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Author Topic: FreeCAD - unique open source CAD program for 2D and 3D modeling  (Read 6322 times)
dave benson
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« Reply #15 on: November 24, 2017, 11:36:09 am »

Here are some shots of  exporting a selection of geometry from CB which then I imported into Freecad.
Once in Freecad  you have a couple of choices of how to turn the 2d geometry into 3d geometry.

In this instance I clicked on the sketch and applied the constraints and once the sketch was solved I padded it
into the Front Bearing Plate  for my new turrets.

I've also included a shot of my pref's for the importing of .dxf's.
What I do is change these to suit the format of the .dxf file (.eg R12 R13 2006 ect.)
sometimes I have to turn "Import as blocks" off.

 


* export from selection from cb dxf Capture.PNG (260.35 KB, 705x573 - viewed 55 times.)

* Freecad Prefs for importing dxf's from cb.PNG (87.79 KB, 732x564 - viewed 60 times.)

* export from selection from cb dxf imported into in Freecadd.PNG (17.29 KB, 810x492 - viewed 41 times.)

* imported geometry from CB Capture.PNG (58.98 KB, 1146x587 - viewed 52 times.)
« Last Edit: November 24, 2017, 11:40:33 am by dave benson » Logged
Dragonfly
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« Reply #16 on: November 24, 2017, 12:00:20 pm »

Thanks Dave,
I seem to be on the right path, just have to refine the details. Will try it based on your example.
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« Reply #17 on: November 24, 2017, 19:35:09 pm »

Dave, I arrived at the last but one picture but the extrusion I make does not form the internal holes an cavities. As if only the outer contour is the forming shape. Struggling with it but no idea where the cause is. I suspect the shapes should be somehow connected into a single one (like CB region) but can't find a way to do it.


* FailedExtrude.jpg (149.34 KB, 1356x790 - viewed 68 times.)
« Last Edit: November 24, 2017, 19:37:27 pm by Dragonfly » Logged

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dave benson
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« Reply #18 on: November 24, 2017, 21:51:04 pm »

If you go to the Draft workbench there are tools to unite faces or convert the geometry to a sketch object.

You'll find that when making a model with geometry from an external source that you have to tweek it a bit,
and you would usually use a couple of different workbenches to achieve this.

(Although I didn't have to do this for the CB generated fileabove ) as I made a sketch object before padding it.

For instance the move tool on the Draft workbench is a lot easier to use than some of the tools in the Part or Part Design workbenches to do the same task.

If your file is not a state secret then post it, and I will get it to the point at which i showed for the drawing above
and explain what I had to do to get it to work.

Dave
Edit :just finished cutting the above and except for a complete power failure half way through job, "car into pole further up the street") it went well but slowly, because of the Troc mops for cleaning up the disk brake rotor, not complaining though they work well if you have the area in your part to generate them.


* Front Plate and cut Ratchet test file.png (1178.65 KB, 1000x750 - viewed 67 times.)
« Last Edit: November 24, 2017, 22:21:50 pm by dave benson » Logged
Bubba
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« Reply #19 on: November 25, 2017, 02:13:34 am »

I follow this thread with great interest because this FreeCad program looks really impressive by just browsing thru. The interface, layout, mouse commands very similar to early versions of Catia. Program I was using frequently while working for a living Wink. The thing that I cannot get past is lousy handling of the inch scale. In sketcher you draw 2" circle and in the bottom right corner displays metric values, I just don't have much faith in this program till the unit system is handled better. For you guys using metric system it should be nice software to learn and use.
I guess I'm with Bob, back to my ViaCAD I go Wink
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dave benson
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« Reply #20 on: November 25, 2017, 03:28:28 am »

Hi Bubba

This is the prefs screen from my newly minted "FreeCAD_0.17.12619_x86_dev_win" binary.
so things might have changed, I'll have a look later to see if it's ok.
I know they have been discussing this for a long time and were going to use a translation method between the interface and the Python code under the hood. which will always be SI units
Dave


