Problems with Pad when constructing girder bridge deck

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PeterSD
Posts: 167
Joined: Sat Nov 13, 2021 8:54 pm
Location: UK

Problems with Pad when constructing girder bridge deck

Post by PeterSD »

OS: Windows 10 Version 2004
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24291 (Git)
Build type: Release
Branch: releases/FreeCAD-0-19
Hash: 7b5e18a0759de778b74d3a5c17eba9cb815035ac
Python version: 3.8.6+
Qt version: 5.15.2
Coin version: 4.0.1
OCC version: 7.5.0
Locale: English/United Kingdom (en_GB)

I am new to this.
I have constructed the base of the bridge as a Part.
I have then added the girders and padded them below the base without problem.
I have started the side walls and padded them to the to the top of the base again no problems.
I have added the top to the walls (3mm overhang both sided of the wall). This is where I have a problem with padding. I cannot find a way of attaching the start point of the pad to the top of the wall. It appears at the base, and when I increase the height, the overhangs rise until they obscure the walls above. Further increasing lifts the walls higher.
I have tried all types in the Pad drop down and failed.
Can anyone please help me?
Thank you
Kind regards
Peter
Girder Bridge Deck Construction.PNG
Girder Bridge Deck Construction.PNG (238.42 KiB) Viewed 6695 times
TheMarkster
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Re: Problems with Pad when constructing girder bridge deck

Post by TheMarkster »

You need to position the sketch you use to make the pad. There is an attachment offset property for this purpose, assuming it is attached to the xy plane. Now that your first post is approved you may attach your model for further investigation. Easiest way is to drag/drop onto the text field where you type in your post.
chrisb
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Joined: Tue Mar 17, 2015 9:14 am

Re: Problems with Pad when constructing girder bridge deck

Post by chrisb »

Can you link an image of the desired final result? We may suggest a different way of modeling this, e.g. by modeling a section or using a linear pattern for the girders.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
PeterSD
Posts: 167
Joined: Sat Nov 13, 2021 8:54 pm
Location: UK

Re: Problems with Pad when constructing girder bridge deck

Post by PeterSD »

TheMarkster wrote: Sat Dec 11, 2021 5:37 am You need to position the sketch you use to make the pad. There is an attachment offset property for this purpose, assuming it is attached to the xy plane. Now that your first post is approved you may attach your model for further investigation. Easiest way is to drag/drop onto the text field where you type in your post.
Thank you for my approval and your comments.
I am not sure how to 'drag and dop' I carried out the process and it did not seem to work.
I selected the sketcher item which produced the screen shot I made. Enabled clicked the Part and returned to the sketch which resulted in the image below.
Kind Regards
Peter
Sketch view.PNG
Sketch view.PNG (85.82 KiB) Viewed 6585 times
PeterSD
Posts: 167
Joined: Sat Nov 13, 2021 8:54 pm
Location: UK

Re: Problems with Pad when constructing girder bridge deck

Post by PeterSD »

chrisb wrote: Sat Dec 11, 2021 7:22 am Can you link an image of the desired final result? We may suggest a different way of modeling this, e.g. by modeling a section or using a linear pattern for the girders.
Thank you for your reply. Please see my attached image.
The image is similar to what T am aiming at but the the girders under the bridge need to be Jack Arch and I wanted the deck to be longer and wider.
Kind Regards
Peter
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papyblaise
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Re: Problems with Pad when constructing girder bridge deck

Post by papyblaise »

just by seeing the 2 images, I think we have to make the Pad upwards so click the "invers" check mark
chrisb
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Re: Problems with Pad when constructing girder bridge deck

Post by chrisb »

You can upload your FreeCAD file, so that we see what you have done so far.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
chrisb
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Re: Problems with Pad when constructing girder bridge deck

Post by chrisb »

I would start with something like this:
SnipScreenshot-fc28ce.png
SnipScreenshot-fc28ce.png (13.89 KiB) Viewed 6462 times
You could use a mirror here too, but that may be overkill. Next could be one single girder, with the previous sketch for external references:
SnipScreenshot-6093d7.png
SnipScreenshot-6093d7.png (7.61 KiB) Viewed 6462 times
Pad it using an expression (Pad.Length) to the same length as the previous

Multiply the girder with a liinear pattern. Set Length with an expression:
Sketch.Constraints.width - Sketch001.Constraints.girderWidth
SnipScreenshot-92f30f.png
SnipScreenshot-92f30f.png (22.18 KiB) Viewed 6462 times
This has the advantage that you can very easily adapt the number of girders.
Attachments
girderBridge.FCStd
(27.73 KiB) Downloaded 23 times
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
PeterSD
Posts: 167
Joined: Sat Nov 13, 2021 8:54 pm
Location: UK

Re: Problems with Pad when constructing girder bridge deck

Post by PeterSD »

Thank you chrisb and papyblaise for your replies. I am sorry I have not responded earlier but I am busy at the moment but will read your replies more thoroughly later and reply more fully later.
I set my email settings to be informed when replies are made to this thread but have received no emails for your posts. I shall have to re-check my settings - probabbly did something wrong :oops:
Kind regards
Peter
PeterSD
Posts: 167
Joined: Sat Nov 13, 2021 8:54 pm
Location: UK

Re: Problems with Pad when constructing girder bridge deck

Post by PeterSD »

Thank you chrisb and papyblaise for your replies. I have now gone through your comments, downloaded your GirderBridge attachment file and the Sketcher Guide (thanks Chris). I have a lot to learn ;) . Not surprising at all. All my learning has been done wading through hours of YouTube tutorials and string things together from this source.
I have managed to rduce the size of the photo ( which does appear in my earlier post but will give you a better idea of what I am targeting ). Please excuse the poor print quality of the 3D print. I bought my first 3D printer a couple of weeks ago and have had to familiarise myself with it.
Enhanced-1.jpg
Enhanced-1.jpg (202.95 KiB) Viewed 6334 times
I think that I shall have to spend the next couple of days reading through things and then rebuilding my FreeCAD document and shall publish the results on this thread.
Once again, many thanks for your support.
Kind regards
Peter
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