DCG discussion thread

galway.gaa

eoccork wrote: »

In the official sample paper in the intersecting planes question it says: Determine the angle of inclination of the line of intersection to the vertical plane.
Does this mean you look perpendicularly at the line of intersection in plan? or am I completely off!?

Anyone else think that time could be a huge factor? How long are you giving to each question?

i think time is the only real problem on this paper to be honest. i reckon ill get the short qs done in about 20mins. that should leave 40mins for the other qs but i think ill get them all done in 35mins and give the extra time to the interpenetration as i find this one the most time consuming

Prowetod

eoccork wrote: »

In the official sample paper in the intersecting planes question it says: Determine the angle of inclination of the line of intersection to the vertical plane.
Does this mean you look perpendicularly at the line of intersection in plan? or am I completely off!?

Bump

Des23

Would you not just throw it onto a cone and rotate it? thats what we for it anyway. Just the oppisite of what you do for mining questions when they say that a borehole has an inclination of 30 or what ever..

mink_man

the laminas question from the state sample paper, (c) determine the angle of inclination of the line of intersection to the vertical plane???
how do you do this???

ironclaw

Make one the line in either the plan or elevation horizontal relative to the X1, Y1 axis. The true lenght and angle will be in the other view.

DCG questions are so hard to explain in words! :pac:

mink_man

ironclaw wrote: »

Make one the line in either the plan or elevation horizontal relative to the X1, Y1 axis. The true lenght and angle will be in the other view.

DCG questions are so hard to explain in words! :pac:

i dont understand, do i get it as an edge view first? or what?

ironclaw

mink_man wrote: »

i dont understand, do i get it as an edge view first? or what?

You could do an edge view, tell ya what, I'll do it and upload it later to Flickr, might be easier

Basically, you have a line in the elevation

Now that line is also in the plan

Pivot the one in the plan to the horizontal

Now, move the one in the elevation relative to it.

You are now seeing the line at 90 degrees, thus a true lenght and true angle.

Isaac702

Thanks this is one of the things I did not fully understand. I should be able to answer the question if necessary now.

mink_man

ironclaw wrote: »

Make one the line in either the plan or elevation horizontal relative to the X1, Y1 axis. The true lenght and angle will be in the other view.

DCG questions are so hard to explain in words! :pac:

ironclaw wrote: »

You could do an edge view, tell ya what, I'll do it and upload it later to Flickr, might be easier

Basically, you have a line in the elevation

Now that line is also in the plan

Pivot the one in the plan to the horizontal

Now, move the one in the elevation relative to it.

You are now seeing the line at 90 degrees, thus a true lenght and true angle.

i think im kinda gettin it now, you swing the loi in elevation until its level but then in plan, when you bring that dow, what do ta join that to?

Delta Kilo

If you have to get the dihedral angle, when you get your first auxiliary where you look across the line of intersection, the angle the line of intersection makes with the x1,y1 axis in your auxiliary is equal to the angle of inclination. Just mark it in their instead of doing the rotate method.

errlloyd

Ok ladies, lets talk long questions...

What can come up?

Solids in Contact
Axonometric
Intersecting solids
Skew Lines
Perspective
Developments

.............

Ok so now. What actually WILL come up.

Skew Lines is apparently a definite...

So whats we have 5 other possibilities (or more I could be wrong) for 2 other questions, of which we have to do 1. To be covered I guess we need to do 4, are there any we can rule out?

galway.gaa

skew lines is deffinate for a short question id say but for the long questions id say planes and traces, interpenetration and developments maybe. ive only looked over the first 2 topics but i think it will be very similar to the sample paper

Damien671

I'd guess intersecting solids and possibly solids in contact but as their fairly similiar I don't think they would both come up

Des23

I would put money on two of the three long questions being out of:

Planes, could be 6 points, with a little bit at the end on true inclinations

Solids in contact, usual jazz, will have to use loci and find traces for a tangential plane.

Interpenetration nothing unusual I would think because they take long enough.

The two option questions I'm doing are fairly predictable:

Structural forms: nothing unusual, have to get sections of a hyperbaloid of revolution to find a curve, or find circle using straight line elements, then for the hyperbaloid surfaces I'd say we will have to find either the line of curvature or plane director, most probably the latter.

Geologic Gemoetry:
Sloping road as usual, maybe a curve if they are feeling dangerous.
Nothing unusual can come up in mining: Strike, length, dip and apparent dip are all that will be there I'd say.

Short questions will just be a combo of what doesn't feature on the long questions, conics perspective/axonmetric other stuff...

Prowetod

Did anyone else get 58degrees for this?

mink_man

anywhere that tells you how to do the interpenetration q's, i cant do them at all!

eoccork

eoccork wrote: »

Did anyone else get 58degrees for this?

You don't have to measure; you only have to indicate which angle it is.

Prowetod

-JammyDodger- wrote: »

You don't have to measure; you only have to indicate which angle it is.

I know its just so I can check if I am right. Our teacher said to include the angle as well but its not necessary.

eoccork

eoccork wrote: »

I know its just so I can check if I am right. Our teacher said to include the angle as well but its not necessary.

Ah right right. Well, 58 rings a bell with me (from some drawing).

errlloyd

Well I didn't do it portrait, so I can't get the last part, but here we go, yes the ****ing thing is upside down. But I think that's right so far. (If you download it to flip it, use paint to invert the colours, its not any easier to see, but its cool.

Oh one thing to note, I initially forgot the line of intersection was going to connect to point A, when it did I was like "**** I must have made a mistake" normally if I make a mistake its grand, but if you make one that "makes the question easier" you lose a **** load of marks. So I originally drew the line wrong, its still wrong in elevation1, but you can see its ok in plan, (although the wrong one is still in heavy, I am too lazy)

Final Edit, if you are planning on scanning anything, don't use Green pencil, its ****ing ****...

errlloyd

Actually if anyone wants a mildly enhanced version (I.e I went over the lines in paint, lol) I'll send you one.

If anyone is doing more of these, can we all do the same ones, possibly question 16 on page 268 of the orange book?

I'll upload the solution if I get it.

Des23

pg 287/288 or the red/orange book does it to the standard that will be asked in the exam, failing that you could try and do an old HL one, although it will be harder you can get the solution on the internet and the OL ones won't have the aux. plan, which will be asked if it comes up. Our teacher only did the OL standard with us, never did aux. plans or anything, had to do it myself.. along with a lot of the course if im being honest.

mink_man

the sample paper again, how do you do the surface gometry q, the one with the circe to square duct?

There's already 2 or 3 threads on DCG!

papu

quick sketch , gets the jist across

for horizontal plane you just do the same in the plan make a cone and move it down

Prowetod

Also if anyone gets a chance could they explain QA-4 on the official sample paper part (ii)

Does it just require you to continue the line you got in part one in plan until it hits the XY line?

errlloyd

Hmm papu, I don't think that's the answer. Banter. Nearly 100% sure you're going to need to do an Aux, nearly, but not quite.

Delta Kilo

Little tip for people practicing drawing q's. Divide all the measurements by 2 and draw it on A4 paper. Saves a lot of hassle and time and you can still do it the exact same way.

Prowetod

errlloyd wrote: »

Hmm papu, I don't think that's the answer. Banter. Nearly 100% sure you're going to need to do an Aux, nearly, but not quite.

No its right, I did it both ways and got the same angle...

Also if anyone gets a chance could they explain QA-4 on the official sample paper part (ii)
Does it just require you to continue the line you got in part one in plan until it hits the XY line?

errlloyd

Take it back, works fine. You do actually still need the Aux for part 4.