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Did I unknowingly switch to some special mode?

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  • Jacant

    Where did you get the model from?

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  • Me Here

    All my own work. I ran a geometry check and it highlighted a "trimming error":

    But it would not let me correct it. By which I mean, I attempted to slice the model with a plane at the transition from cylinder to cone but it would not let me, despite that that is how it was created. Nothing else I could think of to try would allow me to correct the error, so I threw the model away and recreated it from scratch.

     

    This time, I added the slot to the head before combining the 3 parts together and dodged that problem. However, this time instead of a single error, I ended up with 18!

    16 of those where easlily (if unsatisfactorially) corrected by removing some rounds:

    which left just 2:

    Both seem to refer to the same conincal surface -- I can see no change when I switch from highlighting one to the other -- and is the sam error msg as the first time, but twice instead of once. And there doesn't seem to be a darn thing I can do about it.

    And that oppitimises the problem with DSM; the entire lack of any official support/help channel.

    As good a job as you and Tim do in your efforts to help DSM users, when things go wrong at the internal level, we are all floundering around in the dark attempting to find workarounds for problems, regardless of whether those problems are bugs, or just arise through bad technique.

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  • Me Here

    (Update: See here https://i.imgur.com/EYFLlVH.png for the content of the pending approval post above.)

    After posting the above I noticed/remembered that I had also applied a round to the transition from cylinder to cone; and given the previous problem of rounds causing errors, I removed that also. This time, the problem surfaces/edges moved completely:

     

    Which is very disconserting, especially as the two surfaces and the edge between them were created by DSM in a single Pull operation.

    Ie.After full pull:

    But reproducing that and checking gives a clean bill of health:

    So then I set about recreating the conical tip section. Starting with the cross-section profile at the end of the cylindrical section, I calculate the parameters to produce the helical paths required for the 3 keypoints:

    I trim 0.1mm off the ends of the 3 helixes (Pull doesn't like scaling to zero); select the face and the 3 guidepaths:

    And full pull (no 'normal to origin'):

    Then I use Blend to fix up the blunt tip to a point:

    Combine the lot together to form a solid:

    Now the scarey bit, a geometry check:

    So far, so good.

    Now combine the nose cone to the cylinder and check again:

    So far so good (as the falling man was heard to say repeatedly).

    Now recreate the head:

    So far, so good!

    Now combine the two:

    And a final geometry check:

    And all is good.

    So what went wrong last time and the time before?

    My only conclusion is that adding the rounds screwed the pooch.I cannot be bothered to prove that because it would do no good as no one is listening :(

    Just another brick in the wall.

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  • Jacant

    I'm watching and listening ;)

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  • Me Here

    :) Noone "official".

    Ie. As with the whole debarcle with -- having to constantly realign sketch grids to the origin, but having manually add a point at the origin because it won't allow you to select the origin as a target for realignment unless the plane of the  sketch grid you are trying to align happens to pass through the origin -- that has been kicking around and causing problems since v2 to my knowledge (and I seem to recall you said it came up in v1), nothing changes and no explanations are forth coming.

    It may be that there is a good reason for assigning apparently random orientations and translations when new sketch grids are created; but without an explanation, it just looks like a bug or bad design choice. As such it reflects badly on both SC and RS.

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  • tab...

    Buk,

    Origins may be set / repositioned , stored and quickly accessed for sketch planes positions

    They need not be displayed, they can be on another layer and off but still be used to quickly place a sketch in a repeated orientated location using the sketch tool bar.

    It's a bit quick, i hope this helps.

     

     

     

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  • Me Here

    S'all very well and such, but it requires knowledge a forthought of those drawing planes that I'm going to revisit, and  still requires that I realign the drawing plane provided at that location back to the origin -- and often as not -- the default coordinate system orientation; before I can create this just-in-case-I-need-it extra origin(s).

    Whereas, if new drawing planes were always created aligned to and origined at the global origin, I would only need to take these steps, if there was a good reason for doing so.

    Given that I have *never* -- as in, not once, not ever, in all my use of DSM -- created a drawing plane and thought," Oh yes. That origin and alignment are exactly what I wanted"; who benefits from this apparently random positioning?

    The very best I can say for it is that sometimes -- and I mean less that 20% of occasions; far less -- the orientation of the new grid plane doesn't matter. The rest of the time it creates unnecessary -- and often frustratingly difficult -- extra work for less than zero benefit.

    By way of example of this "frustratingly difficut" process, using the example from the OP. I construct the parallel 'body' of a screw and then open a new sketch plane on the end of that body to do the prep work for creating the nose cone:

    Even though the global origin -- that I need to be aligned to -- is right there on screen; nothing I do will allow me to use it to realign this sketch plane.

    I've taken to starting every new document by creating a 'Construction' component and adding a point named "Global origin" for use in those innumerable situations when I need to refer to the global origin, but DSM will not allow me to select it, even though it is on screen. And that's a nonsense.

    If new sketch planes were always created centred at the global origin, and aligned to the global coordinate system if the sketch plane is orthoganal to it, then it would be 'right' far more times than it is now. And on those rare occasions when some other alignment makes sense, there will usually be a model face edge or vertex that the user can use to achieve the alignment they want.

    There seems to be no logic behind the current behaviour, and there is definitely no benefit to it!

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  • tab...

    The logic is, quick most often used , most often usual requirement etc, hence default XY sketch positions are placed in the mid position of a face... and that can be amended easily or certain geometry preselected will zero the XY plane placement.

    For more complex situations, a global 000 Origin may be copied and placed onto a face, then it's axes may be orientated to the face quickly by successive axes selection and orientation.

    Yes i agree that having to use Origins is harder than not to, but they can be very handy - it's usual to revisit common part planes of interface and even more valuable to come back to virtual positions / alignments where there isn't any real geometry.

     

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  • tab...

    Going back to that pulled screw...

    For a kind of 'follow-on' , there is the use last sketch plane command. After Pull, or at any time. rmb 'Use last Sketch Plane', click ' Move Plane', key 'U' and select face.

    Only takes 2 secs.

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  • Me Here

    That would be convenient but for the fact that I need to define a point that forms the apex of the cone before I could do that; and that requires me to define a drawing plane axial to the screw, so the last drawing plain is no longer that one.

    In any case, that's a weak specific argument against a strong general case. And tedious.

     

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