Sciencemadness Discussion Board - Why are pencil sharpners magnesium?

Why are pencil sharpners magnesium?

peach - 18-2-2011 at 17:54

When everything of a similar nature is aluminium?

plante1999 - 18-2-2011 at 18:08

honestly i want to know , like you, why.

psychokinetic - 18-2-2011 at 18:43

Mine is made of Al.

I feel left out.

condennnsa - 19-2-2011 at 02:26

strong and superlight?

Random - 19-2-2011 at 02:34

Actually, I know only one company that makes magnesium pencil sharpeners. It is KUM from germany. I saw a lot more metal pencil sharpeners and those are made from aluminium. I think it's not the problem in metal, they mostly use aluminium, but KUM uses magnesium because their pencil sharpeners are worldwide known by that, even on them it's written magnesium. People think then it's something special, mostly those who don't even know what is Mg, kids who sharpen their pencils think "Oh yeah, I have MAGNESIUM pencil sharpener, I'm cool!" Now I understand why they have bigger price though..

If you want to test pencil sharpener if it's made of Mg, just drop a little vinegar on it, it will start bubbling if it's Mg.

a_bab - 19-2-2011 at 03:00

The Mg pencil sharpener feels unbelievably light. Although originally covered in some protective (Ni?) layer, in time corrosion becomes obvious, the sharpener slowly gaining the Mg color (blueish grey).

The first time I realised (some) sharpeners are made of Mg it was quite a revelation to me. It was like "hey, this surely looks like being made of Mg. (scratch scratch). Let's do a vinegar test. EVRIKA!"

I have later discovered Mg to be used in especially in laptops, and some old mobile phones. It used to be for me a really scarce thing, but nowadays it can be found everywhere. The chances are that anyone has at least a bit of magnesium in the house, and a lot in the car (kilos).

Arthur Dent - 19-2-2011 at 05:11

Quote: Originally posted by a_bab

The chances are that anyone has at least a bit of magnesium in the house, and a lot in the car (kilos).

Interesting. Aside from the "mag-wheels"which are really a magnesium/aluminium alloy, where would one find Mg in a motor vehicle?

I'm starting to wonder where I could find magnesium in my own house. If anyone knows of unsuspected sources of magnesium in your house, please share your info!

Robert (wildly scurrying around the house with an eyedropper-full of vinegar)

a_bab - 19-2-2011 at 06:24

There are countless applications for Mg.

I dunno; there is a high possibility that your water heater has a Mg sacrificial anode.

The car can have many parts made of Mg. It's a Mg alloy, with 5% Al in general, but it will still do most of the tricks pure Mg does.

I'm uploading some books with pics concerning Mg use for everyday objects.

cyanureeves - 19-2-2011 at 06:44

i googled magnesium producers and guess who makes it cheaper and is biggest producer? china! u.s. has plenty of oil but the middle east can crank it out cheaper. but honestly i thought it was just a europe thing.

peach - 19-2-2011 at 08:12

I thought it might be something to do with tradition with the pencil sharpeners. I can see the advert in my mind "Tired of having lumpy steel sharpeners in your in your pocket? Ours weigh nothing!"

I know Ferraris have magnesium engine blocks, but I don't know what else in a normal car is.

[Edited on 19-2-2011 by peach]

blogfast25 - 19-2-2011 at 08:15

Peach: when I first heard of magnesium pencil sharpeners I thought it was an old wives tale; it seems such overkill when Al would work just as well. Yet it really true: quite a few of them are made from magnesium.

Perhaps someone made a silly mistake writing up a specification and the metal then just got stuck in that market somehow?

a_bab - 19-2-2011 at 08:38

OK; just uploaded 3 books on the ftp (UPLOADS folder). All the file names start with "Magnesium". They are the bible of Mg use in consumer objects. Smash your TV and open your mind

Ferrari does not have Mg engine blocks, but VW Beetle (old models) does.

Audi A6, VW Passat, Fiat Lupo all have kilos of Mg in them. The parts are usually the gearbox and airfold intake. VW beetle has the engine block made of 95% Mg, and it weights some 9 kilos.

http://www.google.com/images?q=magnesium+scrap

peach - 19-2-2011 at 09:05

You're right, it doesn't. I'm not much of a car guy. I had a read of the wiki's and it says some of the components are magnesium, but not the entire block.

