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Re: Working wiht plexiglasss - little off the subject
--- In Electronics_101@..., jong kung <jongkung01@...> wrote:
For glued edges, you don't need it to be polished. And in my experience, and from my plastics people at PSI in Tacoma, never glue flame-polished edges.I would like to use plexiglass as my project Steve Greenfield AE7HD |
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Re: Working wiht plexiglasss - little off the subject
On 26/01/2011 16:03, vaclav_sal wrote:
I would like to use plexiglass as my project enclosure (so everybody can see my messy design!)Methylene chloride dissolves it, and can be used to "solvent-weld" it. How do you polish plexiglass? ( The cut edges need to be polished) Toothpaste works well, but you can buy a special polish. Leon -- Leon Heller G1HSM |
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Re: Working wiht plexiglasss - little off the subject
Square tight fits make for a strong joint. I glue a facing dish to my table
saw blade before cutting to get square cuts, then just hit the edge lightly with sandpaper before gluing. Glad you brought plexiglass up as I need to build a go box for my radio gear, one where the radio stays mounted and you just grab it and go, take it out set it up connect power antenna and you are transmitting. Either that or make out of wood. 73 Tom kf5feo From: jong kung [mailto:jongkung01@...] Sent: Wednesday, January 26, 2011 10:58 AM To: Electronics_101@... Subject: RE: [Electronics_101] Working wiht plexiglasss - little off the subject BUT, you have to be really really careful not to round the edges...On the TV show, it did round the edge (ever so slightly). But they wanted that effect. But why would rounded edge be bad? Would that create a place for the "crack" to start? Or you are saying that complete square edge would look better attached to another 90 degree edge. Just curious. I have no opinion either way. Jong |
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Re: Working wiht plexiglasss - little off the subject
typically rounded edges are done with a round over router bit, then the
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faces are polished. It is all a matter of taste, and structural requirements. High end shops will anneal the material after each machining, solvent welding and polishing step to relieve all stress and prevent crazing in the future. (sorry I used to own a aquarium and filtration manufacturing company in the 90s, this was my daily work) On 1/26/2011 11:57 AM, jong kung wrote:
BUT, you have to be really really careful not to round the edges...On the TV show, it did round the edge (ever so slightly). But they |
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Re: Working wiht plexiglasss - little off the subject
MEK is the common plexi solvent welding material, also another material
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called resin-bond, or craftics cement 44 The joint is only going to be as good as your prep work. The cleanest joints are completely true, fine finished to a 200 grit and then capillary filled on a floating bed using very fine wire to suspend the sheet. Most vendors simply flame polish with a torch, better vendors use a combination of sanding papers up to 2000 grit and plastic polish, and or a slow buff and a white polishing compound. These are labor intensive methods. On 1/26/2011 11:03 AM, vaclav_sal wrote:
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Re: Working wiht plexiglasss - little off the subject
They have a special glue for plexiglass and you polish it the same way as
metal. For a trick painted look, paint it on the inside and let the color show thru or you can paint it on the outside just as you would metal. You can tap and screw it together if your pieces are thick enough and cut it just like wood. Hope this might help 73 Tom kf5feo From: rtstofer [mailto:rstofer@...] Sent: Wednesday, January 26, 2011 10:31 AM To: Electronics_101@... Subject: [Electronics_101] Re: Working wiht plexiglasss - little off the subject --- In Electronics_101@... <mailto:Electronics_101%40yahoogroups.com> , "vaclav_sal" <vaclav_sal@...> wrote: see my messy design!) and if not accessible it looks crappy. (So what if they use it to get fingerprints.)plexi. Thanks for reading.Almost everything you need will be available at Tap Plastics: MEK (methyl ethyl ketone) is often used to join acrylics as all you really do is melt the surfaces together. There is a special 'dropper bottle' that has a metal needle to dispense directly into joints. It doesn't take much and the surface tension of MEK is probably zero. It flows everywhere. Cant the assembly such that the MEK is flowing down into the joint. You can sand the edges to get them fairly smooth and then hit them lightly with a torch. Practice on some scrap first. There are some plastic polishes available on the web site. I frequently use acrylic sheets to build electronic projects because it is easier to obtain than aluminum sheets and is very easy to cut and assemble. Richard |
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Re: Working wiht plexiglasss - little off the subject
