Author Topic: A sticky situation  (Read 4406 times)

Nelson Longflap

  • Riding a bike is meant to be easy ...
A sticky situation
« on: 27 April, 2018, 02:56:18 pm »
With help from my granddaughter I managed to break my glasses; a clean fracture in the middle of the nose bridge. Replacement is horribly expensive, and I've nothing to lose by attempting to glue the two halves together. To maximise chances of success I'm seeking recommendations from anybody here who knows about adhesives. The glue I have in stock is a generic two part "rapid" epoxy from Wilkinsons, and some Bostik contact adhesive. Does anybody know of anything better that might give me some faint hope of sticking what is quite a small contact area? (I imagine superglue will most likely give a bond that is far too brittle, so is a non-starter - but please correct me if I'm wrong about that.) The following pics illustrate the problem:

IMG_20180423_081400 by Nelson Longflap, on Flickr

2018-04-27_12-11-15 by Nelson Longflap, on Flickr

2018-04-27_12-10-52 by Nelson Longflap, on Flickr

2018-04-27_12-09-31 by Nelson Longflap, on Flickr

All advice much appreciated ...
The worst thing you can do for your health is NOT ride a bike

Re: A sticky situation
« Reply #1 on: 27 April, 2018, 03:39:50 pm »
Plastic frame? If you can get hold of it dichloromethane will do a plastic 'weld'

Re: A sticky situation
« Reply #2 on: 27 April, 2018, 03:40:43 pm »
Metal frame? Try soldering.
Duct tape is magic and should be worshipped

Nelson Longflap

  • Riding a bike is meant to be easy ...
Re: A sticky situation
« Reply #3 on: 27 April, 2018, 03:46:41 pm »
Plastic frame? If you can get hold of it dichloromethane will do a plastic 'weld'

Thanks both. The frame is 100% plastic (sorry - I should have said in the OP).

(My bold) ... is there a good reason why dichloromethane may be hard to obtain? Just the name sounds carcinogenic  ???

ETA: I asked my mate google who says it's a VOC used in paint and aerosols; also used to extract caffeine from coffee ... and it is carcinogenic and damaging to the nervous system in a sufficiently high dose.
The worst thing you can do for your health is NOT ride a bike

Re: A sticky situation
« Reply #4 on: 27 April, 2018, 03:55:21 pm »
Plastic frame? If you can get hold of it dichloromethane will do a plastic 'weld'

Thanks both. The frame is 100% plastic (sorry - I should have said in the OP).

(My bold) ... is there a good reason why dichloromethane may be hard to obtain? Just the name sounds carcinogenic  ???

It isn’t hard to obtain, you can get it on eBay.
We are making a New World (Paul Nash, 1918)

Torslanda

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Re: A sticky situation
« Reply #5 on: 27 April, 2018, 04:06:48 pm »
Do you have 'accidental damage' cover on your contents in-sewer-ants...?

Might be worth a punt. #justsaying
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Well that's the more blunt way of putting it but as usual he's dead right.

Re: A sticky situation
« Reply #6 on: 27 April, 2018, 04:08:46 pm »
Plastic frame? If you can get hold of it dichloromethane will do a plastic 'weld'

Is that the "active" ingredient in the solvent welding gunk used for plastic pipework?  If so you can get the solvent weld cement at any plumbers type place, builders merchants or possibly even B&Q.  Might be quicker than eBay.

Nelson Longflap

  • Riding a bike is meant to be easy ...
Re: A sticky situation
« Reply #7 on: 27 April, 2018, 04:46:42 pm »
Do you have 'accidental damage' cover on your contents in-sewer-ants...?

Might be worth a punt. #justsaying


I thought I had the additional cover, but it must have been some previous insewerants ... but if I did have it there would have been a £75 XS to pay, plus a warning that the cost of my insurance would rise, making it only marginally worthwhile, if at all.
The worst thing you can do for your health is NOT ride a bike

Nelson Longflap

  • Riding a bike is meant to be easy ...
Re: A sticky situation
« Reply #8 on: 27 April, 2018, 05:08:26 pm »
Plastic frame? If you can get hold of it dichloromethane will do a plastic 'weld'

this looks like the stuff ... user feedback suggests it works on some plastics but not all.

I could try writing to the frame manufacturer to enquire what plastic they use, and any glue recommendation they may offer. If I run out of patience I'll go ahead and experiment with the dichloromethane.

I did ask my optician's mechanic who said he'd had no long-term success glueing breaks like mine because the surface area is insufficient to give a durable join, but I didn't ask what glue he used. I'm surviving OK on my spare specs and so may as well have a go at mending for the personal satisfaction and the money saved.
The worst thing you can do for your health is NOT ride a bike

andytheflyer

  • Andytheex-flyer.....
Re: A sticky situation
« Reply #9 on: 27 April, 2018, 05:15:46 pm »
Not sure about the plastic welding - not all plastics behave the same way.

