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  1. #21
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    I'd second what mmoe said -
    I used AutoCAD from ~1985-2009 and was a huge evangelist, but it's not something that can be learned part-time or casually. Our rule of thumb was basically that somebody using it full-time, and making an effort to push their knowledge, could become reasonably proficient in a couple of years. Any less than that, IMHO, and you'd be scratching the surface.

    Not to take anything away from it, but there are almost certainly easier and more affordable tools available for the casual user. For that matter, if you don't need fancy parametric or drawing capabilities, you might be better off just learning BobCAD itself, and avoiding the whole translation issue. Maybe you have some other compelling reason to stick with ACAD, but if you were just getting into 3D, then I'd seriously consider investing the effort into an easier tool. It sounds as if this might be a fairly part-time endeavour. Learning AutoCAD just to model and toolpath a few shapes might be analogous to using a pile-driver to drive tomato stakes in your garden.



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    I only know BoB and still a beginner/novice in the CAD world.BUT one thing I have seen time and time again is Mr. Burrman showing someone how it can be done in BoB.He has had people challenge him, that stuff could not be done in BoB,and of course they were wrong.BoB maybe not fastest or best,but is capable for sure for the complexity of parts it sounds like you are doing.
    You already own the CAD in BoB,is there a reason it is not good enough ? It sounds like you could kick AC to the curb and spend your time on something that works right in the same program as your CAM.Many advantages to that.



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    Hey Gang,
    I got a bad case of "sleeping in the bathroom for 24hrs"... and so did the rest of the family. it was awesome! yikes! sorry for the delayed response. I am not married to AC at all. Just something I picked out of the air and learned it. I can draw a ski and all layers on it in about 10-20minutes. I think it doesn't import into bob cad very well at all and I'm all about kicking it to the curb if I can find a better method.

    1.) I don't drawl the skis on BC because it's on the computer in the basement hooked up to the CNC. I have three small kids so my time down there is very limited. Also, I'm sure there is a much easier way of drawling on it but just making lines on the program i find more complicated. For instance, in AC i can start a line and say I want it 1550mm long. In BC, I have to enter the starting point and the end point and that consists of math. I could only imagine how hard it would be to drawl two different radius (front of mid point and back of mid point and then have to blend the two.
    2.) I'll look into the suggested programs: Bonzai 3d (maybe to expensive) and ViaCAD (more my range). I'm open to whatever will import into BC flawlessly.
    3.) I've attached the base outline can someone look and see why the tool path doesn't follow the curve correctly as previously mentioned.
    4.) mmoe, i know it's the holiday but did you have a chance to generate an example
    Cheers,
    ~Brad

    Attached Files Attached Files
    Last edited by skimann20; 12-27-2013 at 09:15 PM.


  4. #24
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    Brad,
    I'll put something together later tonight. I'm not an expert on skis, so what I model will just be a generic representation of a ski. Obviously, you can spend more time than the 3 minute video I show in order to fine tune the various aspects of a ski's design which I'm not going to address for lack of knowledge. The one thing with Bonzai is that you would be able to unroll the modeled parts to create a flat version of what would create the 3d model. This may be an invaluable feature for your process, or may not be useful at all. Since I don't produce skis, I couldn't say as to how they are made. If I'm guessing, I'd suppose that you would start by modeling the desired 3d shape of each layer, then unroll those that are normally processed flat (base and cap materials?) while leaving the parts that are normally 3d (core?). Again, that may not be the way it's done, so I'm just making a few assumptions there. If that's indeed the way it's done, Bonzai would allow you to model the entire product in 3d, then unroll those 3d parts such as the base into a 2d object that fits the 3d part. This feature is not in Viacad (or if it is, I've never found it). If that's the sort of products you plan to design frequently, the extra $350 that Bonzai costs may pay for itself many times over in time savings. I do a lot of pattern work, and have been intending to buy Bonzai for those same reasons. I can model my desired final shapes, then extract patterns for cutting fabric to create those shapes (like tents for example).



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    Mmoe,
    Your assumptions are almost correct. Nothing is done with the top sheet, it gets trimmed out when the ski gets cut from its flashing. it goes like this
    1.) the finished ski shape
    2.) base (2D) is stepped in 2.25mm from the finished size all the way around the ski to account for edges. (i do not go around all the way, i leave the tips and tails unwrapped. so i have a step in)
    3.) Core (3D) is stepped out 5mm on the sides from the finished ski shape. if its a 1800mm ski, the tip spacer is 140mm and tail spacer is 110 so you have a 1550mm core.

    here are a few examples:
    WhiteRoom Skis:: Drawing skis in CAD
    snowbaord layup in solid works: (the sidewall ark is not how you do it for a ski. you need two different radius)
    one more for you:
    :: View topic - Solidworks this one is very advanced for me, but somewhere I'd like to go...



