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Up Topic Welding Industry / Technical Discussions / Grit
- - By G.S.Crisi (****) Date 03-17-2004 22:37
English being not my mother language, would any of you gentlemen explain me what exactly means the GRIT of the grinding disks that are used for cleaning welds and welding ends? Thank you.

Giovanni S. Crisi
Sao Paulo - Brazil
Parent - - By CHGuilford (****) Date 03-17-2004 23:04
I may not have the terminology exactly right but .....
The grit is the size of the abrasive particles that are bonded together to form a grinding stone or grinding disc.
The higher the grit number, the smaller the grit size and the finer the finish you will get. That is because the grit number is loosely described as the number of particles that will fit into a given area. Grit is graded by the mesh size of a sieve.
Hope this helps and I'm sure other people can add to it.

Chet Guilford
Parent - By dee (***) Date 03-18-2004 00:15
To extend Chets remarks...
In some cases it also refers to the abrasive material itself, for example corundum (SiC) or aluminum oxide which both are quite common grit compounds.

It means "sand" (particularly as applied to use and translation from a foreign language, but in non-technical daily use it holds a more dynamic connotation- "sand" is inanimate or dead, "grit" is or will be doing something) and originated from what I think was an old middle-English word for the same.

...slightly off-topic it also relates to an individual's personal character trait which I think traces its root to the gizzard, a digestive organ which, with the help of foreign particles such as sand, help the animal grind through hard and tough protective coatings on seeds &c. In this context it alludes to an individuals ability to tenaciously persevere and overcome any obstacle- somewhat akin to toughness but conoting a noble element of character.

Regards
d

out of curiosity what is the Portugese technical equivalent? (presuming that is the predominant language)
Parent - - By jwright650 (*****) Date 03-18-2004 12:09
Hi CHG,
Would the "given area" be a square inch?

180 grit meaning,
180 particles to the square inch bonded on the sand paper or grinding disc?
Or would it be referring to the number of openings (180 in this case) in a square inch in the seive or screen to filter out the grit particles to make the 180 grit abrasive material?

John Wright
Parent - - By CHGuilford (****) Date 03-18-2004 14:23
John,
I believe it is measured in square inches and it is the number of wires evenly spaced in that distance, both directions, to form a wire mesh. (Wire size is controlled also.)

Grit size, at least for blasting and I presume for other uses, is the mesh size that the grit will pass through. It's a bit more complicated than that. You have to use multiple mesh sizes, stacked large on top and smallest on bottom, put in a weighed sample, and calculate percentages by weight that collect in each sieve after shaking it for a measured amount of time. That's why I didn't want to try to answer more specifically, it is a very detailed process and does not give an absolute particle size, just a rough (no pun intended) estimation of the majority of the particles.

Grit size would not mean the number of particles in a linear inch. The wires in the mesh take up space also, so the actual dimensions of 180 pieces of grit will not add up to a 180 mesh size.

Chet
Parent - By CHGuilford (****) Date 03-18-2004 22:06
I stand corrected. Grit in sandpaper apparently is the number of particles that would fit in a linear inch. Thank you Lawrence for that link showing that, and yours too John.
Chet Guilford
Parent - - By jwright650 (*****) Date 03-18-2004 14:34
Giovanni,
I guess the way to describe what grit stands for is to say that the number(referring to grit) would indicate the roughness (texture) of the abrasive material bonded onto the disc.
Higher the number = finer grit abrasive(finer texture),
Lower the number = larger grit abrasive(rougher texture).
John Wright
Parent - - By dee (***) Date 03-18-2004 16:51
JW,
I enjoy the opportunity to exchange, having been somewhat shut-in recently. I'm not trying to disagree, and in fact I've thought of just deleting this comment without posting it, but i figure this foreword will serve as sufficient perspective. Any note of criticism is unintentional.

The Spanish term for the word "grit" relates to grain. I have seen grit, in this technical use context, described as "abrasive grain". I wonder if the southern victual "grits" comes from the same "root"?

Parenthetrically, my point of all this language trivia is that I suspect the technical principles apply more or less universally here. Sand specifications were, I would think, carried to the "new world" with the earliest of settlers and explorers, not invented by us here independently.
Funny, I cannot find a conversion table to translate the specification from English to Metric, but I suspect the actual word they use is probably a direct translation of one of these words I tried to throw. Realizing Mr Crisi has been published in the AWS Journal I also thought it would be at least of some use to him to go to that depth. Some who speak only English wish they had his ability to communicate as efficiently.

Finally, is my recollection correct that Portugese is the official language of Brazil? (if not I'm in trouble)
Parent - - By jwright650 (*****) Date 03-18-2004 17:11
Dee,
I try and take all criticism as constructive, UNO(unless noted otherwise).
Learning is an evolving process that keeps us eager to learn more and more. My ignorance of other languages is a very real hinderance and I wish I had taken language classes in school before my brain was cluttered with all the junk/slang that I have absorbed which makes my English so poor.
I only hope other forum users will help me when I am mis-guided/mis-informed on anything whether it is languages, sand, grit, welding or code issues. I am eager to learn and appreciate any help that is given.
Take care and hurry up and get well soon,
John Wright
Parent - - By dee (***) Date 03-18-2004 17:17
:-)
Parent - - By RonG (****) Date 03-18-2004 17:31
Naw, Grit is the measure of you ability to withstand hardships and over come them, like in "TRUE GRIT".

