Had Another Go

[Nigel Graham 2Participant @nigelgraham2]

My problem with the set exercises was not grasping what was actually happening. As long as what I made on the screen matched what was expected I assumed I was doing it correctly, but I couldn’t really see how or why. I’ve drawn analogies with experiences elsewhere, where I identified basically the same weakness: inability to think in abstract, or to learn without understanding but finding the understanding hard or impossible.

Where I mentioned particularly matrices, it was because they illustrated the problem perfectly. You might learn you times that number by this, then the next “that” and “this”, then…, to match the answer in the back of the book. You have no idea what was “right” about it beyond the Infants’ School level of each multiplication; not what you were really doing, what was really happening, what it all meant. If it was wrong it was only by some silly arithmetical slip or multiplying the right that by the wrong this. Not why it was the wrong this. Similarly with CAD, I could not see the basic principles. So when I hit problems I had no idea what I had actually done wrong where – and it could have been many steps back.

 

No, I’ve not forgotten or ignored Jason’s set of instructions for drawing that frame. I printed them off – then found for some reason a gap in that – but became too demoralised to attempt them. Thar row of cubes was the first CAD model I’d created since trying to model those chassis parts.

 

I know 3D (or come to that, 2D) CAD is not for making scrappy drawings, in that it offers you a way to make very high-quality, very accurate drawings. That comment is about what I’ve managed to produce; which is rough.

That I’ve struggled to learn CAD for so long must show something – no ability to advance beyond a very basic level.

[Nigel Graham 2]

On Nigel Graham 2 Said:

That I’ve struggled to learn CAD for so long must show something – no ability to advance beyond a very basic level.

It’s certainly a good example of why trying to teach yourself something complicated when you don’t know what you don’t know, is unlikely to end well. Those unknown unknowns are a major limitation in any subject, and are why I failed A-level maths – there was no explanation what the various mixes of trig and calculus were actually supposed to do.

[Nigel Graham 2Participant @nigelgraham2]

Well, Jason, I thought I’d better try what you suggested. This is as far as I managed:

The lowest line is where it should be. (I used the dimensions from my sketch of the real thing but that shouldn’t affect it.)

The top one is stuck on that 7.25″ distance. I typed in its correct distance from centre (6″ ) but it wouldn’t move. I deleted it, drew a new line, tried moving it. No. It stays stuck to the rest of the formation.

The image is of that first attempt. I tried again this time deleting the bottom line. That made the two top ones obligingly move to the intended 6″ distance as if that was stored for use.

So tried to add the lowest line and that behaved as above: stayed stuck in line with the others.

Went back to your instructions to see if I’d missed something, but if I have I could not see what.

Tried once again this time deleting the middle, angled line. I could then draw it back in but of course it is slightly longer than it should be because I’d not adjusted the others to the correct overall length. Probably not significant here but it might be on something else.

[JasonBModerator @jasonb]

It looks to be down to how you placed the three lines initially. If you look at the middle and top lines there is a green — constraint next to them which is the co-linear constraint which puts them in line with each other.

If you start by just doing three undimensioned lines starting with the bottom one and letting it snap to vertical, mid one at any angle and then the top one again let it snap to vertical. Then dimension their vertical lengths and then the offset from the mid line you may do better.

Also looks like you did not start the first line the horizontal axis line, though that is not critical

 

[JasonBModerator @jasonb]

Should be like this when you place the three basic lines

[JasonBModerator @jasonb]

This might help

 

[Nigel Graham 2Participant @nigelgraham2]

No – still can’t see what I’m supposed to do where and how.

I managed to create the dog-legged line, then when I tried the next bit saw only a blue box on the grid. What’s that supposed to be?

Developed the C-shape, couldn’t make the Symmetry constraint work – deleted the complete figure and drew it again, now by dimensioning it equally about the centre-line.

Is a closed figure actually that or a set of individual lines? They seem to behave as the latter.

Then couldn’t see what to dimension it from (as with the [600/2] value in your example), and which way. The only visible lines on the screen were the grid. I decided I must have gone wrong by drawing the back of the C on the axis, so copied it sideways from that by the supposedly right distance and deleted the original.