I think teller glazing is polycarbonate (Lexan) for impact resistance
? ________________________________ From: jong kung <jongkung01@...> To: Electronics_101@... Sent: Wed, January 26, 2011 10:21:37 AM Subject: Re: [Electronics_101] Working wiht plexiglasss - little off the subject ? I would like to use plexiglass as my project
What to use for gluing. ==== Besides that, I saw on Modern Marvels they use a torch heat to make the sawed off ends clean and ice like.?? This was the kind of plexiglass used for bank tellers.? I would try it out on scrap plexiglass and do some experiments first. Jong [Non-text portions of this message have been removed] [Non-text portions of this message have been removed] |
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Re: Working wiht plexiglasss - little off the subject
BUT, you have to be really really careful not to round the edges...On the TV show, it did round the edge (ever so slightly).? But they wanted that effect. But why would rounded edge be bad?? Would that create a place for the "crack" to start?? Or you are saying that complete square edge would look better attached to another 90 degree edge. Just curious. I have no opinion either way. Jong [Non-text portions of this message have been removed] |
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Re: Working wiht plexiglasss - little off the subject
solvent glueing is the old?tried and true method
? "And of what kind are the men that will strive for this profitable preeminence, through all the bustle of cabal, the heat of contention, the infinite mutual abuse of parties, tearing to pieces the best of characters? It will not be the wise and moderate, the lovers of peace and good order, the men fittest for the trust. It will be the bold and the violent, the men of strong passions and indefatigable activity in their selfish pursuits. These will thrust themselves into your government and be your rulers."- Excerpt from "Dangers of a Salaried Bureaucracy" addressed to the Constitutional Convention members by Benjamin Franklin in 1787 ________________________________ From: vaclav_sal <vaclav_sal@...> To: Electronics_101@... Sent: Wed, January 26, 2011 10:03:28 AM Subject: [Electronics_101] Working wiht plexiglasss - little off the subject ? I would like to use plexiglass as my project enclosure (so everybody can see my messy design!) My questions: What to use for gluing. Superglue leaves nasty residue film on everyting and if not accessible it looks crappy. (So what if they use it to get fingerprints.) It needs to be strong, fast drying and absolutely invisible. How do you polish plexiglass? ( The cut edges need to be polished) I recall using toothpaste, but there must be something made specificly for plexi. Thanks for reading. Vaclav AA7EJ [Non-text portions of this message have been removed] |
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Re: Working wiht plexiglasss - little off the subject
James M. \(Jim\) Geidl
BUT, you have to be really really careful not to round the edges...and it
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happens real quick. Richard suggested practicing on some scrap and that is a great idea. James "Jim" M. Geidl, K6JMG No trees were harmed in the sending of this message; however, a large number of electrons were terribly inconvenienced. -----Original Message----- |
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Re: Working wiht plexiglasss - little off the subject
--- In Electronics_101@..., "vaclav_sal" <vaclav_sal@...> wrote:
Almost everything you need will be available at Tap Plastics: MEK (methyl ethyl ketone) is often used to join acrylics as all you really do is melt the surfaces together. There is a special 'dropper bottle' that has a metal needle to dispense directly into joints. It doesn't take much and the surface tension of MEK is probably zero. It flows everywhere. Cant the assembly such that the MEK is flowing down into the joint. You can sand the edges to get them fairly smooth and then hit them lightly with a torch. Practice on some scrap first. There are some plastic polishes available on the web site. I frequently use acrylic sheets to build electronic projects because it is easier to obtain than aluminum sheets and is very easy to cut and assemble. Richard |
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Re: Working wiht plexiglasss - little off the subject
James M. \(Jim\) Geidl
Vaclav
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You may polish it with fine sandpaper then rubbing compound. Remember, if you are polishing the edges you want to keep them flat and square if they are to be glued to another piece of plastic, therefore, sand and polish against a flat surface to avoid rounding them over. You can also use a jointer or power plane very effectively. Put the edges together that you wish to join with some blue masking tape and take acetone in a syringe and run it along the seam. It will wick into the joint and that's it. James "Jim" M. Geidl, K6JMG No trees were harmed in the sending of this message; however, a large number of electrons were terribly inconvenienced. -----Original Message----- |
