Has anybody ever tried to melt and re-cast records to use as a blank to start from. I have this box of "not to my taste" records that have been taking up space in my garage. I was thinking it might be possible to melt them down in a double boiler bath with an oil as the boiling liquid then cast into a simple round mould and turn on a lathe.
Maybe this is too far out there.
Dumb idea?
Maybe this is too far out there.
Dumb idea?
Poindexter said:
Can you post the specs. pertaining to the "lower Qm" for both acrylic and polycarbonate? I can't find any such info anywhere.
Actually, from what I can find Acrylic is slightly denser than Polycarbonate. I don't think you need a material deader than acrylic. It's already a very inert material.
http://www.machinist-materials.com/comparison_table_for_plastics.htm
Polycarbonate density
0.043 Density (lb/in³)
Acrylic density
0.044 Density (lb/in³)
SCD...
some time ago I suggested a glued and stacked platter made of old records (only the worst possible records to be used of course)...
As far as density goes, with a little more research...
PVC record compound: 1.34g/cc
acrylic, cast (as most pieces are cast and then machined): 1.18-1.19g/cc
polycarbonate: .950-1.54, g/cc, 1.20g/cc average
Lexan (DuPont, polycarbonate): 1.19g/cc
later,
stew
some time ago I suggested a glued and stacked platter made of old records (only the worst possible records to be used of course)...
As far as density goes, with a little more research...
PVC record compound: 1.34g/cc
acrylic, cast (as most pieces are cast and then machined): 1.18-1.19g/cc
polycarbonate: .950-1.54, g/cc, 1.20g/cc average
Lexan (DuPont, polycarbonate): 1.19g/cc
later,
stew
Yah, all that stuff is somewhat variable, as all the manufacturers have their own secret sauce.
I based my read just on feel, as I worked with both materials in another life, back in Honolulu in the seventies and eighties. The polycarb (actually Tuffak) felt a little denser to me, and the difference in resonant qualities was quite noticeable. If I held a piece (say, a couple sqare feet) of Plex by a corner and tunked it with a fingernail, it would ring some. The polycarb was more flexible, and sort of leathery, tough; it just went thud. Gimme a break, I'm an instrument maker; tunking stuff is, like, a compulsion.
I can see, however, how that tough nonresonant character might make the polycarb a lot more of a headache to machine accurately.
P
I based my read just on feel, as I worked with both materials in another life, back in Honolulu in the seventies and eighties. The polycarb (actually Tuffak) felt a little denser to me, and the difference in resonant qualities was quite noticeable. If I held a piece (say, a couple sqare feet) of Plex by a corner and tunked it with a fingernail, it would ring some. The polycarb was more flexible, and sort of leathery, tough; it just went thud. Gimme a break, I'm an instrument maker; tunking stuff is, like, a compulsion.
I can see, however, how that tough nonresonant character might make the polycarb a lot more of a headache to machine accurately.
P
SCD said:
I think it's clever, though I was reading further up the thread, thought it up, then found your post beating me to it, so consider the source.
But, I think you could take an existing platter, make a plaster cast, then pour in the hot vinyl. You might even just take a tub of plaster and push a record into it to make the cast. You'd probably need to do some sanding ans shaping after, but you'd have to do that anyway.
dsavitsk...
the moulding method may not be that great, but SCD has some excellent machining capabilities (ask to see some pix of his stuff...it's absolutely gorgeous)...
Poindexter, it does make absolute sense. Think of Lexan vs regular old acrylic or polycarbonate sheet. hit it with a hammer or a sharp object...the poly/acrylic usually shatters, the Lexan doesn't. That in itself suggests that the Lexan is better at energy dissipation than the regular old poly/acrylic.
One thing that continues to blow me away is the idea that somehow massive/denser, blah, blah blah, is the way to go in audio. From my own personal experience I can say that often (although counter intuitive) the opposite holds true. Lighter stuff doesn't store as much energy, it can dissipate the energy introduced to it at a much faster rate. This of course does not help the idea of using a platter as a flywheel ...but there are very easy ways to overcome the lower mass (because , after all, the mass only serves one purpose and that is to conserve the angular momentum and hence the Inertia).
peace out ..
stew
the moulding method may not be that great, but SCD has some excellent machining capabilities (ask to see some pix of his stuff...it's absolutely gorgeous)...
