Thread: Vertical belt guard repair?

I would be interested to know how you got that gathered look Ken,looks like it would take a bit of practice.

PC

The gathered look is a reflection of my face!

Ken

Too easy. Cut and shape a piece of MDF to act as backing, cover it in greaseproof paper/duct tape/other mould release, clamp it on and put some fiberglass mat on, and dab epoxy on with a paintbrush cut nice and short (not one of your good paintbrushes!)

Use chopped strand mat (its just like the glass showing there); I'd be lazy and just pull a few pieces to rough size (pulled to size so it has rough edges rather than neat cut edges) but you could vee the existing edges and cut bits out if you wanted. Slop down epoxy (pad it on so you don't move/pull out fibers) and let it set.

When set, any irregularity in the surface can be filled with more epoxy, then you can slap on the paint!

[ame=http://www.youtube.com/watch?v=SsoKAHU5xUw]YouTube - How to Repair Fiberglass[/ame]

Thanks MS,

Looks too easy, reckon I'll have a go. Can I get the materials from Bunnings or someplace similar, or am I best directed to a boat supply place?

Ken

Got the stuff to repair my boat trailer fiberglass mudguards from bunnies.
Don't know if they are the best price though.

I get my fibreglass and epoxy from a local speciality shop - the fibreglass is about 1/2 - 1/3 the bunnies rate, and I prefer using epoxy instead of polyester as it bonds to everything so much better and it's a handy wood (and everything else) glue (I don't feel like paying $120 for 250 ml of araldite at the green shed...West epoxy works out to about $40-odd for 600ml).

As with anything, get it nice and clean so the glue isn't fighting 20 years worth of oil.

Oh. It is messy, so don't wear decent clothes, and accuracy in mixing is essential so measure it, don't eyeball it. Gloves are a real good idea too. Vinegar for clean up when you are finished.

Hi MS,

Since you have given me the inspiration to have a go, and I've had a look at the youtube video, it seems that two different types of fibreglass are needed. Chopped mat for filling and a woven mat for the top layer. Do you agree, and what is the difference between epoxy and polyester, and where do these come into play? As mentioned, I know nothing about fibreglass, but by the end of this exercise, I will.

I presume "clingwrap" or similar is a good release medium?

Ken

For something like that cover, I'd just use chopped strand mat. It's not what I'd call a highly stressed component, nor do you need the gelcoat layer - so woven fabric is unnecessary.

The difference between polyester and epoxy - polyester is cheaper (about 1/2 the price of epoxy) and significantly weaker.

Clingwrap is a bit too thin for my taste - a thicker plastic is better so you don't have to worry about catching and tearing it.

If there are any running cracks from the break, I'd drill a hole (maybe 5mm diameter) at the end of them to make sure they don't remain stress raisers. The hole can be filled with thickened epoxy later.

After making and placing the support, the real-world process I would follow would be:

• Cut out 2-3 patches of chopped stand mat, each somewhat larger than the last.
• Tease the edges of them so they are not meticulous cut edges. (it's easier to work a ragged edge in.)
• Don gloves.
• Mix about 60ml of epoxy (50ml resin, 10ml hardener if it's West Epoxy.)
• Apply epoxy to repair area using a dabbing action.
• Slap down the first (smallest) patch - should overlap the broken edges slightly.
• Dab on more epoxy so the fibreglass wets out (the fibreglass goes transparent just like a tee shirt at a wet tee shirt competition, but the content is less interesting.)
• Add next patch.
• Swear as patch gets stuck to your glove and resists all attempts to go back where it should, and ends up as a scrunched lump on the end of your gloved finger.
• Throw gloves and now useless patch out, don new gloves, cut out new patch and reapply.
• Dab on more epoxy, add next patch.
• Dab down with brush, add more epoxy if required.
• Add another layer of patch if it's not looking roughly as thick as the rest of the cover.
• Feel free to add a glueproofed board on top and clamp it down to make it all nice and flat.
• Let it set.
• While waiting for it to set, discover the bit of mat you threw away earlier is now stuck to the car door. Panic as you try to clean it off before the now rapidly curing epoxy sets.
• Unclamp and inspect. Trim excess with a sharp knife if the glue is still green, or a dremel/file if it set.
• Fill any little voids on the visible side with some fresh glue thickened with wood dust from a random orbit sander or talc or flour, and sand flat when dry. (you can make it just like polyester bog, but much more durable!)
• Stridently deny any knowledge of what has happened to the best dressmaking scissors, or why they now have what appears to be fibreglass stuck to them.

See also:
http://www.westsystem.com/ss/use-guides/

Hi MS,

That's a very concise description, how could I go wrong? Reckon I'll try and purchase a repair kit, so will have to take what is offered. I see Selleys sells a kit.

Many thanks,

Jen

OK,

Been to Bunnies and purchased 1.5 sq.m of chopped mat, a 250g tin of "Diggers" fibreglass resin and a 15ml bottle of "Diggers" hardener. The tin measures 70mm dia x 70mm high.

It states on the tin, to 100ml of resin, add 2.5 to 3 ml of hardener on a cold day, or 1.5 to 2ml on a warm day. Great!...... how much is 100ml and how much is 2ml. Do I need to buy a set of plastic kitchen measuring spoons?

According to one of my recipes, one table spoon equals 20ml, & from the web, I litre equals a block 100mm x 100mm x 100mm.

Q1. How do I go about measuring this stuff?
Q2. Is there a solution used for clean-up, or is it not necessary? (wear ladyfriend's teeshirt?)
Q3. Can 2ml be equated to so many drops?
Q4. How important is it to get the right mix?

Your guidance will be appreciated.

Ken

Use a paper cup (that's plain paper, not plastic and not waxed paper) for mixing polyester resin.

Q1. How do I go about measuring this stuff?
ummm with a graduated measuring cup.....normally for polyester resin I just measure by eye as unlike epoxy, the polyester catalyst is just there to kick off the set. The 'small' coffee cup size is 250ish ml, so half-ish gives me about 125ml.

Q2. Is there a solution used for clean-up, or is it not necessary? Not necessary - throw everything covered with polyester resin out after use. If you must use the good china, acetone or enamel paint thinner (not turps) before it sets.

Q3. Can 2ml be equated to so many drops? Yes. Drop drops into small graduated measure to 10ml, divide number of drops by 5. (this averages out drop size and provides an easier to measure quantity). I use 'about a half teaspoon full' for a half coffee cup of polyester resin, which gives me about 2.5ml, but this is real bucket chemistry. For accurate measurement of small volumes, pick up a 1ml syringe from the local chemist. (I use an electronic scale that reads to 0.01 gram when I need to be accurate.)

Q4. How important is it to get the right mix? Not hugely for polyester. Extra catalyst won't hurt, but at the extreme, too little and it may not go off. Adding too much catalyst speeds up the set - so instead of 15 minutes you might only get 5.

Oh - the catalyst is MEKP - methyl ethyl ketone peroxide - so eye protection is a good idea.

MS,

again, many thanks, I'll be down at the hospital tomorrow, so will grab, I mean "borrow" some syringes.

Ken