
Sikaflex works great on aircraft 2024 t-3 & t-6 aluminum. The metal will tear before the Sikaflex bond gives up. Also great for dissimilar metal contact. Just my two cents worth as an aviation metal smith | ||
| DavidInWilmNC Rating: N/A |
Thanks for the info. Originally, I had planned on using luan attached to the aluminum (alum laminated to luan). I was thinking that this might help give the alum a smoother look and help with adhesion, as the wood would be attached to the frame. I haven't heard of anybody using this, so I'm not sure that it would be such a good idea. | ||
| Lew Poppleton (Lewpopp)
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David......HOW DARE YOU MENTION NEWMAR AND COMPARE A DUTCH STAR TO ANYTHING ON THIS SITE UNLESS IT IS THE TRASH PILE OUTSIDE. | ||
| DavidInWilmNC Rating: N/A |
I was waiting for that from somebody! ;-) | ||
| RCBishop
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Check the archives for more information on Sika Products.... FWIW-  RCB "64 Crown Supercoach (HWC) | ||
| akrom Rating: N/A |
RE: (Just More Of My Ramblings...Don't mind Me..) We've learned not to! akrom | ||
| fredmc Rating: N/A |
What do you think holds ALL the windsheilds on new cars? Sikaflex. Fred Mc. | ||
| Jtng Rating: N/A |
WOW. So 3M's totally out of business? (My neighbor's windshield in her 2005 Ford leaks like a sieve) | ||
| bowlingshoegiverouter Rating: N/A |
yeah...& the airplane guy says they don't use rivets on planes now,just glue two pieces of metal together & it's stronger than the metal.....yeah...sure | ||
| niles steckbauer (Niles500)
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Fred - the main thing holding the windshield in is duh 'wind' - reverse airflow and it wouldn't be there very long - Niles P.S. - I will now start checking my commercial airplanes for the proper riveting - BTW How many rivets on a Lear Jet? | ||
| bowlingshoegiverouter Rating: N/A |
one on each corner | ||
| gusc Rating: N/A |
Old design lightplanes still use rivets, but modern ones are composits and adhesives. Large aircraft are mostly milled and glued. Most lightplanes are 1930-1940s technology including engines and airframes. If Rich says SikaFlex will do the job there isn't much doubt in my mind it is true, he sells rivets too. As an aircraft mechanic I have done my share of riveting and it is far from the ideal system. It is actually a pain in the neck! The one good point about rivets is that at least they can be removed even though it is messy unless you are one of the few sheet metal experts in existance-- and there are very few. I'm not one of them! | ||
| Rob King Rating: N/A |
FWIW I have avoided jumping into this fray in the past to see how my friends coach faired. He had(operative word) a model 15 Eagle with fiberglass sides 4' tall by 42' long that he sikaflexed. Took a forklift, a scaffold system, 6 people and 4-5 hours per side. He still had to use rivets "here and there" to hold the fiberglass on while the sika dried. The big manufacturers have the budget to make jigs to do that that we busnuts don't have, therefore, there we will still have to be some rivets. Anyway, after just 1000 miles the fiberglass has twist creases, paint popped, and sections pulled away. He said he talked to sika( no reason to doubt but didn't verify),heard "wrong temperature at application time, wrong humidity, took to long to apply fiberglass, worked in sun", etc. Last I talked to him he sold it and is proweling for another eagle to convert. I will tell you, it looked great when it came from the paint shop. I vowed then to do my Prevost that way but this little voice in my head kept saying "wait and see", yes I take medicine for it but it is still there. Glad I did. I used butyl tape on the frame tubing and then riveted the aluminum panels into place after heating with a "weed burner torch". With my Prevost it was absolutely necessary to have the panels preformed to fit even with the rivets. I can't imagine how I could have taken nonformed panels, applied glue and then held them there for hours while the glue dried. I am young enough(52 years) to be open minded but I just don't see this sika for the busnuts in the backyard. If I had an unlimited R&D budget and wanted to advertize that I was putting out top technology product AND was looking for lots of return "customer repairs", thats a different story. I'm not, I want to build one coach that will last me for the next 20 years while I travel to see this great land, America. Just another opinion, right or wrong. Rob 91 Prevost | ||
| Jim Ashworth (Jimnh)
