20 replies to this topic

[BigG]

Mesh Definition

Edited by BigG, 08 September 2004 - 09:06 AM.

[neo]

Hi, I'm new at this forum and I?m planning to make my first rocket.
But I wonder how large the grains should be, I red somewhere that it should be 6 mesh. But then how large is 6 mesh in millimetres or centimetres?

Marcel

[Yugen-biki]

To get the mesh size you can count the number of openings in one inch of screen. The number of openings is the mesh size. A 4 mesh screen means there are four little squares across one linear inch of screen. A 100 mesh screen has 100 openings, and so on.

You don?t need to make grains. A powder may work as good. But a to coarse powder, and it will not solidate good enough.

There are many posts in this forum about rockets. Please make a serch and you will surely get a lot of info.

[Richard H]

Just to clarify, it's the number of openings in one linear inch.

[paul]

I think this picture shows it......

[neo]

very big thanks!
I found a lot of info on this site.
thanks agen.

Marcel

[NUKE]

I know that someone else may have already alsked this question but when i am searching i cant find what i need.
please tell me what is mesh and how will i know what is the mesh of my Al,Fe etc.

Thank you

[The_Djinn]

Mesh is basically another word for sieve... like kitchen sieve or tea strainer for example.
depending what size mesh your Fe / Ti etc passes through will tell you what size it is.

Mark

[neo]

I've asked that same question a wile back but this is how it is (at least what I think):
mesh is a way to measure small things (like you didn?t understood that...)
if you have Al that is 300 mesh then you can put 300 pieces of Al in a row so they cover 1 inch. The synonym of mesh is also web, net. And that?s how you measure it, you have a net whit some tiny holes in and those particles that fall through are smaller then the mesh is on the net or web?
the stupid thing about mesh is that it's only you guys in the UK that use it, all the other people uses microns... it is the same thing whit inches, it's just you an the usa that uses it. (maybe some other countries but that I don't know)

anyway. that?s how it is.

[BigG]

Ok. Some information about sieves, because I think this thread so far is quite confusing.

First NEO, the mesh standard is an international standard. The American were the first one to move away from it, and generally the mesh system is still used more then millimetre system. There are reasons for that, although I suspect they will all move to microns at some point.

Second, the definition on this thread suggests that mesh 4 will have an Aperture Sizes of 25.4/4 = 6.35 millimetre, and that is wrong. Mesh #4 hole is 4.75 millimetre. By the same logic mesh #200 is 127 micron where is real life it’s only 75 microns.

The definition is right, you will have 4 holes over an inch on a four mesh screen, and 200 holes an inch on a 200 mesh screen. However, the wire itself takes some space as well, and this count to the difference between the simple division and reality.

To know how much microns are in a specific mesh you need a mesh table. Here is a link to the best sieves company in the world (British naturally) and their specification table. If you roll down the screen you will find the American standard and near it an international standard alternative. This is a good table to use for converting mesh size into microns.

http://www.endecotts...cifications.htm

Edited by BigG, 08 September 2004 - 09:25 AM.

[v_x]

HI, am new... so forgive the silly question if you will

What does it mean when a mesh is given as a minus number eg

'Aluminum, flake, flitters, coarse

-20 mesh, dark flake, coated. Eckhardt (German) #41813/G

Used in glitter compositions.'

This is from the skylighter web page.

[Richard H]

Here is a quick summary:

+Number = Particles retained on the screen
-Number = Particles pass the screen

Number = Particles pass the screen

[BigBang]

Hi all, before i ask my question, i'd like to say hi to everyone, as this is my first post. I have been reading this forum with interest for ages, but only just become a member.
My question is regarding mesh sizes. I am not familiar with these, so as to have some sort of idea what people are describing, can anyone tell me the approx. mesh size of say......sugar salt and flour, and what it means when there is a - (minus) sign in front of a mesh size. thx

Andrew.

[thewildething]

Hi BigBang,
Please search before you ask questions, go here for a Mesh definition : Mesh

Welcome anyway mate.

Marcus.

[thewildething]

However, the wire itself takes some space as well, and this count to the difference between the simple division and reality.

I wonder if anyone could tell me if the diameter of the wire is somehow proportional to the apeture size. There must be some sort of standard of thickness because, if not, then the size of the partical could be different depending on the thickness of the wire in any one sieve. A sieve with one mm apetures and one mm thick wire would have a 'mesh' size of 12 right? but the same sieve with 0.1mm thick wire would have a mesh size of around 23, even though the particals are the same size. Microns are the true size of the apeture though. Can anyone answer this?