Re: detection of alluminium
There acid to test types metal?
I never worry about it unless I am? welding or foundry work.?
Stainless is a different story because you know if 400 type and if a magnet sticks then 400 most machines it a bad day
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Dave?
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On Tue, Sep 24, 2024 at 06:05 AM, Jacques Savard wrote:
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I have? some? metal? from? picnic table? whit glass?
2 interrogation
A? howto? verify? it is alluminium? ?maybe? magnnetic? ok? but? do you have? any other? method? like? acid? vinegar? or so
B? ?is it possible to? make a check? playing? dising? whit? sand blasst? on? these? kind? of? tenpered glass table? or? no? everything? exploded
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jack 47 71
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Re: detection of alluminium
I don't have one of these tabletops, but I had a thought. A cell phone has a polarizing filter. Would that also show the effect?
On Wed, Sep 25, 2024 at 9:52?AM Mark Kimball via <markkimball51= [email protected]> wrote: It isn't absolutely necessary to use two polarizers, if you have a pair of polarizing sunglasses.? Indirect light from the sky on a clear day is partially polarized, so just put them on and look at the sky through the glass.? Sky light isn't 100% polarized so the contrast between the light/dark regions won't be as dark as with a pair of polarizing filters.? But just about everyone has some polarizing sunglasses lying around.
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I see this effect most often when driving since the car's windows are made with tempered glass.
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Buffalo John
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Re: detection of alluminium
It isn't absolutely necessary to use two polarizers, if you have a pair of polarizing sunglasses.? Indirect light from the sky on a clear day is partially polarized, so just put them on and look at the sky through the glass.? Sky light isn't 100% polarized so the contrast between the light/dark regions won't be as dark as with a pair of polarizing filters.? But just about everyone has some polarizing sunglasses lying around.
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I see this effect most often when driving since the car's windows are made with tempered glass.
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Re: detection of alluminium
Dear Roy, Many thanks for the Maltese pattern detection method for tempered glass. Regards, David (nr. Oxford, UK)
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On 25 Sep 2024, at 00:56, Roy via groups.io <roylowenthal@...> wrote:
? Aluminum will react with a strong base, ferrous metals won't. Probably the easiest to obtain is a drain cleaner; the kind you want will contain either sodium or potassium hydroxide. You'll probably need to scratch the surface (to break the oxide layer) under a pool of liquid. Magnesium is much less common due to cost & manufacturing difficulties.
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Tempered glass MUST be annealed before attempting to cut it, otherwise the whole piece shatters into little cubes as soon as any part of the surface is breached. An easy way to identify it is with 2 polarizing filters - put the glass between the 2 of them & rotate one of them; tempered glass will show a, "Maltese" cross pattern, plain glass won't.
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Roy
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Re: detection of alluminium
Aluminum will react with a strong base, ferrous metals won't. Probably the easiest to obtain is a drain cleaner; the kind you want will contain either sodium or potassium hydroxide. You'll probably need to scratch the surface (to break the oxide layer) under a pool of liquid. Magnesium is much less common due to cost & manufacturing difficulties.
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Tempered glass MUST be annealed before attempting to cut it, otherwise the whole piece shatters into little cubes as soon as any part of the surface is breached. An easy way to identify it is with 2 polarizing filters - put the glass between the 2 of them & rotate one of them; tempered glass will show a, "Maltese" cross pattern, plain glass won't.
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Roy
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Re: detection of alluminium
If you have concentrated nitric acid, that won't harm aluminum but will attack most other metals, including magnesium. Also, shaving of magnesium will burn brilliantly. (That's how they made flashbulbs).
On Tue, Sep 24, 2024, 9:05 AM Jacques Savard via <jacquessavard= [email protected]> wrote: ?
I have? some? metal? from? picnic table? whit glass?
2 interrogation
A? howto? verify? it is alluminium? ?maybe? magnnetic? ok? but? do you have? any other? method? like? acid? vinegar? or so
B? ?is it possible to? make a check? playing? dising? whit? sand blasst? on? these? kind? of? tenpered glass table? or? no? everything? exploded
?
jack 47 71
?
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Re: detection of alluminium
Perhaps Archimedes could assist.
On Tuesday, September 24, 2024 at 07:52:13 AM PDT, paul mcclintic via groups.io <cannontandem@...> wrote:
Not sure if it is a shape you could figure out its volume. If it is you could weigh it and see if that is the correct for that volume of material. Paul M
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Re: detection of alluminium
There are some chemical ways to test aluminum but require strong chemicals.? Calculating the density is a much safer way to go.
