fiberglass caps

[ruthi]

OK, so we raised the roof on our Dina 9 inches. There are no caps for it, so we are going to fiberglass in the gaps. Has anyone else done this? Do you have knowlege about it that might help us. All help appreciated.

[JackConrad]

When we raised the roof on our MC-8, we found a deal on MC-9 style caps, but standard height.  We used them and added a strip of siding aluminum to fill the gap between the new cap(s) and the bus.  Jack

[NJT 5573]

Fiberglass is pretty easy to work with.

There are 2 kinds, boat glass and automotive glass. Boat glass is very rigid and I have seen it used but the best is fiberglass mat, aka automotive. Boat is so rigid that it tends to delaminate in automotive useage.

I would go to Fruehauf or Wabash Trailer and pickup a flat sheet or more of side wall fiberglass made with mat, (normally used in reefer trailers). I'd cut it into the shapes until I had all the pieces rough shaped and pop rivited to the coach and each other. You can use some wood, steel or aluminum 90 degree brackets and pop rivits to hold it togather if you need to, bend the 90s if you want more or less angle on the pieces. Then I would use mat to join the pieces togather. just cut the mat with some old sissors and lay the pieces on repeatedly until you get it stuck togather. Grind it to shape a time or two and reapply more mat and use a paint brush to apply the liquid glass with the hardner mixed in until you are happy with what you have. Use some bondo and bondo files to get it smooth, then finish sand it smooth. You need to work glass in warm temps as it sets up from chemical reaction. An alternative would be to purchase a cap made for another bus that looks close and modify as needed.

Eagle has a sguare rear cap available that may work on both ends for you as well as other possibilities.

For the build part of this if you piece it, use a pretty aggressive grinder, it will save alot of time

[ruthi]

This is what we have to work with. Pretty straight gap around the back , and the front top, has a lower area, and the raise starts behind the driver area. We want to leave the front low in order to put the satelite.

[Jeremy]

Fibreglass essentially consists of two things - resin and fibre. There are various types of both but there is no difference between the materials used in boats or vehicles beyond the obvious factor of choosing the right sort for the job in question. Whether a fibreglass structure is rigid or flexible depends upon the choice of materials and the thickness of the laminate, and it is true to an extent to say that more flexible is better than stiff in some circumstances. Epoxy resin for instance, which is typically used in stronger, higher performance laminates, is technically more flexible than cheaper polyester resin, with vinylester being somewhere in between. Also, the higher the percentage of resin in the laminate higher the local stiffness will be, but at the expense of strength and weight. The amount of resin used is dependent on the skill of the laminator and the type of fibre used - using mat will use lots of resin, whereas if you use roving or a cloth or fabric then the amount of resin used will be progressively reduced.

All this is overly technical to your application however, which just requires a standard polyester resin and the most basic sort of mat (known as CSM or chopped strand mat). The main thing to decide is how to create the shape of the fibreglass panel you are producing - there are various ways to do this, and I would probably use different methods for the front and rear caps. The rear cap is easy as it only has a single curvature; for this I would make a very simple mould using a sheet of wood curved to match the curve of the vehicle, then laminate your panel into that mould, using a release of some sort to prevent the fibreglass sticking to the wood. Alternatively, using pre-made flat fibreglass sheet as previously described is also a good approach, but I think you will still need to make the corners from scratch as you won't be able to bend the flat sheet tightly enough to achieve the required curvature, and 'cutting and shutting' the flat sheet would then either leave a horrible shape or require lots and lots of filler.

The front cap is more tricky as it will involve compound curves to get the shape you describe. My approach here would be to create the shape you want using foam sheets and then laminate directly onto the foam, with the foam thus becoming part of the structure. I actually described this process in some detail quite recently in another post about making one-off caps.

Hope that helps; don't worry if the any of the above sounds difficult - it really isn't, although fibreglass can be a messy material and unpleasant material to work with.

Jeremy