FreeCAD

[bambuko]

FreeCAD: Your own 3D parametric modeler
It may not be everybody's cup of tea
and the learning curve can be frustrating...
but it is very usable!
Here an example of WIP - live steam in gauge O based on LBSC's Bat (but modified in line with gauge O Guild standard):

 

[bambuko]

I have made a bit of progress
The motion is bit more complete including valve gear (clip eccentric), axle pump, all beginning to fit together:

and a screenshot of the whole thing so far:

 

[AndyB]

I agree - FreeCAD has come a long way in the past couple of years.
A steep learning curve, as with any package that has lots of functionality. I've not tried anything with motion yet.
Looks like you've done the hardest bits now though!

Andy

 

[bambuko]

I agree - FreeCAD has come a long way in the past couple of years...

I am using Link branch of master FreeCAD (realthunder - Overview)
and specifically Assembly3 workbench (https://github.com/realthunder/FreeCAD_assembly3/releases/tag/0.1)
Master branch of FreeCAD (available for Win, Mac and Linux FreeCAD: Select your platform)
is probably the way to go if you are new to FreeCAD?

... I've not tried anything with motion yet...

It's not really absolutely necessary,
after all masters of the past designs (LBSC, Greenly, Evans, Young etc, etc) managed with paper and pencil
but to someone like myself, who spent all my working life using 3D CAD
it is an obvious and enjoyable way (and a project in itself... ).
Plus, hopefully doing it this way, will avoid mistakes that so proliferate model engineering designs of the past...

 

[adrian]

That seems to be a very polished application for an open-source community developed project.

 

[Chris Veitch]

That seems to be a very polished application for an open-source community developed project.

It is, I'm also very impressed with it - it seems to be a very active project which suggests it has a decent future and it's nearly 20 years old now.

I'm probably not alone in being a bit disappointed at the changes to Fusion360 licensing after I'd spent quite a while struggling to grasp the basics. Certainly FreeCAD seems to provide a viable alternative which is possibly easier to learn (although having spend time with Fusion360 probably gave me a basic grasp of what I needed to know) so I doubt I'll be spending much time with the AutoDesk product form now on.

 

[bambuko]

...Certainly FreeCAD seems to provide a viable alternative which is possibly easier to learn...

It is perfectly viable, but not in any way easier - it is simply different and sometimes very quirky

.....although having spend time with Fusion360 probably gave me a basic grasp of what I needed to know...

no, probably not. First thing you need to do when switching, is to forget what you are used to.
FreeCAD forum has plenty of ex-Fusionistas complaining that FreeCAD doesn't do things the way that their old CAD did...

PS I am not trying to discourage you (quite the reverse) but it's not easy

 

[simond]

I’m not sure.

I have no experience with FreeCAD or Fusion, but I use Solidworks at work, and learned 3D CAD using Creo/ProE. I had previously taught myself 2D TurboCAD which I understand to be a clone of AutoCAD, and before that, had learned CADAM, a 2.5D CAD system that developed into CATIA. I struggle with 3D in TurboCAD, but I made the transition from Creo to Solidworks relatively painlessly, without tuition, passed the basic user test, and would be confident to model pretty much anything, thought clearly aware that the 8-hours-a-day users will be a million times quicker than I will, particularly for those odd forms and weird geometries.

I guess the point I’m trying to make is that there’s a way of 3D design-thinking that you need to learn, and once that’s in your head, you need to learn the grammar of the system you’re using. Of course, when being taught a particular commercial system, these are simultaneous, like a child learning to speak. I think the grammar simile is apt - I read that if a child hasn’t learned a language by the age of 4 or 5, it’s simply too late, they then cannot learn. Happily, CAD is more forgiving, you can learn the concepts, and the grammar, at any age. And having learned the structure, the specific system grammar is easier to assimilate.

I’d recommend diving in, and hope the inevitable difficulties can be resolved without discouragement.

