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Cracked Acrylic - how to repair?

G

GruntPuppy

pfm Member
The path to turntable happiness is never smooth. I received a second-hand SRM Azure plinth kit, and thanks to the gentle care of Hermes there's a crack in the lower acrylic plate, near to the motor bolt-down point.

Can any of you recommend a glue or specific acrylic repair product that I could use to bring this back to life?

I really don't want to send this back - I won't get another chance at this product at the price I paid, and if I can repair it I will.

JG9vne.jpg
 
A cyanoacrylate should work, choose a low viscosity grade so it will wick into the crack. I would also consider carefully drilling a small hole at the very end of the current crack to prevent it progressing.
 
Forget it.
There is a 25-yer-old star crack in my LP12 lid from when I managed to drop a heavy, pointed object on it. It is the same today as then.
You would only hide the crack, if "glued", if the glue had the same refractive index as the acrylic, which would be a miracle.

The other hassle with using any liquid to join the crack is that it would flow across the acrylic as much as it would wick into any crack, especially if the desired (very) low viscosity.

Unfortunately, whether the crack will run can only be determined in retrospect..... A minute drill at the end of it would almost guarantee that it wouldn't though, if you have such a drill and good eye-sight and a steady hand. It rather depends on the real cause of the crack - shoddy handling seems unlikely, to be honest, especially if that is the only hassle, so internal stresses seems more likely, and it will run if that is the case.
 
Sadly, I have a "before" pic from the seller showing the plate before despatch - with no crack. Unfortunately the post-Hermes situation is - crack. The Pure-AV that was delivered by the same driver - thank goodness the box was well packed, because the outer packaging looks like it's been the star of a football match, ie the ball.

I could drill out at one end of the crack, but it would be extremely tricky to do so at the other end - which itself is near a motor bolt-down hole - so this area is going to be subject to vibration.

I'm beginning to think it would be best to wash my hands of this, and put in a received damage request for cancellation from eBay. I really don't want to, but I don't see much in the way of options here :(
 
Chloroform will do it without too much fuss ........judicious use of masking tape helps.
Not always a strong bond but easy to persuade into the crack (which will be clean I would think)
 
miktec said:
Chloroform will do it without too much fuss ........judicious use of masking tape helps.
Not always a strong bond but easy to persuade into the crack (which will be clean I would think)
Click to expand...

It's just a shame it's so bloody hard to get hold of! A solvent adhesive should have the necessary thinness of viscosity to be subject to capillary action. I would like to drill out the ends of the crack to prevent it spreading, but it's in a fussy area. I really am in a quandary with this.
 
GruntPuppy said:
Sadly, I have a "before" pic from the seller showing the plate before despatch - with no crack. Unfortunately the post-Hermes situation is - crack. The Pure-AV that was delivered by the same driver - thank goodness the box was well packed, because the outer packaging looks like it's been the star of a football match, ie the ball.
Click to expand...

So the box that this was delivered in was OK?
If there was internal stress, it could perfectly well crack in transit, no major mishandling required.

Chloroform? Acrylic soluble in chloroform??????? It really isn't viscosity either, it is surface tension that would draw anything into a crack - viscosity would determine speed.
Acetone would be just as good, or a better solvent - FAR more generally available.
 
Vinny said:
So the box that this was delivered in was OK?
If there was internal stress, it could perfectly well crack in transit, no major mishandling required.

Chloroform? Acrylic soluble in chloroform??????? It really isn't viscosity either, it is surface tension that would draw anything into a crack - viscosity would determine speed.
Acetone would be just as good, or a better solvent - FAR more generally available.
Click to expand...

The box had seen better days, the packing was piss-poor - not enough absorption packing around the outside, or on top or bottom.

Since the solvents used seem to be highly volatile, a thinner solvent would be better, so that the capillary action is as fast as possible. I've gone for one that sets rapidly, and evaporates cleanly (allegedly - time will tell). I really don't fancy spending £60 on chloroform - smallest quantity I could buy is rather more than I need! That said, this 50ml bottle is massively more than I expect to use, and the warning is that once the seal is pierced the solvent will evaporate within a fortnight.
 
GruntPuppy said:
Since the solvents used seem to be highly volatile, a thinner solvent would be better, so that the capillary action is as fast as possible. I've gone for one that sets rapidly, and evaporates cleanly (allegedly - time will tell). I really don't fancy spending £60 on chloroform - smallest quantity I could buy is rather more than I need! That said, this 50ml bottle is massively more than I expect to use, and the warning is that once the seal is pierced the solvent will evaporate within a fortnight.
Click to expand...

Solvents are basically all "thin", all the common ones anyway. Solvents do not set, they dissolve the plastic either side of the join/crack, hopefully, essentially mixing the two surfaces together. To achieve that, they need to hang around for minutes. As I said, acetone would probably be the best/simplest choice. As for whatever you have bought evaporating from the bottle within 2 weeks...………………….. I have some polyethylene bottles of MEK in my garage that are 10+years old and they have lost 10-20%, in glass they'd have lost VERY little - you've been told a load of baloney.
 