Poindexter, it does make absolute sense. Think of Lexan vs regular old acrylic or polycarbonate sheet. hit it with a hammer or a sharp object...the poly/acrylic usually shatters, the Lexan doesn't. That in itself suggests that the Lexan is better at energy dissipation than the regular old poly/acrylic.
One thing that continues to blow me away is the idea that somehow massive/denser, blah, blah blah, is the way to go in audio. From my own personal experience I can say that often (although counter intuitive) the opposite holds true. Lighter stuff doesn't store as much energy, it can dissipate the energy introduced to it at a much faster rate. This of course does not help the idea of using a platter as a flywheel ...but there are very easy ways to overcome the lower mass (because , after all, the mass only serves one purpose and that is to conserve the angular momentum and hence the Inertia).
peace out ..
stew
Well I am still thinking the recycled record concept has some possibilities. The wikopedia referenence indicates it has an 80'c melting point. Tha seems a little low to me but if it is accurate then it will be even easier to experiment.
dsavitsk has helped me along with my idea. A simple plaster cast or anything similar, that is just a bit bigger than the diameter of the desired circle will work for the casting. You could even make the mould from a stack of 3/4" plywood ssections with a +-13" hole in them. Use a bit of cling wrap as a liner and you have a simple mould made.
A person will need a lathe to do the turning. Given the diameter of the disc, it will need to be a lathe of a decent size. I would think the lathe would have to be capable of swinging a 14" disc at least.
Maintaining a constant temperature in the melting pot so as not to over heat the plastic will be important.
The turning and shaping part will likely be by design then trial and error.
I think it has potential
Becoming less of a dumb idea?
dsavitsk has helped me along with my idea. A simple plaster cast or anything similar, that is just a bit bigger than the diameter of the desired circle will work for the casting. You could even make the mould from a stack of 3/4" plywood ssections with a +-13" hole in them. Use a bit of cling wrap as a liner and you have a simple mould made.
A person will need a lathe to do the turning. Given the diameter of the disc, it will need to be a lathe of a decent size. I would think the lathe would have to be capable of swinging a 14" disc at least.
Maintaining a constant temperature in the melting pot so as not to over heat the plastic will be important.
The turning and shaping part will likely be by design then trial and error.
I think it has potential
Becoming less of a dumb idea?
SCD said:
How about some sort of epoxy, like what they use to pot transformers, or fill in the ends of caps in metal tubes?
An externally hosted image should be here but it was not working when we last tested it.
For making a mold, you might also start with a block of something -- a couple pieces of plywood glued together -- and machine it out with a router.
at the student machine shop (read - old equipment)i have cut acrylic on a lathe on several occasions.
i use kerosene as a lubricant and have found that a sharp hard cutting tool is essential. a carbide tool is the best that i've used - there may be something better.
there have been some other good material suggestions but one i don't think has been mentioned is delran. delran is much easier to machine and cheaper than acrylic (doesn't come on cool colors though). not sure how susceptible it is to warping though.
i use kerosene as a lubricant and have found that a sharp hard cutting tool is essential. a carbide tool is the best that i've used - there may be something better.
there have been some other good material suggestions but one i don't think has been mentioned is delran. delran is much easier to machine and cheaper than acrylic (doesn't come on cool colors though). not sure how susceptible it is to warping though.
okapi said:
A water soluble coolant works best in machining acrylic, at least in my experience. Delrin (trademarked by Dupont) costs me more than acrylic. Are you sure you're not talking about a generic acetal rather than Delrin?
Any plastic or performance plastic will warp or move during machining, especially if excessive tool force or heat is generated during the cutting process. The key to success is cutting all surfaces to remove stress as equally as possible. I've been machining various performance plastics for the past 25 years without issue but I have the proper tools and equipment to do the job.
be careful remelting vinyl as a diy project. It is very combustible and the smoke is toxic and carcinogenic. Although of course the construction products industry, biggest consumer of PVA's, would say otherwise. Also, the vinyl used in records may have some filler that further complicates remelting. If you are intent on trying it, chop up the vinyl into as uniformly small pieces possible and do it outside.
Any plastic casting usually suffers from bubbles. As molten plastic cools it shrinks; open casting a platter would produce a concave top surface.
Flame or vapour honing most plastics, commonly done for fabricated plastics like display cabinets, is a very quick process with beautiful results. But disastrous long term as both methods depolymerize the plastic where flamed or vapoured. Over time this produces internal cracks which just continue to grow and become very unsightly, eventually the edges start to chip and break.
