Broken my black case.

Mark Griffith

I have cracked the bottom of my Inspo case.I have tried fixing it with car fibre glass which lasts about 4 dives.Any body suggest a better method?
Many thanks
Mark

Deepthought_reloaded

Don't know how much experience you have with GRP but many people try to repair the visible crack which usually fails - the damage is like the tip of the iceberg - the real damage extends much further

To do a good GRP repair you need to feather/chamfer the edges of the crack upto about an inch or even more on thicker GRP - a sanding disk at slow speed is good but wear a mask and DONT use an angle grinder

Use a good quality marine epoxy and if you want, it is possible to add a pigment so the repair will be invisible.

if you can access the back that makes for a neater repair - it may be that it requires some support to keep edges aligned and bridge any gaps, drill small holes and use scrap wood but a piece of plastic will stop the resin sticking to the wood.

Be very precise on mixing the resin (the car stuff is usually much easier on this) as setting too quickly means rushing the job plus generates heat which weakens repair.

Paint some (colored) resin into the repair and then cut a single layer of matting to shape - place it into the repair, paint more resin on top then stipple the matting THOROUGHLY which spreads out the fibres giving a much stronger repair.
Paint more resin, slightly bigger piece of matting, stipple etc.

keep repeating until youve nearly filled the wide/shallow V resulting from the chamfer then finish with resin only to protect the surface.

Done right a GRP repair should be as strong as the original.

Mark Griffith

Many thanks for the info.What does GRP mean?The crack is along the bottom of the base so access is easy.
cheers
Mark

Grizz

how much is a new case U.S. Dollars.
i noticed a crack in my case also, so much money for a Rebreather with so cheep a case

Mark Griffith

Apd quoted £90 plus PP for the back part of the case.
cheers
Mark

divetheworld

Glass re-inforced Plastic.

and it doesnt bond to ABS very well regardless.

90 quid is a lot for that, save the rest up and get a travel frame.

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camerone

You're right - GRP bonds very poorly to ABS. Even epoxy doesn't do a great job.

You can get a reasonable mechanical bond between the ABS and the plastic through sandwiching the two - as in you patch both the inside and outside of the case, and make sure you fill through, with a couple of solid holes from both sides, so the the piece can't go anywhere. You have to use the minimum amount of resin for the amount of glass, and you need to build up several layers. You're plugging, though... a good rough surface on the plastic will help with the adhesion, as what you have is only a mechanical surface bond, not a chemical bond. If you sand the ABS of the case with coarse sandpaper before trying to fill it, it will help to promote the weak adhesion.

You must definitely use epoxy resin, and use a woven mat (E-glass, or S-glass) that is compatible with epoxy based resins; the poly resins that most car parts places use and the chop mat are not appropriate for this type of work. Marine grade epoxy is the key, as is working in warm enough conditions and being absolutely anal about your mixing ratios. Epoxy is not forgiving about sloppy measurement, unlike poly resin which just changes the cure rate if you put too much or too little.

Instead of fiberglass, a good alternative is to "fill" the crack with more ABS, which you can chemically melt into place. ABS is soluable in acetone (nail polish remover...)

What you can do is get some black ABS from a scrap of something or other, or your friendly local plastics supplier, and shred it into a powder (I rub the plastic on sandpaper, then every so often, dump the powder into a dixie cup...) Mix the powder with enough acetone until it is dissolved and you have a thick syrupy sludge, which can then be used as filler. Use a syringe to apply straight acetone to both sides of the crack, let it soften for a couple of minutes, and then use your black ABS sludge to fill in. After the acetone evaporates, you'll have an ABS plastic fix, and it should be good as new.

divetheworld

Not bollocks, good explanation.....green your way.

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Deepthought_reloaded

ABS? Yep, Please disregard my earlier GRP post, the 'plastic welding' method mentioned earlier is your best bet for a repair

BUT, If you can't make that work you could have a go at fibreglassing a new one - Coat your original in silicone and fibreglass all over it to make a negative mould - remove the original and clean up the negative, give it a coat of silicone/wax then make a new copy in GRP... Repeat for a spare, repeat for a friend.......

To be fair the 90 quid is probably MUCH easier but if you enjoy a challenge...

I think someone had done this for the yellow part of the housing and was punting them out in various non standard colours...

divetheworld

They were doing composites too, wonder who that was?

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