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Constraints/Dimensions or No Constraints/Dimensions in 3D Modeling
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Upper cylinder head.
Upper cylinder head.
Upper cylinder head.
Upper cylinder head.
Upper cylinder head.
Upper cylinder head.
Upper cylinder head.
Upper cylinder head.
Upper cylinder head.
Upper cylinder head.
The holes in the bottom of the head were for core supports, and they would have had probably screwed plugs in them, or perhaps pressed plugs.
The holes in the bottom of the head were for core supports, and they would have had probably screwed plugs in them, or perhaps pressed plugs.
A few assembly and miscellaneous screens.
And so piece by piece, if you have the old drawings, you can recreate a 3D model for an old engine, and then print patterns, and make a running scale engine.
It takes time and patience.
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It takes time and patience.
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You can see that I do most of my sketching work in Autocad, and then import that sketch into Solidworks.
Perhaps this clears up how I create 3D models, or perhaps this just muddies the water.
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Perhaps this clears up how I create 3D models, or perhaps this just muddies the water.
.
Pat I've not gone through all your mass of postings but just reading the first few.
"I always draw a centerline at the X,Y,X axis, and then offset that centerline over a specified distance."
Specifying a distance is giving a dimension and constraining the item to an axis
"I extrude out to some random length, and then edit the value in the window."
You enter a valve which is a dimension
"Whenever possible, I put the origin of the circle, or at least the origin of the part at the X,Y,Z intersection.
There is a window on the left side of SW, and when you draw a circle, the window will show the circle origin, the circle radius, and some other info.
You can manipulate any of the circle info in the window, but I only change the radius to my desired dimension."
You are constraining the origin to a specific point
You change to your desired dimension, if that is not using dimensions I don't know what is
So your circle is fixed in a specific place, of a specified diameter and extruded a specified amount. all constraints and dimensions. Not really what you said " I have never used constraints or dimensions"
What do you do if drawing something from scratch where there is nothing to trace over, you would have to add even more dimensions otherwise it would just be randon sketches of an unknown size
As for those assemblies you have again constrained each piece to another eg the piston is concentric to the bore, the cylinder cover is constrained to the top of the cylinder with a "mate" or some such and so on. That list down the side is all the constraints of the assembly otherwise all the parts would be floating about with no fixed position or relation to another
"I always draw a centerline at the X,Y,X axis, and then offset that centerline over a specified distance."
Specifying a distance is giving a dimension and constraining the item to an axis
"I extrude out to some random length, and then edit the value in the window."
You enter a valve which is a dimension
"Whenever possible, I put the origin of the circle, or at least the origin of the part at the X,Y,Z intersection.
There is a window on the left side of SW, and when you draw a circle, the window will show the circle origin, the circle radius, and some other info.
You can manipulate any of the circle info in the window, but I only change the radius to my desired dimension."
You are constraining the origin to a specific point
You change to your desired dimension, if that is not using dimensions I don't know what is
So your circle is fixed in a specific place, of a specified diameter and extruded a specified amount. all constraints and dimensions. Not really what you said " I have never used constraints or dimensions"
What do you do if drawing something from scratch where there is nothing to trace over, you would have to add even more dimensions otherwise it would just be randon sketches of an unknown size
As for those assemblies you have again constrained each piece to another eg the piston is concentric to the bore, the cylinder cover is constrained to the top of the cylinder with a "mate" or some such and so on. That list down the side is all the constraints of the assembly otherwise all the parts would be floating about with no fixed position or relation to another
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I had the same thought. I would guess that quite a number of constraints are coming through from the AutoCAD sketch.
It may be that Pat is thinking of "constraints" as limited to things such as, "this circle is tangent to that line" or "this line is centered between those points" or so on. But the most basic constraint is a specific coordinate or dimension. Setting a line to begin at 0,0 and extend to 25,14 provides a fully constrained line in 2d space.
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I'm not at my SW PC right now but to answer your question you simply toggle the relations view on or off from a command in the main display. If you normally like them off (as I do), just update that in your settings & the sketch will look cleaner. If you ever want to temporarily check a relation, toggle it back on. Its analogous to turning on solid shaded view vs wireframe view. Sometimes you need to see the model a certain way in certain circumstances, but you are free to display any way you like.
You may think that SW is constraining (pun) you but its actually helping you. You can start out drawing orthogonally & you are getting live feedback in many forms. If you are pretty accurate with the mouse, it assumes you probably want to be orthogonal. Then as you develop the sketch it provides you temporary faint yellow, dashed 'helper' guidelines showing likely logical choices you might be contemplating on the next step; perpendicular to, parallel to, aligned to... You can simply choose to ignore them & carry on or utilize them on the fly which speeds up the sketching process, up to you.
