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it's a crank arm, the problem with it is the threading for the crank puller is destroyed (my bad) which would make it very hard to extract , what's unique about this crank arm is something i believe called a q-factor,which allows it extend a lot further from the base of chainset, which is beneficial in case you want to have a bash guard
by comparison you can see a regular cyclone freewheel crank arm, which touches the edges of the bashguard even after you apply 2 spacers which is not normal.
this crank arm costs 175$ and i'm guessing it would cost more for me to produce it myself but it would still be nice drill to use onshape, right?
If wanting to be cute, you could do a partial revolve -- in other words, a sector of a flat-bottomed, cone skirted solid -- but there's little point, because the next step would be to draw the view looking along the axis of the crank rotation, and "Extrude/Intersect" so as to cut away the surplus part of that solid.
That would leave only extruding the outer lever of the crank in one direction (eg the same direction as the last extrude) and then an "Extrude/Remove" at right angles to that, to remove the underside.
The first two screenshots show the early stages I described above, concerned with creating the inner portion of the crank.
The only slightly tricky part with this procedure is correcting the shape of the sloping faces. The second screenshot shows the natural curve at the highlighted edge. To copy the crank in the photo, this edge needs to be straightened. The key to doing this is to create a lofted surface, and then use that to "Replace Face"
But I'm thinking you're probably not wanting to dive this deep at this point in your exploration of Onshape?
There are good reasons why the folk at Onshape chose basic engineering objects involving primitive (generally orthogonal) geometrical features and faces for the demos, rather than hammer heads or offset bike cranks.
A realistic hammer head would be surprisingly difficult to model, as it happens - a lot harder than your crank.
Good luck in sneaking up on the fun stuff - I think you're wise to moderate your ambitions at this early stage, now that you've seen a typical issue with fancier geometry.
A single sketch and a single revolve creates a nail or a plate.
It would be a bit like devoting an entire tutorial for new car users to saying "This is how you open the driver's door"
I personally think the guys who make the demos do a pretty good job of picking shapes which expose important procedures, one at a time and in a logical sequence, without getting into tricky stuff like your crank.
There are Onshape demos where a single sketch and a single revolve appear in the sequence of constructing a simple part.
I personally think you are making their job unrealistically and unnecessarily hard if you want them to choose objects which are universally familiar to people with no engineering background. Onshape is (by and large) an engineering tool.
There's a whole webinar coming up, on Sep 1 on this topic, for anyone in this position.
https://www.onshape.com/sketching-basics-sept-1
Elhanan,
First a little story... Back in the 90's the company I worked for transitioned from 2D AutoCAD over to what was then the pinnacle of CAD software Pro/E. There was a young mold designer that had a lot of trouble grasping the idea behind 3D CAD. He took all of the classes offered by our CAD vendor yet he would still come to me with questions like, I want to create this kind of feature but there is no command for it. After thinking about his issue for a while I hit upon what he'd missed going to all those classes. It was my experience when going to a CAD class that most of them failed to teach a very important aspect of creating 3D CAD models, I'll get to it in just a bit.
So... Here I am helping this guy who's trying to find a way to create a model and he can't find the specific command to do what he wants. So I give him this analogy, When you do a tutorial or go to class, they will explain something like this, "This is the screwdriver tool, it's used for installing and removing screws" and then you leave the class, get back to work and someone hands you a paint can and you come over to me and ask, "Hey I need a paint can opener tool to open this can and they don't have one" and my reply is "Use the screwdriver tool" and the moral of the story is this... Most tools can be used for much more than their intended purpose.
OK so here's what most teachers fail to teach. The set of commands in the software are like a box of tools. We'll give you one example of how to use them but there are many different ways that one tool can be used in order to achieve a particular modeling goal and... It's up to you to utilize those tools in a creative manner to solve your modeling challenge.
Take for example the bike pedal crank. Andrew chose to start with a revolve and then cut away a "C" shape to create the model, but he could have just as easily started by extruding the top profile and then cutting the side profiles away, he could have started by extruding just the hub and pedal joints and then connect the two with a loft feature and so on. Just as a writer creates an outline to keep the story on track so must you create a strategy that will help you create the shape (part) you need.
So with all of that said, You are a tinkerer and more than likely you've used a screwdriver to scrape off an old gasket or a wrench to bang on something.
Apply that same thinking to using the tools in Onshape and you will be surprised at the things you can create.
Good luck!!!
If there's been a better, more thoughtful and timely first post on this forum, I missed it!
Welcome, and I (for one) look forward to more ...
I'm also interested in a slightly different question: what specific educational benefits would "familiar objects" provide?
(... assuming such universals even exist. The ones the OP listed would be familiar to a carpenter, but not necessarily to a surfboard maker or horologist).
I commented above as to why I thought it impractical to comply with his suggestion, but setting that aside, there seems a more fundamental question. I don't quite get why an object with simple features should need to be familiar to be instructive. I always thought that curiosity was an advantageous characteristic of smart species, like dolphins, certain birds, and primates, who are typically especially attentive to objects which are unfamiliar...
Of late, I wonder if education and parenting have conspired, in some parts of the world, to unduly prioritise emotional security over new experience?
I'm not directing this question at anyone in particular, just anyone who might be interested.
the educational values in using familiar objects is to get what i'd like to call the "aha" factor, causing people to look on objects they've seen or used all their lives in a new way , decomposing it in their mind as cylinder , tubes, circles,( "you know now that i think about it , that thing really just of basic shapes") as java software developer with OO thought pattern and analasys i've started to look at anything around me as a component, i've also applied it to ebike, using sprockets as components , and adapters as other reusable objects.
I guess I was assuming, perhaps wrongly, that anyone who had got as far as experimenting with Onshape would already have well and truly made that mental leap, or they wouldn't be seeking some way of recomposing objects from basic shapes.
Were you making the suggestion that tutorials should choose familiar objects because you had trouble decomposing unfamiliar objects into shapes, or because you thought other people might?
i had prior (very little) experience using blender with 3d modelling, and tutorials over there always started with basic shape like a square or a sphere and started building up to something
btw this is something i DO plan on trying to build in the future, the reason is this things are 6061 aluminmium, and i already destroyed the threadings on two of them, need it out of steel
https://www.paragonmachineworks.com/cgi-bin/commerce.cgi?preadd=action&key=B4016
To make a pencil for example, the tutorials show you how to start a sketch, draw a hexagon, extrude it and apply a draft to get a point. All the relevant skills are there from the ground up, you just have to piece them together.
As onshape grows there will be more and more youtubers doing their own tutorials of whatever objects they choose but they will still be sketching, extruding and modifying just like the current ones.