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Author Topic: Am I crazy: Roof raise and fiberglassing?  (Read 5317 times)
luvrbus
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« Reply #15 on: February 05, 2010, 10:20:04 AM »

oh well to each his own here you want find anybody doing major marine work RV work or Corvette's without chopper guns


good luck
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ruthi
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« Reply #16 on: February 05, 2010, 10:22:59 AM »

Brian, i think you were the one who told me before the website to go to to resize my pictures to post. Give me the site again and I will try and post some.
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Mixed up Dina, ready for the road as of 12/25/2010
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« Reply #17 on: February 05, 2010, 10:28:26 AM »

Here are some photos of a Dina bus identical to mine.  They show how I would cut the fiberglass caps.

These photos were shamelessly stolen from another thread on the forum.  These are photos of Ruthi's Dina.  I flew out to Atlanta in November to see this bus in person.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #18 on: February 05, 2010, 10:35:56 AM »

 brian dont known how much you need to fill after you raise roof but i pulled the sides & roof off a moterhome
 you can cut what you need then just fiberglass the seams a lot less work check local junk yards they might give
it to you  i  used it to skin sides and rear of bus today i am using some to make a sunviser over windshild a lot
eazyer then starting from scrach picture of the two sides of moterhome laying in my yard 40 ft long good luck
ps i have a roof raising vidio if you want one john
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bevans6
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« Reply #19 on: February 05, 2010, 10:53:44 AM »

I do a fair bit of fiberglass work with my race cars, in fact one of them is a fiberglass tub monocoque.  I tend to go for very light and adequately strong for the application, which always ends up  being a couple of layers of cloth, mat on the outside for finish, and epoxy resin if repair work that needs to bond to existing 'glass, and polyester if new work or if strength isn't as much of an issue.  Chopper gun is a good production technique if strength and weight are not issues - it is a good way to get a lot of material down, but the chopped mat has very little strength and the volume of resin also makes it weak, and very heavy.  It's good for making boats, bathtubs, Corvette panels, but there are better ways if speed isn't the main thing.  The reason you use epoxy in repair work is you are only getting a mechanical bond, not a chemical bond, to the existing material and epoxy is far better at that.

I make a lot of in-place molds doing repair work - I use materials at hand to create something I can lay some layers onto, then build up from there.  If you use foam as the mold or to lay glass over, you need to use epoxy, as the polyester resin dissolves the foam. 
a good way to do something large in place like a cap raise would be to build up the form of what you need from foam - styrofoam boards, shaped with sanders and knives and rasps, spray foam insulation carved to shape, etc, get it really close to shape, and lay the fiberglass over it, then remove the foam from the inside with scrapers and such.  You can use filling modifiers (almost like gel coat) in the resin to get something to sand smooth, or even a light coat of bondo to sand smooth for the finish on the outside.

All that said, I hate doing fiberglass work!  It's nasty, itchy, time consuming, dirty, dusty and nasty...   But if you want it done right, sometimes you have to do it yourself.

Brian
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« Reply #20 on: February 05, 2010, 11:24:30 AM »

So Brian, it appears you recommend epoxy instead of polyester for a job like this?  Aren't the two primary advantages of polyester the cost and the ease of shaping the cured product?  I have done fiberglass and epoxy on hobby rockets in the past and the cured epoxy seems to be near impossible to sand.

I found a guy who does fiberglass body work for $25 an hour, but he declined after I sent him photos.  He said he couldn't do it because it wouldn't fit in his shop.  I did ask if he could do it outside when the weather gets warmer.

Here are photos of Ruthi's bus after the fiberglass work was done.  I couldn't attach them all to one post.
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« Reply #21 on: February 05, 2010, 11:59:52 AM »

If I was patching into existing fiberglass, yeah, I'd personally use epoxy.  If I wanted to be able to sand the exterior layers, I would use this stuff:  http://westsystem.com/ss/410-microlight/   You can mix it to about the consistency of peanut butter and paint it on as the outside layer.  I often use it almost as bondo for a top coat, or as a kind of gelcoat layer as the first coat into a mold, depending on what I am doing.  It's really easy to sand.  I use West system for all my epoxy stuff

If you aren't all that worried about strength (I don't think the cap of a bus is all that structural or load bearing, but I haven't really looked at them closely) then polyester will form an adequate bond with existing.  You need to sand though the gel coat into the actual fiberglass, and you need to abrade thoroughly with 80 grit paper.  You can't form a good bond to the gel coat.  You also need to clean with acetone., then do your layup.  If you do your layup in stages, if it gets hard and cured you need to de-wax the outside and treat it like existing - clean, sand extensively with 80 grit paper and so on.  Polyester is cheaper than epoxy, but I tend to choose based on what I am trying to accomplish and the strength requirements, not the cost.  I also buy both by the gallon, so once I have it, I just use whatever...

It's really important, with either method, to keep the amount of resin as low as you can while still saturating the cloth or mat.  I paint it on with disposable paint brushes, and when I have it all saturated I mop up all the excess with paper towels to get it as dry as I can.  Works really well.  Also, the cloth is used to create strength, and the mat is used to create bulk and to make a smoother surface, but it isn't very strong.

hope this helps a bit.  Like I said, I hate doing fiberglass work so I learned how to do it right the first time, so I didn't have to do it as much.  I just do bodywork and repairs, I don't do much structural work.