* Freecad system units.PNG (82.82 KB, 741x336 - viewed 58 times.)
« Last Edit: November 25, 2017, 03:30:51 am by dave benson » Logged
Dragonfly
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« Reply #21 on: November 25, 2017, 13:48:26 pm »

Not a secret at all, Dave. It's a flange for air intake manifold of a car engine. The task is to make a transitional flange one face of which fits the head intake ports and the other - the shape of the manifold ports. Because the manifold is from the same manufacturer (Toyota) but from a different version of the engine. I have drawn the geometry of both and have it in .DXF format. Doing this I had to manually trace some of the shapes from a scanned image of the surfaces of both the original and the new manifold flanges. Drawing them in FreeCAD will be a difficult task for me as it needs determining the length, radius and center of each arc in the contour. That's why I am trying to use the geometry I have ready.
I am a complete newbie in 3D CAD and I guess I have to start with learning and comprehending the terminology used, like 'sketch', 'draft', 'wire', etc.  Which I am doing now by reading the manual. But it will take time and for the moment I don't even need a complete model for machining, just a model to verify is it possible to do the air channel transition over a 30 mm thick flange.
I have opened the .DXF files in CamBam, converted all to poly and re-exported back. And FreeCAD reads them correctly. But I have no success in trying to make an extruded shape out of it.
I am attaching the .DXF for the cylinder head intake ports.

P.S. Import settings appear to have quite different effects on the resultant FreeCAD objects. If I select to convert shapes to sketches, for example, I get a set of sketches and shapes, if conversion to draft objects is selected - a set of polylines is created. And I am at a loss how to proceed with them further. I have dedicated my time today to reading, vewing tutorials and trying to apply what I've learned. I definitely need to get some 3D CAD skills not only for this particular task.

* Flange-Head-poly.dxf (65.57 KB - downloaded 32 times.)
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Bubba
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« Reply #22 on: November 25, 2017, 14:09:53 pm »

This is the prefs screen from my newly minted "FreeCAD_0.17.12619_x86_dev_win" binary.
so things might have changed, I'll have a look later to see if it's ok.
**************************

Hi Dave,

I have installed the new FreeCAD .17 . That why I have expressed what I see in it, compared to previous .16 version..


* Capture.JPG (63.73 KB, 654x699 - viewed 52 times.)
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EddyCurrent
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« Reply #23 on: November 25, 2017, 14:12:42 pm »

Rhino stl attached. (just in case all else fails)
CamBam can also extrude it using the extrude solids plugin but it also fills in the holes which is not desired.

* flange.zip (1454.97 KB - downloaded 20 times.)
« Last Edit: November 25, 2017, 14:14:48 pm by EddyCurrent » Logged
Dragonfly
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« Reply #24 on: November 25, 2017, 14:37:46 pm »

Rhino stl attached. (just in case all else fails)
CamBam can also extrude it using the extrude solids plugin but it also fills in the holes which is not desired.
Thanks Eddy,
But a single .STL is not enough because the final part is a rather complex design. And they cannot be 'welded' together. That's why I need to work in 3D CAD.
In CamBam, if you convert the geometry into a Region, 'Extrude Solids' does the holes too.
Here is a .cb file I made with CB for Linux. As you can see there a two base extrusions 15 mm thick with an offset to each other which gives the basic idea of the complex flange. But for the port holes transition I need the 'Lofting' function.
I didn't provide the two shapes in my previous post because I need to get to grips with making more simple 3D parts in FreeCAD.