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    Quote Originally Posted by skimann20 View Post
    3.) I've attached the base outline can someone look and see why the tool path doesn't follow the curve correctly as previously mentioned.

    Cheers,
    ~Brad
    Use the "contour command" on your geometry, then remove and reselect geometry for the feature.

    The contour command will use a fitting process on those super shallow arcs and give them the added definition the toolpath needs.



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    Quote Originally Posted by skimann20 View Post
    Also, I'm sure there is a much easier way of drawling on it but just making lines on the program i find more complicated. For instance, in AC i can start a line and say I want it 1550mm long. In BC, I have to enter the starting point and the end point and that consists of math.
    If you look at the line continuous tool, then you may be interested in the "coordinates" method? I'm not sure I followed the "I have to give it a "start" as well as an end part. I mean, we would have to tell a line where to start in ANY drawing program. If you use the coords option, just start the command and hit spacebar, then type a value into the "x" field and continue?

    I'de like to know the workflow you were looking for...


    I could only imagine how hard it would be to drawl two different radius (front of mid point and back of mid point and then have to blend the two.
    I don't understand this. Maybe we could explore it?



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    It is a complicated process and I'm having a hard time creating a video that is short enough, while also being at all detailed. I'll say a few things regarding the process and work on it a bit more later.

    First, Bobcad has the tools to do this, but it would not be my preference to do it there. Regardless of where you model this kind of part, one of the most useful tools is "tangent between 3 entities", which is included in Bobcad as well as Viacad an many other CAD systems. If you are trying to blend two arcs together, the easiest way to create a good transition it to have them coincide tangent to each other. Here's a quick video showing the way I would approach creating a ski edge that has two radii that blend at a point which is not exactly at the mid-point of the contact edge. You can do this in a few different ways, but I find that it's easiest for me to create circles of the diameter that the ski is wide at each point, then mirror the same size circle across the axis where the junction between the two different edge radii meet. I then use the shared middle circle and the two same size mirrored circles to create the front radius and back radius independently. Since they both meet the shared middle circle tangentally, they blend very smootly across from one radius to the other at that point. Just to be sure it's closed, I then join/trim them together at that point. Other similar areas where multiple curves are to meet and transition can be handled similarly.

    For the example, I'll be ignoring the tip and tail sections and I'm using a total effective edge section of around 1500mm with the front being 850mm and the rear being 650mm. I'm creating a tip width of 130mm, a mid width of 100mm and a tail width of 110mm just as an example. There will be one radius going from the tip to the mid width, then a second radius going from the mid width to the tail. They should appear to blend in the middle. I'll do them on opposite sides of the ski just to make it more clear how the arcs are created from through a "tangent to three entities" circle, then mirror them to create two sides. Just to show what the blend looks like, I'll create a solid showing the shading of that transition, but this video is not yet meant to be a "ski", just show how to blend these curves at a predetermined point. While I use the tip and tail circles as part of the 3d model, it's only for the purpose of showing what the shape of the side is and normally these are just meant to be construction lines. Here they are just convenient for closing the contour to extrude a 3d model.



    Video quality isn't perfect, but I think this shows the transition between radii is pretty smooth, no kinks. I use the same basic strategy to create the profile view where two arcs intersect going in opposite directions to create a smooth transition.

    Last edited by mmoe; 12-28-2013 at 10:28 PM.


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    Brad,
    I think that the snowboard video shows a very different thought process in that he is drawing a plan view and then bending it. This can also be done in Viacad, but the problem is that you would have to know what the unbent shape is in plan first, so that when it is bent into place, it matches the intended length and final plan shape. The process I'm thinking makes more sense to me is to show the projected plan view, which is what you want the shape to be after it is bent, then extract the bent part out of this information. You can then later unroll that shape into the actual flat plan view in programs like Rhino or Bonzai, but unfortunately that is not yet possible in Viacad to my knowledge.

    I'm finding that my method would work best to create the top and bottom faces of the ski/snowboard, but I'm still working on closing those faces into a solid. I'll do a quick video later to show how the solid can be made very quick and dirty, but the tip is a little off since the intersection of the plan and profile extrusions create an odd situation there. There are about 3 or 4 different ways I can think of to clean that up and finish it off, but I'm not yet decided on which is the best. The quick and dirty way can create a perfect bottom surface, it's just the top edge of the tips (front and rear) that end up clipped off a little. This will make sense when you see it. If you were to create a top and bottom surface instead of an intersecting solid, you then just need to cap the sides to finish it as a solid. Either method takes about the same amount of effort I'd guess, but both seem easier than what I saw in the Solidworks video you posted.

    Adding the side profiles for the edge and chamfers, etc. just take some time creating a couple more solids, then subtracting them from the sides of the ski/snowboard solid. I'm not going to model the core, base, and top separately since the same logic applies to all of them. It would just be three independent similar operations that create the whole.



