Microthruster fabrication

[seriously disabled]

How are microthrusters fabricated? Are they made by the same fabrication techniques used to make computer chips?

[insane_alien]

no, they're far to big for that.

[seriously disabled]

no, they're far to big for that.

 

So how?

[insane_alien]

well, from what i've read they are millimeter scale so i assume a miniturised form of milling.

[seriously disabled]

well, from what i've read they are millimeter scale so i assume a miniturised form of milling.

 

But how does miniaturized milling actually work?

[insane_alien]

same way bigger ones do but smaller.

[seriously disabled]

same way bigger ones do but smaller.

 

But if the parts are so small, how can you see what you are milling without a microscope or something like this?

[insane_alien]

4 millimeters across does not require a microscope. magnifying glass perhaps.

 

but anyway, the machines likely to be used like lathes have controlls that are much finer than that, you can get high precision ones that have micrometer control.

 

not that much of it will be done by hand, it will likely be a computer controled process.

[seriously disabled]

But how do you manufacture micrometer-scale parts for these computerized lathes?

[insane_alien]

the parts arent micrmeter scale, they just have that sort of precision.

[seriously disabled]

the parts arent micrmeter scale, they just have that sort of precision.

 

But how are lathes designed to have micrometer-scale precision?

[insane_alien]

typically gearing mechanisms on the controls to make a large action smaller.

[seriously disabled]

It's hard to me to follow what you are explaining insane_alien because I don't know how a lathe works.

 

A lathe is called מחרטה (machreta) in Hebrew but since I've never worked in industry and never actually worked with lathes or CNC machines and since I don't have a degree in mechanical engineering, it's pretty hard for me to figure this stuff out all in my head.

[insane_alien]

right, basically a lathe works by spinning the object in question and a blade is moved in from the side to shave bits off of it until it is the desired shape.

 

the way you move the blade in and out is usually by turning a handle. this can move the blade in and out. you can use a screw mechanism or a gear mechanism to move it. by being clever with your gears and screws you can reduce the movement cause by one turn of the handle. right down to one turn results in the blade moving one micrometer. but this is usually only on computerised machines(who wants to move something at a micrometer per turn right?).

 

by using fine control such as this a 4mm diameter combustion chamber is easy to make. they just use the same method the use on larger thrusters. but use more precise machines.

[louis wu]

Uri

 

the insane one has been telling you the truth.

 

When I specify tolerances for manufacture of small components I often use ±0.01mm.

A standard CNC machine will achieve this tolerance quite happily.

Still smaller tolerances can be met at a price.

[seriously disabled]

right, basically a lathe works by spinning the object in question and a blade is moved in from the side to shave bits off of it until it is the desired shape.

 

But how does a 4mm combustion chamber look like?

Edited January 23, 2010 by Uri

[insane_alien]

like the bigger ones except just under half a centimeter across.

 

the basics are going to be the same as a larger rocket, all that is different it that it is at a scale where it is difficult to maintain combustion.

 

i suggest you go read up on normal thrusters, milling and latheing techniques and how they work. wikipedia or howstuffworks.com will suffice.

[seriously disabled]

In this video, starting from 0:58, how is it possible that the line trenches the hob (the cutting tool) leaves on the spinning gear are completely symmetrical despite the fact that the machine is stopped before the gear manages to complete the last (360 degree) rotation?

[npts2020]

The cutting tool and gear are synchronized through gears in the lathe. As the gear being cut slows down so does the cutting tool by the same amount (probably a proportional amount). No matter what speed the chuck (part holding the piece being lathed) moves, the cutting tool speeds up or slows down by the same amount. It works the same for doing threading on a lathe.