* Flange2.cb (997.84 KB - downloaded 21 times.)
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EddyCurrent
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« Reply #25 on: November 25, 2017, 15:30:02 pm »

Good idea about using Region in CamBam  Cheesy
Regarding 'welding' together, I often draw 3D objects as separate parts then use a "Boolean Union" to make them into one object.
As you say, the only way forward is to get to grips with FreeCAD.
« Last Edit: November 25, 2017, 15:33:12 pm by EddyCurrent » Logged
dave benson
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« Reply #26 on: November 26, 2017, 02:52:43 am »

Here you go:
I've supplied the Freecad file as an example.
Here is the link for this guy on youtube how I've found to a good tutor.
paul randall
https://www.youtube.com/channel/UCnxMaGMCrWAQgwF61ISRpGw
This guy is very talented as well.
cad1919

this is just from my notes as I went along
{
The file is large for how much geometry that's in it ?

in freecad there's multiple copies of the geometry (try import settings)

to get a fully constrained sketch use the draft workbench convert to sketch tool

There were 3 copies of the geometry I did whittle the "shapes" down and extrude them but this took half an hour to get right and was very fiddly.

just use the sketch method.  30 seconds to do whole job!
1.... Import the geometry
2..... Delete Multiple  copy's of the geometry
3.....On the Draft workbench, use the upgrade to sketch tool.
4.....Extrude that sketch and you get what you want.

Dave

edit: Opps here's the freecad file in next post


* Imported into Freecad from CB Export selection to multiple copies 2.PNG (42.14 KB, 894x534 - viewed 43 times.)

* File pulled apart.PNG (82.84 KB, 1010x622 - viewed 37 times.)

* after extrude notice some lines extrude in the wrong direction.PNG (50.34 KB, 803x610 - viewed 39 times.)

* Final extruded manifold.PNG (89.6 KB, 859x688 - viewed 38 times.)
« Last Edit: November 26, 2017, 02:54:47 am by dave benson » Logged
dave benson
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« Reply #27 on: November 26, 2017, 03:01:25 am »

Freecad File:

* Mainifold Test for Freecad.zip (1009.84 KB - downloaded 19 times.)
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Dragonfly
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« Reply #28 on: November 26, 2017, 11:35:42 am »

Thank you very much, Dave, for your time. Much obliged.
Quote
The file is large for how much geometry that's in it ?
Which file? The .DXF I supplied is ~65 KB. If you used the CB file I attached in my reply to Eddy yes it has multiple layers with overlapping geometry and extruded objects in it.

Quote
in freecad there's multiple copies of the geometry (try import settings)
Yes, as it appears, but I thought it is something normal. And didn't dare delete the unneeded geometry which made a mess in the properties tree. All because I don't know what's normal and what not working with FreeCAD. Sad   Your example enlightened me much on this matter.
But importing external geometry seems somewhat like magic - depends very much on importer settings and the version of AutoCAD the .DXF is saved to. If I open the same file in LibreCAD and simply save it as R12 version, it differs in the way the importer interprets it.
Looking at your example I set the import preferences to create sketches. Opened the same .DXF file and had one fully defined sketch alongside copies of the comprising geometry. Deleted the latter leaving only the sketch. In the Draft workbench upgraded it and it resulted in 'Wire'. Switched to Part workbench and applied 'Compound'. Then extruded the compound and voila.  Smiley
(This is based on what I read from the help and watch on YouTube yesterday but I must admit I am still not confident in what I am doing. But I have a result anyway.)
Thanks again.
Ivan


* Step1.jpg (142.04 KB, 793x1010 - viewed 39 times.)

* Step2.jpg (141.53 KB, 795x1015 - viewed 36 times.)

* Step3.jpg (146.53 KB, 819x1029 - viewed 46 times.)
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« Reply #29 on: November 26, 2017, 20:14:46 pm »

I did some progress today.  Wink
Apart from everything else one of the faces has a 10 degrees angle relative to the other.
Didn't make the mounting holes. Will do them the traditional way. The most significant part for 3D work are the air channels which have to be milled from both sides.


* Flang1.jpg (121.55 KB, 1242x927 - viewed 39 times.)

* Flange2.jpg (91.72 KB, 1004x724 - viewed 39 times.)
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