DCG~ Geologic Geometry

KokaNoodles

Got a few problems with the map question. Hoping someone could help me

• How do i get the measurement if it says 1 in 20 falling/rising. Like, how far do i measure out from A if it says from A-B 1 in 20...
• And second, anyone got an easy way to get the boreholes, I never quite learnt them in class, and the books are jus mindbending

Please and thank you :pac:

Paddy001

You wont be able to measure 200 most of the time, it will fall say 20 in 200m which is equivalent to falling 10 in 100m so you can measure 100cm down the road and at that point it dropped ten. Then work fro there. Cut plane goes at te low end of the road and embankment at the higher part. Its also the height of the road being built you go by and not the contours. Hope that helps

Boreholes: There's really no easy way, maybe look at a paper and solution from the old course

timmywex

KokaNoodles wrote: »

Got a few problems with the map question. Hoping someone could help me

• How do i get the measurement if it says 1 in 20 falling/rising. Like, how far do i measure out from A if it says from A-B 1 in 20...
• And second, anyone got an easy way to get the boreholes, I never quite learnt them in class, and the books are jus mindbending

Please and thank you :pac:

Counter Interval x scale x gradient

galway.gaa

So whats your thaughts on the test on friday?
im kinda lookin forward to it. its probably my best subject so im hopin for an A1.
im not to sure what the paper is like, my teacher was all talk about things he was goin to do but ended up doin nothin.

ive two questions about the paper:
1. will interpenatration and planes and traces deffinatly come up
2. can solids in contact come up as a long qustion?

if anybody knows anything helpful about the paper that would be great. thanks:)

Prowetod

galway.gaa wrote: »

So whats your thaughts on the test on friday?
im kinda lookin forward to it. its probably my best subject so im hopin for an A1.
im not to sure what the paper is like, my teacher was all talk about things he was goin to do but ended up doin nothin.

ive two questions about the paper:
1. will interpenatration and planes and traces deffinatly come up
2. can solids in contact come up as a long qustion?

if anybody knows anything helpful about the paper that would be great. thanks:)

1. No, but probably/hopefully :P
2. Yes, hopefully!

Just keep on doing the first 2 or 3 papers and you should be grand!

galway.gaa

eoccork wrote: »

1. No, but probably/hopefully :P
2. Yes, hopefully!

Just keep on doing the first 2 or 3 papers and you should be grand!

our teacher said he was goin to get us the sample papers but he didnt. can you get them anywhere on the internet? so your predictin planes and traces, interpenetration and solids in contact?

Prowetod

galway.gaa wrote: »

our teacher said he was goin to get us the sample papers but he didnt. can you get them anywhere on the internet? so your predictin planes and traces, interpenetration and solids in contact?

If I was giving tips I would say planes and traces and interpenetration as long q's, then solids in contacts a short q.

Here is the Official Sample Paper

Pygmalion

I got an A in TD in Junior Cert but have no idea how I'll do on Friday.

No idea what's on the paper, assumed that Interpenetration and Intersecting Planes were 100% going to come up so prepared for just them for part B... Have roads and mining done which seems like it actually is 100% guaranteed though.

VinnyTGM

No idea, although I'm going to practice the papers.

--paul--

Paddy001 wrote: »

You wont be able to measure 200 most of the time, it will fall say 20 in 200m which is equivalent to falling 10 in 100m so you can measure 100cm down the road and at that point it dropped ten. Then work fro there. Cut plane goes at te low end of the road and embankment at the higher part. Its also the height of the road being built you go by and not the contours. Hope that helps

Boreholes: There's really no easy way, maybe look at a paper and solution from the old course

What? if the gradient is 1 in 20 faliing then it will drop 5m if you go 100 metres down the road i.e 5 x 20=100? definitly not 10 m down if you go 100m down the road.

For mining geometry join the footwalls and headwalls in the elevation and go paralel to the footwalls from one of the headwalls and horizontally from the other headwall. this gives you a point on the strike, do the the same in the plan using the point you found on the strike, then look along the strike which gives you the dip and thckness.

Delta Kilo

OK. Each contour line on your map is at a 5 meter interval. Therefore, you have to multiply the gradient i.e. 20 by 5. This gives you 100. Every 100mm, you mark plus or minus 5 depending if it is rising or falling.