Re the relations view (little green symbols on all the corners & intersections). This is too busy for my liking too but the fact that its there to utilize is providing you important information. You may think something is centered or tangent but you have no way of knowing for sure unless you see the relations. Its kind of a visual shorthand.
In reality, the exact same thing is going on in Autocad but behind the scenes. In fact hidden well enough that its practically useless. If a line happens to be at 89.895 deg because you inadvertently drew it that way, not orthogonal 90-deg the way you intended, how would you ever know? I suppose you could dimension the angle against a reference line or confirm in th eproperties box (from distant memory), but are you going to go through that effort with the entire sketching exercise, thousands of lines & arcs? It adds a lot of overhead that the SW engineers solved for you decades ago. Its like driving without a map or GPS. You may eventually get to your destination, but there is surely a better way with passive guidance upon request. Thats what the relations are about.
btw SW does not constrain you in any manner. If you really want to zing a line off at an angle, go ahead. The whole idea of sketch is literally 'sketch'. Get the profile looking visually about right almost in a freehand manner (step-1). All the lines are blue. Then go back & define the dimensions (step-2), now all the lines become black = confirmed fully defined. The relations aspect is kind of of an in-between thing, this line perpendicular to that line, this hole centered at that point, this fillet occurs between these 2 lines... But its an important thing as I showed in my example. You can have all the dimensions locked down, but if any number of relations are not correct, well simply, the part is therefore not correct. In reality that means the drawing dimensions will faithfully reflect this error you created & the part will not be machined correctly nor potentially fit correctly. Where is the fun in that?
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My understanding of "constraints" is about like my understanding of 3D modeling in general; it tends to be a bit hazy, and almost certainly not completely understood.
And I think we are mixing metaphors here too.
My understanding of "constraints", which may or may not be accurate, is as follows, and this relates to Solidworks compared to Autocad.
I don't have experience with other 3D modeling programs.
In Autocad, I almost always start sketches there, and typically draw a centerline vertically and horizontally, and then offset lines a given distance from those lines, to generate a sketch.
I can grab any line, drag it over, and no other line will move, because there are no relations (constraints) in Autocad.
If I create the same sketch on a 2D plane in Solidworks, the program automatically associates every line with the next lines drawn.
If I drag any line, it affects all previous lines, and will try to drag/stretch them too.
If I offset in SW in a sketch, it will offset every line I have previously drawn, not just the one line I have picked.
Solidworks assumes that when you offset, you want to offset everything on the screen, and that is never the case for me.
When I drag a line in a sketch, I never want that to drag/stretch every line on the screen; again Solidworks is making a false assumption to "help" me.
With "help" like that, who needs Solidworks? which is why I do most of my sketches in Autocad.
Here is a random tutorial I found.
If you look at 5:29, she uses the dimension button to add a dimension and "lock down" the sketch.
I highly recommend you not do this. I never do this.
So defining a radius for a circle in the dialog box on the left is entirely different from adding a dimension using the dimension button, and so I disagree, I am not constraining anything, but merely defining a size.
Constraining that size is what I call a constraint.
And I think we are mixing metaphors here too.
My understanding of "constraints", which may or may not be accurate, is as follows, and this relates to Solidworks compared to Autocad.
I don't have experience with other 3D modeling programs.
In Autocad, I almost always start sketches there, and typically draw a centerline vertically and horizontally, and then offset lines a given distance from those lines, to generate a sketch.
I can grab any line, drag it over, and no other line will move, because there are no relations (constraints) in Autocad.
If I create the same sketch on a 2D plane in Solidworks, the program automatically associates every line with the next lines drawn.
If I drag any line, it affects all previous lines, and will try to drag/stretch them too.
If I offset in SW in a sketch, it will offset every line I have previously drawn, not just the one line I have picked.
Solidworks assumes that when you offset, you want to offset everything on the screen, and that is never the case for me.
When I drag a line in a sketch, I never want that to drag/stretch every line on the screen; again Solidworks is making a false assumption to "help" me.
With "help" like that, who needs Solidworks? which is why I do most of my sketches in Autocad.
Here is a random tutorial I found.
If you look at 5:29, she uses the dimension button to add a dimension and "lock down" the sketch.
I highly recommend you not do this. I never do this.
So defining a radius for a circle in the dialog box on the left is entirely different from adding a dimension using the dimension button, and so I disagree, I am not constraining anything, but merely defining a size.
Constraining that size is what I call a constraint.
