Thread: help -- alum backing plate to strengthen concealed hinges in aquarium cabinet

What is happening is called galvanic corrosion. This will continue regardless of whether or not you use aluminium. If the design of the hinges permit, you need to use marine grade stainless steel hinges and screws. Plugging the existing screw holes with match-stick size bits of hardwood will give you a fresh start where the hinges mount.

Craig.

Thanks Craig

I've done the matchstick thing many times which is why i've gone with alum plates. Basically the alum plates are anchored with 4 screws, the hinge cup sits on top of that and screws into the alum plate, same with the mounting plate thus eliminating the problem of repairing screw holes in the timber. For now I'm stuck with this set of nickel plated hinges .

I have 3 doors on the cabinet and I can't get my head around whether the extra 3mm alum cause the doors to overlap despite the +-2mm adjustment of the hinges ...am I making sense?

Trouble is the so-called professional who specified the entire aquarium setup used chipboard for the cabinet and mdf for the doors instead of all being treated pine (so I got duped).

Please help

Its a girl thing

bigorangecat,

Always hard to comment precisely without seeing it but it sounds to me like your suspicions are well founded.

If you are fixing the alli to the surface of the cabinet then I am sure there is every chance you won't have enough adjustment in the hinge (assuming we are talking about cabinet hinges and not butt hinges)

hinge.png

To rectify this you will need to check/recess the alli into the cabinet for a flush detail.

Another option may be to reem/drill the existing holes to 6 or 6.5mm and insert a plastic plug.

imagesCA8JJYAA.jpg

Once again, it's a tricky one to provide a solution for without seeing it.

Craig.

From reading your two posts mentioning hinge cups, I assume that the cabinet has doors mounted with euro style cabinet hinges similar to what is used in modern kitchens etc.

If this is the case, adding a 3mm spacer between the door back and hinge cup will put the door 3mm further from the carcass when the doors are closed. If you attempt to compensate for this by adjusting the hinge arm position at the wall mount end, the edge of the door will most likely clash with the carcass face when opening the door, as the modification and compensation has shifted the axis of rotation of the hinge to be inside the carcass. On the other hand if you do not compensate for the added spacer, the doors will stand out and not be flush with any other features on the cabinet face.

Similarly adding a spacer between hinge arm and cabinet side will offset the hinge from the cabinet wall leaving a gap at the hinge side of the door and causing an overlap at the openning side. You have a small amount of adjustment available to allign the doors and match gaps between them, but as you said this adjustment range is smaller than the offset you have added. Depending on the hinge family used, you might be able to swap hinges/mounting clips etc for different units to recover the difference, but you would still need all of the adjusment range just to get the doors to fit into their openings.

If the presence of salt water is killing the hinges, I suspect that the ali plate that you are using may be susceptable to corrosion as well unless it is definitely a marine grade alloy. I also assume that you are screwing nickel plated steel hinges to the ali, using some form of screw. I have concerns about the screws holding in the ali in the long term, and also about any dampness establishing electrolysis between the dissimilar metals in the combination.

Regarding material selection, both chipboard and MDF are available in Highly Moisture Resistant variants which should be suitable for damp area use, typically used in kitchen, laundry, bathroom fitouts so this should have been adequate if used. Similarly high end hinge families use knock in technologies where the hinges and mounting clips can be fitted into oversized screw holes using screws mounted in plastic bushes. With this technology, there is better holding power in the mounting, and if the hinge needs to be replaced, the screws release from the bush which remains in place for reuse, avoiding having the substrate break down from repeated insertion/removal of screws.

Thanks everyone, you have confirmed what I dreaded. I'm as mad as a cut snake with the workmanship but thats another story, thoughts of replacing the cabinet are on my mind but not in my budget so I'm stuck with a chipboard-mdf combo that is beginning to bow (ouch!!)

Yes the new hinges are Hefele 110-deg soft closing clip-ons nickel plated ....any ideas on the most effective way to preserve them from salt damage?. I just installed one door (without alum plate) and found that the cabinet side is 5mm out from top to bottom so even adjusting the hinges don't work ...besides the fact that the mounting plates are screwed into chipboard that just flakes and makes them spin without grip (expletive...expletive...expletive!!)

So I've decided to toss the alli backing plates, instead I'll insert 20mm hardwood dowels and make new screw holes yet again ...seems the dowels are getting wider with each hinge changeover. Ahhh the fun of marine addiction

you all have been fantastic, thanks once again
Samantha

Its a girl thing

To stop the corrosion build up on car battery terminals they are painted/coated, another solution is to smear vasaline over the terminal, just wondering how the same thing would work on your hinges??? Might be a bit messy but it should get some more life out of them.


Pete

Ok...some points...

Putting a dowel in the screw hole won't do what you want, which is hold a screw. Putting a dowel in will mean that you will then be putting a screw into end grain.

End grain and screws don't mix, as the screw threads can act just like little chisels and break the end grain over time, with the result that the screw comes loose (again).

Here's what to do:

Buy some marine epoxy Bote-Cote Reliable Marine Epoxy .

It'll only cost you like $15 and it is invaluable as it is specifically for that horrible mix of wood and salt water.

Remove any previous repair material/loose bits.

