CAD/CAM discussion forum > 3D CAD/CAM > Sketch Constraints

Sketch Constraints

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OldForumPost

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Message 1 of 30

 Sketch Constraints
19-06-2008 03:54 . am | View his/her posts only
My impression is that many sketch elements jump around unexpectedly when applying some constraints, particularly tangents. Unless I auto-constrain first, then start deleting the undesired dims and constaints, which adds time and picking.
Also, I would really like to be able to select the midpoint of a line and constrain to that. In 3D I can select the midpoint of a line, why not in Sketch?
Thanks

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ChrisWard2k2

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Message 2 of 30

19-06-2008 04:22 . am | View his/her posts only

Hello CoulDes

There is a mid-point constraint you can use. On the Tab-deck toolbar, Constraint tab, second icon menu from the left, fourth option in the drop-down icon menu.

If you are new to VX and wish to define a complex Sketch (consider multiple simple ones as an alternative), I suggest drawing the basic overall shape first with the constraint solver switched off (via Edit/Preferences). Then apply the key constraints required to suit and apply the auto-constraint command to fully constrain the geometry (if this has not been achieved by your manual constraints). Add detail like fillets/chamfers last of all when you have a stable, well constrained basic shape.

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OldForumPost

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Message 3 of 30

20-06-2008 03:13 . am | View his/her posts only
Chris,
Sorry, I find the mid-point constraint in VX somewhat difficult to use. It seems I have to create additional geometry like a construction line(s) to do this. Why not allow the user to select the midpoint of an already existing line. Consider a simple trapezoid where the user wants to create a horizontal or vertical alignment to the midpoint of two parallel lines. You can't do this directly in VX without creating additional geometry, and what seems to me to be a lot of extra picking.
Overall I find the sketching personallity of VX much less intuitive and harder to control than that offered by other systems (and for me very frustrating).
Rather than just defending the way VX does or demands the user to do things I would appreciate it if VX did a more focused survey/research particularly with new users to see what the user expects/wants to happen.
Regards.

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ChrisWard2k2

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Message 4 of 30

20-06-2008 06:00 . am | View his/her posts only
Hi CoulDes

Well, we have. The Sketcher is currently undergoing a great deal of improvement and the popular customer requests are in the forefront of that work. The customers that find VX Sketcher non-intuitive are mostly those that are used to a different Sketcher - long-term VX'ers would feel the same if they had to use another product that does things in a different way. The VX Sketcher has some unique strengths, such as it's ability to contain more than one profile and drive more than one 3D Shape, and the fact that it can handle a large amount of entities. So, with the enhancements in place, the VX Sketcher is hopefully destined to become your best friend.

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OldForumPost

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Message 5 of 30

20-06-2008 08:53 . am | View his/her posts only
Chris,
Thanks for the info and I appreciate your comments.
Another question about sketches. When I try to re-use a sketch I see the dialog message displayed "Sketch re-attached to xxxx" It seems to work fine, but is there any potential about corrupting the database, or any other issues with doing this?
Thanks

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ChrisWard2k2

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Message 6 of 30

20-06-2008 10:54 . am | View his/her posts only

None at all, it is confirmation that what is expected to happen in the database has happened.

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Paul

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Message 7 of 30

21-06-2008 02:32 . am | View his/her posts only
Hi CoulDes,
I'd like to confirm Chris' comments re users of other system struggling with sketcher.
I struggled the same for a longish time. However I am sorted now and realise mostly is was moi. Sketcher is diff to the d3. It is also a lot less menu dependent. You can do a lot with out ever going off the drawing area.
Getting familiar with the commands and constraints is required.
A cool thing in VX is you can almost copy and paste almost anything. It actually uses a clipboard.
Other things like referenc lines can be toggle to be sketch lines whilst still being references or they can be traced etc. There are lots of quite powerful ways of doing things.
One that has proved handy for me, is being able to edit a sketch and reference a feature that is later in the history than the sketch, then unlink so it is now a curve exactly the same as a surface silohuette or what ever you referenced.
Hope the curve flattens out a bit for you soon.