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A friend had a 2003 Prevost XLII with the glued on sides. A mechanic clipped a chainlink fence post just behind the entry door and the side of the bus peeled off all the way back to the fridge. Installation procedure is critical to the success of a glued joint. Talking to Creative Coach in Polk City, FL he said the training he had instructed wiping down the materials with one wipe in only one direction with a fresh cloth. For the second wipe, new cloth and more cleaner, one wipe in one direction only. When panels are applied you have one chance to get it right. Pull back just a little and you need to remove all adhesive and wipe it down again. I can also attest to the MCI panels coming loose after talking to my local bus company. Give me rivets, I know they will work for 30 years. Jim (with tight riveted panels) | ||
| Bill Glenn
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Hey David We have an Eagle so I do not know how that compares structuraly to an MCI, but I wanted the smooth look also. I used F.R.P. instead of aluminum but the issue of seperation and bonding of framing and skin is basically the same. (well not quite, electrolysis and all) The tape gives you the seperation and consistant initial bond and glue thickness and the sika gives you long term strength. I chose to use 3m V.H.B. double sided tape along with sika, and 3m 5200 on some panels. (comparing products and performance) I had to reorder the double sided tape because the thickness of the tape was wrong on the first order. (to thin) My thoughts were, ARE, that the double sided tape will hold the panel exactly at the desired position and thickness until the adhesive has cured. I used cheap hinges and E.M.T. tubing and welded up a jig that held the panel flat out and would swing up and place the panel in final alignment. Using this double sided tape makes proper initial placement critical. (kind of like contact adhisive, you get 1 chance to get it right) After placing the panel on the jig and swinging it up and down (with no adhesive, or tape) and ensuring that it went into place every time, we used the tape and a good bead of sika and pressed the panel in place. If the paint is properly adhered to the metal frame and there is no grease, oil, or dust to prevent the adhesive bond this stuff works. In fact the F.R.P. (fiberglass reinforced plastic) will shread and delaminate before the glue gives up its bond. This has been over 3 years and is still holding up fine. Good luck with your choices. Bill Glenn | ||
| Jtng Rating: N/A |
Re: "We have an Eagle so I do not know how that compares structurally to an MCI" From everything I've read and heard, the Eagle has a frame and the skin is applied to it. The skin (both inside panels and exterior) on the MCI are part of it's "frame" and integral to the overall structure. Even the window frames are considered part of the "frame". When I removed the racks and seats, seat rails, etc, I found that when the air is out of the air bags and/or the bus is not level, the front door will jam. That did not happen prior to the removal of those components. They are all part of the overall structural design of the bus. For that reason, I would be hesitant to rely on a glue alone, to hold exterior panels to the sides. Flexing -will- occur on a converted MCI. The flexing may exceed the limits the glue manufacturer set. And the manufacturer does stress the qualifiers of their warrantee. | ||
| DavidInWilmNC Rating: N/A |
JTNG, I'm curious about the door jamming with the racks, seats, and seat rails being out. Did that happen with the inside alum. panels and windows in place. Does yours have a lot of rust in the walls? Maybe some damaged sections of frame? I have the inside alum. panels, racks, seats, and seat rails out and a slightly unlevel yard. My 8 doesn't seem to flex though. I don't doubt that they can. I guess it depends on a lot on the particular bus. I've also considered riveting panels over the window openings on the inside where they won't be seen... like the lower inside panels. This would prob. give a good bit of support as well as better attachment points for the cabinets, etc. Thanks for all the input, guys. | ||
| John that newguy Rating: N/A |
I'm not too sure about the MC8, but there is some difference in the construction between the MC8 and later MC9. No, no rust in the side walls, just the usual amount over and under the windshield. Water seems to get in by way of the front rain gutter attachments and windshield gaskets on most of the 9's. (I can remember having a soaked logbook after a run with a nearly new MC9, years back). I have somehow managed to seal the front leaks in mine (I hope). Both inside and outside panels, window frames, etc, are part of the overall MC9 structure. Even the luggage racks and seat rails play an important part of the structural integrity of the bus. I didn't notice any difference until all the air was out of the airbags and the bus was on very uneven ground. With air leveling, the bus will remain fairly level, side to side and front to back. Just because the door doesn't jam, doesn't mean a bus's structural integrity hasn't been compromised by changes to it's original design. Yeah, I'll get flamed for these comments, but we all do what we want, regardless of consequences and will swear we're right because it's what we want to build. Regardless.... replacing the inside aluminum panels with any other material, weakens the structure. (OK...let me go put my fireproof jockeys) | ||