Then fill the buggered up screw holes with epoxy. The marine stuff is like runny honey so it will also make its way in between any broken/water affected chipboard in the area, giving it a bit more strength.

When the epoxy hardens, drill screw holes, and you can screw the screws back in. (you can also embed the screw threads in the epoxy when you first pour it in, but unless you have a tiny smear of Vaseline on the thread...it'll be a right b*tch to get out).

That'll hold the screws.

Then if you are near the sea, visit a marine shop and inquire about stainless steel cup hinges. Blum and Hettich make one, but I don't know if they have them easily available in Australia...but there are enough boatbuilding places around to try.

If it turns out that the hinges are in the "economically unviable" price range, then a smear of Vaseline will also do the trick, even if it's a little messy.

If it makes a difference between the cabinet needing immediate replacement and getting another couple of years from it, you would also consider relocating the hinges to a new position above or below the original so that you have fresh board to work with. Combined with oversized holes and plastic plugs, this might give you time to save for a better unit over a couple of years.

It won't help with panels being out of plumb etc, but that may be able to be resolved if the unit can be unloaded and rectified. You would need new pockets in the doors but I can drill them for you free of charge if you can bring them to Croydon, or alternatively cabinet shops in your neighbourhood should be able to do them at minimum cost. You would end up with the existing mounting holes visible on the inside of the doors, but the pockets and possibly the screw holes can be covered with plugs or possibly your ali mounting plates or similar. Send me a PM if I can help.

Metals come in what's called an "electromotive series." That has to do with their conductivity.
You put any two different metals together, with some sort of electrolyte solution in between (salt water) and one of those metals will ROT at the expense of the other.
That explains why serious boats have "sacrificial anodes" made of zinc. That piece rots at the expense of all the other different metals in the entire boat. Simple replacement.
So, do precisely as CMB/Craig suggests =
marine grade, stainless steel hinges and marine grade, stainless steel screws. The implication is that with the metals being the same = no corrosion.

Well I tried wider hardwood dowel to hold the hinges but didnt work out well...chipboard has crumbled too much.

I have now gouged out a 6mm deep square section inside the cabinet with my trusty multi-function tool . I'm planning to insert acrylic plate to support the hinge screws. Will the hinge screws loosen in acrylic over time? Should I also insert plugs into the acrylic screw holes?

Also I painted rust protector on the hinges but they still rusted, so now I'm off to get marine grade stainless steel. Ideally I'd like to put a protective cover over the hinges as well but wondering if thats overkill.

Quoting myself...

Originally Posted by Master Splinter

Putting a dowel in the screw hole won't do what you want, which is hold a screw. Putting a dowel in will mean that you will then be putting a screw into end grain.

End grain and screws don't mix, as the screw threads can act just like little chisels and break the end grain over time, with the result that the screw comes loose (again).

Marine epoxy, marine epoxy, marine epoxy...

Did I say marine epoxy?

If you add an acrylic plate to the mix, that's just one more thing that water vapour can get behind; plus you have to secure it to the cabinet, so that's time for a few more screws that can rust and loosen up over time.

A little sales pitch for epoxy...

They build boats with epoxy as the ONLY fastener - and that's not just piddling little rowboats for your Sunday on the lake, that's 50 meter ocean-going 'ooops is that a category 4 storm' luxury yachts. Timber hull held together with epoxy.

Marine epoxy is runny; the way you use it to fill dodgy holes is first (after cleaning out any not-really-working repairs) is to apply a quick surface coat so it can run/sink/soak into any borked chipboard, then with the remaining batch you mixed up, add in some filler material such as sawdust, flour or talc to thicken it up and splodge that in the hole. Hold in place so it doesn't slump out with a bit of board (covered in plastic wrap so it doesn't stick).

WEST SYSTEM | Use Guides - Bonding Hardware

Originally Posted by Master Splinter

Quoting myself...



Marine epoxy, marine epoxy, marine epoxy...

Did I say marine epoxy?

If you add an acrylic plate to the mix, that's just one more thing that water vapour can get behind; plus you have to secure it to the cabinet, so that's time for a few more screws that can rust and loosen up over time.

A little sales pitch for epoxy...

They build boats with epoxy as the ONLY fastener - and that's not just piddling little rowboats for your Sunday on the lake, that's 50 meter ocean-going 'ooops is that a category 4 storm' luxury yachts. Timber hull held together with epoxy.

Marine epoxy is runny; the way you use it to fill dodgy holes is first (after cleaning out any not-really-working repairs) is to apply a quick surface coat so it can run/sink/soak into any borked chipboard, then with the remaining batch you mixed up, add in some filler material such as sawdust, flour or talc to thicken it up and splodge that in the hole. Hold in place so it doesn't slump out with a bit of board (covered in plastic wrap so it doesn't stick).

WEST SYSTEM | Use Guides - Bonding Hardware

Master Splinter you are a genius, I'll follow your advice. Thank you so very much.

It would be easier if you could orient the cabinet so you could let gravity do the work of holding the epoxy in place while it sets. But make the filling batch nice and thick and it shouldn't be too tricky. (I have a couple of bottles of sawdust saved from using power tools that I use to thicken epoxy).

Oh, and don't buy araldite, unless you really like spending too much money. Any proper boat or fibreglass store should be able to help, or the Bote Cote people.