Understanding FreeCAD Lesson 3.1 Model a Piston Crank Shaft Assembly Animation in Part Design A2Plus
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- เผยแพร่เมื่อ 1 มิ.ย. 2024
- In this 4 part lesson we use FreeCAD to model a piston head, connecting rod and crankshaft in the Pat Design workbench an assemble and animate those in the A2 Plus assembly workbench as though they were moving in an engine. The A2 plus workbench will allow us not just to connect the individual parts but allow simulating the movement allowing them to move in a mechanical motion together. We will then move on to scripting, animating the parts making them move together. From lesson 2 we learnt about master sketches and using those in the part design, we are going to be utilising these in in this workflow both in the modelling and the a2plus assemblies.
In part 1 we will first draft the master sketch in Free CAD's sketcher to create a simplified version of the mechanism at it's lowest position and them in same video model the piston head using revolves, datum planes, pads and pockets. We will learn how easy it is to constrain these parts using master sketch throughout to keep our constraints neat and tidy
In part 2 we will move onto the controlling arm and crank shaft.
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A lot of great functions explained here. I'm looking forward to the following parts of this lesson. Thank you!
Gracias por tan excelente explicación...👍
Another excellent video - I'm thoroughly enjoying this series and continue looking forward to the next ones.
Thank you
The way you drop the little bits of diffrent ways you can do things really Gets one thinking about all of the tools you can use to achieve a result but in a very fluid way. Masterful tutorials. Thanks for the contributions.
Thank you so much for the comment, glad your enjoying. Freecad gives you so many choices that you can really be creative with the product.
This is a very clear, well laid out workflow. Thank you!
Thank you, and thanks for the feedback
Another excellent tutorial!
Can't wait to animate it!
Great to hear your following then all the way through. Thank you for the comments.
Great tutorial. Bought you a coffee. I am a newbie so making the datum planes seemed fine by me. Not sure why others say it is a confounding item? My biggest issue with freecad is I always wind up trying to figure out where I have too few or too many constraints. Great series. I have many more to view.
Thank you so much for the donation. At the end of the day its up to you how many constraints to add. Even if you set them all as datum and its fully constrained it may not be the best practice but it still achieved your end goal. You can always go back and refine your project. And that's when you really start to learn.
I think that having this come up much later in the series, redone to work with .20, would probably be a good idea. It would also help if there was a (correct steps only) point-for-point summary at the end of the video, that skips the explanations and what not to do, and just shows the creation of the sketches and other stuff, for comparison with the work done, as a sort of video visual checklist, to make sure this was really done right.
I'm having to redo this from scratch, a month later, because the A2+ WB is giving me crazy, unsolvable "conflicting constraints" errors that even the finder tool doesn't help with, as it only deletes the currently created constraint, not the actual problem triggering the error message in the first place. I have to believe it's some problem in the Master Sketch, or one of the other sketches for the different bodies, so that's what I'm re-doing.
Thank you. You're an inspiring Master 👍
I am really enjoying this workflow; it is really magnificent when coupled with the Spreadsheet, which further allows parameterization and calculation of constraint values based upon their relationships. Thank you so much for the work that you do to bring the rest of us up to speed. I really *would* love it if there were a tool in the sketcher to "create an edge which is both linked to external geometry and also an actual normal edge" but that's what's great about FOSS, really.
I just need to know more Python. ;)
Thanks for sharing how you are using and building on the workflow. It's great to get comments like these as it shows other how to utilise other aspects of freeCAD. It's a love of mine to share this knowledge, I have a love of open source software and I personally think people need to be aware of the alternatives out there. I work in the area of supplying solutions to the imaging and photography industry and all I see day in and day out is in house subscriptions to services such as Adobe when the alternatives such as Gimp, Inkscape and Darktable are side lined due to the leaning curve. It's my aim to bring awareness of free alternatives especially CAD and 3D (a love of mine) by supporting the projects with tutorials.
I am not sure of what your application is with the link of geometry. Would a subshape binder cater for your needs?
I have been trying to figure out a way of bringing some more python tutorials to my channel, just trying to find a subject.
Thanks once again for the comments.
Nice video again, I watched the whole thing. It's giving me some inspiration for a course I'm developing myself. I know this kind of stuff is hard to do exactly right and you're certainly doing an admirable job of it. So please take the following as constructive criticism and encouragement.
(I remarked on your use of Clone instead of Shapebinder on an earlier video so I won't go into that again.)
In this video it's obvious that you wanted to demonstrate datum planes in some way. But in this project you're modelling they aren't strictly necessary to achieve the end result. You could have easily just made all your sketches on the base XZ-plane. I feel your use of datum planes here will confuse newbies. If they are following along, trying to replicate all the actions in the video, they aren't going to understand why the datum planes would be helpful or necessary - because in this case, they are not.
Personally in my FreeCAD modelling I find datum planes rarely necessary or even useful, not to mention they add clutter to the model tree and they complicate the process. I do find them useful if I need to offset/orientate more than one sketch in a peculiar way. If there's only one sketch that needs to be placed somewhere, I will just offset the sketch itself. It's what I would teach learners to do as well.
Also I would not recommend attaching datum planes or sketches to any generated faces. I'm sure you know why (TNP).