Cheers

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Kevin

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Message 8 of 30

25-06-2008 02:39 . pm | View his/her posts only
I hate to be a party pooper but I'm one who has never really gotten to grips with the VX sketcher. Yes I have used others from SolidWorks, Think 3, Ashlar etc and yes I am perhaps too used to that way of working. Chris I read your comments on VX being unique but honestly that is just not the case. In all D Cubed sketcher variants I have used (Ashlar, Think3 and SolidWorks) you have been able to drive multiple solids/surfaces, have multiple profiles, etc with no issues. The biggest drawbacks of the VX sketcher to me are the lack of an offset constraint (serious issue IMHO) and that you cannot really drag sketch entities around whilst maintaining constraints.

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ChrisWard2k2

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Message 9 of 30

25-06-2008 04:12 . pm | View his/her posts only

...but you have to pick the Sketch as a Sketch in most other applications, something you have never been bound to in VX. This was unique to VX, perhaps others some where might have copied the idea. If you have not got to grips with the VX Sketcher, that's a shame because it is a very powerful tool. The forthcoming enhancements will make it more intuitive.

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Paul

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Message 10 of 30

25-06-2008 08:25 . pm | View his/her posts only
Hi Chris,
is there a wish list for the Sketcher upgrade? I would say most of us have come across aspects of sketcher that could be better but how is that experience/input being collated?
And what is the proposed upgraded version.
Cheers

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ChrisWard2k2

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Message 11 of 30

26-06-2008 10:12 . am | View his/her posts only

Hi Mudcrab

The wish list consists of comments collected from User Group meetings and the PCR System. The target release is v14, so it is already too late to add anything major to the list for this time around, but suggestions for enhancements are always welcomed and every single one of them is reviewed by VX Corp. A number of the problems to be attended to are actually from your PCRs!

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Kevin

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Message 12 of 30

26-06-2008 05:13 . pm | View his/her posts only
Is the offset contraint in there , and dynamic dragging?

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ChrisWard2k2

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Message 13 of 30

26-06-2008 05:18 . pm | View his/her posts only

Yes, they are

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Paul

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Message 14 of 30

26-06-2008 06:33 . pm | View his/her posts only
Hi Chris
sounds great. I will look forward to V14 with eagerness but keep breathing.
Please pass on my encouragement for getting Sketcher to be a TOPCLASS act.
Cheers

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ChrisWard2k2

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Message 15 of 30

05-11-2008 07:58 . am | View his/her posts only
Hello everyone, I'm sorry to have to inform you that I was wrong, offset curve constraints have not been incorporated into VX v14. The capability has of course been requested and so I hope it does make into the new release.

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Mike

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Message 16 of 30

05-11-2008 04:15 . pm | View his/her posts only
Folks, we may not have the Offset Distance Constraint but we do have the new Sketch command, DRAG. I have added a short movie here for your viewing pleasure. After viewing this, let me know if you think the STRECH command has out lived its usefullness.

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Steve

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Message 17 of 30

06-11-2008 08:30 . am | View his/her posts only
Sweet!
So when is 14 going to be released?

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Paul

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Message 18 of 30

06-11-2008 02:55 . pm | View his/her posts only
When is 13.7 going to be released???? Sorry Steve, but 13.7 comes before 14. No queue jumping OK.

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Paul

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Message 19 of 30

06-11-2008 04:55 . pm | View his/her posts only
Hi Mike,
finally drag with constraints. Hooray. Stretch has its uses, I wouldn't throw it out, maybe take if off the RMB and repalce with the drag.

Other sketcher Q's.
a) When you apply a parallel curve set are all the parallel constraints applied?
b) Will lines points etc keep there relative orientation when other dimensions are changed? e.g will flipping of sides occur?
c) Can dimensions be automatically applied to geometry as it is made as in Geometry Rectangle.
d) Are arcs a reliable curve yet? e,g maintain end location and conatct with the tangent curves?

Enough....

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Steve

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Message 20 of 30

07-11-2008 07:06 . am | View his/her posts only
Quote

Originally posted by: mudcrab
When is 13.7 going to be released???? Sorry Steve, but 13.7 comes before 14. No queue jumping OK.