I could not resist it. I guess I don't have much grit.
Parent - - By dee (***) Date 03-18-2004 17:41
covered... (third post from top)
...kinda like in the movie with Kathn Hepburn and who was the guy, some Canadian character in the movie, I think? I remember there was some white-water action.
Parent - - By G.S.Crisi (****) Date 03-18-2004 23:52
I remember two pictures played by Katherine Hepburn. The first is "African Queen", starring also Humphrey Bogart, and the second is "Guess who comes for dinner", starring also Spencer Tracy.
Two masterpieces. They don't make (I'd say they're not capable to make) pictures like those nowadays.
Giovanni S. Crisi

Parent - By jwright650 (*****) Date 03-19-2004 00:39
I'll have to agree with you, in that they(Hollywood) can't seem to make movies like those old ones. They won't admit it, but the movies that are fit to watch with your kids(rated as "G' for general audiance) make the most in revenues and the junk(rated "R" for restricted) that isn't fit to watch, just don't bring out the movie goers quite as well.
John Wright
Parent - By dee (***) Date 03-20-2004 06:15
Well, one reason is they would have a hard time getting those characters- they broke the mold.

Actually,"African Queen" was the trick question- Bogey ws the Canadian who with Hpeburn's prodding, showed the kind of grit John Wayne did in the sequel to "True Grit"; 'Rooster Cogburn"

regards
d
Parent - - By jwright650 (*****) Date 03-19-2004 10:51
Dee,
Could this be the movie you had in mind?
http://images.amazon.com/images/P/6305754934.01.LZZZZZZZ.jpg
John Wright

PS. never mind, that is the same movie Lawrence had a link to.
Parent - By RonG (****) Date 03-19-2004 17:34
Now Thats some Grit!!!!!
Parent - By RonG (****) Date 03-19-2004 21:04
Funny you should mention A Canadian.
A "Grit" in Canadian speak is a political liberal.
Parent - - By Lawrence (*****) Date 03-18-2004 17:50
http://images.google.com/imgres?imgurl=www.woodzone.com/articles/sandpaper/100grit.jpg&imgrefurl=http://www.woodzone.com/articles/sandpaper/&h=476&w=330&sz=29&tbnid=dKi0uMzORzMJ:&tbnh=125&tbnw=86&prev=/images%3Fq%3Dsandpaper%2Bgrit%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8


http://images.google.com/imgres?imgurl=westernposterpage.com/truegrit1.jpg&imgrefurl=http://westernposterpage.com/truegrit1.htm&h=502&w=344&sz=42&tbnid=Phf-Jr7LgVsJ:&tbnh=126&tbnw=86&prev=/images%3Fq%3Dtrue%2Bgrit%26start%3D80%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26sa%3DN

http://images.google.com/imgres?imgurl=www.augustachronicle.com/images/headlines/070202/bowl_of_grits.jpg&imgrefurl=http://www.augustachronicle.com/images/headlines/070202/slideshow/slide1.shtml&h=262&w=400&sz=22&tbnid=VGwzcOjcDr0J:&tbnh=78&tbnw=119&prev=/images%3Fq%3Dbowl%2Bof%2Bgrits%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8

Parent - - By jwright650 (*****) Date 03-18-2004 17:54
Yes, Lawrence, you have the subject covered.
Great links!
John Wright :)
Parent - - By dee (***) Date 03-18-2004 18:14
yup, but nope- not the movie I was thinking about- where's the water?

but back on the practical side of the conversation,
more info; source for any depth Mr Crisi may require


3M Co. - Abrasive Systems Div.
Address3M Center, Bldg. 223-6N-01
St. Paul
MN
55144-1000

Telephone 1-651-575-3469
Fax 1-800-852-4668
E-mail Web www.mmm.com/abrasives
Parent - - By jwright650 (*****) Date 03-18-2004 18:19
D,
I did find a few grit conversion charts....

http://www.ameritech.net/users/knives/grits.htm

http://www.cs.rochester.edu/u/roche/rec.wood.misc/grit.sizes.html

http://www.reade.com/Sieve/grit_conversion.html

http://www.faceters.com/askjeff/answer67.shtml

http://www.unc.edu/~rowlett/units/scales/grit.html

http://www.facetingmachines.com/grit-mesh-micron.shtml

...that maybe helpfull in determining the size of grit.

Check them out,
John Wright

Parent - By dee (***) Date 03-20-2004 06:23
Thanks JW!
That is right on the button!
regards
d
Parent - By kam (**) Date 03-19-2004 08:32
First thing that comes to mind is that abrasive newspaper that kids used to pedal in our neighborhood when I was a kid. Do they still sell that thing?

: )

kam
Parent - - By G.S.Crisi (****) Date 03-18-2004 23:45
Thanks to all of you, gentlemen. I'm quite surprised that my question deserved not less than 15 answers (so far).
My confusion arose from the fact that in Portuguese (the language spoken in Brazil, as dee correctly says) there's only one word (grao) to mean the grain size, appearance etc.
For example:
Grain size would be: tamanho do grão,
Grain chemical composition would be: composição quimica do grão,
and so forth.
I've received a catalog on grinding disks written in English, in which the words "grain" and "grit" are used, and hence the confusion.
Now, and thanks to you, the idea has been cleared up.
Giovanni S. Crisi

Parent - - By dee (***) Date 03-20-2004 06:18
we're like vultures, hanging around looking for something to pounce on... ..you're very welcome
Parent - By Mike W (**) Date 03-20-2004 10:15
Yeah, we are here to help. There is a food in the south US called grits.
Up Topic Welding Industry / Technical Discussions / Grit

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