| niles steckbauer (Niles500)
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Jtng - It is MHO that sheathing the interior; 1) using 1/2 to 5/8 hardwood multi-ply material 2) layed horizontaly 3) staggered joints 4) fastened directly to the frame members at relatively close intervals (not using furing strips) 5) with the possible addition of foamed glue on the frame members Would provide an adequate or even argumentively superior shear strength capacity to the that of the original MCI design. If you could get the figures on the original design shear load, you could compare that with the figures available from the APA for various types of sheathing - What do you think? Niles | ||
| Jtng Rating: N/A |
Niles- We could raise the Titanic and rebuild it with enough plywood to withstand a collision with an iceberg.. We could also add so much plywood that the thing would sink without seeing an iceberg... We want to remove the original light-weight, but strong, aluminum panels and replace it all (ceiling and walls) with 5/8 plywood? And we're going to do that without changing the engineered structural design of weight vs dimensions.......! (?) Hey... we all do what we like to do. We tear it apart and rebuild it "our way". I'm not an engineer, so I will leave the structural design as near original as I can. That's my choice. Others can do as they please... They can use glue to do what rivets were intended to do, or use extension cords instead of wire engineered for the purpose.. I simply noted for conversational purposes, that the bus was designed and engineered as a complete unit; inside and outside metal coverings, floor and ceiling and walls... The luggage racks, seat rails and handrails... And even the window frames, are all part of the unit as a whole. Tamper with one area, and you've changed the structural integrity of the entire unit. If it matters or not, is open to debate among all that haven't engineered the original bus in question. But only the engineers of the original design, know the answer.. And FWIW, I believe they said it with their terminology of the MC9's design..... (monocoque construction). | ||
| niles steckbauer (Niles500)
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Monocoque (def) - A metal structure, such as an aircraft, in which the skin absorbs all or most of the stresses to which the body is subjected. Does not define skin as "metal" - only the stucture - and certainly does not eliminate the possibility of plywood skin - I only mentioned 1/2 thickness or more because of cheaper cost factor - there are many suppliers of 1/4 to 5/16 light weight 4 to 5 ply veneer sheathing that would meet the strucural standards required while not adding extraneous weight to the vehicle - my query was merely meant to offer the question as to why you would expend so much $$$ and energy replacing structural integrity by making alterations to the frame members and/or the exterior skin when you can use the interior skin (which you are going to do any way) to replace the deficit shear load you lost by removing the other structural components - additionaly transfering the shear load to the interior "skin" would allow for less stress and structural load on those "sika'd" exterior panels - just tryin to kill a few birds here - Niles | ||
| John that newguy Rating: N/A |
Say whaaaaaa? "why you would expend so much $$$ and energy replacing structural integrity by making alterations to the frame members and/or the exterior skin when you can use the interior skin " I don't know how anyone else is doing it, but the outside and inside skins on mine are staying the way I found them. I'll be paneling over the existing interior aluminum and possibly painting the ceiling. Although the removal of the racks and seat rails depreciate the bus's original design somewhat, I'll learn to live with it. I do not plan to reinforce the structure, nor would I know where to begin, as far as seat rails and racks. Aside from "shear", there's the difference of tinsel strength and flexibility between a wood product and metal. Even the types of metal products used, carry a difference. I personally have never been aware of any wooden airplanes at the local airport... I seriously do not think you can find a wood product that can be as light as aluminum and be able to the job aluminum is capable of doing. And before we go too far down this path.... Yeah sure, there are the miracle plastics that can exceed/excel aluminum... But projects are engineered around a specific material . Our tired old bus was designed without the benefit of modern plastics and were designed around the metal products available. My point to my initial comment, was that the bus loses a certain amount of structural stability when we make modifications to it. And to that extent, I would be cautious in my quest to eliminate rivets and instead use a glue, to hold exterior panels in place. | ||
