There is a crack in the perspex dial glass of a radio. It runs from the mounting hole and ends somewhere in the middle of the dial glass.
1. How to stabilise the crack? In the old days people used to drill a small hole (1mm or less) right at he very end of the crack. Then the crack does not grow longer. Is this technique still valid?
2. Is there any clear material the crack can be (at least partially) filled with? I guess it shall have refraction index close to perspex, not dissolving the perspex and that can be polished later. Does such treatment exist? Perhaps furniture polish can be rubbed into the crack? Is it recommended, say to sparingly apply super-glue on the crack, which is very runny, and after it infiltrates the crack and hardens, polish the surface?
3. Is there any recommended way of cleaning the crack of dirt, grime, etc.beforehand -- so that the crack is less visible.
> There is a crack in the perspex dial glass of a radio. It runs from the
> mounting hole and ends somewhere in the middle of the dial glass.
> 1. How to stabilise the crack? In the old days people used to drill a small
> hole (1mm or less) right at he very end of the crack. Then the crack does
> not grow longer. Is this technique still valid?
Yes, but obviously you will still have to original crack to live with/
> 2. Is there any clear material the crack can be (at least partially) filled
> with? I guess it shall have refraction index close to perspex, not
> dissolving the perspex and that can be polished later. Does such treatment
> exist? Perhaps furniture polish can be rubbed into the crack? Is it
> recommended, say to sparingly apply super-glue on the crack, which is very
> runny, and after it infiltrates the crack and hardens, polish the surface?
Depends on how wide the crack is. Also, maybe you can super glue it together.
> 3. Is there any recommended way of cleaning the crack of dirt, grime,
> etc.beforehand -- so that the crack is less visible.
IMHO, it's always a good idea to clean stuff.
You do not say if the Perspex (plexiglass) is just a clear covering for the dial markings underneath on a metal dial or if the dial markings are on the Perspex.
If the first case (just a clear piece) replacement Plexiglass is available in many thicknesses and is very easy to work.
If the dial markings are on the Perspex (and are not white), then you can:
1) scan the original dial
2) "Fix" the crack with photo editing software.
3) Print the fixed scan on a transparent sheet of plastic as used for overhead projectors.
4) Fasten item from step 3 to new piece of Perspex.
If the dial markings are on the broken piece and -are- white, you may have a problem, as white is difficult to "print". Maybe change to gray or black???
On Feb 6, 5:10 pm, Carter <k...@ameritech.net> wrote:
> On 2/6/2012 5:46 AM, Alex Pogossov wrote:
> > Hello,
> > I might need an advice of the forum.
> > There is a crack in the perspex dial glass of a radio. It runs from the
> > mounting hole and ends somewhere in the middle of the dial glass.
> > 1. How to stabilise the crack? In the old days people used to drill a small
> > hole (1mm or less) right at he very end of the crack. Then the crack does
> > not grow longer. Is this technique still valid?
This is called "stop drilling". It works but you must be sure you get
the very end of the crack.
"Perspex" may or may not be the same as what is sold in the US as
"Plexiglass", or "Lucite".
In some cases there is a solvent that will liquify the plastic and
allow it to re-solidify acting as a glue. In some cases there is not.
> On 2/6/2012 5:46 AM, Alex Pogossov wrote:
>> Hello,
>> I might need an advice of the forum.
>> There is a crack in the perspex dial glass of a radio. It runs from the
>> mounting hole and ends somewhere in the middle of the dial glass.
>> 1. How to stabilise the crack? In the old days people used to drill a >> small
>> hole (1mm or less) right at he very end of the crack. Then the crack does
>> not grow longer. Is this technique still valid?
> Yes, but obviously you will still have to original crack to live with/
>> 2. Is there any clear material the crack can be (at least partially) >> filled
>> with? I guess it shall have refraction index close to perspex, not
>> dissolving the perspex and that can be polished later. Does such >> treatment
>> exist? Perhaps furniture polish can be rubbed into the crack? Is it
>> recommended, say to sparingly apply super-glue on the crack, which is >> very
>> runny, and after it infiltrates the crack and hardens, polish the >> surface?
> Depends on how wide the crack is. Also, maybe you can super glue it > together.
OK. I will try the super-glue
>> 3. Is there any recommended way of cleaning the crack of dirt, grime,
>> etc.beforehand -- so that the crack is less visible.
> IMHO, it's always a good idea to clean stuff.
Is alcohol the best?
> You do not say if the Perspex (plexiglass) is just a clear covering for > the dial markings underneath on a metal dial or if the dial markings are > on the Perspex.
> If the first case (just a clear piece) replacement Plexiglass is available > in many thicknesses and is very easy to work.
Unfortunately it is not just a clear flat piece. It is curved and has markings printed on it -- different colours for different bands. Most of them are white. So I can not easily make a reproduction and also must be very careful not to rub the print off when cleaning and handling.
