i think nurbs modeling is best way for precision modeling rhino is leader of nurbs modeling but
i found smaller software that name is moi3d it has very convenient snapping system and have Practical tool set for modeling it is good refrence for precision modeling in blender
blender must have more edit curve tools like fillet or offset
Snap in vertex slide is really needed example
Also let me revive this old thread I made asking for better snapping as NP_Station does
I think the snap to edge behavior for rotations needs to be completely redone, basically. You snap to whatever point on the edge is closest to your cursor at any given moment, which isn’t actually useful for anything. What you want is to snap to the point on the edge where the rotation brings your selection closest.
You would want to snap to the point where the vertex is actually aligned with the edge.
I just about dropping this one here and hoping it will be implemented https://www.youtube.com/watch?v=XrEPpHGoKlk
I would love to see Nurbs tools in Blender, but I’m worried that this is out of the developers to-do list… 
Maybe a dedicated crowd funding for that could make it possible… 
(Sorry for the offtopic)
Those snap proposals looks great though!
one thing at a time…
Meanwhile, precision modeling and better snap certainly go in that direction …
and then to be honest the nurbs seem to me a bit obsolete,
meshes with ngons technology can give more effective results if Booleans were developed better …
in fact, more than the nurbs, a visual feedback system would be needed to manage the “surfaces” and “segments” … a manipulation technique similar to that of moi 3D and obviously as a result tools similar to moi itself … in a sort of " fake nurbs edit mode ".
There is already a couple of addon that uses splines to make surfaces with curves similar to modeling via nurbs.
this application (shapr3d) mentioned in this tread makes the idea, I think that is the direction to be taken for CAD modeling …
i actually had a better idea in mind if this is going to be implemented by blender or as an add-in which i am considering creating it myself … here is what i am thinking 
just like Moi 3d, I think it’s inspiring to give an insight into how these applications handle snapping and precise modeling … I’ll post this tutorial that explores the functionality of Shapr3D, I think it helps a lot to clarify the ideas
You can already see some of the changes commented on in the original post in the Snap Utitlties addon:
Remembering that these changes would be an early step (to solve the immediate problem).
Nurbs will benefit from these changes.
I agree that the snap on the rotate operator needs attention. But I think the idea of choosing a base point would be a good start before we propose new solutions.
and then the magic appears …
it seems like a great start!
that’s what made your video come to mind:
for an effective single edit mode that also has “fake nurbs”
I think you could have a single edit mode but with the addition of two other selection modes
1 “surfaces” which are the selection of entire surfaces (a collection of polygons that have the shape of the nurbs surface)
2 “loop Segments” that would be the selection of segments (a collection of edges polygons that can also form curves) similar to that of moi 3d
with obviously the right visual feedback for these two modes
so they would have:
vertex select, edge select, face select, surface select, segment select
I hope you understand the meaning of what I mean
Noki, you’re confusing nurbs with BREPs. Trimmed nurbs surfaces are used as an intermediate step to create a mesh for BREPs, but whenever you describe nurbs, you seem to be referring to solid modelling or BREP. Nurbs are just surfaces which can be trimmed, extruded, shaped in a freeform manner, etc. In other words there is not much more to these geometry types than what Blender is already capable of. BREPs are nondestructive representations of volumes defined by operations like projections, extrusions, sweeps, booleans, holes, and bevels which can be used to create or modify a solid volume, without a lot of the limitations you see on polygonal operations. For instance mesh booleans are non-associative, and have often fail when calculating co-planer faces or when multiple vertices sit in the same location. Mesh booleans usually require modifying the resulting mesh by hand to prepare the surface for later operations like bevels. BREPs don’t care about these limitations. They mathematically calculate the volume and represent it using nurbs surfaces which are then used to generate mesh surfaces for display, plotting, and renderin
This is off the topic of what I’m saying Blender is badly in need of. Believe me I would love for BREPs to be natively supported. A STEP importer would be nice,too. Because that would mean I could fully ditch Autodesk products, but that’s not what I’m really looking for here. I want a way to quickly place, rotate, and scale an object with enough precision that it is quick easy to make renderings of mechanical components and architecture, for instance, without a lot of headache. It is an achingly absent feature of Blender. One that isn’t missing from any other rendering software I’ve used in the last 20 years.
I know what the nurbs are, and no I’m not confused …
If I talked about “fake nurbs” there’s a reason, and I think it’s an excellent solution around the corner and it’s to create a visual representation of “fake nurbs” that are created and processed by tools and manipulators that build mesh surfaces that are very similar to the shapes of the nurbs surfaces but would always be modeling mesh.
I mean a collection of tools that create surfaces similar to what this addon does
if I want to create a solid model this would be composed of so many “fake nurbs” surfaces (that are always mesh ) … the sense of all this would be to have the advantages of modeling nurbs made of Booleans,and trims operations (for this reason I wrote that they need better boolean) and modeling precision on mesh modeling.
is not necessary to have nurbs and not even breps, it’s something new that you could get “with little effort”
And I do not think it’s off-topic, otherwise what would you mean by “precision modeling”?
All these fancy (and no doubt useful) features are being discussed while you can’t even change the snap increments in blender!