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Re: detection of alluminium
I assume by from a picnic table you mean it is a frame or part of a frame. If it looks like a cast part, then if it is magnetic, it is not aluminum. If it isn't magnetic, it could be aluminum or magnesium. Aluminum is 2.7gm/cm^3 and magnesium is 1.74 gm/cm^3, so if you can weight it and measure the volume (Archimedes), you can figure out which one it is.
you can also check out searching for "test aluminum versus magnesium"
Here is one example
On Tue, Sep 24, 2024 at 6:05?AM Jacques Savard via <jacquessavard= [email protected]> wrote: ?
I have? some? metal? from? picnic table? whit glass?
2 interrogation
A? howto? verify? it is alluminium? ?maybe? magnnetic? ok? but? do you have? any other? method? like? acid? vinegar? or so
B? ?is it possible to? make a check? playing? dising? whit? sand blasst? on? these? kind? of? tenpered glass table? or? no? everything? exploded
?
jack 47 71
?
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Buffalo John
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Re: detection of alluminium
Not sure if it is a shape you could figure out its volume. If it is you could weigh it and see if that is the correct for that volume of material. Paul M
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?
I have? some? metal? from? picnic table? whit glass?
2 interrogation
A? howto? verify? it is alluminium? ?maybe? magnnetic? ok? but? do you have? any other? method? like? acid? vinegar? or so
B? ?is it possible to? make a check? playing? dising? whit? sand blasst? on? these? kind? of? tenpered glass table? or? no? everything? exploded
?
jack 47 71
?
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Re: Brazing (was: Re: Large work holding)
I? verify? on? the? box
it is? mark? 50? amp
it? look to me? a bit? to hight? but? that? is? 500w? around?
the ok
jack 47 71
nb? the first? messge? said? server? was? bad? configured ??
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It's not just the lower melting temperature; the cadmium makes the liquid flow better.
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Roy
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Re: Turning Brass on 7x16?
Good find! The picture is better than my text ;-)
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Roy
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??? interesting , whats the power source ?
??? thanks
animal
On 9/22/24 8:01 AM, Jacques Savard
wrote:
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here? the photo? of? my? special? carbone welder
the black part? are? insulated? ?and? the 2 part? can be?
move? to? touch or? a bit? distenced for? plasma? building
jack 47 71
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Re: Brazing (was: Re: Large work holding)
I used sil-phos in refrigeration. Doesn't need flux, prepping is minimal, stands up to relatively high pressures; Needs higher temps though.
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Re: Brazing (was: Re: Large work holding)
here? the photo? of? my? special? carbone welder
the black part? are? insulated? ?and? the 2 part? can be? move? to? touch or? a bit? distenced for? plasma? building
jack 47 71
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Re: Turning Brass on 7x16?
I've turned brass fitting many times on the LMS 5100.? ?Never went to specific bit geometries - just used the indexable carbides from low-priced sets or other chinese turning tools.
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Lone Tree, Colorado? ?USA
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I ALWAYS use cadmium-bearing alloys because of their lower melting temperature. I keep a window open in my basement shop and a fan blowing from one side? so any fumes get diluted and blown away from me.? I'm still vertical. So far.
The 95/5 alloy is the nicest Pb free plumbing solder! I still miss the Cd containing brazing alloys for their ease of use; that's with my head - the rest of the innards are happier not being exposed to it.
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Roy
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Re: Turning Brass on 7x16?
It might not be clear to everybody what "stoning a tiny flat" really means.? This is called "dubbing" a drill and here is a pretty good photo I found online.
It isn't really a less sharp edge (you still want a very sharp edge), but one with zero rake angle.? This prevents the drill from corkscrewing in with soft metals or plastics.? It is a VERY handy little trick.? As another bonus, it is safer when drilling soft materials because it is far less likely the drill will "grab" into the material as a sudden surprise.
Charles E. "Chuck" Kinzer
On Saturday, September 21, 2024 at 04:21:52 PM PDT, Roy via groups.io <roylowenthal@...> wrote:
The main things are no top rake & stoning a tiny flat (instead of a sharp edge) on drill bits.? Those sharpening differences keep the tool from pulling itself into the work.
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Roy
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davesmith1800
BuffaloJohn
