V0.19: Clayton Steam Wagon--UPDATE #4

[ppemawm]

I have started this project to test the stability of V0.19 and to practice some new techniques introduced in V0.18 sketcher. This model is being created from drawings by J.A.M De Waal (http://www.vapeuretmodelesavapeur.com/t ... pe-4ft.pdf) of a 1/6 scale originally designed by Robin Dyer (http://www.john-tom.com/OldBookPlans/Cl ... 0Truck.pdf). PartDesign workbench and mirror and clone tools from the Part workbench were primarily used to create the model. All parts and bodies are in one file. Assembly workbench is not used.

So far, I have completed the basic frame and suspension of the truck and the complete trailer with all the fasteners:

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Most of the components are fairly straight forward with the exception of the wheels which turned out to be quite complex. It took several iterations to achieve a valid solid. The problem seemed to be related primarily to the tangency of the large fillet on the webs at the outer diameter.

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This is my first time exploring the capability of the CarbonCopy tool in the Sketcher workbench. In previous projects I used shapebinders of master sketches (https://forum.freecadweb.org/viewtopic. ... 97#p230797) to link all the components in articulating mechanisms. In this model, I am using CarbonCopy to essentially accomplish the same thing.

It begins with a master sketch of the main component to which all the rest of the mechanism attaches. This master sketch is then duplicated (Edit>duplicate selection) to capture its attachment properties. Next, the geometry in this sketch is deleted and replaced by a CarbonCopy which links the duplicated sketch to the master sketch. This CarbonCopy sketch is then duplicated as a starting point for each added feature and for each new body. Any extraneous geometry in the duplicated sketch is converted to construction geometry and new geometry is added as needed and constrained to the construction geometry. In this manner, all of the bodies can be linked as shown in the following screenshots:

The variable in the master sketch is the angle of the reverser arm with respect to the cabin floor highlighted above.
With proper constraints, this angle can be changed to verify the positions of all the linked bodies shown in the second view.

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The second variable is the angle of the lever which releases the latch. These views show the effect of varying the
arm angle and the lever angle.

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CarbonCopy is remarkably stable even for large changes in constraints as demonstrated by this example and somewhat easier to use than shapebinders IMO. One annoying feature of Edit>duplicate of the master sketch is that it kicks the duplicated sketch out of the Body which has to be dragged back into the active body. It seems like it should know that it belongs in the active body.

The only issue I had was with a fillet on the lever which would fail randomly with a change of the lever or arm angle constraints. Other than that, overall, V0.19 has been pleasure to work with so far. Stay tuned for future updates.

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.16653 (Git)
Build type: Release
Branch: master
Hash: aaae82970461c10b76281f4e4454ab086b5f7f21
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: English/UnitedStates (en_US)

[chrisb]

And again one of your extraordinary models. Thanks for sharing.

[abdullah]

CarbonCopy is remarkably stable even for large changes in constraints as demonstrated by this example and somewhat easier to use than shapebinders IMO. One annoying feature of Edit>duplicate of the master sketch is that it kicks the duplicated sketch out of the Body which has to be dragged back into the active body. It seems like it should know that it belongs in the active body.

The only issue I had was with a fillet on the lever which would fail randomly with a change of the lever or arm angle constraints. Other than that, overall, V0.19 has been pleasure to work with so far. Stay tuned for future updates.

I sit down in my couch, dim the lights and keep ready for another amazing master project of yours

Nice to see you testing carbon copy intensively. Let me know if it fails somewhere or if you see how it can be improved.

To be honest with you, I did not even know that FreeCAD had a "Duplicate selection" option. I am not sure how that one works. I have not found a way to copy one sketch within a body without it popping out of the scope of the body...

About the fillet on the lever and tangencies, there should be room for solver improvements... maybe for 0.20...

[chrisb]

"Duplicate" has the advantage over Copy/Paste that it just copies the selected object and doesn't ask too many questions.

[ppemawm]

Nice to see you testing carbon copy intensively. Let me know if it fails somewhere or if you see how it can be improved.

In this proposed work process, I invariably turn all of the geometry of the CarbonCopy master sketch to construction geometry so that the new feature geometry or the start of the base feature for a new body can be added. So, it might be nice to have that done automatically to save a step. One downside I can see with this approach is that the sketches get more complex than the master sketch because you are always adding geometry. I am a devoted fan of "simpler is better" when it comes to sketches. But, the constraint solver seems to handle the more complex sketches quite nicely.