I'd use an epoxy, but reinforce the joint.  I'd epoxy a strip onto the back side (i.e your nose side) once the main joint has set.  You can get brass or aluminium strip from a model shop - or eBay, for a few £. I think a strip maybe 1/16 thick (1.5m) should do it. 

I'd make a small jig to hold the nose bridge against whilst the epoxy sets - being an aero modeller I have plenty of balsa and ply to hand, but you should be able to think of something. If you had a bit of ply, say 1/4" thick, you could shape an edge to match the nose bridge shape in the horizontal plane, then temporarily fix the two parts to the shaped edge of the ply with thread or small cable ties, through holes drilled in the ply.  Sounds complicated, it isn't really, and you need to hold the awkward 2 parts together in the correct alignment whilst the expoxy sets.

Whatever, you need to be able to firmly hold the two parts together whilst the epoxy sets - even if you use the 5 minute version. If you use epoxy, you can clean off any excess with meths before it sets.

Don't think the specs will ever be the same again but you should be able to molish a working repair with planning!

TheLurker OTP may be along shortly - he's another aeromodeller and may have alternative ideas.


Re: A sticky situation
« Reply #10 on: 27 April, 2018, 05:23:39 pm »
I'd also attempt to reinforce the joint. Perhaps a pin vice and a micro drill bit to drill a few mm into each face of the break, then a piece of wire to bridge the joint.

Nelson Longflap

  • Riding a bike is meant to be easy ...
Re: A sticky situation
« Reply #11 on: 27 April, 2018, 05:58:58 pm »
Not sure about the plastic welding - not all plastics behave the same way.
I've written to the frame manufacturers in Denmark for technical advice on the plastic, and any recommendations for adhesives.  And made clear I'm not expecting any guarantees!

Don't think the specs will ever be the same again but you should be able to molish a working repair with planning!
I agree ... the important thing is to maintain the alignment of the lenses, it would be a real headache otherwise  :o

I'd also attempt to reinforce the joint. Perhaps a pin vice and a micro drill bit to drill a few mm into each face of the break, then a piece of wire to bridge the joint.
Very sound advice Philip, and in line with my first thoughts. My second thoughts were that I don't have the tools for such a delicate operation, and probably not the skills to use them successfully on a first attempt ... Andy's exoskeleton idea may be more doable given my skills, but wouldn't look as good.

Thanks for all the ideas  :)
The worst thing you can do for your health is NOT ride a bike

andytheflyer

  • Andytheex-flyer.....
Re: A sticky situation
« Reply #12 on: 27 April, 2018, 06:10:15 pm »
I'd also attempt to reinforce the joint. Perhaps a pin vice and a micro drill bit to drill a few mm into each face of the break, then a piece of wire to bridge the joint.

Exactly.  I'd do the same but I'm aware that whilst I have those small tools, not many do!  It needs a bit of 2mm steel rod - the sort I make servo rods from to actuate aeroplane control surfaces.  I thought about suggesting doweling the joint, and that would be a big help, that's a skill that not everyone has - and this is maybe not the place to attempt to develop that skill.  I successfully repaired some African hardwood salad servers that way but the joint was about 8mm across so I had a bit of room to play with. A specs bridge is going to be a tough one to get right.

A few holes through the reinforcing strip and into the frame (being careful not to go all the way through (!)) will certainly help the bond if that ends up being the preferred solution.

Whatever, simply bonding the broken surface is not going to be strong enough in the longer term.

Paul

  • L'enfer, c'est les autos.
Re: A sticky situation
« Reply #13 on: 27 April, 2018, 06:18:34 pm »
Or - and I’m just thinking outside of the box here - you could sew the lenses into a full face balaclava.
Might be tricky to travel in, mind.
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Re: A sticky situation
« Reply #14 on: 27 April, 2018, 06:44:26 pm »
I'd also attempt to reinforce the joint. Perhaps a pin vice and a micro drill bit to drill a few mm into each face of the break, then a piece of wire to bridge the joint.
^ This.
Absolutely.
You are going to need number drills, as opposed to those measured in millimetres or decimal point sizes thereof.
They are thinner than a thin thing - a model shop or watchmaker supplier could be your most effective source for these.
And piano wire.
If you are able to make more than one pin joint, so much the better.
With a steady hand, you should be able to make more than one hole on that area where it has fractured.
Don't worry too much that the holes on opposite sides of the fracture don't line up perfectly.
Do the best you can, and rely on rubbing down the excess adhesive to get a decent looking joint.
It's highly likely that the frames are acrylic - in which case any cyanoacrylate adhesive will do.
Personally, I'd go for one of the thicker ones as these have gap-filling properties although they are slower to cure.
You could use an accelerator but, as with most things, you don't get something for nothing - an accelerated bond is usually weaker than one which hasn't been accelerated.

FWIW I've used the above method to successfully repair broken mould formers with a wall thickness of 3mm or less on a number of occasions.

