Problems with Pad when constructing girder bridge deck

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PeterSD
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Re: Problems with Pad when constructing girder bridge deck

Post by PeterSD »

bambuko wrote: Fri Jan 07, 2022 4:05 pm Perhaps if you have said:
I have (rather than I shall) attached corrected version in this post (and renamed it rather than leaving exactly the same name ...
there would have been less confusion ;)

Anyway, I have opened your file and both of my previous posts stand. You still have one dodgy/un-necessary line,
guess which one is it? (I have red arrowed it in both of my previous posts)

sketch.png

You can easily correct it, resulting in:

Deck(bambuko).FCStd

Is that what you are after?
So the extra line was my Line 1, the one connecting the LH upright to the wall end. The connection to the sketch being made along the External Line (9) along the top surface of the body. My line 1 was the EXTRA Line
This was a completely different set up from my previous attempt but the same as that which worked for me previously. (Noted that I should always be consistent in my approach. I think Chris was hinting at this in his post of last night which made me reconsider my approach,
Kind regards and many thanks.

Peter
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bambuko
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Re: Problems with Pad when constructing girder bridge deck

Post by bambuko »

You don't need a line to constrain a distance between two points
Where you need a line, you can use construction line instead of "normal" sketch line - construction line is ignored when it comes to creation of solids.
I am sure you will get there in time ;)
I am using Link branch and Assembly3
you can also download ... and try it here
excellent Assembly3 tutorials here
PeterSD
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Re: Problems with Pad when constructing girder bridge deck

Post by PeterSD »

bambuko wrote: Fri Jan 07, 2022 4:51 pm You don't need a line to constrain a distance between two points
Where you need a line, you can use construction line instead of "normal" sketch line - construction line is ignored when it comes to creation of solids.
I am sure you will get there in time ;)
Thanks for the above. This exercise in building the bridge, is a very useful way of learning FreeCAD in a focussed way. Thanks very much for your support.
Kind Regards
Peter
PeterSD
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Re: Problems with Pad when constructing girder bridge deck

Post by PeterSD »

Hi All
I have been reviewing my approach to FreeCAD, how things have progressed in my learning experience and the build so far. What has prompted this is, I feel my approach so far, is very clunky and probably far more difficult than it should be. I have had the opportunity to see a number of approaches that others have used to tackle the building of the module and I really appreciate those suggestions which I have received, also for the comments on the process I have used and queries I raised.
One thing that is very clear to me and essential, is that the steps of the build must be properly labelled. This ensures I have documented the build flow such that I can understand it clearly to reach the end goal and also maintain the design in the future.
The design that I am building is part of the structure which will need to be Mirrored on the Y-Axis then Multi Transformed along the X-Axis to form the complete bridge Deck. Based on this, my understanding was that I was forced to build the structure on one half of the Y Axis to allow the build to be mirrored later. Similarly, I had to treat the build on the X-Axis in the same way. This approach is perfectly good on the Y Axis but, on the wall side, where I need padding & mirroring functions, I am forced to double the number of these functions.
I have read through the Part Design options and would appreciate any comments and guidance. For instance could I use offsets to position a vertical axis intersecting the X axis in the centre of the wall and which the PartDesign functions would operate correctly?
Kind Regards
Peter
chrisb
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Re: Problems with Pad when constructing girder bridge deck

Post by chrisb »

PeterSD wrote: Sun Jan 09, 2022 2:49 am For instance could I use offsets to position a vertical axis intersecting the X axis in the centre of the wall and which the PartDesign functions would operate correctly?
You can use a construction line to mirror one or more features at. If you have more than one construction line they are numbered sequentially as they are created.
Furthermore you can create a PartDesign Plane with or without using Expressions to mirror at a completely freely definable way.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
PeterSD
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Re: Problems with Pad when constructing girder bridge deck

