Alibre Model / View-Cube Orientation

[John HinkleyParticipant @johnhinkley26699]

Phew! Progress!

John

 

[Nigel Graham 2Participant @nigelgraham2]

Thankyou Jason& John!

Don’t get too excited though.

I have altered the eccentric rods to overcome the mismatch, and thickened the expansion-link to suit, but have not measured the new drawing edition to see if it is still the same length as the originals already made in real metal. It was very difficult because the original rod was a collection of about 10 different extrusions and extruded-subtractions; but at least it put the assembly drawings right. I didn’t bother with the fillets originally in the rod. They can go in a workshop drawing version.

I have added simplified versions of the guide-bars and the expansion-link,  but it became more and more difficult, and I started to see constraint errors appear all over the place with no obvious links to the last move. I have not counted the constraints but I think it’s well over twenty. Oh, and I had to add a new central XZ plane because the whole assembly was no longer on the original, plus three more to align the guide-bars. So it still has the potential to fall to bits and I am not sure I can safely add any other parts.

 

All of the viewing-angle selectors have become totally meaningless in direction, and extremely sensitive. The slightest touch or shake of that cube with the mouse sends the whole image gyrating widely in unexpected directions, skidding across the screen, changing size randomly and generally out of any proper control.

The little frame symbols on the tool-bar at least move it by fixed amounts but don’t correspond to anything on the screen, and computer thinks I want the assembly lying on its side instead of standing upright.

 

[JasonBModerator @jasonb]

When I start a new assembly I “Anchor” the first part once I have added any constraints. This ensures that it stays in the same place and any subsequent parts added will also move to the first part as they are constrained rather than risking the whole assembly jumping towards a newly inserted part.

To anchor a part right click it and from the drop down options click “Anchor”. You can always remove it at a later date if needed.

The laying on it’s side is because you started the assembly with that plate which was drawn on it’s side. If you don’t constrain it so that it is flat then any subsequent parts added will also be on their sides. So fist job after inserting should have been to constrain one surface to the flat horizontal XZ plate. It is no different to you assembling the engine in the workshop if you start by holding that plate on it’s side and keep it like that as other bits are bolted on it will always be on it’s side. So lay the plate down flat first and then add the bits on top or below as they are inserted, it is just like picking the first plane to start sketching a part on – you need to pick the right plane to start assembly on.

[Nigel Graham 2Participant @nigelgraham2]

Thakyou Jason – given my familiarity with three-dimensional co-ordinates I ought not have all this confusion with their CAD brethren! So I tried a quick test as I think I understood what you mean. I drew a square on that Xz plane, and extruded it, added that hollow to give a defined “way-up” and “which-way-round”; and the results are as below.

It’s just not intuitive. If I try using the other planes to start it still ends up all weird! My milling-machine doesn’t work like that – its “X” is upwards and downwards, not off to one side, the knee moves up and down and the top of the table faces upwards. Similarly with any conventional co-ordinate geometry.

 

 

At least I have enough information in that assembly to start modifying those parts already physically made where necessary, and to design the further components.

The eccentric sheaves and straps are made but not the rods, so seeing that mistake has at least meant I can get those right before some hours of metalwork. That error was not a CAD-driving one. I’d miscalculated the dimensions.

The one big part I definitely want to be certain of before cutting any metal is the cylinders: machined out of a solid billet of cast-iron stock bar.

[blowlampParticipant @blowlamp]

Is there a setting in Atom where you can make Z the elevation axis and Y the vertical axis when in top view?

 

Martin.

[Michael GilliganParticipant @michaelgilligan61133]

Whilst I fully accept David’s assertion that any orientation is valid … This does seem [to me, at least] the most intuitive.

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It relates back nicely to mathematical graphing.

MichaelG.

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Ref. https://support.shapr3d.com/hc/en-us/articles/7873937480604-Orientation-Cube

[Nigel Graham 2Participant @nigelgraham2]

Cor, don’t CAD publishers love to use extraordinarily complicated examples to demonstrate how clever their staff draughts-people are, even just to show a basic point!

 

My point exactly, Michael, though I use Alibre Atom, not Shapr3d.

Alibre uses a similar, though simpler, indicator / rotator it calls its “View Cube”.

 

I can not make my 3D models and the assorted orientation and planes tools follow that normal 3D-geometry convention. They do not even agree with each other on the screen.