The Beetle's is? Also a made in Germany product. Smash your VW and have magnesium (or an angry VW fan*).

There's a video of a ferrari engine block being cast and finished here. Looks cleaner than my kitchen in there. The sand cores alone look amazing.

*A German friend of mine has a really old, very original and shiny Beetle, which he used as his ride when getting married. I don't think it even has electronic indicators, just the paddles.

condennnsa - 19-2-2011 at 09:52

that video is beautiful, peach

The WiZard is In - 19-2-2011 at 12:02

Quote: Originally posted by a_bab

I have later discovered Mg to be used in especially in laptops, and some old mobile phones. It used to be for me a really scarce thing, but nowadays it can be found everywhere. The chances are that anyone has at least a bit of magnesium in the house, and a lot in the car (kilos).

Years ago the local power company was replacing gas pipes
leading into the houses on my block w/ plastic covered pipe.
The pipe was welded to a wire coming from a large bag labeled
Magnesium ground electrode.

WOW Christmas has come early this year.

Wrong.

The Magnesium was magnesium sulphate epson salts.

Sigh.

kmno4 - 19-2-2011 at 13:13

You reminded me that I have something freak : 1kg piece of cast Mg.
Price was not very big, about 25 euros/kg.......

blogfast25 - 19-2-2011 at 13:46

Magnesium car parts date back to at least 1955: the fatal Le Mans crash in 1955 and resulting fire was exacerbated by the Mercedes containing high Mg alloys which catch fire ‘easily’…

psychokinetic - 19-2-2011 at 14:22

If so called 'mags' are Mg with 5% Al, then are your wheels shat if you drive through a vinegar spill, acid rain, or other acid that may be on the roads?

astroturf - 19-2-2011 at 15:06

Quote: Originally posted by psychokinetic

If so called 'mags' are Mg with 5% Al, then are your wheels shat if you drive through a vinegar spill, acid rain, or other acid that may be on the roads?

Alloy wheels are not Mg, they are Al. I don't think any factory alloy wheels that are real mags.

Arthur Dent - 19-2-2011 at 15:58

Quote: Originally posted by astroturf

Alloy wheels are not Mg, they are Al. I don't think any factory alloy wheels that are real mags.

I was under the impression that mags were made out of the "magnalium" alloy, but after few searches, I see that very few manufacturers still use that alloy, having switched a long time ago to solid aluminium instead.

I stand corrected.

Robert

Magpie - 19-2-2011 at 16:36

For about 25 years I had a Lawnboy lawnmower, which had a magnesium (or Mg alloy) deck. It was 2-cycle and very light, a pleasure to use. It looked similar to this one:

http://www.flickr.com/photos/56202158@N00/42886250/

peach - 20-2-2011 at 00:58

The pedals on my bike are magnesium. But I'm not sawing them up. I also have a Raliegh Burner from the 80's, I'm sure some of you must remember them. That one is presnapped after I took a shortcut down some stairs. Unfortunately, it's all steel.

dann2 - 20-2-2011 at 06:44

Did I read somewhere (on this board) that a bold boy once set his friends pencil sharpener on fire!

a_bab - 20-2-2011 at 06:48

Higly unlikely. A large part of the sharpener must be melted first before having a chance to take fire.

peach - 20-2-2011 at 07:30

I tried that, with a blowtorch and roasting the corner of a pencil sharpener (well, the remains of one) for about a minute solid.

I wasn't expecting it had a good chance of going, but it did nothing bar melt a bit.

I think the large mass of metal is heatsinking too well to actually ignite. The same pencil sharpener cut up into chips will burn however.

[Edited on 20-2-2011 by peach]

cnidocyte - 20-2-2011 at 07:45

What pencil sharpeners are made of magnesium and what percentage of magnesium is in them?

Random - 20-2-2011 at 08:54

KUM pencil sharpeners, I think it's almost 100% magnesium

plante1999 - 20-2-2011 at 09:01

STAEDTLER sharpener also is Mg at 95% (arround).

Pok - 27-2-2011 at 14:52

Did anyone answer the question yet?

I think: magnesium prevents the corrosion of the iron blade in the sharpener. Magnesium doesn't form a good oxide layer as aluminium does. The metal (magnesium) will have a direct contact with the iron blade - so electrons can easily flow (from or to?) the magnesium. The oxide layer of an aluminium sharpener might act like an isolator and prevent this flow of electrons (maybe!!!). Magnesium is less noble than iron. The magnesium works like a sacrificial anode. Instead of corroding iron the magnesium will corrode (very slowly). Without iron corrosion the blade will stay sharp! I've got such a 10 year old magnesium sharpener and used it many many times - it still is super sharp.