>>> 3. Is there any recommended way of cleaning the crack of dirt, grime,
>>> etc.beforehand -- so that the crack is less visible.
>> IMHO, it's always a good idea to clean stuff.
> Is alcohol the best?
Now that you tell us it is a curved piece and has the bands printed on it, IMHO you are getting into very dangerous territory. There is no telling what might dissolve the printing; alcohol -may- be too strong, possibly even soap and water may make the printing go away. IIRC definitely do NOT use any glass cleaner with ammonia in it.
Sorry, but now that you mention the printing is on it and the piece is curved, you have a very delicate situation...
Possibly, maybe, try to glue it together with just a dot of super glue on the end of a toothpick...or due to the circumstances, you may just have to live with it.
Alex Pogossov wrote:
> "Carter" <k...@ameritech.net> wrote in message > news:jgpmkt$li4$1@dont-email.me...
>> On 2/6/2012 5:46 AM, Alex Pogossov wrote:
>>> Hello,
>>> I might need an advice of the forum.
>>> There is a crack in the perspex dial glass of a radio. It runs from the
>>> mounting hole and ends somewhere in the middle of the dial glass.
>>> 1. How to stabilise the crack? In the old days people used to drill a >>> small
>>> hole (1mm or less) right at he very end of the crack. Then the crack does
>>> not grow longer. Is this technique still valid?
>> Yes, but obviously you will still have to original crack to live with/
>>> 2. Is there any clear material the crack can be (at least partially) >>> filled
>>> with? I guess it shall have refraction index close to perspex, not
>>> dissolving the perspex and that can be polished later. Does such >>> treatment
>>> exist? Perhaps furniture polish can be rubbed into the crack? Is it
>>> recommended, say to sparingly apply super-glue on the crack, which is >>> very
>>> runny, and after it infiltrates the crack and hardens, polish the >>> surface?
>> Depends on how wide the crack is. Also, maybe you can super glue it >> together.
> OK. I will try the super-glue
>>> 3. Is there any recommended way of cleaning the crack of dirt, grime,
>>> etc.beforehand -- so that the crack is less visible.
>> IMHO, it's always a good idea to clean stuff.
> Is alcohol the best?
>> You do not say if the Perspex (plexiglass) is just a clear covering for >> the dial markings underneath on a metal dial or if the dial markings are >> on the Perspex.
>> If the first case (just a clear piece) replacement Plexiglass is available >> in many thicknesses and is very easy to work.
> Unfortunately it is not just a clear flat piece. It is curved and has > markings printed on it -- different colours for different bands. Most of > them are white. So I can not easily make a reproduction and also must be > very careful not to rub the print off when cleaning and handling.
>> Good luck and let us know how it works out.
> Thank you very much for the advice.
> Regards,
> Alex
I doubt that superglue will work with this plastic - test on the edge- see if you can bond a toothpick to the edge of the plastic with the superglue. I suspect it will not adhere.
Instead what you want is a plastic solvent - Methelyne Chloride/Dichloromethane - to bond the crack. This stuff is very volatile and difficult to work with nicely. If you can get a hold of a tiny syringe (Diabetic friend?) and use that to apply the solvent, that should work best. Get the solvent at a hobby shop. You want the liquid, not the glue form. May have to get a small bottle of it at a plastic shop.
This stuff MELTS the plastic, if dropped on the face it WILL soften the look (frosted) so be very careful when using it.
Don't breath the fumes either...
John :-#)#
-- (Please post followups or tech enquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com "Old pinballers never die, they just flip out."
Alex Pogossov <apogo...@tpg.com.au> wrote:
>>> 3. Is there any recommended way of cleaning the crack of dirt, grime,
>>> etc.beforehand -- so that the crack is less visible.
>> IMHO, it's always a good idea to clean stuff.
> Is alcohol the best?
Never use alcohol on perspex / plexiglas. It causes cracking.
-- David Griffith
davidmylastn...@acm.org <--- Put my last name where it belongs
>>>> 3. Is there any recommended way of cleaning the crack of dirt, grime,
>>>> etc.beforehand -- so that the crack is less visible.
>>> IMHO, it's always a good idea to clean stuff.
>> Is alcohol the best?
> Now that you tell us it is a curved piece and has the bands printed on it, > IMHO you are getting into very dangerous territory. There is no telling > what might dissolve the printing; alcohol -may- be too strong, possibly > even soap and water may make the printing go away. IIRC definitely do NOT > use any glass cleaner with ammonia in it.
> Sorry, but now that you mention the printing is on it and the piece is > curved, you have a very delicate situation...
> Possibly, maybe, try to glue it together with just a dot of super glue on > the end of a toothpick...or due to the circumstances, you may just have to > live with it.
> Alex Pogossov wrote:
>> "Carter" <k...@ameritech.net> wrote in message >> news:jgpmkt$li4$1@dont-email.me...