Simon

 

[michael080]

I guess the point I’m trying to make is that there’s a way of 3D design-thinking that you need to learn, and once that’s in your head, you need to learn the grammar of the system you’re using.

Fully agree, I have been comparing solidworks and inventor some years ago and they were quite comparable to use. We went for solidworks because inventor had a nasty tendency to break flat sheet metal designs if they became too complex.

3D-Cad can be intuitive if you understand the concept of adding and removing volumes from the body you design

BUT: I am a mechanical engineer working in a small team of phycists and electrical engineers. It is always puzzling me if these brilliant folks come to me with plans for a mechanical design.

What I want to say: Understanding your CAD-system won't make you a mechanical engineer. This is not a huge problem, because we are not desinging nuclear power plant reactors, but you still need a basic understanding of mechanics -- how to get a function into a piece of metal -- if you want to get a satisfying result.

Michael

 

[simond]

I’d note that I’ve not found an easy way of using Solidworks to prepare artwork for etching, which is a pain, as I’d like to do some (hobby) etches and Solidworks is my go-to CAD nowadays. I did some etches for work two years ago, designed the parts in SW (to fit into the 3D assembly) and then reconstructed them in TurboCAD. This works, but it’s a bit clunky, and not something you’d want to do with complicated parts (like a loco, for example)

We did talk to SW tech help about it but they were not able to offer a work stream that would do this, so if anyone knows how to do etches from SW I’m all ears!

Simon

ps. I also am a Mech Eng, working with Electronics, Software Engineers, and a Physicist.
I have observed what I call Simon’s law. If the basic problem is electronic, it will be fixed in software. If it is a mechanical problem, the electronics will work around it, and if it’s software, it’ll be quicker/cheaper/more effective to change the mechanical design.

 

[bambuko]

In FreeCAD you can export 2D things (in X-Y plane) to DXF.
For things on other planes I use "link" option to created linked feature that can be "transformed" independently of source thingy to X-Y plane to allow export to DXF (which only happens in X-Y plane). Bit clunky and I only explored it for laser profiles (so don't know how usable it would be for etches?) but doable.
Having said so, I would the first one to admit that despite doing all the modelling in 3D I wouldn't be without 2D package.
I use both, each for it's own purposes.

 

[simond]

Yes, the opportunity to export 2D images to DXF exists in SW too, of course, and I think from any plane, though I’ve not tried very hard. And SW has a very comprehensive sheet metal capability, which allows folding, etc., into a 3D form, but essentially it treats the blank as a 2D form with constant thickness.

The trouble is that a typical etched part is not like that, it is a 2D form, but includes a series of cut-away bend lines, or other details, eg half etched areas, and these need to appear on the artwork, and in particular, this kind of bend does not exist in SW.

My approach for the PCB tags that I required at work was to create the 3D part, “unfold it”, add the half etched areas for bend lines and then create the matched DXFs. It was actually quicker to redraw the unfolded shapes in TurboCAD than to export them. All the bend allowances were drawn directly in TC. Given that the parts were pretty simple, it was easy enough to have both programs open, one on each screen, and do it that way. More complex forms might well be better exported.

I use TC for all my laser cutting, I first purchased it as V12, which must have been in the mid nineties? I’ve got a newer version now…

and this is all very well, but has little to do with FreeCAD!

 

[Focalplane]

I have never tried 3D Cad other than that software that Google decided it didn't need. I agree about the need to understand the grammar of a software package. Ironically I can think in 4D (structural movement of rock formations through time) quite easily but then I am not recording any of my thoughts for others to interpret.

This is a very old animation that is only 2D plus time. 3D plus time would be awesome! I am sure the young ones in today's oil business (is there one?) have made many such reconstructions:

https://www.beg.utexas.edu/files/agl/animations/KNZARAFT.mp4

 

[simond]

I'm used to thinking in millimetres, not kilometres...

 

[michael080]

... and in seconds, not Megayears

I've also been trying to find a workflow for etched parts and I think the only half decent way SW allows is to design a laminated layer of parts to simulate the half etched slots.