Yeah, but, but, but... 13.7 will be out on Friday. Not sure WHICH Friday, but it'll be out on Friday

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Mike

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Message 21 of 30

07-11-2008 09:20 . am | View his/her posts only
Thanks Steve for covering my behind. Friday sounds good. How about "soon?"
Really, I won't know 'till the fat lady sings.

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Mike

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Message 22 of 30

07-11-2008 09:57 . am | View his/her posts only
Mudcrab,

All good questions;

a. No, at this point the offset has not changed from version 13. No constraints are added.
b. Flipping sides does occur in DRAG. Remember, if you have a fully constrained sketch, DRAG will not do anything. So, a partially dimensioned sketch will move but since the entities that are dimensions can't change size, the only way to get them to flip is to use the dimension option.
c. I have to answer this with a question. Are you talking about just drawing a line across the screen, will that dimension? No, There are too many ways to constrain a line, some don't require dimensions at all.
d. Sorry, I should have included an example of this in the video. I can see a sequel coming. I want to wait to do this until the next round of enhancements get built into the product because I want to show you the new Constraint Status window also.

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Paul

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Message 23 of 30

09-11-2008 01:50 . pm | View his/her posts only
Thnaks Mike,

Item a). This really needs addressing. 99/100 when I apply a parallel ofset, I want to keep it at that relationshp with the originating geometry and if I change the dims of the original geo. the parallel set should move accordingly. Having to add end/tangency/parallel, and construction lines (no offset constraint!!!!!) to do this is tedium plus and painful as th arc end constraints are flakey within the current solver.

Regards item b) Orientation. I am not referring to flipping sides during a drag. I saw that in the Premier video. Very nice.
I am talking about when dimension/s are changed elsewhere and resolve is applied. The chirality argument has previuosly been given. But this is unsatisfactory as in a fully constrained sketch - cannot add anymore constraints (spare anchors), sometimes objects will flip to the other side from where they should be. I have experimented to reproduce this is other software but never been able to. Stuff stays where it is put. In VX, Circles and arcs are particuly prone to this.
So my question is really has the problem of relative positon being maintained been resolved?

The associated question is: Why does solver allow tangent contraints to let the geometry drift of into virtual space. e.g. the virtual extenionsion of an arc when previously the two geometries were touching. I guess this is the flakey arc contrant problem again - never quite sure when tangency required end points constraint which are then deemed redundant by the solver, locking up further constraint addition but without them the geo. is unstable.
Not an easy one to describe without pictures.

In summary, when I place geometry on one side of another piece of well contrainted geometry, I want it to stay there until I tell it to move by either adding contraints or dims. that make it move to the other side - not move there just because the constraint to stop it moving do not exist.


Cheers
Spellign good. typing rubbish....

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Mike

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Message 24 of 30

11-11-2008 03:01 . pm | View his/her posts only
Paul,

I know you have PCRs in the system. Let me look them up and make another video demonstrating that the chirality issues are resolved. If you know specific PCR numbers just email them to me and I will test them.

This has been very frustrating for all involved but long time users like Chris and myself have gotten so used to the sketcher behavior that we just know you have to make small changes; use the arrow keys to creep up on the value you want. So I guess the first rule of sketching still applies: Sketch pretty close to scale, then add dimensions. Since I have been playing...practicing with Version 14 this suggestion/rule/workaround is not as important.

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Mike

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Message 25 of 30

11-11-2008 03:08 . pm | View his/her posts only
Paul,

I know that you are aware that there is an offset command in the part mode that is parametric. If that is an option for you, great. If not, I understand and your request has been issued in a PCR.

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Paul

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Message 26 of 30

12-11-2008 02:32 . pm | View his/her posts only
Hi Mike,
I appreciate familiarity with sketcher encourages creativity and there are many work arounds.

However, let me provide the simplest possible example of the problem of unpredictability.

RMB, Draw a line starting at the origin and head for the 5 o'clock position.
RMB, Dimension the line.
Now keyboard edit (numbers not gestures) the value of the length by say 50% less, then repeat this for 100% larger or anything you want.

You will observe the line angle can/may/is likely to/ change dramatically from dimension to dimension.

Eventually it will settle down and hover around the 3:15 psn. The longer the line the closer to horizontal the shorter the closer to vertical.
Interesting chirality....