Dont forget the golden "FAT/CAB" rule, fill arcs at top height, cut arcs at bottom height. Hope that helps!

EDIT: Skew boreholes is very similar to skew lines... Level line in elevation and go parallel to other line... gives you true length and true direction in plan...just look along that line which is known as your "strike"

Frolick

The papers that are avaible are too long appearently... We're really been left in the dark time wise

errlloyd

That FAT/CAB is genius. Love you.

Boreholes = Skew lines

mink_man

the fat cab rule? whats that? i know when you do the roadworks you have to draw a circle of radius,whatever the cut or fill ratio is so ill try and do it on this!

A-->B=level
B-->C=in in 20 rising which lets say is 5:100


A

---

B

---

C

---

D


so my question is radius 5 circle go, is it at B or C????

errlloyd

Is it cut or fill?

galway.gaa

i reckon that because so many people are left in the dark it will be marked really easy. 1st year and all that like. itll probably be marked harder next year. so in that respect good times LC09

Frolick

Cut close(Cc) Fill far(Ff)
Thats the way i learnt the rising road
Cc=Cirlcle is close to your starting point Ff=Circle is at the end point

mink_man

so fill will be at C and cut will be at B?

mink_man

Cut close(Cc) Fill far(Ff)
Thats the way i learnt the rising road
Cc=Cirlcle is close to your starting point Ff=Circle is at the end point

and if the road is going down is the opposite correct? fill close, cut far?

Frolick

Depends on the contours and height of B
Lets say
A--->B was level at 65 going to C raising at whatever
If the contours are less then 65 its Ff
If contours are more than 65 its Cc
till whatever point

mink_man

Depends on the contours and height of B
Lets say
A--->B was level at 65 going to C raising at whatever
If the contours are less then 65 its Ff
If contours are more than 65 its Cc
till whatever point

so fill is always at the other point whereas cut is always at the point you are at?

Frolick

mink_man wrote: »

and if the road is going down is the opposite correct? fill close, cut far?

It depends on your starting point really, but ya
You need to cut you make a circle on the starting point at whatever radius
You need to fill you make a circle at the end point at whatever radius

carefulnow99

well lads,
just a few things i know this prob aint the thread but since were all doin DCG----

how did everyone get on in the mocks? we all done pretty useless but in fairness i got only 32% but that was with knowing 1 question and bluffing the rest been honest.

did ye get the whole course done? cause we certinly didnt only for my g.f's bro been a arcitecht i was screwed

and is it just me or do all DCG teachers seem to like been honest,not really give a sh!t? mine certinly does'nt as he told the 5th years now this is word for word-

"ah i dunno a few want to do it( refering to 6th years doin higher) but like its alot a work i hope they decide to drop been honest there are a few well able for it but well , i just dont have the time,,,"

what can i say to that? now... out of a class of 28 only 5 are doin higher becuase they dont feel confident enough doin higher which i feel is pretty unfair. and he is aftermissin loads of days cause he is showin the other teachers how to do the course,, which is a disaster been honest cause he is unreal lazy.

so thats it really hope we all do well folks nd best a luck to all of ye's

errlloyd

You lads successfully just confused the **** out of everyone.

If you are looking UP HILL, and you are doing FILL where is the circle.

corkkerry

Remember the feeling all year...will the Recession come up in Irish??? and it did!!:)

The sound of relief that burst through the exa hall....well in relation to DCG..................it will look like a photocopy of the sample paper....same layout...stick to that and now that small tricky things in short q's like /auxiallary van points and we'll be grand.

There will be no major shocks I guarantee

Delta Kilo

Right Im assuming my bogger accent here because some serious deliberation has to be done.

Say youve marked out the height intervals on your road.

50

---

55

---

60

---

Cut: 1:1.5 Fill: 1:2

Formation level is 55 but you have a big dirty 65m contour line coming down right through ya. So you need to cut. You set your compass to 7.5 (5by1.5) and by the fat/cab rule you swing your arc from 50 and join back to 55.

Frolick

Wel its depends on the rate of increase of the road.
Every 20m it goes up 1m, so it ain't always fill

Delta Kilo

Frolick wrote: »

Wel its depends on the rate of increase of the road.
Every 20m it goes up 1m, so it ain't always fill

No it isnt but in fairness if you cant spot what is cut and what is fill then you shouldn't be doing DCG.