Then what? Where is the guide-line? I kept raising an error called a “Top-Bot-Conflict”, or similar, meaning or explaining nothing to me.  So tweaked the view to see what the heck I’d generated…

I’d generated complete rubbish: totally wrong orientation, totally wrong place, planes all haywire….

 

Hopeless.

If I want to represent angle or channel-section frames in 3D, I’ll have to do so symbolically or partially.

 

[Michael GilliganParticipant @michaelgilligan61133]

I hesitate to throw-in yet more advice, Nigel … but I think I may have found a tutorial that would suit your mind-set.

Caveats:

1. I have only watched a few minutes so far
2. it includes advertising for ‘Brilliant’
3. I am unlikely to ever actually use Alibre Atom

With all of that said: I plan to watch it later today, just for the sake of background learning.

MichaelG.

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https://youtu.be/YyXBWuQy3ss?feature=shared

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[JasonBModerator @jasonb]

Just noticed my text did not match what I had highlighted in those instructions back on page 5 or showed in the video. Should say

Select the ZX plane on the tree down the left of the screen and click “activate 2D Sketch”. The axis and plane swill move on the screen but the orientation is looking at the top of the chassis, rear at the bottom of the screen, front at the top.

Don’t start again. Open the file right click sketch 1 from the list down the left and then select delete. Now follow the instructions and click ZX plane, activate 2D and draw the guide lines. Your C section should be OK.

Otherwise it looks like you are doing OK, You have the guide line and you have the C section.

 

A closed feature is made up of lines but the last line needs to meet the first to close it. That is why the guide lines you draw first give the warning as they don’t join up at teh ends.

[David JuppParticipant @davidjupp51506]

Put simply – for a sweep to work, the path must reach or pass through the plane which the profile sketch is on.

In the file shown by Nigel, the fastest fix would be to copy the sketch content from the current path sketch into a new sketch on the ZX plane.

[David JuppParticipant @davidjupp51506]

In the Joko Engineering video linked by Michael, sweep is dealt with from about the 56 minute mark.  It gives a clear explanation of what sweep does, by walking through an example.

Joseph, who produced that video has subsequently been hired by Alibre as VP of Customer Engagement – a big part of his job is making videos both for promotional purposes and as tutorials.  He has added a lot of content to Alibre’s YouTube channel.  He’ll even produce custom videos on specific modelling tasks requested by users.

[Michael GilliganParticipant @michaelgilligan61133]

Thanks for the info. David

… It looks like my instinct was good 🙂

 

MichaelG.

[Nick WheelerParticipant @nickwheeler]

When using sweeps, I create a new construction plane along the path the sweep is going to follow. Name it, to make it easy to select from the menu rather than clicking on a visual representation(I generally turn those off to remove confusing clutter) for the profile creation. Project the end of the path into the new sketch, so the profile can be constrained to it.

While that is a couple of extra steps if an existing plane could be used, I find the discipline reduces frustrating problems like creating the profile on the wrong plane, or it not contacting the required path. Naming the planes, parts and operations makes adjusting them easier. Or possible if I come back to it after time – it’s much easier to pick and understand rail profile plane than plane 23.

[David JuppParticipant @davidjupp51506]

Nick – technically the path does not need to contact the profile, though it often will.

[Nigel Graham 2Participant @nigelgraham2]

Sorry, Jason & Dave –

It still went to rats.

Delete Sketch 1… From the list or the drawing? Not from the list. I could select it but the whole menu that includes ‘Delete’ was off (light grey).

Copy Sketch Two…. I can’t see how you do that.

 

I think I accidentally deleted the wrong sketch, but anyway when you go from the first to the second and the planes rotate, what are only lines disappear into the axis lines, possibly somewhere where they cross a large green square that appears on the screen but indicates nothing.

I drew that ‘C’ shape yet again, because the first was lost, but I can’t make that Symmetry constraint work so have to dimension things like that from the axis. At least I found a slightly quicker way to draw it.

Then what? What is that dimension you give for it (300mm in your example) between?

Back in 3D mode, the two new sketches are there but nowhere near each other and the section profile faces the wrong way. Just like the first time.

 

I thought I was making some progress forwards a few weeks ago. I still am but now the wrong way, in full reverse gear. I honestly thought that beam in 3D would be far simpler than that cylinder-block. It isn’t. A single straight piece of channel is, but those bends make it too hard for me.