I don't exactly know - but this would be the only explanation of this magnesium "wastage" to me.

look here at "test 4" and "experiment 5":
http://translate.google.de/translate?hl=de&sl=de&tl=...

[Edited on 27-2-2011 by Pok]

few old hard drives

jimwig - 28-2-2011 at 08:58

good work POK

in my dumpster diving days i ran across quite a few old hard drives probably from main frames... upon taking them apart they had large MG labeled plates inside.....

got about a dozen or so of them---

Magpie - 28-2-2011 at 09:08

Yes, good post, Pok. Although I had been following this thread it was not until your post that I realized that it was not the blade but the base that was Mg. So it is a sacrificial anode for the iron blade. Now the use of Mg makes sense.

I looked for Staedtler or KUM sharpeners in my local office supply place but they did not have those brands.

ElectroWin - 5-3-2011 at 15:05

Quote: Originally posted by peach

When everything of a similar nature is aluminium?

you cant make a pencil sharpener from aluminum because pencils use graphite, and graphite causes aluminum corrosion.

more Mg in the house

K10 - 5-3-2011 at 15:13

I think it will be for cost reasons and ease of working it as it's cheap enough rather than weight saving as a sharpener isn't that much. I have a few of the Mg types around but never realised that is what they were made of or that graphite corroded aluminium. Still steel wouldn't be hard to cast and cheaper probably and not exactly heavy in your pocket.

I notice a lot of pedal bike parts are made from Mg due to lightweight but they tend to be a ripoff considering it is cheap and easy to work. Unsure on figures or if it's true but hear it isn't as strong as 6061 and 7005 alu alloys that most MTB parts are made from. 6061 is tougher and good tubing etc and 7005 harder so good for chainrings as well as tubing but for a fair few other parts it is good choice due to weight/strength ratio.

Main body of my front forks (bottom half of Rockshox Toras) are magnesium I think. Things like Mg pedals, brake calipers and so on are popular too although I use alu ones myself.

[Edited on 5-3-2011 by K10]

[Edited on 5-3-2011 by K10]

a_bab - 5-3-2011 at 23:34

Quote: Originally posted by ElectroWin

Quote: Originally posted by peach

When everything of a similar nature is aluminium?

you cant make a pencil sharpener from aluminum because pencils use graphite, and graphite causes aluminum corrosion.

You are actually wrong. MOST of the sharpeners are made of Al, and only a few fancy ones are made of Mg.

I don't see why on Earth graphite would corrode Al either. Graphite is really an inert thing.

ElectroWin - 1-10-2012 at 04:49

Quote: Originally posted by a_bab

I don't see why on Earth graphite would corrode Al either. Graphite is really an inert thing.

don't believe me, try this experiment. take any aluminum part, like a sliding door, and try lubricating with graphite. it will seize up.

wallschem - 2-10-2012 at 03:59

They use Magnesium because they use the powder sintering process in manufacture

[Edited on 2-10-2012 by wallschem]

froot - 2-10-2012 at 06:31

I don't know if anyone here has tried to tap a screw thread into aluminium, if you have you'll agree with me that Al binds to the tap even with lubricant leaving you with an undesirable result, and the same with using fine threaded screws in an Al part, slightly overtighten and the thread strips.

This is why Mg is used, it's toughness allows for the use of fine threaded screws and hence the need for a fine threaded screw to secure the blade to a pencil sharpener.

Incidentally, any light metal part you come across that has fine threaded screw holes in it will most likely be or have Mg in it, that or Ti.

vmelkon - 4-10-2012 at 15:13

Quote: Originally posted by froot

This is why Mg is used, it's toughness allows for the use of fine threaded screws and hence the need for a fine threaded screw to secure the blade to a pencil sharpener.

I had a solder gun and the screws and the thing was aluminum. The screw broke after a couple of uses. Al is too soft. Idiot manufacturer!

Sydenhams chorea - 7-10-2012 at 07:34

Quote: Originally posted by plante1999

STAEDTLER sharpener also is Mg at 95% (arround).

I always wondered if Staedtler pencil sharpener turnings would be of sufficient purity for Grignard reactions.