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Re: Working wiht plexiglasss - little off the subject
I would like to use plexiglass as my project
What to use for gluing. ==== Besides that, I saw on Modern Marvels they use a torch heat to make the sawed off ends clean and ice like.?? This was the kind of plexiglass used for bank tellers.? I would try it out on scrap plexiglass and do some experiments first. Jong [Non-text portions of this message have been removed] |
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Re: Working wiht plexiglasss - little off the subject
acetone is the best for gluing
On Wed, Jan 26, 2011 at 10:03 AM, vaclav_sal <vaclav_sal@...> wrote:
[Non-text portions of this message have been removed] |
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Re: Working wiht plexiglasss - little off the subject
If I recall correctly, "plexiglass" is an old trade name that DuPont Corp. used for their version
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of a particular acrylic material. Every plastics manufacturer had a trade name for their various products. So, first you must know exactly the generic or technical name for the material you are working with. Then, you can find the correct adhesive for that particular material, and how to cut, mold and/or machine that material. You can Google the trade name of the material you want to work with, and then find the correct methodologies for working with that material All of these "plastics" ...whatever they are called commercially, are specific polyresin formulations, each requiring different working techniques. There is no "one adhesive fits all" situation. If you use the wrong technology with a particular material, you wind up with a ugly, unstable, cracked and warped mess. Roland F. Harriston, P.D. **** vaclav_sal wrote: I would like to use plexiglass as my project enclosure (so everybody can see my messy design!) |
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Working wiht plexiglasss - little off the subject
I would like to use plexiglass as my project enclosure (so everybody can see my messy design!)
My questions: What to use for gluing. Superglue leaves nasty residue film on everyting and if not accessible it looks crappy. (So what if they use it to get fingerprints.) It needs to be strong, fast drying and absolutely invisible. How do you polish plexiglass? ( The cut edges need to be polished) I recall using toothpaste, but there must be something made specificly for plexi. Thanks for reading. Vaclav AA7EJ |
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Re: question
How hard would it be to build it and drive an LCD display instead?That depends on your skill level.? In one of my old electronics mag, basically they build an "o-scope" by basically (a) inputting the voltage - aka probe (b) sample the voltage - aka Analog to Digital conversion (c) drive some LED matrix circuit In essence you just need to replace the LED matrix to some sort of LCD screen.? You can send the voltage level to a PC and graph it, OR use a microcontroller like AVR Butterfly (a microcontroller & LCD in one package for $20). The AVR butterfly may or may NOT not be the best way.? If I understand correctly, most of the IO pins are taken up by the LCD I/O.? I don't know first had.? You need to do a little research. Of course this is all general theory.? You need to work out the details.? That's really the hard part.? :-( There are plenty of people online who sell DIY LCD o-scope kits.? They are usually low freq (not bad for home robot projects) and something single trace (always bad idea).? Let google be your best friend.? :-) ===== What SG wrote previously is something to consider too.? You really need a baseline of good and accurate meters and test equipments (DMM, o-scope, signal generator, etc.) before you should make and use home-made versions.? Basically if your base yardstick is IFFY, how do you know what else is accurate (or inaccurate). Jong [Non-text portions of this message have been removed] |
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Re: question
Ok, so the CRT for a scope isn't something I want to do then. I just need a scope and I don't want to drop even a couple of hundred for one right now. I was looking at one in a Forrest Mimms book that I have and thinking of building it. But the 100 LED display looked a little lame. How hard would it be to build it and drive an LCD display instead?
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I do have 100 red LED's coming and I may go that route. Right now all I need to do is some testing on a robot that I am building. It is the Insectronics robot from the book and it is my first attempt at building a robot. --- In Electronics_101@..., "Roland F. Harriston" <rolohar@...> wrote:
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Cheap (inexpensive) Oscilloscopes Re: question
How much do you want for them?
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--- In Electronics_101@..., "AlienRelics" <alienrelics@...> wrote:
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Steven AE7HD
Leon
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