Had Another Go

[Nigel Graham 2Participant @nigelgraham2]

Jason –

I’d not intended including bolt-holes on the CAD model because the real chassis is already made and the CAD’s purpose here is to help me design the next stages.

If I can’t use the mirror tool to reflect the finished beam, then I take it the only possible use is in duplicating the initial sketch to produce the section profile.

….

Nick – 

Sorry, but you’ve lost me there.

My problem is not being unable to use the sweep tool within a specific project, but being unable to use it generally.

I tried to understand it but it confuses me completely. I could not see how you place the line the profile is supposed to follow, or locate and orientate the sweeping object so it will follow the line.

I managed, sort of, to create a few bits of round “rod” but without really knowing what I was doing. They paralled the guide-line but away at some random distance to one random side. Yet that was “just” a circle along straight lines and regular arcs. Or is this supposed to happen? Does it matter? I’d assumed the profile would run along the line.

The manual did not help me. It apparently says the profile should be on a different plane. Well, I can see it can’t lie on the same plane as the guide-line, but also it does not need start on the line.   Which means that in sketch mode you can see one but not the other, and in 3D they have no clear relationship to each other, but if they cross, overlap or one passes through the other it won’t work. Or so it seemed to say.

Then when I tried other shapes I hit the usual problem of things facing the wrong way.

This is all why I concluded the Sweep tool is an advanced method beyond me.

 

As for “Creating dimensioned, mirrored, swept profile, fully editable chassis rails would be a good 5 minute in-person exercise“……

Five 5 hours genuinely would be a realistic estimate for me, based on how long other models have taken.

Even if I was able to complete it, and that’s extremely unlikely, it would leave a long trail of errors like failed constraints, and high move-count numbers.

“in-person”? Umm, well, obviously. The PC won’t drive itself! 🙂

[David JuppParticipant @davidjupp51506]

Nigel,

I think you have misunderstood the manual.

In simplest terms, imagine a round bar with some bends in.  A section across the bar (a circle) is the profile sketch for the sweep that models the bar.

A line along the centre of the bar is the sweep path.

In many cases the profile sketch is on a plane that is perpendicular to the plane that the path sketch is on – though the actual rule is that they can’t lie on the same plane (if they did, the resulting sweep would have zero thickness, hence not a valid solid).

[Nick WheelerParticipant @nickwheeler]

The in person isn’t you, but a tutor/mentor/guide/whatever you want to call them. Everything you need to know to create a reliable swept profile can be explained, demonstrated and followed by you in five minutes. If I was that person, I’d use your chassis as the demonstration as you need it, have the details and understand the part.

To get predictable results try this:

open a new file however Atom requires.

 

ensure that the origin and 3 base planes are visible, even if you don’t normally work like this.

 

create a new sketch on the XY plane

 

starting at the origin, draw a 3 piece cranked line with each length 150mm long, and 45degrees at both angles. That’s the path for your rails, and represent the shape. Dimensions are random guesses. Constrain the parallel lines so they’re also parallel with the Y axis.

 

create another new sketch on the XZ plane

 

To make the demonstration simple, use the rectangle tool to draw a 100×50 rectangle with one of the corners fixed to the origin.

 

Close both sketches, but leave them visible.

 

start the sweep tool, which will ask for a path – which is the line in the first sketch, and a profile – which is the rectangle in the second.

 

Click OK.

 

That will sweep the profile along the path to give a cranked solid bar. If you want it to be hollow, edit the second sketch by offsetting the rectangle lines by 5mm. You could alter the dimensions to 150×75(doesn’t actually matter), change to profile to a seven pointed star or whatever else takes your fancy.

This would be a basic five minute demonstration from an in person tutor sitting with you. Once you can repeat this reliably including editing after the sweep, then more complex(don’t think of them as advanced!) methods like not attaching the profile to the path, or creating the profile plane directly from the path could be discussed.

 

I agree that manuals for computer programs are absolutely hopeless for learning how to use it. They’re full of unexplained jargon, atrocious English, and terrible explanations. They read like they were translated from Chinese by someone who doesn’t speak English or Chinese but has a dictionary for each.

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