| Brian (Bigbusguy)
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I would think what some are saying could be true. But I see 1000's of converted buses some with raised roofs and I dont see any of them bending in two or any thing going wrong from what ever most converters done to them . Some have 50% of them with rusted out frame members some have removed the inner skins and I still dont see any problems. AS to glueing on the pannels with that SikaFlex it sounds to hard to get it to work and if its too hot too cold raining not a full moon it will not apply right. Piss on that. I rivited my panels on . It would be nice to try to have my $1000 bus look like the million $$ rigs with no rivets. But from a 100 feet away they all look the same. Brian 4905 Vancover WA (Amtrack Depo for now) | ||
| paranoidoftheoceanguy Rating: N/A |
I have 800 S/S pop rivets in 6 blanked out windows .& I have peace of mind | ||
| gusc Rating: N/A |
John newguy, There are thousands of wooden airplanes at every airport in the country. Not only are they made of wood but most are covered with fabric also. During WW2 there were many airplanes made completely of wood including the skin. Probably the most famous was the Mosquito made by the British and one of the fastest airplanes built then. They were used as bombers, photo and spy planes and didn't have guns because German planes couldn't catch them. There are still wood wing airplanes with wood skin being made today both by factories and home builders. | ||
| gusc Rating: N/A |
Jim Bob, I own 18 vehicles from '31 to '94 (My newest). All the older belt fan driven ones (Except the diesels) overheat in hot weather during slow traffic driving or in parades, none of the electric fan models overheat. | ||
| TWODOGS (Twodogs)
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HMMMMMMMMMM ???? | ||
| Jtng Rating: N/A |
Gusc- Would you replace the metal on a modern all metal aircraft with plywood and expect it to fly as it was engineered to? If you replaced most of the wood on an old wooden aircraft with metal, would it fly as well as designed? It isn't a question about the ability to engineer a substance for a specific use, it's the issue of changing the substance that was initially engineered, to something that was not considered during the initial engineering. If an new aircraft was designed to use glued exterior panels safely, it doesn't mean that any older aircraft can safely use glued panels instead of riveted. Buses are a lot like that. | ||
| TWODOGS (Twodogs)
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if you have problems on how rivets look.....don't get a bus | ||
| DavidInWilmNC Rating: N/A |
hey 2dogs... kinda late for that idea, as I've already got a bus. It's not the rivets MCI put in that I object to, it's the fact that I know I won't get them in as straight that I ojbect to. Besides, what's with your earlier post "no rivets....so....the bus mfg. must be wrong all these years...." I'd say 'what's with no belt-drive fans...so... the bus mfg. must be wrong all these years..." | ||
| Jtng Rating: N/A |
OUCH! | ||
| niles steckbauer (Niles500)
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Isn't a REPORT on FANS due out in 119 hours and 20 minutes? | ||
| Jtng Rating: N/A |
Dave- I made a simple jig that placed each rivet (drilled hole) almost exactly where it looked best. Glue may work fine, but be aware of the "extra" amount of flexing of a converted bus. | ||
| TWODOGS (Twodogs)
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kinda try to remember what was said in the last 5 posts about the fans | ||
| Jim Bob Rating: N/A |
Gus, I'm not saying electric fans don't have their place. I was just poking TwoDogs with my sharp stick. But if your factory built 1960 to present car overheats at any speed, it needs maintenance. Obviously, an older vehicle or one with added air or automatic may have problems. A pancake fan can do wonders there. Are we in agreement? By the way, 18 vehicles?? I'd LOVE to be your insurance agent! | ||
| niles steckbauer (Niles500)