To confuse people further-does anybody use the "tadpoles" to indicate whether it is cut/fill. Remember, tadpoles always go UPstream.

Frolick

Delta Kilo wrote: »

No it isnt but in fairness if you cant spot what is cut and what is fill then you shouldn't be doing DCG.

To confuse people further-does anybody use the "tadpoles" to indicate whether it is cut/fill. Remember, tadpoles always go UPstream.

Ermmm, we're talking about a road that is raising aren't we? If your talking about a level road, ya you can find it no bother. However, the rate of increase of the road is VERY important! That tells you where to put the circle. You double that, you double the radius measurements (which people usually do to get closer to the end point).
Not all raising roads are fill...

errlloyd

Anyone else noticed the best Tech Drawing teachers are always Boggers, with serious bogger accents.

corkkerry

hahahaha...ya boggers!!! quality

Paddy001

--paul-- wrote: »

What? if the gradient is 1 in 20 faliing then it will drop 5m if you go 100 metres down the road i.e 5 x 20=100? definitly not 10 m down if you go 100m down the road.

For mining geometry join the footwalls and headwalls in the elevation and go paralel to the footwalls from one of the headwalls and horizontally from the other headwall. this gives you a point on the strike, do the the same in the plan using the point you found on the strike, then look along the strike which gives you the dip and thckness.

Sorry your right, dunno what I was thinking!

Fince

Delta Kilo wrote: »

No it isnt but in fairness if you cant spot what is cut and what is fill then you shouldn't be doing DCG.

To confuse people further-does anybody use the "tadpoles" to indicate whether it is cut/fill. Remember, tadpoles always go UPstream.

so if ur cutting, the tadpoles are starting on the road side, and the sqiggle is going away from it and if ur filling the tadpole will be away from the road, with the sqiggle towards the road?

errlloyd

Fill has the tadpoles head right beside the road. Cut has the tadpoles tale beside the road.

KokaNoodles

Thanks all, but tbh im still a little confusd

Say for instance, B is at 55 and B to C is 1 in 20 falling

fill= 1in1.5
cut=1in1

How far out do i have to go? Dont know why i cant get this

Paddy001

KokaNoodles wrote: »

Thanks all, but tbh im still a little confusd

Say for instance, B is at 55 and B to C is 1 in 20 falling

fill= 1in1.5
cut=1in1

How far out do i have to go? Dont know why i cant get this

1 in 20 falling means when you go down 200m the road has fallen 10m. Therefore if you go down 100m it falls 5m, yes? Just go down as fas as you can and work out how much it has fallen then. You will only be ably to go down 100 most of the time. Next, at your new point draw your cone. If the whole thing is cutting just draw the one cone, cone will be radius 5 then as the cuttings is 1:1 and you have went down 5m so its 5mm cone. If you need to use an embankment cone, the ratio is 1:1.5 so the cone for this will be 7.5mm is that clearer?

Frolick

Any ideas what the short questions might be?

galway.gaa

Frolick wrote: »

Any ideas what the short questions might be?

i reckon well see skew lines, tangant planes?, solids in contact. there the 3 id go for if they were on

can anyone put up the list of possible qs they can ask on the short qs? that would be extremely helpful

Paddy001

galway.gaa wrote: »

i reckon well see skew lines, tangant planes?, solids in contact. there the 3 id go for if they were on

can anyone put up the list of possible qs they can ask on the short qs? that would be extremely helpful

short q's
skew lines
perspective
axonometric/dimetric/trimetric
ellipse/hyperbola/parabola
oblique planes

Long q's core
intersecting planes
interpenetration
conic sections (NB focal sphere)
oblique planes
axonometric/dimetric/trimetric
perspective

Frolick

axonometric/dimetric/trimetric
They came up in both sample and PRE paper so i would say it would come up in the short questions

Des23

The only paper that will have any bearing on what we get on Friday will be the official sample paper. That is the only one made by the SEC the others are made by companies. Axonmetric wasn't one of the long questions on that. I'm not saying that it won't come up, it obviously is a possibility, I'm just saying that you can't base predictions on the sample/pre papers. Which were in fact probably not made until after our paper was made.