ETA - Oh, and I'd steer clear of Dichloromethane - it is a known carcinogen - I'm still trying to figure out what to do with the half litre of the stuff  I have in the cupboard under my stairs - But it looks like you have this covered upthread.



Mrs Pingu

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Re: A sticky situation
« Reply #15 on: 27 April, 2018, 07:04:03 pm »
My Dad welded his plastic frames back together with solvent years ago. Only thing he noticed was that the nose was a bit tighter than previously, but he had the frames where the nose pieces were part of the frame, rather than separate pads like you have, which will adjust a bit.
If you were going to try solvent make sure & not get it on your lenses :)

Alternatively if they're not too old could you buy the same frame again and get the lenses swapped over?
Do not clench. It only makes it worse.

Kim

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Re: A sticky situation
« Reply #16 on: 27 April, 2018, 08:24:36 pm »
If you were going to try solvent make sure & not get it on your lenses :)

I'd have thought step 1 would be to remove the lenses from the frames however you're going to attempt this.

Re: A sticky situation
« Reply #17 on: 27 April, 2018, 08:26:34 pm »
If you were going to try solvent make sure & not get it on your lenses :)

I'd have thought step 1 would be to remove the lenses from the frames however you're going to attempt this.
Indeed.
Dichlo will eat acrylic lenses.

Re: A sticky situation
« Reply #18 on: 27 April, 2018, 09:24:20 pm »
Have you tried a reglaze quote from ASDA?
Get a bicycle. You will never regret it, if you live- Mark Twain

Re: A sticky situation
« Reply #19 on: 28 April, 2018, 05:10:25 pm »
Gorilla glue would do it I think but the cramping might be tricky.

I'll happily 2nd ASDA as I have been using their opticians for oh 5 years+ now and my trifocals come in at £120 for two pairs.

PH
Bees do nothing invariably.

Nelson Longflap

  • Riding a bike is meant to be easy ...
Re: A sticky situation
« Reply #20 on: 29 April, 2018, 08:55:51 pm »
Thanks for all the excellent ideas, and the exotic left-field thoughts; I'm not quite ready yet for a steam-punk balaclava, but it's an intriguing prospect ...

I'm now tooled up with pin vice and some fine drill bits which were inexpensive and will I'm sure be handy for future micro-projects even if I don't use them on this one; I'll wait to hear from the frame manufacturers before doing anything in case they tell me something useful ...

Alternatively if they're not too old could you buy the same frame again and get the lenses swapped over?
This is the guaranteed to succeed advice. I did price up replacing just the front of the frame (ie transferring arms, lenses, and nose pieces). I got two quotes, from Boots and a small independent Optician, both were £190, which was enough to persuade me to try repairing the broken frame. And as a bonus I enhance my DIY skills  :thumbsup:

I'll take my time and aim to get things right first time, following advice here.

Yacf is wonderful - I was relatively clueless before posting here. Thanks again all round  :)
The worst thing you can do for your health is NOT ride a bike

iddu

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Re: A sticky situation
« Reply #21 on: 02 May, 2018, 01:22:02 pm »
If you’re not fussed about appearance, epoxy appropriately sized modelmakers tubing over the bridge ends...
I'd offer you some moral support - but I have questionable morals.

Re: A sticky situation
« Reply #22 on: 13 May, 2018, 03:40:14 pm »
Came across this. No idea if any good.
http://www.specfixer.co.uk/
Get a bicycle. You will never regret it, if you live- Mark Twain

Nelson Longflap

  • Riding a bike is meant to be easy ...
Re: A sticky situation
« Reply #23 on: 23 May, 2018, 01:40:43 pm »
Just to report back ... this wasn't my finest DIY moment. The join at the bridge is a tiny area, about 5 or 6 sq mm. My plan was to follow andytheflyer's advice to glue at the bridge then reinforce along the back of the bridge. I tried the rapid setting
  • epoxy, which cures to transparent, but I wasn't able to clamp the frames satisfactorily to enable curing without sagging. Cyanoacrylate glue dries fast but brittle, and the weight of the lenses quickly snapped the join before I could get started on the reinforcement. So, having satisfied myself that amateur repair isn't easy, I followed Mrs Pingu's advice to replace the frame (in fact just the front part worked out least expensive).


Thanks everybody for all the helpful advice  :thumbsup:

  • In this case, 'rapid' = around 24 hours to fully hard
The worst thing you can do for your health is NOT ride a bike

Re: A sticky situation
« Reply #24 on: 27 May, 2018, 06:52:49 pm »
Plastic frame? If you can get hold of it dichloromethane will do a plastic 'weld'

Thanks both. The frame is 100% plastic (sorry - I should have said in the OP).

(My bold) ... is there a good reason why dichloromethane may be hard to obtain? Just the name sounds carcinogenic  ???

It isn’t hard to obtain, you can get it on eBay.

Model shops do Plastiweld which is a liquid. Are they not covered on your house insurance?
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