Getting Scales By Method

Hi, after reading various articles about scales and chord progression I still found myself lost as in to:
"how do I get those scales by myself, without having to consult on it?"
Altough there are lots of articles around building scales, none aproaches the subject with a clear formula that explains you how do you get those basic I,II,IV, V, etc...At least, one that shows you how you could get them without having to do it by memorizing those 1 - 3b - 4 - 5b stuff, i propose to show you the basics of building them from the cromatic scale using the tone intervals.
Yes...you may ask, are you that newbie around a guitar?
Well, there is no shame as to admit you just do not know something, so yes I am.
Let's first check a few things you need to know to be able to build these scales.
1. I know the musical notes by heart: (C,D,E,F,G,A,B)
2. I know where there are not "#" or "b" notes (E->F and B->C)
3. I know what a tone and semi-tone are (1Tone = 2Frets | 1Semi-Tone = 1Fret)
4. Examples are in Key of E.
All check?
Let's move on.
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1. Getting a Major Scale:
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It is composed of a sequence of tones and semi-tones that allows you to find it's notes. To find it's notes we will use the 12 tone cromatic scale, let's start by trying to find E Major Scale.
E - F - Gb - G - Ab - A - Bb - B - C - Db - D - Eb
Ok, so now we have the cromatic scale all opened up and ready to use, let's find those I,II,III,IV,etc, notes.
To do so, we use the Tone Intervals, which in the Major Scale are:

Root - Tone - Tone - SemiTone - Tone - Tone - Tone - SemiTone
(Root one octave above it's start)
(R)    (T)    (T)    (S)        (T)    (T)    (T)    (S)

Aplying this to the cromatic scale we get:

E - F - Gb - G - Ab - A - Bb - B - C - Db - D  - Eb - E
R       T        T    S        T       T         T    S(R)
I       II      III   IV       V       VI       VII   VIII(R)

I: E
II: Gb
III: Ab
IV: A
V: B
VI: Db
VII: Eb
VIII: ENow we have the notes that build the Major scale.
There are lot's of applications to this, you can get the chord progression notes for lot's of blues and rock and roll songs, I,IV,V in the 12 Bar Blues for instance.
But what's really important to retain is the Interval, that (R)-T-T-S-T-T-T-S, because with this you can start playing a scale without even having to remember the notes, just follow the tone progression in the fretboard.
Ok, so this was easy, let's jump to a minor scale.
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2. Getting a Minor Scale:
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The principle is the same, what changes is the Tone sequence:

Root - Tone - SemiTone - Tone - Tone - SemiTone - Tone - Tone
(Root one octave above it's start)
(R)    (T)    (S)        (T)    (T)    (S)        (T)    (T)

Aplying it to the cromatic scale of E you'd get:

E - F - Gb - G - Ab - A - Bb - B - C - Db - D  - Eb - E
R       T    S        T        T   S        T         T(R)
I       II  III       IV       V   VI      VII        VIII(R)

I: E
II: Gb
III: G
IV: A
V: B
VI: C
VII: D
VIII: E______________________________
3. Getting a Pentatonic Scale:
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So, pentatonic scale, what the hell is it? As it's name sugests, it's a five note group (Penta).
What happens here is that we pickup the Major or Minor Scales and remove designated notes from them to get the Major and Minor Pentatonic Scales.
Major Pentatonic Scale
- Remove the IV and VII notes from the sequence we built from the Major Scale and we get
I: E
II: Gb
III: Ab
V: B
VI: Db
Ending up with 5 notes.
Minor Pentatonic Scale
- Remove the II and VI notes from the sequence we built from the Minor Scale and we get
I: E
III: G
IV: A
V: B
VII: D
Ending up with 5 notes.
In order to play this scales we just have to re-arrange our tone structure, for instance, in the minor Pentatonic scale, because we removed the II and VI notes, the tone intervals are now diferent, they are someting like this:

R - T+S - T - T - T+S - T(R)
I   III   IV  V   VII   VIII(R)

Try it out and play it on the guitar, on the E Low String, you'd get something like this:0 - 3 - 5 - 7 - 10 - 12(one octave above)
R - T+S - T - T - T+S - R(one octave above)
E - G - A - B - D - E(one octave above)
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4. Blues Scale:
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In order to get the blues scale, just pickup the Minor Pentatonic and insert a Vb between IV and V.
It would look like this:

0  3  5  6  7 10
R T+S T  S  S T+S
I III IV Vb V VII
E  G  A  Bb B D

____________________________Okay, that's about it. This is not the best nor the most used way of doing things, but if you understand this concept of doing things, you'll be able to understand the way you can simplify all this process with other methods.
Cheers.