With all that said, I thought this lesson was well done. You chose a good example project to demonstrate the concept of a master sketch and various other techniques. And I'm always delighted to see people spreading knowledge about FreeCAD.
Just my 2 pence, do with them what you will. Good luck!
Thanks for the comments, constructive criticism is always welcome. Yes I did want to demonstrate the datum plane and I totally picked the wrong way to do it, I agree, there was no need to add them. I started doing a video of optimising the model as there are a few other things I will like to change like there is no need for datum constraints to remove the arc from the piston head bottom. I should of named the radius constraint in the master sketch, added just a circle for the material I wanted to remove in a new sketch and used a formula referencing that constraint and adding a a few mm to the radius. It would again reduce the complexity of the model. Regarding the clone instead of shape binding that is purely down to preference as it gives me the added flexibility of scaling. Again thank you so much for the comments, these kinds of comments are key for people to adopt freecad. Guidance and best practices are quite sparse with this software. I just started doing some research of best practices with datum planes and its pretty hard to get a definitive answer. It's great to have these kind of comments and it's a great way of going through the whole design cycle especially for people who are not in the industry and don't have that support . To anybody else who's reading this, nobody should be against criticism and be put off creating content to help others, when it's constructive like this is worth it's weight in gold. Thank you once again.
Possible time-saving note: It looks like mirroring is best done for shapes that don't need a lot of constraints added. I'm guessing that if you add all the work done for just drawing the 3 point arc on the left side of the smaller circle inside the large one, and compare that to all the work done on the same arc if it's mirrored, it would come up about the same, or possibly take less time if you just draw the 3 point arc manually again.
Also, there are some constraints missing from the Master Sketch that are necessary for optimal point placement. In the largest circle, the left-hand line drawn from the center point to the outermost point (on the left of the circle) needs a height constraint, because (at least on my screen) it will still move up and down independent of the rest of the drawing without that constraint. The mirror-opposite line (on the right) seems to be well constrained as I follow along in the tutorial, but I had to add a second height constraint to the left line. Having a grid/snapping set up for metric (and turned on) would probably have avoided this, however, I'm personally doing things without it being set up that way (long story there). For those who are doing things differently with the grid/snapping, as I am doing, it's necessary to add that left-hand line height constraint.
Thanks for the video. I needed an example of a master sketch, and this one was quite timely.
If there's a video I REALLY want, it would be about how to efficiently invent and iterate with FreeCAD. I always find I regret the approach I take with freeCAD at some point in all my projects. At some point, I want to modify the design (maybe after a prototype) and then the tool becomes the barrier to making the changes. I think using master sketches will help me, but I get the sense there's more to it.
Glad it was useful for you. I have a big build coming up next year after I have taken delivery of a 3d printer. I will be doing a lot of prototyping and field testing and I think it may be good to bring in what you suggested. Thanks again for your comments.
Hello. Thank you for the videos. They are simply the best FreeCAD tutorials in existence.
I'm curious about one thing. It just seems needlessly clunky to have to jump to the Draft WB for a single cloning operation. Why isn't there a "clone sketch" option in the Sketcher WB? Is the "master sketch" approach not good practice according to the FreeCAD team or something?
Thank you for your kind comments regarding the videos, really glad they are helping everybody. It's something that I wish I had when I started learning. I agree in regards to the tools and jumping about but I can see the reasons why. It is due to the multiple workbench design. The same you can say about the sub shape binder. I have used that tool for what I do in other workbenches probably more than in part design. It's a question of where do you put it. If there were less workbenches then it would flow so much better. The good thing is you can customise your tool bar, I have done a video of two regarding that and that really helps when it comes to speeding up the process. Freecad to me is like my toolbox in my garage. I have multiple drawers and each tool can be used for a task other than what it is intended for (I keep using my chisel as a screw driver)
excellent contribution
Very simple!👍🙂
just to make sure i understood, at 18:00 you used the external geometry in order to have the points of the side of the piston so that you could create the spaces for the piston rings right?
Thanks you verry good
Glad you enjoyed, watch out for the rest of the series coming soon.
Instead of using a datum plane for the piston couldn't you use an origin plane on the xz plane?
Was just about to write the same comment. I can´t see the need for those two datum planes, adding extra complexity to the model when not needed. I often do it myself just because I use datum planes a lot not considering at the time that the base planes are right there :) Maybe there's something he has in mind for the following videos? Using the datum planes for something.
Thanks for the lesson. It's very useful. I think the final height of your Pin head sketch is 90 mm, and not 100 mm. Am I right?
Did you skip where you added the inner circle on the master sketch Cam where the connecting rod goes to?
It's around 9 minutes in
@@MangoJellySolutions The problem is you DID add a circle at 13:49 with no explanation nor dimensions. Go there then rewind a few seconds and you'll see what we mean. Thanks
22:08 I wish you would have explained the "Pocket result has multiple solids" error instead of dismissing it silently. The pocket hit the grooves, splitting the object into multiple pieces.
None of the cranks people generate have, about the axis of rotation, the counterweight mass located opposite that of the piston and rod.. If you’re going to rev it up, have everybody stand back.
Lol, can't wait for the bang 😂😁
I noticed this too and had to go back and look since it's been years since I've torn down an engine. Still a great video though. I'm looking forward to how to add oil passages :-)
@@robcarnaroli269 You will have to remove the slot if you wanted to do that ;)