….

As for that video – “Introductory”? Hardly, at over an hour long By the time it’s reached “Sweep” an hour in, so evidently an advanced stage, I for one would have forgotten most of what went before, and be very confused about the rest. The presentation, starting with the publicity ornamenting by professional, very experienced draughtspeople showing off, is very discouraging if you find 3D CAD hard to learn. Not only Alibre – all the major CAD manufacturers do that.

This video is even worse on viewing it. The start destroys your confidence immediately by plunging straight into three or four extremely advanced examples, then a wretched advertising break. That’s where I closed it. Is it really intended for professional CAD users converting to Alibre from another make?

I tried again, a few minutes forwards to see what it might be like (something about freehand squiggly lines…?), but being YouTube, Google lathers everything with irrelevant, peurile commercials. They even break into videos every minute or so with them. I can’t be doing with it.

It certainly could not help me avoid this sort of shambles, and yes, this my second attempt though very like the first:

[Nigel Graham 2]

On Nigel Graham 2 Said:

As for that video – “Introductory”? Hardly, at over an hour long  […]

Oh well … Sorry I spoke !

I honestly thought it would be right for you, Nigel

I am enjoying learning from it, even though I don’t expect to ever use Alibre Atom

MichaelG.

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Edit: __ it’s not for me to judge, but if you can’t spare a couple of hours to follow a free tutorial  of this quality, then I would recommend you resurrect the drawing board.

[Nigel Graham 2Participant @nigelgraham2]

Oh, sorry, I didn’t mean to criticise you!

I find tutorial videos very difficult by being single, continuous flows of too much information too fast for me to absorb. This isn’t new: I struggled even when young and using proper text-books, to learn anything difficult. If it’s broken by advertisements, I’d lose it straight away.

Also I find videos do not always show clearly exactly what the tutor is indicating. It’s even worse if he points to it for barely a second, and meanders the pointer around the screen.  Computer displays do not lend themselves to hi-fi reproduction on other computers.

 

This one deterred me just by its introduction. I don’t imagine you are expected to be able to copy that cylinder-head and turbine afterwards, but their being demonstrated implies the instructions rise to that rarified level in the hour or so of the actual teaching time. I take it those examples are only to advertise Alibre’s and the tutor’s own abilities – but he probably gained them via University, considerable industrial training and years of full-time experience.

I could not cope with such a huge volume of knowledge crammed into a single session, especially if it rises beyond whatever it reveals as my level for learning it.

Even that 5-second snippet I saw only a few minutes’ worth in, had just finished something about a carefully-plotted hexagon then abruptly dived into scribbling freehand over it. Eh?? If the ‘Sweep’ tool appears about an hour in – how advanced is its use?

I should say I don’t know how long the video is, and how much of that time is actual teaching, nor what it does finish with. To establish that I’d need let it run while doing other things (in the workshop even!), and come back near the end.

So, no, sorry, but a video like that would not help me. It would do the opposite. Also if Google interferes with it as it usually does to YouTube videos, it would be even worse.

[Swarf MakerParticipant @swarfmaker85383]

It is a shame that you chose to view the example video that MichaelG suggested, using YouTube – with all its advertising distractions.  If you go back to Michaels link and click the square on the bottom right of the link, then you can watch the video ‘outside’ of YouTube without any advertising.

The advanced models at the outset are unimportant since they are just to illustrate what the education could lead you to accomplish. They are shown as purely introductory and I would have expected you to appreciate that  – so ignore them.

Don’t rush to try and find the sweep section.  Just take time to fully appreciate the sketch section and don’t go any further until you have explored all the factors that define a properly constrained sketch.  It is very clear, well presented and completely fundamental to any parametric CAD programme.

You need to watch and listen to each step, stop the video and consider whether you understood what the implications of that step might have toward accomplishing your own sketches. Go back in the video and watch/listen again and see whether your understanding matches what has been presented.  Then try an example for yourself.  When that action is fully understood, then you can go on to the next step in the video and learn the use of a different constraint or construction process.  Again, stop the video before it goes to another feature and repeat the learning and experimenting process until it has sunk in and you are able to use it.