I can find nothing on the website that states what it is or contains, but the fact that it specifically states no residue, it can only be a solvent. Legally, it will have to state on the bottle, what it is. In which case, odds-on, acetone. Acetone is the major ingredient (by far) in nail polish remover, but you couldn't use nail polish remover as it generally has some water and a humectant such as glycerine, added. If there is nail polish remover in the house, just check by smell when the bottle arrives. That price would get you a litre of acetone delivered from Amazon.

The process is usually called solvent welding - I have used it very successfully on PETG using MEK, but that was two sheet, laid together, which is the usual case. See how you get on, but be careful to use a minute amount and to mask as far as possible, the problem with masking being that the tape adhesive is very likely to be acetone-soluble, so may wick the acetone faster than the crack, leaving a milky finish, as far under the tape as it has wicked.
 
Vinny said:
I can find nothing on the website that states what it is or contains, but the fact that it specifically states no residue, it can only be a solvent. Legally, it will have to state on the bottle, what it is. In which case, odds-on, acetone. Acetone is the major ingredient (by far) in nail polish remover, but you couldn't use nail polish remover as it generally has some water and a humectant such as glycerine, added. If there is nail polish remover in the house, just check by smell when the bottle arrives. That price would get you a litre of acetone delivered from Amazon.

The process is usually called solvent welding - I have used it very successfully on PETG using MEK, but that was two sheet, laid together, which is the usual case. See how you get on, but be careful to use a minute amount and to mask as far as possible, the problem with making being that the tape adhesive is very likely to be acetone-soluble, so may wick the acetone faster than the crack, leaving a milky finish, as far under the tape as it has wicked.
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Thank you for the pointers. I'm planning on masking as much as I can, given the awkwardness of the space, and will be as careful as my trembly digits will allow. Depending on the success of the repair, I may well mask and blow over the machined recess with a black acrylic. It won't look to out of place, what with a lot of the fittings for the plinth kit being in gloss black. Who knows, it may persuade me to take the path of sanity, and not go with a gold-plated Audio Origami arm setup ;)

I wonder if AO do a black chrome...
 
Dicloromethane will bond acrylic and can be purchased. However if you are not to far (cb11) youi could give you some chloroform, or try a local sign shop.
 
Put in for an eBay claim/return. You've paid good money, the seller packed badly, what you've ended up with has little to no resale value.
If the seller has any sense they'll not want it back and give a partial refund, if not just send it back.
 
Vinny said:
Chloroform? Acrylic soluble in chloroform???????
Click to expand...

You sound surprised ...

Used to do a fair bit of acrylic bonding back in the '80s and Chloroform was generally recommended as the quick and easy option.
Acetone does the job but is quite nasty stuff to work with and gets very messy very quickly.
Proper two-part Tensol acrylic bonder is the best for corner joints etc. but far too thick for something like this ....
 
JimmyB said:
Put in for an eBay claim/return. You've paid good money, the seller packed badly, what you've ended up with has little to no resale value.
If the seller has any sense they'll not want it back and give a partial refund, if not just send it back.
Click to expand...

I would, but (1) I can't justify buying this product brand new, and (2) I've never seen another one for sale second hand.
 
miktec said:
You sound surprised ...

Used to do a fair bit of acrylic bonding back in the '80s and Chloroform was generally recommended as the quick and easy option.
Acetone does the job but is quite nasty stuff to work with and gets very messy very quickly.
Proper two-part Tensol acrylic bonder is the best for corner joints etc. but far too thick for something like this ....
Click to expand...

It's just a shame that chloroform is so carefully controlled, and expensive. To get hold of it, you have to buy quite large quantities I've found.
 
miktec said:
You sound surprised ...

Used to do a fair bit of acrylic bonding back in the '80s and Chloroform was generally recommended as the quick and easy option.
Acetone does the job but is quite nasty stuff to work with and gets very messy very quickly.
Proper two-part Tensol acrylic bonder is the best for corner joints etc. but far too thick for something like this ....
Click to expand...

Back in the 70's, when I started work with ICI, access to chloroform was restricted, in fact, all but banned, acetone, we slopped about by the 10's gallons, literally, the factory used (and recovered) thousands of gallons per week. You would rather use an anaesthetic than reasonably harmless, but flammable, acetone?

Chloroform is tricky to source for Joe Public for very good reasons.

http://www.labchem.com/tools/msds/msds/LC13040.pdf

http://www.labchem.com/tools/msds/msds/LC10420.pdf
 
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Ian G said:
Dichloromethane !
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And the obsession with methylene chloride is due to? Also rather unpleasant compared to acetone, one chlorine different to chloroform and not an especially good solvent for most acrylics.

Fantastic for cleaning paint brushes though, the original ingredient in Nitromors. The fact that it is no longer used in Nitromors, should tell you something.
 
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