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*snip* JTNG::It isn't a question about the ability to engineer a substance for a specific use, it's the issue of changing the substance that was initially engineered, to something that was not considered during the initial engineering.:: *snip* Bus to RV Conversion (def) - Taking a vehicle originaly designed and engineered to transport passengers and cargo to a vehicle which is used as an RV. Heck John - the whole bus conversion thing is predicated on screwin with the original bus design and engineering - Doing it YOUR way is all about how much your going to change YOUR buses structure - the minute you remove that first component you have altered the structure - now how are you competently and inexpensively going to replace the structural integrity you removed? - that was the reason for my post - every converter has to sheath their walls and ceilings - if they can sheath the walls and repair the damage done by the removal of their racks,seats,windows,skins,etc. at the same time it certainly would be more cost effective - BTW wood and steel have remarkably similar properties when it comes to structural performance - Niles | ||
| Brian (Bigbusguy)
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My belt driven 54 chevy car dont over heat in stop N go traffic in hot weather but its a chevy LOL My bus dont have any belts and dont have any electric fans It dont over heat It also has the cool looking rivits. Brian 4905 | ||
| Marc Bourget Rating: N/A |
Niles, Is it fair to conclude your post with the simple statement that wood and steel have remarkably similar properties without saying more? I agree with your points but I'm worried that an inexperienced newby will overlook the wisdom placed in the body of your post and take to heart only the last comment. Could you provide more information/explanation about competence and integrity please? | ||
| Bob Belter
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Ho, BusGuys, Lots of talk about butyl rubber tape, which is an architectural sealant. It is NOT an adhesive. In fact it behaves more like a cross between tar, and rubber. You MUST use rivets to fasten the skin with butyl tape. For a try, take a piece of aluminum, some butyl tape, and hang it on a vertical frame in the hot sun. Good instant "grab", but it will drift. I was a while deciding to do my skin with butyl tape, rather than Sika Flex, and realized that I didn't have the means to clean the structure, and fix the aluminum as it cured. I have no leaks in my Eagle done with butyl tape. Enjoy/s/Bob | ||
| John that newguy Rating: N/A |
Niles- I'm gonna' go out on a limb here: Wood products are heavier per square inch than any metal product, if compared for strength. The aluminum panels used for the inside walls and ceiling in an MC9, strengthen the entire bus and are part of it's designed structure. Replacing it with any wood product that will allow that same amount of strength as aluminum, will result in added weight. "As a rule of thumb, aluminum is three times heavier, but also three times stronger than wood. " I'm paneling over the existing aluminum walls, but the paneling will not add more weight than the luggage racks that have been removed. In fact, the paneling may weigh about the same as the original wall covering/AC venting that covered the aluminum panels. Actually, all this is trivial dribble.. A bus load of passengers with luggage in all the rack space is far heavier than solid oak walls and ceiling. I doubt making the bus top heavy, is of concern. My only concern with using glue to hold exterior panels, is that the glue is not designed to take excessive flexing and twisting of the material it is bonding. Where a bad twist may dimple a riveted panel, it will likely pop apart a glued joint. And removing the balance of a popped glued panel will be 100x more difficult that drilling rivets. Hey... we all do things "our way", but it is always good to hear other's ideas and views. Hell.... I listen to it all, then do it my way, anyway......Sometimes, regrettably. | ||
| niles steckbauer (Niles500)
Rating: N/A |
Marc, In order, 1) I never asked anyone to assume that any structural member of any type could replace any structural member of another type - I suggested that anyone could inquire as to the original factory engineered spec and see if you can match it with a comprable wood veneer sheathing - I have not done this because I do not own a MCI w/ monocoque - ergo it would be stupid of me to do the math - I have suggested to others who DO HAVE an MCI w/ monocoque, that have not yet done their conversion, that it might be practicable for them to transfer the load as expressed in my post. 2) The data on which I relied for my postulate was 'common sense' - by trade I am a building contractor - In the past I have consulted many reference materials in my possession as a matter of my trade - although not specific, they provide load factors for various generic materials w/ various dimensions - irregardless they are inconsequential to my trade now since Fla adopted their new building code which now requires certified performance standards for all structural components (out w/ Da book and common sense) - This knowledge along with practicle experience nonetheless is a rational basis for my assertions. 