Changing the length of the line should make NO/en oh/Oya/Geen/Nari/Non/Naw/Nein/Iie/Nae difference whatsoever to the angle!

This is so elementary I remain gobsmacked that it is excused as chirality or deemed acceptable.

As an alternative, dimension the angle relative to Horizontal(or Vert), then change the angle, and the length changes. That means there a is a Y or X constraint inhehrently present but not shown. What should happen is the angle indeed change about the apex of the angle dim or the first drawin point of the line and the length should remain the same.

All this type of behaviour does is make using sketcher slower and more tedious than it could be.

So Mike, Sketcher V14 - Predictable or Random? (Note more predicatable is only less random)

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Paul

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Message 27 of 30

12-11-2008 03:02 . pm | View his/her posts only
Hi Mike,
just after I did the post I had a sketch do the whole McCoy.

FYI Pics attached.

Order of construction.

Angled (downward) line - constrained.
Top (of T) line constrained by midpoint and perp.
3 point arc - approx located.
Angle lines fron T ends to ends of arc. - Add tangency then solve.
Add Symmetry to arc or angle line end points. Pic 1.
Solve. Pic 2.

Fun eh? Symmetry - yes, tangency yes, end points - yes, intent - NO.

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Paul

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Message 28 of 30

12-11-2008 03:40 . pm | View his/her posts only
Hi Mike,
it's sequel season, but I'm at the box office before you.

Here are more shots of the self morhing sketch started below.

Pic 3 Angle dim applied.
Pic 4 Angle solved
Undo
Pic 5 Add radius dimension. Note, it should allow this but doesn't-
Pic 6 Toggle radius to driver - solve = OK

A little bit further on, I added some more geometry and am unable to add further constraints.
Inquire Constraints says fully constrained but it aint.
I copy and paste this sketch into a new file - attached - and try to sort it out.
Some where along the line it is confused - perhaps it caught it from me.

I know there are many other ways of building this sketch but, Does it really have to be this hard?

Cheers

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Mike

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Message 29 of 30

18-11-2008 08:21 . am | View his/her posts only
Here is the second video I promised showing the progress that VX has made in the sketcher. I think we have addressed the chirality issues that have been a thorn in our side.

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Paul

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Message 30 of 30

18-11-2008 04:04 . pm | View his/her posts only
Hi Mike,
nice vid. Captivate does a nice job.

Production comments:
Caddywonkus - lovely word - lets get in into Wikipedia - means: unexpected behaviour of virtual lines, pints etc., on a screen during a CAD session, whose unpredictable behaviour defies explanation (otherwise known as chirality) and simultaneously avoids design intent whilst raising heartrate and verbal response to the inanimate machine, the software authors and any other objects considered causal by the user........ (

Dimensions should be a different color to the drawing lines - try dark blue - very peaceful (I need that)

"OUR OLD SOLVER"??? Our solver IS the new one! We dont have the NEW one yet so the old one cannot exist for us! Until I get my grubby little hands on the NEW please refer to my solver as the current one.

Technical comments:
Looks like some of the issues are in control.

What happens to a line position if it is just in space. Not related in any way to the origin or other geometry and then you change the angle or the length?

I like the reversion back to highlighting the lines whilst adding contraints. I think the highlight could be in bold . (My choice is magenta when on a light background - yellow is feeble on white)

Does the delay solve choice stick until changed or always revert to the default? And what is the VX policy on choices like that? Always stick or always default or random??? Does window position remeber the last placement or always default?

Do angle dimensions go past 180 deg yet?

I note that the line to arc end point coincident is still not indicated on screen. Is there actually a constraint there? If so, what is it and should it be indicated. If it is not there , what holds the end point coincident? The current solver can lose the implied end point - does the new solver keep them?

FYI: If you apply the symetry to the arc end points, only one tangency is required - assuming the end point coincidence exists - (how would you know?) In theory, the exhibit sketch is over constrained with the two tangencys'. Correct me if I am wrong....

Oh - DOF???? How about Degree of Freedom or 'caddywinkus'.

Right now - more is better - keep up the videos Mike.

Cheers


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