It would also be helpful if something could be added in the model tree that distinguishes the CarbonCopy sketch so that it would be easier to keep track of how the sketches are linked. I do that now by renaming the sketch, an extra step. Perhaps a different symbol or unique name could be provided.

One advantage is that you do not have to plan too far ahead with the master sketch, just capture the attachment points of the bodies to be added to the first body. I usually use the first sketch of the first feature of the first body as the master sketch rather than a separate sketch. As you add bodies, you can CarbonCopy previous beginning sketches of other bodies if necessary as you build out the (sub)assembly as shown in the example below.

This is a good way to "design in context" when creating assemblies. If anyone is interested in this process, I could strip out the reverser sub-assembly and attach the file if it is not too large. Please realize that I am experimenting at this point to find the best approach so it may be a bit confusing to follow.

This sketch is a CarbonCopy of a duplicated CarbonCopy of the master sketch of the Arm body. Sounds complicated but it is not in actual practice. All of the orange constraints are from the CarbonCopy(s).

This sketch is to add a revolve feature. I use an edge in this sketch as the reference axis.
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[kisolre]

So, it might be nice to have that done automatically to save a step.

Since this might not always be the desired behavior current process works Ok for me. If you are in normal geometry mode all imported geometry is imported as is. But if you are in construction mode all imported geometry is imported as construction '(what I understand you want here?).

[ppemawm]

if you are in construction mode all imported geometry is imported as construction [geometry]

That is exactly the toggle I was looking for. So, select the construction mode before CarbonCopy.
Thanks for the tip.

[chrisb]

It would also be helpful if something could be added in the model tree that distinguishes the CarbonCopy sketch so that it would be easier to keep track of how the sketches are linked. I do that now by renaming the sketch, an extra step. Perhaps a different symbol or unique name could be provided.

This seems reasonable, because you use CarbonCopy like a special sort of ShapeBinder. In general the CarbonCopy can be changed, parts can be removed constraints can be edited, it is even possible to add further CarbonCopies. I would be rather surprised, if just the usage of this convenience tool would lead to a different kind of symbol in the tree.

[abdullah]

In this proposed work process, I invariably turn all of the geometry of the CarbonCopy master sketch to construction geometry so that the new feature geometry or the start of the base feature for a new body can be added. So, it might be nice to have that done automatically to save a step.

Have you tried to first click the "toggle construction geometry" button and then use CarbonCopy? Then everything should be construction geometry.

One downside I can see with this approach is that the sketches get more complex than the master sketch because you are always adding geometry. I am a devoted fan of "simpler is better" when it comes to sketches. But, the constraint solver seems to handle the more complex sketches quite nicely.

If one imports just one master sketch it should be fine, but if one imports a sketch which was already the result of applying CarbonCopy of another dossier complexity increases geometrically with each successive "carbon copy". Dependencies are then difficult to track...

It would also be helpful if something could be added in the model tree that distinguishes the CarbonCopy sketch so that it would be easier to keep track of how the sketches are linked. I do that now by renaming the sketch, an extra step. Perhaps a different symbol or unique name could be provided.

I have thought of making the tree more revealing with respect to references. But when one sees a dependency graph, it starts to be difficult to see how to modify the tree so that it is useful.

One advantage is that you do not have to plan too far ahead with the master sketch, just capture the attachment points of the bodies to be added to the first body. I usually use the first sketch of the first feature of the first body as the master sketch rather than a separate sketch. As you add bodies, you can CarbonCopy previous beginning sketches of other bodies if necessary as you build out the (sub)assembly as shown in the example below.

Yes, you can do it. I have used it and works reasonably well. However mixing different sketches over bodies increases the complexity quite a lot. If you are disciplined, it is very powerful and you can have a good boost in productivity, but if something goes wrong it starts to be difficult to track all the dependencies. Now I do understand better the naming you mention above.

This is a good way to "design in context" when creating assemblies. If anyone is interested in this process, I could strip out the reverser sub-assembly and attach the file if it is not too large. Please realize that I am experimenting at this point to find the best approach so it may be a bit confusing to follow.

It is always interesting to know what you are doing exactly with the tool. It is like handing your car to a formula 1 driver. You get amazed how it can be used...

[ppemawm]

Have you tried to first click the "toggle construction geometry" button and then use CarbonCopy?

Yes I have, at the suggestion of kilsolre, and it is exactly what I wanted. Thanks for all your comments.