>>> On 2/6/2012 5:46 AM, Alex Pogossov wrote:
>>>> Hello,
>>>> I might need an advice of the forum.
>>>> There is a crack in the perspex dial glass of a radio. It runs from the
>>>> mounting hole and ends somewhere in the middle of the dial glass.
>>>> 1. How to stabilise the crack? In the old days people used to drill a >>>> small
>>>> hole (1mm or less) right at he very end of the crack. Then the crack >>>> does
>>>> not grow longer. Is this technique still valid?
>>> Yes, but obviously you will still have to original crack to live with/
>>>> 2. Is there any clear material the crack can be (at least partially) >>>> filled
>>>> with? I guess it shall have refraction index close to perspex, not
>>>> dissolving the perspex and that can be polished later. Does such >>>> treatment
>>>> exist? Perhaps furniture polish can be rubbed into the crack? Is it
>>>> recommended, say to sparingly apply super-glue on the crack, which is >>>> very
>>>> runny, and after it infiltrates the crack and hardens, polish the >>>> surface?
>>> Depends on how wide the crack is. Also, maybe you can super glue it >>> together.
>> OK. I will try the super-glue
>>>> 3. Is there any recommended way of cleaning the crack of dirt, grime,
>>>> etc.beforehand -- so that the crack is less visible.
>>> IMHO, it's always a good idea to clean stuff.
>> Is alcohol the best?
>>> You do not say if the Perspex (plexiglass) is just a clear covering for >>> the dial markings underneath on a metal dial or if the dial markings are >>> on the Perspex.
>>> If the first case (just a clear piece) replacement Plexiglass is >>> available in many thicknesses and is very easy to work.
>> Unfortunately it is not just a clear flat piece. It is curved and has >> markings printed on it -- different colours for different bands. Most of >> them are white. So I can not easily make a reproduction and also must be >> very careful not to rub the print off when cleaning and handling.
>>> Good luck and let us know how it works out.
>> Thank you very much for the advice.
>> Regards,
>> Alex
> I doubt that superglue will work with this plastic - test on the edge- see > if you can bond a toothpick to the edge of the plastic with the superglue. > I suspect it will not adhere.
> Instead what you want is a plastic solvent - Methelyne > Chloride/Dichloromethane - to bond the crack. This stuff is very volatile > and difficult to work with nicely. If you can get a hold of a tiny syringe > (Diabetic friend?) and use that to apply the solvent, that should work > best. Get the solvent at a hobby shop. You want the liquid, not the glue > form. May have to get a small bottle of it at a plastic shop.
> This stuff MELTS the plastic, if dropped on the face it WILL soften the > look (frosted) so be very careful when using it.
Yes, I am familiar with diclorinethylene and have it. It is a natural solvent for perspex, but I was reluctant to use it because it will make the crack frosty, especially if I spill or smear it. I would prefer less visibility of the crack rather than more strength of the bonding.
What I was asking -- is there any clear non-drying or hardening gel with the refraction index close to Perspex? In this case I though, I could rub it in and make the crack less visible, though not avtually fixing the crack.
>There is a crack in the perspex dial glass of a radio. It runs from the >mounting hole and ends somewhere in the middle of the dial glass.
>1. How to stabilise the crack? In the old days people used to drill a small >hole (1mm or less) right at he very end of the crack. Then the crack does >not grow longer. Is this technique still valid?
>2. Is there any clear material the crack can be (at least partially) filled >with? I guess it shall have refraction index close to perspex, not >dissolving the perspex and that can be polished later. Does such treatment >exist? Perhaps furniture polish can be rubbed into the crack? Is it >recommended, say to sparingly apply super-glue on the crack, which is very >runny, and after it infiltrates the crack and hardens, polish the surface?
>3. Is there any recommended way of cleaning the crack of dirt, grime, >etc.beforehand -- so that the crack is less visible.
> On Mon, 6 Feb 2012 21:46:01 +1100, "Alex Pogossov"
> <apogo...@tpg.com.au> wrote:
>>Hello,
>>I might need an advice of the forum.
>>There is a crack in the perspex dial glass of a radio. It runs from the
>>mounting hole and ends somewhere in the middle of the dial glass.
>>1. How to stabilise the crack? In the old days people used to drill a >>small
>>hole (1mm or less) right at he very end of the crack. Then the crack does
>>not grow longer. Is this technique still valid?
>>2. Is there any clear material the crack can be (at least partially) >>filled
>>with? I guess it shall have refraction index close to perspex, not
>>dissolving the perspex and that can be polished later. Does such treatment
>>exist? Perhaps furniture polish can be rubbed into the crack? Is it
>>recommended, say to sparingly apply super-glue on the crack, which is very
>>runny, and after it infiltrates the crack and hardens, polish the surface?
>>3. Is there any recommended way of cleaning the crack of dirt, grime,
>>etc.beforehand -- so that the crack is less visible.
