Monday, May 10, 2010

Making and installing a Cab-Over Fiberglass Molding (5/26/10)

WARNING;  DO NOT TRY THIS WITHOUT SANE SUPERVISION !!

Joking of course, but THIS kind of project will be above the abilities of some or many, but these photos and text might take those on the borderline of confidence and help them reach higher and be successful.

My mantra has always been, "Anything someone else has done, I can do."  I'm more often right than disappointed..............of course, I am realistic too.

There are many skills here that I cannot put a finger on or name specifically that come into play with a project like this.  Yes it's good to be handy with tools and have had some experience building things on your own before.  Doesn't have to be BIG things, can be 'small' things.  Just should be things that you felt proud about when you were done and maybe pushed your skill limits a bit 'During the Project'.  Care and persistence in  "Reading Directions" off a can, or Internet, or listening carefully is a good start....so do not loose this point.  Take it slow and read and listen to those around you offering labels, experience or 'sites' that can help you learn your way through this.

Nothing I'm going to show you here is beyond anyone that really wants to succeed and has some basic skills and tools.  So enjoy the  post and comment.. pro or con.. if you wish.
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Rebuilding the front of our motorhome was a task that used basic skills, but an array of them.

Rebuilding the roof of our motorhome was a similar project.....more than one thing was going on at any one time and it was good to have a working knowledge of various trades, materials and procedures, before getting involved with this rebuild.  BUT, this is not to say, you cannot LEARN WHILE DOING.  If the 'later' just pace yourself and do not allow frustration to be the victor!  You will be the winner, IF you are tenacious!

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OK, here we go!

I finished the Cab-Over Rebuild on the front of Memory Roads/our Class C, back in January 09, by using Eternabond tape over the corners..... where prior to the rebuild, there had been a sickly aluminum molding.  These molding do not offer enough dimensions to cover the corner space with enough surface to properly affect a confident seal area.  That's MY take on this, so I decided to later on....spend some time, and build a molding that would cover BOTH surfaces of this edge with 1 to 1.5" of material.  The original aluminum molding was I think 7/16"  x  7/8".    I'm now going for probably 1.25"  x  1.25"   or,   1.5" x 1.5" and will wrap this around the perfectly fine Eternabond Tape now in place, but use another sealant between the Eternabond and my newly made molding.  Yup, a double layer of removable protection.  [ Point Here] Try to build anything so that it is repairable...that means... you might need to remove something later-so plan for it NOW!   And, build it better.   You or the next owner might really appreciate the access you are offering.

To Begin:  The concept now is, to make a mold.  A mold that I can pop off a part from.  Yes, it's a one time thing  but I cannot here at my condo, be doing auto body work in our parking lot.  I CAN, work in my garage to create a facsimile of the corners of the cab-over and then,,,,, make a molding to fit it....also in my garage.  So this is the plan.  Much easier on my back too, working on ladders and off a scaffold are fine, but not as easy as making a pattern, then working slowly and yes, longer... ending up with a product I can goop up with a sealant and screw onto the rig.  Did I mention, I have a bad back? Well, I don't want to make it any worse.

I took a large piece of cardboard (saved for this purpose)from a carton of a Chinese Chair manufacturer, and used the flat surface to run a pencil along the edge of the motorhomes cab over to make a pattern
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I then took this pattern into my garage and with simple staging, began to transfer this pattern into a COPY of one side of the Cab Over.
I used scrap lumber that I always keep from one project or another until the pieces are worthlessly small.  As you can see from photos, these pieces worked out fine.  Some were from 1x4's.........others 2x4's.........and others 3/16"x whatever scraps of luan door skins from Home Depot.


The pieces were held in place on over or under the cardboard with some clamps until I screwed on piece to the next to get the basing shape.
I then used a Belt Sander to hand sculpt the curves to the pencil line I had transferred from the cardboard pattern to the wood.

When done, the wood mock up was an exact replica of the cardboard pattern...........  Well at least that's what I'm really hoping for!

You must KNOW I'm in for some surprises here, but let's go with the flow until I get that rude awakening..  Keep the faith and hold on to that smile.  What ever confronts me from here on, I will figure out and overcome, and so can you---if you wish to accept this project.

Two by Four gets the first rough cut with a sabre/jig saw.

Start with ONE and continue until you get the whole shape completed.
Again, the concept here is to make a 'part' from a mock-up of the corners of the Cab Over. I'll do this in my garage, 75' away from my parking space.

Seal the wood mock up with fiberglass resins to seal it in preparation for making this the MOLD you will use to make a 'Part' from.   That 'Part', of course is the molding we are looking to build for the outside edge of the Cab over.








7 comments:

Anonymous said...

very good help here. thank you sir . I just bougth a 1977 dodge rv class c. my first motorhome. It hade some leaks in the roof and I whas kind of douthing I could do it my self. not any more. thanks for the great information.

Ron Sheridan said...

1977 and 1991 are different animals-so to speak. Early construction was often really poor. I rebuilt my Dad's 1968 Class C back in 85 as the whole aft end was almost falling off. Terrible construction, but we saved it and made it better.
I can only recommend you be careful and not waste your time on worthless projects but go forward on the ones you think you can handle.
Have fun if you can.

Anonymous said...

Typical of your usual methodical way you approach anything,as anyone who followed you rebuild will see.I've passed a link to this blogspot to many doing rebuilds.I said this is how it should be done!Way to go Ron .Keep up the good work! Chris

Michael Clark said...

Hello. I'm in the middle of my own rebuild, 1990 Coachman Catalina, and I like your idea of making your own trim, the stock trim is way too small. My question is, why did you choose surfboard resin over common fiberglass resin?

Ron Sheridan said...

I was having problems with long set times using Epoxy Resins I had a large stock of so went to Fiberglass Coatings a major supplier of all things needed for glass work. Asked Pat for advice and he suggested the Surfboard Resin BUT... I think he mistook my question of material for the clearance light mold and maybe he thought "Sky light". The only advantage I can see for his suggestion was the Clarity for making a near glass clarity as in the manufacture of Surfboards. I suggest ANY polyester resin you can find. It sets up fast and is easy to work with, cheap and available anywhere. However, Epoxy resins are a waste of time and $.

Ron Sheridan said...

Addition: The use of Epoxy Resins for the actual 'part' is excellent though.

Polyester resin for mold making and Epoxy or polyester for the part itself.

Richard Sims said...

Ron,
I'm going to try a different way to make a mold for the cab over project on my RV.
I'll use a 2x6x10' stud grade fir, cut slots most of the way through in several places across the width where I need to bend the board into a 6" radius, soak the board in hot water, then make the bend and secure it in position with braces similar to the ones you installed to hold the bend.
In this manner, I plan on having one wold to make two moldings, a left and a right by making the layup across the face of the mold and down both short legs. I'll use pre-impregnated fiberglass cloth activated with water (available from McMaster-Carr Industrial supply). Your idea of using saran wrap for a parting agent is a stroke of genius. I'll seal the mold as you did and wax it thoroughly just for kisses and giggles. After curing, I should be able to pop the rough layupff the mold and split it down the long face to separate the one layupnto two pieces.
I'll keep you posted on how this works out. Right now, it's cold and rainy here in the Pacific NW and not conducive to fiberglass work.