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How to find the scale of a beam in the beam custom feature?
gerald_comeau
Member Posts: 61 ✭✭
I am still taking Learning Onshape courses but also beginning to experiment to see if I can put what I have learned into practice. I have been practicing with the custom beam feature after watching the weldments webinar. I arranged a Wide Flange Beam in a circular pattern to make a carousel platform. The scale I use for the circle is 1mm:12.5mm.
I started with an arc of 400mm radius (400mm:5000mm) and used 5 units of the arc to circle the beam. The circle scale and the beam scale are incompatible. I don't know how to fix this or where I went wrong. Here is the document:
https://cad.onshape.com/documents/b0035e05f853ec87e70c483a/w/e989a161cfa5c90af1778a46/e/7aa7f91b616cf313c39330f1 I knew the scale issue would arise from watching the webinar but went ahead anyway to practice and to illustrate my problem.
To digress, here is a beam I extruded before finding out about the beam feature. The exercise was a failure but it illustrates roughly the relationship in size between the radius of the carousel and the beam.
https://cad.onshape.com/documents/51760939f61b89b9c0e67ad3/w/eb429986dc2536004157d6a0/e/286f333a48cd5287a7b1b4e7
Background: My ambition is to innovate in concentrating solar power. The concept is to use a transparent convex flat lens of the Fresnel type. This lens will direct the sun beam downward to the ground instead of upward toward the sky, as in the case of a parabolic dish. There are significant advantages to directing the beam toward the ground. Capability for heat storage is just one of those advantages. The concept has been attempted in a pilot project, but I don't see any sign that it has gone into production. Here is a 4:35 minute video of that pilot solar power plant. https://www.youtube.com/watch?v=3oN1nh-XWVo&list=PLwCY0cZvkCFFOKYhvBEGWC5gHYktyJhim&index=2&t=0s My concept is very similar but its execution is quite different. My aim is to make a more rugged structure. Also, my goal is to have all the parts of the parts fit into a 40 foot container for shipment and easy assembly at destination.
I started with an arc of 400mm radius (400mm:5000mm) and used 5 units of the arc to circle the beam. The circle scale and the beam scale are incompatible. I don't know how to fix this or where I went wrong. Here is the document:
https://cad.onshape.com/documents/b0035e05f853ec87e70c483a/w/e989a161cfa5c90af1778a46/e/7aa7f91b616cf313c39330f1 I knew the scale issue would arise from watching the webinar but went ahead anyway to practice and to illustrate my problem.
To digress, here is a beam I extruded before finding out about the beam feature. The exercise was a failure but it illustrates roughly the relationship in size between the radius of the carousel and the beam.
https://cad.onshape.com/documents/51760939f61b89b9c0e67ad3/w/eb429986dc2536004157d6a0/e/286f333a48cd5287a7b1b4e7
Background: My ambition is to innovate in concentrating solar power. The concept is to use a transparent convex flat lens of the Fresnel type. This lens will direct the sun beam downward to the ground instead of upward toward the sky, as in the case of a parabolic dish. There are significant advantages to directing the beam toward the ground. Capability for heat storage is just one of those advantages. The concept has been attempted in a pilot project, but I don't see any sign that it has gone into production. Here is a 4:35 minute video of that pilot solar power plant. https://www.youtube.com/watch?v=3oN1nh-XWVo&list=PLwCY0cZvkCFFOKYhvBEGWC5gHYktyJhim&index=2&t=0s My concept is very similar but its execution is quite different. My aim is to make a more rugged structure. Also, my goal is to have all the parts of the parts fit into a 40 foot container for shipment and easy assembly at destination.
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Best Answers
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Cris_Bowers
Member Posts: 281 PRO
@gerald_comeau As Neil stated you should model everything 1:1. The only place anything is typically scaled is in a drawing. Drawings are created by inserting scaled views of your model.
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john_mcclary
Member, Developers Posts: 3,935 PRO
Here are some common tips and food for thought when modeling.