Almost any object has its own (x, y, z) co-ordinates and definite TOP in its normal orientation. In that orientation they agree with normal “world” co-ordinates: x along, y across, z up.

Tip the object on its side: its TOP now faces sideways but is still its “top”. Its axes are also tipped; but not those of the big wide world.

Fine so far and the rotation tools in CAD let you tip the thing over along with its internal axes.

 

Unfortunately I am naive enough to want to draw it upwards from the normal (XY) plane to its definite top at height (z), the axis-arrows all pointing their right way, the other indicators including the “View [orientation] Cube” showing that top as “TOP”, and they staying faithful to it even when I use them to turn it over.

If there is a way in Alibre Atom I have not discovered it. Jason points out it depends how you start the thing, but I tried that example in two different ways and it was still all inconsistent.

 

It may not matter for Part models, which enter Assemblies in any old orientations anyway unless you can plan their foundation sketches appropriately. I can’t.

However, a complicated 3D assembly is far easier if the actual top is at (x, y, z), its base is logically on its (x, y) plane, and all the screen tools say they are.

It’s bad enough being baffled by the mysteries of assembly-constraints, without heavy geometrical confusion as well.

[JasonBModerator @jasonb]

Just turn the Cube off, Alibre managed without it for many years.

I don’t know why you managed to draw your square and circle the “right” way up as I explaind and then failed to use the same simple logic to draw it on other planes. The other planes you would need to start with a flatter rectangle as you would be looking at a side or end.

 

Question For you Nigel. When machining a simple block of metal to clean up all sides square and to dimension how many times does the Z axis of the block change? You mill may keep the same Z axis of the Knee but you are not drawing your mill you are drawing a part.

[JasonBModerator @jasonb]

Here you go Nigel. Drawing a 1-2-3 block three times. First looking down on it, then looking at the front and then looking at the side. All end up in the same orientation but you need to sketch what the part looks like from each of those view points. Click the full screen icon bottom left once the video starts.

Those parts will then display the “right way” up and be inserted into an assembly the “right way” up.

Don’t over think it as David, Julie and I have said once you put a part into an assembly or start machining it you are quite likely to have it orientated in more than one “way up” Hopefully you would not draw two wheel, just assemble using one wheel file and fit to the assembly so each faces the right way.

[David JuppParticipant @davidjupp51506]

For those that have asked, and to avoid Nigel searching for it, there is no option in Atom3D to re-orient the default reference axes.

[Nigel Graham 2Participant @nigelgraham2]

Thankyou.

I know it does not matter for single parts, though if possible I try to draw them orientated as the real piece would be in life.

When drawing it I think how I might make its real version, partly because it is easy to draw something impossible to make. Even the professionals sometimes manage that.

When making it I do not think about its digital representation, but the physical work-piece orientation and tool movements for any given operation. Then (X, Y, Z) matters only on my milling-machine with its 3-axis travels and DRO, within the normal “world” co-ordinate system – with (+Z) upwards.  I don’t use Cartesian co-ordinates in turning, let alone hand-work, just distances and sizes.

The drawing, if an Atom3D one, does not show the construction geometry anyway. It shows centre-lines, on request but rather limited. (Can they be extended to link correlated features, including across elevations?)

 

It’s sticking more than a few simple Parts together in a 3D CAD Assembly I find so hard.

I keep having constraint and plane problems, but the ways the axes run adds to the confusion. Trying to make the planes and assembly’s orientations match so its intended top is shown as the top, baffles me.

[Nigel Graham 2]

On Nigel Graham 2 Said:

The drawing, if an Atom3D one, does not show the construction geometry anyway. It shows centre-lines, on request but rather limited. (Can they be extended to link correlated features, including across elevations?

YES – you can extend centre lines.  Right click on the centre line – then Edit, alter the ‘extension’ value.  (it applies at both ends of the line).

See Help  https://help.alibre.com/articles/#!alibre-help-v28/2d-drawings-detailing-annotations-and-gdt-centerlines-and-centermarks-modifying-centerlines-and-cen-

As the views are aligned anyway by default (though you can turn that off)  features that have centres, should be aligned across views anyway.

[blowlampParticipant @blowlamp]

I can see what’s confusing Nigel.