That video is exceptionally good and if you are prepared to discipline yourself to learn from it one step at a time, such that you fully understand what each CAD tool is able to achieve for you, then the possibility of becoming proficient is close at hand.

Unfortunately, if that measured approach is unacceptable or unachievable for you, then no amount of mentoring will be able to get you to where you wish to be.

 

[duncan webster 1Participant @duncanwebster1]

This is probably rubbish, but here goes. Nigel’s channels appear to be bent in one plane, xy. Could he draw out the plan view as a rectangle with 2 bends, then extrude up and down in z direction to make a 3 dimensional solid, then draw another bent rectangle on xy and cut extrude it up and down in z to convert the solid into channel. To pretty it up you could then add fillets in the corners.

I fear if I download the free trial I’ll spend even less time in the workshop, and I’ve got too many unfinished projects as it is

[JasonBModerator @jasonb]

Nigel. Looks like you have drawn on the wrong planes.

 

As per my correction yesterday you want the Guide lines on the ZX plane you look to have it on YZ and the 300mm is from the Z axis

You also have the C section on the ZX plane when it should be on XY

If you doas  my instructions the two sketches will be in the correct place. This is why your screen shots have the chassis stood on end and mine is flat as it should be.

If you are not quite sure where you are placing a sketch then while in 2D sketching you can either hold down both mouse buttons then move the mouse and get a 3D view which will allow you to see the first sketch. Or click the different view icons of the cube top right.

Send Me and David the file and we can put your sketche sonto th eright planes then you can look at them on your own screen. I’ll PM my email again.

[JasonBModerator @jasonb]

Duncan, yes it’s an option though I feel there will be a lot more needed to do it that way than with the sweep.

[David JuppParticipant @davidjupp51506]

I pointed out the start time of the section of the video on sweep – exactly so Nigel wouldn’t have to sit through an hour.  The video is long because it goes slowly through each item (though there are some diversions).  The annotated timeline does help to pick out specific content.

Michael did point out in his initial link to it, that there is some advertising in that video (fairly near the start) – you can only ignore that by spooling past it as it is part of the video.

NO that video isn’t intended to ‘advertise’ Alibre’s capability – it is not an official Alibre video.  It was produced before Joseph was employed by Alibre.

 

Nigel – your last screenshot looks like it ought to produce something, even if the bends might go the wrong way.  I’d be able to help more specifically if you either sent me the file including the failure, or reported the result, including any error messages.  You don’t even say if you got as far as trying to use the sweep tool.

 

The ‘Large green square’ you mention is a representation of a reference plane – a new workspace has 3 of these which all intersect at the origin.

To copy a sketch – you can open the source sketch, either select all (Ctrl+A) or use one of the other selection options to choose figures to copy, then use Ctrl+C OR the copy icon in the sketch ribbon.  Exit source sketch, start destination sketch and use Paste (Ctrl+V) or Paste Stamper (Ctrl+T) or corresponding icons from the ribbon, to insert the copied figures into the sketch.   Copy & Paste essentially work as in any other Windows application.

The fact that your 2 sketches are ‘nowhere near each other’ probably doesn’t matter as long as your ‘path’ sketch at least reaches the plane that the profile sketch is on.  If it doesn’t reach far enough, the sweep will not do anything.

 

[Nigel Graham 2Participant @nigelgraham2]

Well, I did have a look at that Joko Engineering video and I must admit it is far better than I had feared.

I have had so many disappointments with trying to use training videos, and so much frustration with Google / YouTube, that I am very wary of them.

I watched it until its pause to let you have a go at sketching something; anything it seemed, rather than a rote exercise that lulls you into a false sense of security. It was now nearly 1am, so I didn’t try drawing anything. I did gather I should use those sketch constraints much more than I had been.

I am under no illusions though I could learn to use Alibre Atom, or any 3D CAD, to the level shown by Jason and others on here. I might be able to create individual parts, far less ambitious than that video’s examples; but not full assemblies. I can’t even get something as simple as a “bent girder” right.

[JasonBModerator @jasonb]

As David says, what you have will stil sweep but not in the way you want, you are getting close.

This would likely be the result of sweeping what you have

[Nigel Graham 2Participant @nigelgraham2]

Mmm. I didn’t think it would even be swept because I thought the right part of the section has to meet the start of the guide-line, as well as being the right way round of course.

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