Post by PeterSD »

chrisb wrote: Sun Jan 09, 2022 7:52 am
PeterSD wrote: Sun Jan 09, 2022 2:49 am For instance could I use offsets to position a vertical axis intersecting the X axis in the centre of the wall and which the PartDesign functions would operate correctly?
You can use a construction line to mirror one or more features at. If you have more than one construction line they are numbered sequentially as they are created.
Furthermore you can create a PartDesign Plane with or without using Expressions to mirror at a completely freely definable way.
Thanks Chris :D I shall try things out and see how things go.
Kind Regards
Peter
PeterSD
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Re: Problems with Pad when constructing girder bridge deck

Post by PeterSD »

chrisb wrote: Sun Jan 09, 2022 7:52 am
PeterSD wrote: Sun Jan 09, 2022 2:49 am For instance could I use offsets to position a vertical axis intersecting the X axis in the centre of the wall and which the PartDesign functions would operate correctly?
You can use a construction line to mirror one or more features at. If you have more than one construction line they are numbered sequentially as they are created.
Furthermore you can create a PartDesign Plane with or without using Expressions to mirror at a completely freely definable way.
Hi Chris
I am hopelessly lost in this. Is there an exercise I can use to clarify the setups?
chrisb
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Re: Problems with Pad when constructing girder bridge deck

Post by chrisb »

PeterSD wrote: Sun Jan 09, 2022 7:55 pm I am hopelessly lost in this. Is there an exercise I can use to clarify the setups?
I can prepare some exercises in the next days.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
PeterSD
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Location: UK

Re: Problems with Pad when constructing girder bridge deck

Post by PeterSD »

chrisb wrote: Sun Jan 09, 2022 9:31 pm
PeterSD wrote: Sun Jan 09, 2022 7:55 pm I am hopelessly lost in this. Is there an exercise I can use to clarify the setups?
I can prepare some exercises in the next days.
Thank you Chris. That wold be very helpful. In the mean-time I shall continue reading the documents. Hopefully I shall be better prepared.
Kind Regards
Peter
PeterSD
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Location: UK

Re: Problems with Pad when constructing girder bridge deck

Post by PeterSD »

Shalmeneser wrote: Thu Jan 06, 2022 6:03 pm TNP ?
no file no gain.
I have decided to come back to this topic which has been on hold for some time with a view to completing this task.
I have reviewed your file that you re-built from scratch and, covers most of what I needed to do.
GirderRev_1_SHALM.FCStd
(843.8 KiB) Downloaded 21 times
I have broken down the steps taken in the file and labelled these by re-naming some of the steps to create a flow (Renaming the sketches etc caused the MultiTransform to fail but I ignored this and did not save the changes so the file above, is still intact as received).
Analysis of File.PNG
Analysis of File.PNG (313.12 KiB) Viewed 774 times
Fundamentally, I chose the wrong axis to work with. I used the YZ and you used the XZ axis. I should have realised that most of the work would be XZ and I should have used that. This would have avoided the issues on Symmetry that I was experiencing.
I see now why your starting point was the wall. The workflow I can follow except for the Fusion and Array. I looked up Function (https://wiki.freecadweb.org/OpenSCAD_ExplodeGroup/pl) but could not get any useful information. The picture of the 3D view does help a bit.
Changes for me to make with your approval
  • 1. Removal of Sketch Sketch007 and Pad007 - Not required - unless essential to your model
    2. Insert a LinearPattern to add two extra girders towards the YZ axis centre.
    3, Add a sketch to add the Jack arches to the YZ axis centre.
    4. The length of the bridge should be reduced by at least 1 side panel length to keep the overall length to the printer bed limit of 230mm./list]

    illustration of Girders and Jack Arch
    Deck Rev 4b Re-drawn Sketch003.PNG
    Deck Rev 4b Re-drawn Sketch003.PNG (135.07 KiB) Viewed 774 times
    Items 2 & 3 above, should then be completed on the other side of the Y axis in the Fusion Step?
    Kind Regards
    Peter
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