This is necessary.
just as a point of study and inspiration …
for those who have not already done so, take a look at how the creator of QBlocker has developed a discreet and interesting quick snapping method
mechanical blender author has created a series of many small snapping functions that since they fully follow the blender workflow philosophy, they should be taken into account, or at least take a look at his videos and his build as he operates, to draw from them positive ideas
I attach the link of his demonstration videos, just as a starting point for study
rhino snapping tools is very power full and good refrence for blender developer
http://docs.mcneel.com/rhino/5/help/en-us/user_interface/object_snaps.htm
blender need smart track system can speed up modeling and precise
rhino have good smart track system
http://docs.mcneel.com/rhino/5/help/en-us/options/modeling_aids_smarttrack.htm
http://docs.mcneel.com/rhino/5/usersguide/en-us/html/ch-05_accuratemodeling.htm
that mechanical Blender seems like a next gen thing. Is the development stalled from a couple of years ? will be only for 2.7 ?
I don’t know, it’s a project outside blender and managed by some guys who would like CAD in blender …
At the time there was no response from the main devs so they created this alternative version …
I hope that one day this series of patches will be considered (obviously updated to blender 2.8) because I believe they are really very valid.
My background:
Retired, but still only 62 years old.
Qualified Engineering Drawing Teacher, Mechanical Engineer, Mechanical Designer, IT Developer. Started in drawing office 1978, started with CAD 1981.
CAD Packages used: Intergraph IGDS, Bentley MicroSystems, Matra DataVision (Euclid), SolidWorks, IBM Catia, FreeCAD. AutoCAD in 1987, briefly - hated it!
As a design engineer I can see many things I would like in Blender to make drawing mechanical parts better (CAD Functions), along with the suggestions already made here, might I also add:
So a workflow like: select vertex, extrude, key DC 1.2,1.4,0 extrudes the vertex 1.2 in X, 1.4 in Y and 0 in Z. Or key DR 1.3,45 extrudes the vertex 1.3 at an angle of 45 degrees relative to view positive X (3 O’clock).
So a workflow like: select a vertex, T-snap any existing vertex, accept this location, or key a delta offset like DC 1.2,1.4,0 or DR 1.3,45. This gives us the ability to use another vertex on the model as a starting point for a delta offset.
So a workflow like: select a vertex, extrude, key XY = 1.4,2.6,3.0 this extrudes the vertex to the absolute coordinate given.
So a workflow like: add vertex, key XY 1.4,2.6,3.0 or T-Snap existing vertex and key DC 1.2,1.4,0, or key DR 1.3,45.
So a workflow like: add rectangle, key XY 0,0,0, key DC 2,1.3 creates a rectangle with the bottom left vertex at 0,0,0 and the top right vertex at 2.1,1.3,0.
It is assumed that 0 input need not be added, so DC ,3 means delta 3 in Y axis, for example. XY 0 means all inputs 0, etc.
So a workflow like; add vertex, extrude, key DC 1.2,0,0 key DC 0,1.4, etc, etc, some command to close the polygon, i.e. join the last vertex to the first one.
The ability to create a single vertex and then extrude it around a coordinate defined path then close it is a fundamental requirement for CAD. The ability to tentatively snap a vertex and use this to place a new vertex, or extrude an existing one will greatly improve the workflow and reduce the time taken to create geometry.
So a workflow like; create a geometry - a bracket for example, that will be used extensively in the model, or in many models. Add this to a “Parts” library so it can be easily recalled later (think Pose Libraries…). Each part has an origin and is placed with the origin at the cursor location, or using a T-snap and delta input.
Imaging here you have made a hydraulic cylinder at an angle of 23.45345 degrees to the horizontal and you want to make it 2cm longer, without that operation taking you half a day…
As a design engineer working on a drawing board, I would start with construction lines and work from there, I don’t see the need for this in Blender, if T-snap & delta inputs can be achieved. Things must line up in technical drawing, so T-snap is a must. In all the products I have worked with, Intergraph IGDS was the easiest to use to rapidly create precise geometry. It had a “T” button on the cursor and the ability to input 3 axis absolutes and delta offsets. It also had a Parts Library, although it was called a “Cells Library”.
I don’t see these additions as a large amount of work by the way, just some additional key-ins and the T-snap to make life such easier. The other function I used extensively in those days was “Copy Parallel” - this we have with the “Offset Edges” add-on, so this should be included as well. I also like the ability to select two vertices and join them with an edge, I am not sure if Blender can do this easily, I know we can select two unconnected edge strings and make a face of them, but this is not quite the same thing…
While I am on a flow here, could we also add the ability to create shapes within shapes as holes without having to add a least two edges from inside loop to outside loop, thus creating two Ngons that don’t have holes…
I think that basic, efficient draughting techniques have been lost in not only 3D modelling packages like Blender, but also many CAD packages, the old ways were not always the best, but they certainly had a lot of merit. Systems in the 1980’s had to be very efficient and fast to compete with a good draughtsman and had to run on computer systems that were toys (think VAX PDP 11’s) compared with today’s machines.
Let me know if anyone agrees with me, I am more than willing to expand these ideas, if they are thought relevant still, otherwise I can always enjoy my retirement!
Cheers, Clock.