3) It is evident by looking at the cage of the average MCI monocoque chassis along with its anchor/transfer points and considering the material used for/and thickness of its 'skin' which is congruous t/o its application, that the 'skin' is NOT an absolute structural nexus but merely acts as a structural load transfer and dampening system (ergo - it bends but it don't break) - one continuous sheat of 8x30+ foot of thick plywood would most arguably not work in this situation since it would be too stiff and not provide for the flex obvious to this design - but 8 foot sheats staggered would allow a similar flexing and could transfer the load much the same as the original 'skin' - Remember its the "system" not the "component" that makes it all work - (think of it this way - If you put all the passengers and cargo of a fully loaded 747 scattered onto its 2 wings (upside down), they would fall off - But those wings DO support them along with the weight of the fuselage, equipment , fuel and handle torque and wind loads that are 10 times those of the average bus) 4) If the material used to replace the interior skin loads is equal to what you have removed there is no need to strengthen the external skin or any structural members - if it exceeds it you have just taken some of the load off those sika flex'd exterior skins (the subject originating this post in the first place) and possibly prevented them from failing. 5) I'll admit that fastening is the big question - rivets are a unique fastener with this type structure - thats why I suggested foamed glue (I'm talking about the 2 part product from DOW chemical or its equivilant) - the foam acts as an insulator (sound and temp) while also providing some flex properties - the glue is very strong, bonds to any material, is somewhat forgiving when it comes to surface prep but does not make it impossible to remove the panel if necessary. Anectdotally, I use Structural Steel (and non ferrous metal) components interchangeably with dimensional lumber every day on the same structures - the use of wood vs. metal is mainly proscribed cost, weight, availability, and space considerations - sometimes dimensional lumber (as a single member or sistered as a beam) is most effestive and sometimes it's metal (I,C, or Box beam) - I did find in the old days of wood framing (prior to the new codes) when we typically used "2x4's" (actual dimesion 1.5" x 3.5") that sandwiching 1/2 inch CDX plywood with wood glue between 2 - 2x12's would stiffen a 16 foot header better than a third 2x12 and also provide me with my desired 3.5" plate width. Also look at a typical wood I beam and compare it with light gauge metal (weight vs. load capacities) and see if it isn't superior when Co$t$ compared - I would consider the loads placed on a wood I beam and the interior or exterior skin to be quite similar (vertical and lateral) Niles | ||
| DavidInWilmNC Rating: N/A |
Thanks for all the input, but in this case, I'm not realy changing, substituting, etc any of MCI's engineering except for the windows. I have 3/16" steel angle around the perimeter of each window I've removed. It's going to be welded in place tonight. I'm sure this is stronger than the original window frames, which were fairly flimsy. The window openings have three vertical 1-1/4" square steel tubes welded in place. 1/4" luan is going over this. Finally, the new alum. skin will cover this. It will extend under the roof, being attached with 1/4" monobolt rivets and Sika-flex. It'll actually be riveted around the entire perimeter, with Sika-flex used under the entire skin. The aluminum will basically be treated like a laminate over the luan. I'm sure that this will be stronger than the original windows. They're heavy, but not really rigid. I'll also be replacing a couple pieces of original wall frame which have rusted through. All in all, I feel certain that with the new exterior skin over the windows, welded and reinforced frames over the windows, repaired wall framing, and reinstalled interior skin the bus will be as sturdy as new... or sturdy enough, anyway! I know that the thread has strayed a bit from the original question, and that's fine. It sort of removes the 'blinders' and allows a lot of other relevant points to be made. All this discussion has led me to believe that this is the best solution for covering my windows that I'm capable of performing. |