Isaac702

Personally I dont mind what comes up with a few exceptions.
I dont want solids in contact or a long question on (Insert Topic involving parabola's (directrix, vertex, etc..) here)

Anything else would be easy enough to do.
An added bonus however would be if part a on the Structural Forms question didn't involve the hyperbolic parabola and just used a standard one.

timmywex

Right, my list of section a/b topics are as follows, anyone anything to add?

Planes/Dihedrel Angle
Skew lines
Oblique Planes
Interpenetration
Axonometric
Perspective
Solids In contact
Conics

croker1

personally i think if oblique planes and interpenetration dont come up as b's there will be uproar!!! all im hoping for is a nice interpenetration question and im sorted!:D

anyone doing the dynamic mechanism's question?? i find it fair hard! wat ye think of it???

Frolick

dynamic mechanism hmm...
Very long question, i'm staying well clear of it. Our teacher completely avoided it (aka we ran out of time haha)

-ilikeshorts

http://www.curriculumonline.ie/uploadedfiles/PDF/lc_dcg_sy.pdf

Thats the full curriculum theres a good bit there
Core: (A) Plane and Descriptive Geometry
Projection Systems

•Orthographic Projection
•Isometric drawing and axonometric projection
•Perspective drawing/projection
Plane Geometry

•Construction of Plane figures
•Construction of loci
•Circles in contact with points, lines and curves
Conic Sections

•Terminology
•Ellipse, Parabola and Hyperbola as section of cone and as geometric loci
•Tangency
•Derivation of focal points, directrix and eccentricity.
Descriptive Geometry of Lines and Planes

•Definition of plane, its true shape and inclinations
•Oblique and tangent planes; intersections
•Rectangular co-ordinates
•Skew lines
•Spatial relationship between lines and planes
Intersection and development of surfaces

•Surface development and envelopment of solids
•Intersection of surfaces; intersection of solids
Core: (B) Communication of Design and Computer Graphics
Graphics in Design and Communication

•Design strategies and design appraisal; the processes of design
•Generation and interpretation of design briefs
Communication of Design

•Drawing standards and conventions, presentation methods and layout
•Dimensioning and notation
Freehand Drawing

•Materials for freehand drawing
•Representing shape, form, texture and material; light and shade; use of colour
Information and Communication Technologies

•Graphics and CAD: terminology and software; sketching principles
•Presentation drawings, parametric models; use of templates and libraries
•Image processing and manipulation; data exchange; graphic output
Options: (Choose any 2)
Dynamic Mechanisms

•Involutes, helices and spirals and associated tangents
•Linkage mechanisms
•Cam profiles
Structural Forms

•Singly and doubly ruled surfaces, their projections and sections
•Translated surfaces; hyperbolic paraboloid
•Plane directors
•Geodesic Dome
Geologic Geometry

•Determining dip, strike, outcrop and thickness of strata; profiles from contours
•Use of skew boreholes
•Sections through strata
•Cutting and embankment sections for level and inclined constructions
Surface Geometry

•Development of surfaces, ducting and transition pieces
•Projection of transition pieces
Assemblies

•Interpretation of exploded and assembled drawings.
•Drawing layout and conventions; sectional views, hatching, dimensioning
•Machine surface and texture symbols; modelling assemblies

Des23

We did Geologic Geometry and Structural Forms, I don't know anything about the other questions but just from appearances I would think that these are the easiest two. There are very few new things to learn, just applying what you already know. Some of the structural forms part a questions in the sample papers can be done in five minutes, I just hope they are that easy on friday!

I've been doing old HL questions for the past few weeks, and realistically, while the drawing course is this year worth 60% rather than the 100% of old, it is definitely not true that we only have to know 60% of what they did last year. I would think that a lot of us would be able to answer both old papers fully and do well in the time that they were given. It is 4 questions isn't it?

I don't know what the solution is but it seems like we got a reasonably raw deal.

EDIT:
On consideration we probably wouldn't have much choice, but the point definitely still stands.

galway.gaa

croker1 wrote: »

personally i think if oblique planes and interpenetration dont come up as b's there will be uproar!!! all im hoping for is a nice interpenetration question and im sorted!:D

anyone doing the dynamic mechanism's question?? i find it fair hard! wat ye think of it???

ya were doin it. i think its 1 of the easiest qs. the book explains that section well and if you just work through some examples it can be a question where you can get the full marks