I made a quick video of how the Z axis in Atom appears to point in the negative direction when in Top view, except it’s actually Atom’s positive direction.

So I think Nigel has to contend with the Z axis not coming out of the screen as he expects, but also that it’s now pointing in another seemingly wrong direction.

 

Martin.

[Nigel Graham 2Participant @nigelgraham2]

Thankyou David.

I do keep the imported views in line unless I really need shuffle them to fit the paper. I prefer to keep to default settings where possible, and they usually give me what I want.

 

I think I need look again at buying an A3 printer, ensuring it genuinely is A3, and probably not a multi-colour ink-jet. The drawing I created to investigate my eccentric-rods dimension-error is full-size and takes the whole A4 sheet just for that area of the machine.

 

Martin –

That’s the sort of thing I mean but I don’t think Alibre Atom has anything like the axis controls you have there.

Wht I expect, or rather want, is the not the Z-axis coming out of the screen at me, but upwards towards the ceiling, when I orientate the drawn object so its intended top is at the top of the image or the eventual print. So the Z-axis points sideways if I turn the object on its side, and down into the table when I turn it upside down.

 

[Blimey! I had a haunted workshop several weeks back. Just now I thought the same ghosts had found my computer – a mystery male voice in an accent I did not recognise. Then I spotted I’d not turned off your video before returning, and it had started something else!]

[blowlampParticipant @blowlamp]

Nigel.

What I meant to get across was that you want the Z axis ‘coming out of the screen’ when in Top view and that’s with the X axis pointing left & right and the Y axis pointing up & down, as seen on screen. When in Front view, the Z axis would then point towards the ceiling. Is that what you are after?

Rather than a ghost, you might have ‘auto-play’ or something switched on in the Odysee screen.

 

Martin.

[JasonBModerator @jasonb]

Martin. In Alibre both the View cube and the X-Y-Z arrows are not orientated as they would be if using a mill.

What Nigel wants is to orientate the part so it looks the right way up in it’s intended final position and for that to match both the cube and arrows. Quite simply it Won’t.

Drawn to look the right way up on the screen with his head at the top, face towards the front and side at the side. But his head is pointing in the Y axis not upwards towards Z

Now you can draw it so that his head faces up towards Z but then that throws off the faces of the cube.

If I wanted to insert the two versions into an assembly, they would appear like this when I went looking for the file.

And when inserted into the assembly look like this, as Nigel has difficulty arranging parts within an assembly the suggested man that is the right way up should make it simpler for him if he uses the first method shown

Like Julie I have no problem constraining the men so they both look right.

As I have said up until a few years ago Alibre did not have  aview cube and I seldom use it now. I also just drew the parts as option ! so they looked right on my screen. It was not until I got the CNC that I found that when imported into F360 my man would be laying on his side rather than flat on his back ready to be profiled to shape. Not a problem as it is easy to orient the stock.

Even with F360 having what people here say is the Norm eg Z up. If I drew that man standing with his head Up I would still have to alter the orientation if I wanted to profile the shape so he was laying on his back. If I also wanted some screw holes in the underside of his feet so he would not fall over I would need to do a second setup so his feet faced to +ve Z so which of those three is the Norm.

Just like if you draw a part in MOI, Solidworks, etc. Which way is up if you need to machine from all six sides of a cube?

[Nigel Graham 2Participant @nigelgraham2]

I am sort of used to Parts entering the Assembly screen in all sorts of odd ways, sometimes twirling gracefully like falling Autumn leaves, and settling any old where in any old orientation.

I now use that “Componement Placement” tool’s “Free” mode to grab them by the scruff of the neck and twist them into near alignment and near their locations. I’d prefer a more definite approach but can never align them in their own Part starting-sketch so that happens.

I’ve also mentioned that Cosntraints are on this Earth to baffle me. When I first created the image below I accidentally crossed the eccentric rods. Correcting that took several attempts and many red-lit constraints, and at one point almost the entire list of well over twenty of them lit up!

From this I will create partial drawings to gauge the overall size of the machine, so I can design the casing etc. It has to occupy a definite envelope in the chassis.

Oh…. I thought I would be unable to enter said image (screen-shot thereof). The “Insert image” symbol has been replaced by a little square.

 

 

 

[blowlampParticipant @blowlamp]

Jason.