Brian
« Last Edit: February 05, 2010, 12:04:09 PM by bevans6 » Logged

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« Reply #22 on: February 05, 2010, 12:44:05 PM »

Bevans is spot on with everything he says in my opinion, although personally all the fibreglass work I've done on my bus has been using polyester resin as for me the benefits of epoxy in that application don't outweigh the extra cost. But on my boats everything is done with epoxy as performance is the only consideration (and in fact polyester wouldn't work anyway as they're both built of epoxy & carbon).

One point to make about using polyester with foam - polyurethane foam works very well with polyester, so as long as you use the right foam there's no need to worry about it melting.

Having looked at the photos it seems that the gaps to be filled are basically in areas that are either flat or very shallow single curves - no compound curves, and no radii to speak of apart from the corners. If I was doing this myself I would probably do exactly as Crown suggested - get hold of some flat fibreglass sheet, cut it to fit the gaps and then just laminate over the joints on both sides. The corners can be dealt with either by 'glassing over a piece of shaped foam, or simply over a piece of cardboard that's been bent into the required curve and temporarily held in place behind the gap.

Incidentally - if you need lengths of flat fibreglass sheet to fill your gaps a good source is roofing suppliers - flat roofs are often sealed with fibreglass, and the suppliers sell various standard fibreglass profiles to go over the roof edges etc.  Here's a typical range: http://www.fibreglassroofingsupplies.co.uk/store/-c-419.html?osCsid=56bba8a7750bf4658b83e320c236e7b8

Jeremy


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« Reply #23 on: February 05, 2010, 12:49:58 PM »

We got some scrap fiberglass from a place that works on semi trucks. They just gave it to us.
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Mixed up Dina, ready for the road as of 12/25/2010
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« Reply #24 on: February 05, 2010, 02:07:08 PM »

Brian, here is a pic with the braces in place. If this works, I will post another one.
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Mixed up Dina, ready for the road as of 12/25/2010
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southeast most of the time.
FIRST RALLY ATTENDED: BUSSIN 2011!
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« Reply #25 on: February 05, 2010, 02:11:33 PM »

Here is another one of when it is raised and the extra tubing put in. I will try and take some new pics to post on the boards tomorrow, if it isnt raining.
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Mixed up Dina, ready for the road as of 12/25/2010
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southeast most of the time.
FIRST RALLY ATTENDED: BUSSIN 2011!
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« Reply #26 on: February 05, 2010, 03:07:08 PM »

Just to clarify, I am not using fiberglass on the sides.  I am not too worried about the roof raise process itself.  I am more worried about the fiberglassing. 

The MIG welder I had been using is a little 110 volt MIG welder with no gas that belongs to a friend.  I am looking at buying a used 220 volt welder for this project for $300.  The guy says it takes a 50 amp circuit.  It is probably complete overkill, but the price is right.  It is located some 3 hours away so I'm not sure if I want to drive that far.

I need to add up the total costs for this project and see if I can really pull it off.  Steel, Alucobond panels for the sides, plywood for the walls, fiberglassing supplies, and low profile roof airs start to really add up quick.
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« Reply #27 on: February 05, 2010, 03:14:04 PM »

Brian,
   Just a suggestion, if you decide to do this this year, be sure to allow plenty of extra time, so you do not have to scramble at the last minute to get it done in time for your annual trip.  These kinda projects can easily take much longer than planned.  Jack
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« Reply #28 on: February 05, 2010, 03:44:56 PM »

Brian,
   Just a suggestion, if you decide to do this this year, be sure to allow plenty of extra time, so you do not have to scramble at the last minute to get it done in time for your annual trip.  These kinda projects can easily take much longer than planned.  Jack

Exactly - I'd be thinking far more about the time the job will take than worrying about the cost. Raising a roof is a big undertaking, with all the practical issues associated with the fact that the bus will be un-secure and un-weatherproof for a long period of time if you are only working evenings and weekends. It also affects just about all the work you've already done to the interior of your bus over the last few years.

Having said that, it's one of those things where you'll never be happy with your bus if you don't take the plunge and give yourself enough headroom now. You are presumably feeling that your current headroom isn't adequate, so it would be much better to bite the bullet now - putting the issue off whilst the conversion progresses further will just make it much more difficult to fix the problem later.

If you do decide to raise the roof, be generous. I raised mine as much as I thought I needed, and now really wish I'd made it a just couple of inches higher. Contrary to my own advice though, I'm going to live with it as it is - having done that job once there ain't no way on God's green earth I'm doing it again for the sake of two inches.

Jeremy
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« Reply #29 on: February 05, 2010, 04:08:39 PM »

speaking as a pretty self-taught weldor and fabricator who, after 25 years is starting to get competent at O/A gas welding and brazing, Mig, Tig on mild and stainless steel and aluminium, and who restores and build race car frames - cheap mig welders are the scariest, most dangerous machines out there, simply because it's so easy to do bad welds with them.  You get the ground wrong, the steel isn't clean enough, there is a tiny bit of wind, you try to weld outside an enclosure, you get the feed and speed of wire wrong, the current wrong - and it's just so easy to create welds that do not engage both materials and the bead looks beautiful but it's just sitting on top of one side of the joint.  You can do good work with them, it's just easier to do good work with a good tool.  My Mig welder is a Lincoln SP170, it can be flux-core or gas shield (flux core is far far better for welding outside), it runs from a 220 volt outlet at  20 amps, so you can run a 50 foot extension cord no problem, which is really hard to do with a higher current machine, and it produces a really stable arc that you can control, so you have better control of the puddle.

All I'm saying is, don't cheap out on your machine.  A good machine makes it easier to do good welds, and a vise versa...

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
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