Any professional machine shop can machine polycarbonate or acrylic with a very uniform surface. Hand polishing the edges doesn't take too long and is the only way to ensure long lasting water clear appearance.
Model builders or rapid protoyping shops usually can cast urethane, including clear, in greatly varying densities. Some also do vacuum assist casting to minimize bubbles. Although commercial, it's not too expensive.
Any plastic casting usually suffers from bubbles. As molten plastic cools it shrinks; open casting a platter would produce a concave top surface.
Flame or vapour honing most plastics, commonly done for fabricated plastics like display cabinets, is a very quick process with beautiful results. But disastrous long term as both methods depolymerize the plastic where flamed or vapoured. Over time this produces internal cracks which just continue to grow and become very unsightly, eventually the edges start to chip and break.
Any professional machine shop can machine polycarbonate or acrylic with a very uniform surface. Hand polishing the edges doesn't take too long and is the only way to ensure long lasting water clear appearance.
Model builders or rapid protoyping shops usually can cast urethane, including clear, in greatly varying densities. Some also do vacuum assist casting to minimize bubbles. Although commercial, it's not too expensive.
The other downside to flame polishing is the risk of completely ruining the platter if not done correctly. You only get one shot at it.
Thanks for the words of caution. The melting temp I found on the internet seems a little low @ 80'c. To test this I was planning on puttng a few chucks of vinyl in a boilng water bath to see if it melts or softens to a usable consistency. If it does not melt to a pourable consistency then I will try an double boiler oil bath and raise the temp until I get it to flow. If I keep the vinyl temp low I am hoping it will not be a problem to pour into a mould. A slow gentle pour into a room temp mould may work out fine. I plan on turning the casting on a lathe to create the final shape once cooled.
We shall see. Any other thoughts or comments
We shall see. Any other thoughts or comments
Scott....
did a search for PVC record compound, and for the thermal properties.
The numbers I ended up with suggest a melting point of 180℃ at that temperature vapour will be given off and the flash point of the vinyl may be approached. As you live in a nice temperate climate, at a minimum, I'd do all of this outside. Please be careful (cause I like ya enough to want to see you sometime in the future...).
stew
did a search for PVC record compound, and for the thermal properties.
The numbers I ended up with suggest a melting point of 180℃ at that temperature vapour will be given off and the flash point of the vinyl may be approached. As you live in a nice temperate climate, at a minimum, I'd do all of this outside. Please be careful (cause I like ya enough to want to see you sometime in the future...).
stew
Thanks Stew:
I thought the temp I found on Wikipedia was a lot cool. As I said I am going to try this in an oil bath double boiler set up. I will be using old pots and a cooking oil outside. 180'c should be achievable without too much trouble.
Sort of like melting chocolate. Just real hot.
What could go wrong? (Other than the obvious!)
I thought the temp I found on Wikipedia was a lot cool. As I said I am going to try this in an oil bath double boiler set up. I will be using old pots and a cooking oil outside. 180'c should be achievable without too much trouble.
Sort of like melting chocolate. Just real hot.
What could go wrong? (Other than the obvious!)
laser cutting...
I've had some acrylic laser cut in the past.
Just as when you mechanically cut acrylic, with a laser it cuts and then re-melts. Sometimes some "chipping" occurs when you finally get it cut, and "break" it apart.. This was with a relatively small laser. There are more powerful lasers out there for cutting metal, but I think using high pressure water (Water jet?), or mechanical means (with appropriate solvent/lubricant) may be the best bet.
Obviously a lathe would be the way to go, but at the correct cutting speed, with lubricant, and with very sharp tools.
scd: have you managed the vinyl poured platter yet?.
stew
I've had some acrylic laser cut in the past.
Just as when you mechanically cut acrylic, with a laser it cuts and then re-melts. Sometimes some "chipping" occurs when you finally get it cut, and "break" it apart.. This was with a relatively small laser. There are more powerful lasers out there for cutting metal, but I think using high pressure water (Water jet?), or mechanical means (with appropriate solvent/lubricant) may be the best bet.
Obviously a lathe would be the way to go, but at the correct cutting speed, with lubricant, and with very sharp tools.
scd: have you managed the vinyl poured platter yet?.
stew
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