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Blend tool influenced by the pull direction

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21件のコメント

  • Jacant

    I think you are going about this the wrong way.

    Select opposite surfaces with the 'Rotational blend' option then the select the same faces again with the Add option.

    If you just want to make a 'Donut' shape then select one surface, either use the 'Sweep' option using the circle or use the 'Revolve' option using the axis of the circle.

     

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  • Hugh Keir

    Thanks Jacant,

    Many thanks for taking the time to respond.

    The reason for using the blend technique is because I am using blend tool to link different diameter circles into a donut shape.

    First try following your suggestion did the same.

    I will have to look at it more closely and give your suggestion another try.

    Will feedback once I have sorted.

    Thanks again

    Hugh

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  • Hugh Keir

    Thanks Jacant,

    Got it this time using the rotational blend option.

    Am left with some lines that I can't remove, will try creating again, to see if I can clear them.

    I want to use the donut shape as a cutter tool, so hopefully the split body will not interfere.

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  • Tim Heeney

    Hi Hugh.

    Yes, i also had a similar problem to you with the sectional variation.

    I spilt my guide circle in 4 pieces not 2 and attempted to make 4 solids - somehow the last quadrant never accepted to go the last 90 deg, wanting instead to go the other way around even though the preview looked OK and correct.

    So i cheated - well, maybe not a cheat, lets just say used another method. Each of the 3 quandrants ( transition blend surface only), rmb 'detach' the surface - ending up with 3 faces.

    In structure browser, select all 3 , rmb 'Move to new component'. Then select a neighbouring face to the missing last remaing surface, ctrl C, ctrl V, key 'm' to to move it, rotate through 180 deg. Join surfaces up one by one as shown.

    another way is just a variation of this - make any quarter or half solid - copy it / them and move to req'd position. Join up. Use the tangent on / off and do a geometry check i'd advise.

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  • Tim Heeney

    Ok - got it to work without detaching / copying etc.

    My 4 path centerlines were made by splitting up a circle using 4 cross sectional faces. Always the last segment ( 270 to 360) WAS THE PROBLEM. So, something to do with a circle and it's defining maths. Delete the problem last quadrant centerline, Copy rotate one of the other 3 and blend to make 4 solid quadrants - join.

    Tool tips for Rotational Blend and Periodic Blend seem (?) not to suit your intention - but i often get it wrong...

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  • Hugh Keir

    Thanks Tim,
    When I highlight the complete donut and click the Tangent tool, the outer surface goes solid, the same as yours.

    If I click the donut, there does still appear to be two halves that I can select.

    Am hoping this will not interfere with the donut being a cutter. 

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  • Jacant

    The Lines are only 'Tangent' lines these can be turned off. 

    The 'Tangent' that you see on Tim's screen is this command, he has just added it to his quick access tool bar.

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  • Hugh Keir

    Thanks Jacant,

    I found it, but do not have an icon, seems to work, but not familiar with what it does, so will read up on that.

     

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  • Jacant

    The dotted lines are 'Construction' lines. He has dawn a 90° arc, then moved it around to get four.

    Any line or curve can be changed into a construction line. Just select it and pick the construction icon.

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  • Hugh Keir

    Thanks Jacant,

    Appreciate the help.

    My tapered donut looks like this now, so apart from still being two parts inside is exactly what I set out to do,

    You and Tim have been great

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  • Jacant

    The Display tab has various settings, none will affect the integrity of your model. They are just for visual displays.

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  • Hugh Keir

    Thanks Jacant,

    Donuts work great for creating a convoluted hose.
    How are you creating the videos of the steps you are posting?

    Is there a setting inside DesignSpark to create them? 

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  • Jacant

    Gifcam

    http://blog.bahraniapps.com/gifcam/ 

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  • Tim Heeney

    Hugh.

    Inventive...

    So i thought, that's a lot of work...and what if you change your mind about the sections etc - in a no parametric modeller, it's quite a hassle to change your mind.

    Clearly, it's critical to get the section right first... with that in mind only, here's a little constrained sketch.

    Once the arc's are correct / established, then same procedure as you adopted before.

    Or, by using the mid points between the arcs and revolving squarely at this point, driving circles for the arcs to be blended can be made.

    from there, you get the idea i'm confident.

