Bending and welding acrylic sheet?

[John McNamaraParticipant @johnmcnamara74883]

Upon reflection from memory the Perspex sheets were bent by hand in mid air over a form than placed between two parallel cleats in a board until they had cooled sufficiently to hold their shape. there could be no blemishes on the bend it had to be perfect.

I am pretty sure the gap in the table was bounded by water filled steel tubes, so the radiant heat of the dull red element was narrow band under the Perspex.

The man that did this work was a fine craftsman he came from Westphalia Germany. I have lost contact… A pity.

Regards
john

Edited By John McNamara on 13/08/2017 09:00:08

[VicParticipant @vic]

I spoke to a guy who worked for a company who specialised in this type of work. One of the things he mentioned is that acrylic absorbs water and needs to be dried in an oven for several hours before any attempt is made to bend it.

[Russell EberhardtParticipant @russelleberhardt48058]

Am I the only grumpy old git who gets annoyed by the use of an adjective in place of a noun.

Acrylic sheet, yes. Acrylic plastic, yes. Acrylic, what does that mean? Have you ever heard of white metal being called white?

Sorry, end of rant.  Not getting at anyone here.  It seems to be common usage.

Russell

Edited By Russell Eberhardt on 13/08/2017 10:13:02

[MikeParticipant @mike89748]

Just out of curiosity, where does polycarbonate come into all this, or is it just another name for Perspex? Years ago I tested polycarbonate shooting glasses after a claim that they would deflect a .22 rifle bullet at 25 yards. In fact they just appeared to be "bulletproof" – the impact generated heat which caused the hole to close up after the bullet had passed through. Sorry to wander off the subject…

[mark smith 20Participant @marksmith20]

Posted by Eugene on 12/08/2017 19:22:56:

The method was to heat the chloroform up in a large glass beaker and dissolve powdered perspex in it.

Can't remember the quantities off hand, but I always made sure the fume cupboard was working before I started the job, and got the cigarette smokers out of the way!

Eug

Eugene chloroform isnt flammable.

[egaParticipant @ega]

Posted by Russell Eberhardt on 13/08/2017 10:10:40:

Am I the only grumpy old git who gets annoyed by the use of an adjective in place of a noun.

Acrylic sheet, yes. Acrylic plastic, yes. Acrylic, what does that mean? Have you ever heard of white metal being called white?

Sorry, end of rant. Not getting at anyone here. It seems to be common usage.

Russell

Edited By Russell Eberhardt on 13/08/2017 10:13:02

"acrylic" first appeared in the COD in the sixth edition of 1976 where it was both adjective and noun (in that order). My most recent popular dictionary (Chambers Concise) gives it first as a noun! By way of contrast, Collins COBUILD based on computer-analysed word frequency treats acrylic as an adjective.

"Wight" can be a noun.

I am certainly a GOG but I try not to get annoyed by these things.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Mike on 13/08/2017 10:14:45:

Just out of curiosity, where does polycarbonate come into all this, or is it just another name for Perspex? Years ago I tested polycarbonate shooting glasses after a claim that they would deflect a .22 rifle bullet at 25 yards. In fact they just appeared to be "bulletproof" – the impact generated heat which caused the hole to close up after the bullet had passed through. Sorry to wander off the subject…

Polycarbonate is not the same as Perspex. Perspex, Plexiglass, Lucite, etc., is polymethylmethacrilate. Polycarbonates are polymers with carbonate groups, much stronger than Perspex.

Russell

[Clive FosterParticipant @clivefoster55965]

Vic

Interesting comment about acrylic absorbing water and being tricky to bend if it isn't dried first. I wonder if thats the root reason for our standard practice back in the day being to always get new material if it was to be bent or glued. Stuff on the rack or in the cupboard being kept for simple flat windows and the like. Which, to be fair, was mostly what it was used for.

Mark

Whether or not a gas is flammable doesn't really affect the wisdom of getting cigarette smokers out of the way if there is a reasonable chance of anything beyond very minor leakage into the local air. Good chance of decomposition or reaction when the gas passes over the hot tip. Ofttimes with byproducts rather nastier than the original.