-Always model your parts full scale
-Never round your decimal places. (use .015625 not .016)
-Never eyeball something (humm. That looks close enough)
-Only create a 'drawing' when you need to print a part for manufacture
-Always fully define your sketches (make the blue lines black)
-When you can; use geometry and constraints to define your shape; using the fewest amount of dimensions as possible to capture your design intent
-Keep your sketches short and sweet. The more lines in one sketch the slower it takes to edit/calculate your part studio
-Keep your partstudio feature tree and part count to an absolute minimum. (50 or more features you should concider modling the next part in another studio)
-Don't go overkill on uncessesary details unless you absolutly need them (no screw threads unless you are 3D printing)
-Be clear and take advantage of feature tree folders to organize your tree. Make it so anyone can figure out your intentions easy. Chances are you will be the one going back a week later to edit, and you don't want to be confused either
The above is what separates the CADdies from the BADdies and the Engineers from the Artists
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NeilCooke
Moderator, Onshape Employees Posts: 5,680 
If you think of a map as a drawing of the real thing (which it is) - the same applies when modelling. Model 1:1, create drawing at a scale that will fit on printed paper.gerald_comeau said:john mcclary, ....lean and mean CADdies. That's a great list of tips: and 10 of them too. Trying to be a GOOD student, I have already recognized some of these tips through practice and observation and am working on being mindful of them. I'll be keeping this list for quick reference. Thank-you.
I've got to admit though, I am a little puzzled by the term "model full scale." I've of thought of a scale as always full ....like a map, so many (x) mm to (x) km. It's not possible to squeeze in an additional town from outside the confines of the map ....or try to increase the size of a county without changing its borders, to make room for farmland from outside its borders. That would not be true to scale. In CAD you can blow up or reduce the size of the sketch plane while remaining true to scale, but as in the map you can't squeeze in another beam when there's already a beam there.
There is one thing in Onshape that I don't yet understand. I've noticed that the planar faces are not always in direct relation to the size of the sketch plane or vice versa, as if they're independent of each other. Am I right or am I confused? I'll be relieved once I understand this fully. I've looked and searched for explanations for this and so far have not found anything. I'd be grateful if you could point me to information that would solve this mystery for me.
Am I right in thinking that your 1500mm^2 sketch was your interpretation of sketch planes and scale? A plane is infinitely big and has nothing to do with the size of your sketch. Keep practising - it will click.Senior Director, Technical Services, EMEAI5 -
NeilCooke
Moderator, Onshape Employees Posts: 5,680
BTW - it was I who did the webinar. I may have created the 1500mm sketch as the skeleton for a frame to add beams onto.Senior Director, Technical Services, EMEAI5
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john_mcclary
Member, Developers Posts: 3,935 PRO
basically you should not think of scale at all while modeling. We don't scale, we zoom.
If you draw a house. Make the walls 8ft tall. Don't worry about how it fits on paper. Scale in drawings is basically a way of zooming in/out until it fits. Like pinch zoom in google maps.
But if you were to 3D print that model of a house. It would be the same size as your physical house. 1:1
The only time you will scale is if you want the model to litterally be smaller. Like a model car. Even then you may draw it all 1:1 then the very last feature on your tree is a "transform->scale" which will do all that shrink/grow work for you. When you 3D print it, it will fit on your desk. Instead of your driveway.
5
Answers
Note that all custom profile sketches must be sketched on the Top Plane.
Chris Bowers indicated scaling in drawings. My plan was to make more parts before going there. If I understand you correctly, I'm at that stage now. The challenge now is to use the arc that I've already made and proceed to make parts which fasten the beams together. I should mention here that I intend to do as little welding as possible on this project because the finished product may end up in destinations where there is little industrial infrastructure. For this reason I need to make plates for bolts in the shape of the arc and use these to fasten the beams together. This takes me to sketches. I want to make sketches that will fit. I know the dimensions, but I am not sure if I understand how to arrive at the size of sketch plane I will need. From the webinar, I believe the instructor started the sketch with a rectangle of 1000mm X 750mm, (I'd have to look it up to make sure.) I used a sketch of 1500mm X 1500mm to make the arc so I can use that. Am I right?