This is a cut off corner of a 3d-bent box I desingned in Solidworks to demonstrate the idea. The outer shell is 0,3mm thick and is bent with the standard SW sheet metal tools (bend radius 0,3mm as well). After this has been done, I take the dimensions of the resulting straight areas and create additional parts of the same size, also 0.3mm. These are the laminated to the surfaces of the initial parts. The picture below shows one bent part (outer shell) plus three parts (inner shell)




I think this picture illustrates the idea.



and it also shows that I was a bit sloppy with the upper laminated layer. It is a bit too small.

The idea behind is that the outer shell behaves quite similar to a etched part in the bending zone. The full strength material is strong enough to limit the bending within the etched zone. I am not sure if these assumptions are correct, I couldn't find a better approach and I think this idea is just too complicated for most etched parts.

Feedback is appreciated and if there is a better concept in any other 3D-CAD-system, I would be happy to hear about it.

Michael

 

[bambuko]

...and this is all very well, but has little to do with FreeCAD!

It is internet forum
It is bound to go OT and drift sideways...
I can confirm though that even if there was something in FreeCAD that could cater for your needs, guys, I simply have no knowledge or expertise in etching, so can't help you

 

[simond]

I’ll post one of my bits when I’m logged on at work, my approach was similar to Michael’s, but I didn’t use the sheet metal tool. Michael’s route does give the overall profile of the part, but is going to get messy if there are bends “both ways”.

The issue is that there’s no obvious work route from 3D part to the paired images that are required by the etcher, so work-around are necessary.

 

[bambuko]

And ... getting back on topic , here is the latest.
Moved onto modelling the tender - still long way to go but making progress.
This BTW shows model being assembled on 8ft curve.

 

[AndyB]

My own bit of FreeCAD-ing finally done:

A Midland brake van stove, to drawing 228.
It looks simple, but the firehole door took a bit of trial and error to get right.
Just need to find someone to 3D print a couple for me now.
It's about 23mm high for Gauge 3 (1:22.6), but easily scaled if anyone wants one in any other size.

Andy

 

[Brian McKenzie]

Being curious about FreeCAD, I downloaded it and attempted to draw a sand dome using the method as described in post #25 at the thread Solidworks

Despite the huge difference in the way these two programs function, it didn't take too long to create a 1/4inch thick plate base segment, draped 'saddle-like' on the boiler, and then the two closed Profiles sketched for Lofting the sand dome skirt, sweeping 90degrees around from the top of the boiler to where it slopes down furthermost on the boiler side.

However, I couldn't persuade the Lofting action to follow the curvature of the Guide Rails installed. The lofting always went directly across in a straight line from one Profile to the other.



Then after viewing this tutorial

by Shawn Hymel ("DigiKey");

I installed the two program addons, 'Curves' and 'Curved Shapes' and converted some lines ex the Loft profiles into Bsplines - and used the 'Gordon' surface tool to generate the initial area of Surface (portion at left as below). This was thickened slightly (by 1/4inch which presumably changed the Surface into a 'Solid'?). First use of the Mirror tool then yielded half the base for the sand dome, then after Mirroring all of this again, got the full 360° neatly shaped skirt.

[ Boiler dia is 38.5", sand dome dia. is 23.5" All 'Solids' are 1/4" thick, Lofting Profiles are 1/4" wide ]



As Mr Hymel explained in his video, some of the tools described are a bit erratic as to whether they will work or not. FreeCAD, has certainly advanced, but I wouldn't recommend its use for organic shapes. I sense that tinkering with it might easily become addictive - and a hobby within itself.

My itch has been scratched - and I'll scuttle back to other softwares now. I haven't used SolidEdge before either, but that may well be the best free and competent CAD package. I avoid AutoDesk products because of past shenanigans where company profits, tax avoidance and executive payouts were more important than, and impacted customers.

-Brian McK.