Clive.

[mark smith 20Participant @marksmith20]

Clive, i was just making the point as it reads like theres a risk of explosion.

Many people immediately assume its flammable due to the over powering smell,it also has a high boiling point compared to many  other flammable risk solvents.

The main risk with chloroform ,is if you have an old bottle of it lying about , it can decompose into phosgene gas (like used in trench warfare in WWI) Adding ethyl alcohol to the bottle if storing helps stop this. Most chlroform usually has this or something else in it but repeated opening the bottle causes loss of the alcohol .

Edited By mark smith 20 on 13/08/2017 11:55:04

[Clive FosterParticipant @clivefoster55965]

Cheers Mark

So it is chloroform which goes to phosgene then. Was fairly sure it went to something horrible but couldn't remember what.

Funny how what you know affects how you interpret what you read. Never occurred to me that what Eugene wrote could be taken as reference to fire or explosion risk. Absolutely right that it could be read that way. But I knew about the decomposition thing so that was all I saw.

Clive.

[Neil WyattModerator @neilwyatt]

The adhesive for acylic/perspex is called tensol. easily available, I suggest reading the MSDS and manufacturers data sheet.

I found it easy to sue, but some I got off ebay had gone thick and I couldn't suck it into a syringe.

Did a great job of gluing PLA to acrylic,

[CirclipParticipant @circlip]

" Was fairly sure it went to something horrible but couldn't remember what."

Same reason for not smoking over a "Trike" (Trichloroethylene) degreasing tank.

Regards Ian.

[Steve PaveyParticipant @stevepavey65865]

Posted by Neil Wyatt on 13/08/2017 12:58:32:

The adhesive for acylic/perspex is called tensol. easily available, I suggest reading the MSDS and manufacturers data sheet.

I found it easy to sue, but some I got off ebay had gone thick and I couldn't suck it into a syringe.

Did a great job of gluing PLA to acrylic,

We used to have two grades of Tensol, one as thin as water and the other quite viscous. Perhaps you were supplied with the latter?

[Neil WyattModerator @neilwyatt]

Posted by Russell Eberhardt on 13/08/2017 10:10:40:

Am I the only grumpy old git who gets annoyed by the use of an adjective in place of a noun.

Acrylic sheet, yes. Acrylic plastic, yes. Acrylic, what does that mean? Have you ever heard of white metal being called white?

Sorry, end of rant. Not getting at anyone here. It seems to be common usage.

The battle was lost on that word years ago, from Chambers:

acrylic noun any of various synthetic products derived from acrylic acid, especially acrylic fibre, acrylic paint or acrylic resin. adj relating to, containing or derived from acrylic acid.
ETYMOLOGY: 19c as acrylic acid; otherwise 20c: from Latin acer sharp + olere to smell.

[Dod MoleParticipant @georgeclarihew]

Acrylic, bit like doing the electroluxing.

Hoovering, as in vacuuming the floor, funny language this english

[Neil WyattModerator @neilwyatt]

Posted by mark smith 20 on 13/08/2017 10:25:29:

Posted by Eugene on 12/08/2017 19:22:56:

The method was to heat the chloroform up in a large glass beaker and dissolve powdered perspex in it.

Can't remember the quantities off hand, but I always made sure the fume cupboard was working before I started the job, and got the cigarette smokers out of the way!

Eug

Eugene chloroform isnt flammable.

No, but smoking in the presence of chlorine-containing vapours is not conducive to long life and happiness.

[Alan VosParticipant @alanvos39612]

+1 for using neat chloroform to weld well-fitting perspex joints. They guy who did it machined the parts on a mill, clamped them all up, then ran chlorofom into the joints with a syringe. Very little solvent used. No special ventilation. (1980)

[EugeneParticipant @eugene]

Eugene chloroform isnt flammable.

No, but smoking in the presence of chlorine-containing vapours is not conducive to long life and happiness.

How true. I've seen the result, hence the precaution.

Eug

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