I tend to view the X,Y plane as the ground or floor plane which means the Z axis is up from it. I suppose that is how many others might see it as well.

I drew your stick man accordingly in Front view and it seems clear enough to me:

However, he’s not in the correct orientation for milling, so it’s easy to put him in the right orientation by using one of the Orient tools:

Like so:

Having said that, if it’s just DXF curves that need outputting then I don’t have to reorientate him as I can export the Front view, which automatically writes the curves on the X,Y plane for milling etc.

As here:

Martin.

 

[Nigel Graham 2Participant @nigelgraham2]

Martin –

That’s how I conceive it too, and how my machine-tools work, from long before CAD appeared; so naturally I extend that orientation to CAD as well, irrespective of the make or basic form of that software.

So when I made the drawing version of that engine’s end view above, I explored the Drawing menu more carefully. This connects dynamically to the source Assembly and that in turn to its own source Parts, so modifying a Part carries automatically to the Assembly hence Drawing – very valuable. (Provided you use it with care, especially avoiding a change that may plot, but is absurd physically!)

 

I don’t know if your CAD system has similar but I realised that when deriving the elevation drawings the orientation of the Assembly is less vital.

This because you can rotate a thumbnail control version of the Assembly by 90º steps and choose any of the resulting orthogonal views as the “Front”. So although that above shows one end of the engine, I flipped it upright, made it the “Front” in the menu, switched off the other elevations as they’d not fit the A4 paper, and transferred it to the paper layout. It’s easy to add a note that this is actually the Off-side End Elevation.

I saw many of the professional, (SolidWorks ?) drawings at work had a small isometric image in a quiet corner to help in understanding the main elevations. The Hemingway Kits drawings use the same convention. Alibre Atom also offers this service, though I’m not familar with how to use it so it doesn’t hog the whole page!

 

(The various CAD makes can be very different, of course. TurboCAD, which I started with, offers “World” and “User Defined” co-ordinates, but its default XY base for both 2D and 3D is the “World Plane” as the floor, and in 3D mode growing the extrusions or moving objects vertically is by plus or minus (Z). It puts each item in a little “cage” with its own axis-indicators. However, the main assembly-construction method places each new part’s base-sketch on a “workplane” usually but not necessarily an existing surface of the assembly, so feasibly at an angle to the world plane. Its elevation / isometric view tools are similar to those on Alibre’s tool-bar, with isometric SE as a home orientation, but it has no equivalent “View Cube”. )

[JasonBModerator @jasonb]

That’s it Nigel, when producing the 2D drawing, DXF or DWG file Alibre will let you choose any face as the top, front or side and set the other faces accordingly to 1st or 3rd angle. If you if you wanted to mill that man or send him off to be laser cut you would only need the one outline. Even then you may spin him about so his height is along the mill table and the Laser cutter could do god knows what particularly if nesting him with a batch of other items on a sheet of steel. When the laser cutout arrives who knows which way it will land on your doormat.

Really upto you if you want to sketch the part flat on XY or have it look like it is laying flat when you open the file. Main thing is to try and be consistant.

[Nigel Graham 2]

On Nigel Graham 2 Said:

 

 

I saw many of the professional, (SolidWorks ?) drawings at work had a small isometric image in a quiet corner to help in understanding the main elevations. The Hemingway Kits drawings use the same convention. Alibre Atom also offers this service, though I’m not familar with how to use it so it doesn’t hog the whole page!

To avoid taking up the whole page, just set a smaller scale for the isometric view – unlike the orthogonal projections, it is not tied to the same scale as the primary view.

[Nigel Graham 2Participant @nigelgraham2]

Thankyou:

Jason –

I try to be consistent but it’s not always easy! Perhaps the safest is to stick with the default plane Alibre Atom offers when you set out to draw a new part, so at least everything would be aligned in the same way even if drawn on lying on their sides.

 

David –

Oh yes! I’ve just tried it, finding how to alter the scale actually on the page layout if the first choice is not right. I tried a little centre-line editing too, including removing them from the isometric image.

Whatever the screen-quote scale, the elevations on the Alibre drawing itself are at twice real size, the isometric view at actual size (1:1), and all moved about to fit an A4 sheet while keeping them aligned.

[The Insert Image sign on this message-page has come back. It had been replaced by a little square this morning, though still worked.]

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