     

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  • Hugh Keir

    Thanks Tim,

    That is great.

    I clearly could have set my sights a bit higher.

    I am not familiar with constrained sketches, but have to agree there would be great value in being able to modify the sketch.

    I think the sketch I have made will be close enough for where I am just now, however once the prototype is working, I will no doubt re-visit the dimensions to adjust the curvature and will learn how to use the constrained sketch at that time.

    I used the donuts as a cutter.

    Would you be able to link the your drawings together so they they would create a curve? 

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  • Tim Heeney

    Hi Hugh,

    Making multiples really takes too much time - and beside, only an 'interval' is required for the blend.

    For planning a design, this version offers more benefit as the 'wedges' are normal to the tube radius bend - just type a new bend rad.

    Save this constraint sketch away but WHILST IN THE SKETCHER ( still open) - when you need the sections, open and amend AS DESIRED, then close the sketch, select the resulting face , cut and paste into your new design. Close the file without saving ( or save - as a new file ) - open anytime, sketch always ready to make new sections.

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  • Tim Heeney

    Hugh,

    As an overall idea - this is about it.

    The more practice the easier it gets.

    Here, the corrogations are driven by angles not a radius - so a bit of easy maths to determine overall angle. Internal / external pipe radius are a better sizing parameter to.

    With the first interation of sketcher constraints, i have only basic abilities - but don't let that put you of experimenting.

    Cheers.

     

    You can also use a simple expression to get an exact radial pitch spacing using a given overall angle. Below is for 8 corrugations.

     

     

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  • Hugh Keir

    Thanks Tim,

    That looks great.

    I am using a hose that has known dimensions.

    What would be nice, if it was possible, is to create a bend in the hose that adjusts the dimensions on the ID and OD radii based on the bend radius.

    Here is the hose with the sides extended upwards that I used as a cutter.

    Here is how I used it as a cutter to allow the hose to snap into the part that I will be manufacturing.

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  • Tim Heeney

    Hugh,

    My pretty corrugation generator for a pipe has a external max and min radius being based centrally on a bend radius - it can only do 'simple'

    All this only produces nice shape, but it's not real at all. I expect the hose gorrugation Ext / Int rads not to change much but rather their conical walls to deflect ( and distort - bulge) increasing the corrugation included angle.

    To get real,( in the polite sense), i'd get a hose sample, wack in working pressure +/- some for your application need, shape and restrain in into the 'shape form' for the function you have in mind,  plaster of paris and laser scan - that would capture the 'static' deflected with load, true form - but, perhaps a crude estimation is all that's necessary? Only you know that.

    Approximations by 3D cad or even 3D hyper elastic / plasticity FEM ain't nothing like the real thing baby ( sorry song sprung to mind) . By getting the real hose and fiddling around,  other ideas might be generated.

    I'm assuming your thinking 3D printing ( for now) - these type features are very expensive to reproduce in molds.

    ? am i helping?..

    Cheers.

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  • Hugh Keir

    Thanks Tim,

    You have been very helpful.

    Here is the end result printed out; 3D printing in Nylon makes useable parts in almost no time.

    Easy to create stuff that would be impossible to machine.

    The hose pushes in securely just as I expected - I had previously created a straight version of the part, so thought it would be OK when bent, but nice to see the planning work.

    I will revisit this again to tweak the design and will refer back to your constrained design to practice and learn how to create designs like this.

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  • Tim Heeney

    Hugh,

    Well, that's great - lovely clamping strain relief... yeah, you can do much with a printer - hmm, note to self!

    Anyway, looked at a few hoses here on vacuums - some have helical winds and others parallel rings - those also have different angles between as shown in these gifs. Both have metal rings to keep the hose diameter rigid.

    All that academic now.

    Below is more accurate to actual hose behaviour...but need the real thing.

    Enjoyed playing around with the sketchs - saved so always there if needed.

     

    Above shown is assymetric lead of 6 deg vs 2 deg follow.

    Below shown, symmetric lead / follow 3 deg.

    but is the sketch any good for modeling ? IDK right now.

    Happy your prototype works...

    Tim.

     

     

     

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