Thanks guys.
Enjoy your vacation and get rested up for the hard questions I'll come up with.
-Always model your parts full scale
-Never round your decimal places. (use .015625 not .016)
-Never eyeball something (humm. That looks close enough)
-Only create a 'drawing' when you need to print a part for manufacture
-Always fully define your sketches (make the blue lines black)
-When you can; use geometry and constraints to define your shape; using the fewest amount of dimensions as possible to capture your design intent
-Keep your sketches short and sweet. The more lines in one sketch the slower it takes to edit/calculate your part studio
-Keep your partstudio feature tree and part count to an absolute minimum. (50 or more features you should concider modling the next part in another studio)
-Don't go overkill on uncessesary details unless you absolutly need them (no screw threads unless you are 3D printing)
-Be clear and take advantage of feature tree folders to organize your tree. Make it so anyone can figure out your intentions easy. Chances are you will be the one going back a week later to edit, and you don't want to be confused either
The above is what separates the CADdies from the BADdies and the Engineers from the Artists
I've got to admit though, I am a little puzzled by the term "model full scale." I've of thought of a scale as always full ....like a map, so many (x) mm to (x) km. It's not possible to squeeze in an additional town from outside the confines of the map ....or try to increase the size of a county without changing its borders, to make room for farmland from outside its borders. That would not be true to scale. In CAD you can blow up or reduce the size of the sketch plane while remaining true to scale, but as in the map you can't squeeze in another beam when there's already a beam there.
There is one thing in Onshape that I don't yet understand. I've noticed that the planar faces are not always in direct relation to the size of the sketch plane or vice versa, as if they're independent of each other. Am I right or am I confused? I'll be relieved once I understand this fully. I've looked and searched for explanations for this and so far have not found anything. I'd be grateful if you could point me to information that would solve this mystery for me.
Am I right in thinking that your 1500mm^2 sketch was your interpretation of sketch planes and scale? A plane is infinitely big and has nothing to do with the size of your sketch. Keep practising - it will click.
If you draw a house. Make the walls 8ft tall. Don't worry about how it fits on paper. Scale in drawings is basically a way of zooming in/out until it fits. Like pinch zoom in google maps.
But if you were to 3D print that model of a house. It would be the same size as your physical house. 1:1
The only time you will scale is if you want the model to litterally be smaller. Like a model car. Even then you may draw it all 1:1 then the very last feature on your tree is a "transform->scale" which will do all that shrink/grow work for you. When you 3D print it, it will fit on your desk. Instead of your driveway.
John, I like "We don't scale, we zoom." ....also good guidelines on the usefullness of scale in models.
Neil, so that was you in the weldments webinar. I did not recognize your voice. I thought the audio was better than usual. Did I detect a slight British accent. I have a french accent. The building of the frame of the gocart was dazzling. I thought the square pipes were OK but the the round pipes looked a little flimsy. Would you mind replacing those with W-200 beams? ...just kidding. See. I'm learning.
Serioulsy though, you guys were a big help to me in getting over some hurdles. Many thanks. I have to remind myself that we are in cyber times. We can move Nova Scotia to the Gulf of Mexico with Photoshop in the blink of an eye. We can create Russia conspiracy theories on youtube, we can have a wallet with invisible coins in it and we can make great models, gocarts for example, on Onshape, We could become schizophrenic. What a wonderful woild.
I meant to answer your question but got distracted by something else and forgot. The whole notion of sketch planes and scale were a little foggy in my head and I had no firm idea. I did realize immediately though, what happened when in your Weldments Webinar, you drew the "skeleton" sketch and placed the beam on the edge of it. So I understood that much. I have always zoomed in and out until now by using my mouse wheel but your skeleton sketch showed me another way it can be done. The fog is clearing and the biggest lesson I've learned is always model 1:1. Thanks for the encouraging comment that it comes with practice.