  10. #30
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    Here's a quick video showing the use of "Intersect Solids" to create a rough snowboard shape. The tips could be refined pretty easily at this point by generating some 2d geometry to extract a 3d tip shape. Getting it perfect might take a bit of time and the use of additional objects (probably a cylinder to blend the patch into the radius of the top surface properly). It may also be possible to thicken the bottom plane of the snowboard to 6mm along the normals, which might be the easiest option if it actually works as it should (the thickness of the tips as I modeled them are 6mm which taper to 10mm at the center of the board). Sometimes I find that doing things from the normals doesn't always pan out like it seems it should, so I'll have to give it a shot and report back. I should note that you need to get familiar with workplanes regardless of what software you are learning. In Bobcad, this is the UCS plane selection, in other software you'll hear it called different things. The main thing is that you need to be able to select the plane on which you are generating your 2d geometry and from which the 3d geometry is relative to.





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    And here's yet another quick video showing how to use the surface normals to create a solid without the blemish generated during the intersect. Basically, to keep the tapered mid section, I broke the original profile into three sections, extruded them to three solids (tip, mid section, tip) then did three intersections to create the three final shapes that I'm starting the video with. Same process as before, but with three profiles instead of one so as to allow me to keep the taper in the middle. After the parts are set up as the video shows in the beginning, you simply select the tip, change the object to surfaces instead of a solid, delete all but the bottom surface, then use the "thicken solid" function to create a 6mm thick tip to replace the original. You'll see that the tip ends up perfect at this point, and can be added to the mid section to create a single solid as well.



    I've also attached a .bbcd file so you can see the result. I'll again note that most, if not all, of these functions are possible in Bobcad itself. I just prefer the way that Viacad works, and once I've got the hang of Bonzai more, I'll probably be transitioning into Bonzai nearly exclusively for 3d work. I'm finding Bonzai to be very, very stable for larger files and has features that really make it an excellent product. CAD systems really all come down to personal preference though, so you use what works for your own though process so long as the features are there. Bonzai is more full featured than Bobcad or Viacad, but not everyone will need those extras. If you do (and you might if this is the norm for you), it's worth the investment. Taking a model like this to production parts is a whole-nother thing that I'm not sure is possible without an unroll feature. So while Bobcad and Viacad could take you there from a modeling perspective, I'm not sure it could bring you back again if that makes sense.

    Attached Files Attached Files


  12. #32
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    Realized this morning that the concept of surface normals might not be entirely obvious, so here's an image showing the direction of the normals for the bottom surface. You'll note that they are in the downward direction, which is why I had to use a -6mm value to thicken the solid upwards. You could also reverse the normals first, then use a positive 6mm value to thicken the surface in the same direction. Which ever direction the normals go is the positive direction for the thicken function. In Viacad, you can select an object, right click and select "Show Direction" to display the surface normals. As you can see, the normals run at approximately 90 degrees from the tangent plane at any point on the surface. By thickening the surface along the normals, the edge comes out essentially square to the tangent plane at each point along the edge.





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    ummmm HOLY SMOKES DUDE! this is crazy, you went above and beyond. many thank you's! I'm going to have to read over this a few times and watch the video more than a few times to get it to sink in! You took it to the next level of developing the "molds" for the board shape. Something I would like to get to but had no idea even where to begin and you did it in a 5 minute video... unbelievable. I was just trying to figure out how to extrude a core with a 2mm-12mm-2mm core. I'm sure I'll have some followup questions but this is seriously unreal.



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    Okay I get everything you did in this video but the "Corner Trim" at 3:00. I'm assuming this is a way to smooth the transitions between the two radius? Mirroring the two different points for the different radius is genius! I've never seen it done this way before. I think you're on to something here.



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    Quote Originally Posted by skimann20 View Post
    Okay I get everything you did in this video but the "Corner Trim" at 3:00. I'm assuming this is a way to smooth the transitions between the two radius? Mirroring the two different points for the different radius is genius! I've never seen it done this way before. I think you're on to something here.
    Glad I can help. The corner trim doesn't really change the way the radii intersect, it just makes sure that there aren't any gaps in between them. If there were a gap of even .02mm or so, you'd end up with a non-contiguous group of lines/arcs that would not really extract solids properly or potentially cause other issues. If the math were perfect in the mirroring of the circles and generating the arcs, they should hit the middle circle in a tangent condition at exactly the same point, but since numbers in CAD are rounded here or there in these calculations behind the scenes, those small gaps can become present. A quick trim/join function at those intersections just makes sure they come completely together.

    The use of mirroring the circles around the common mid-point of the ski (which you could place where ever you design it to be) is to facilitate two things. The first is to give the "circle tangent to three entities" function three things to be tangent to that set the correct radius. Part of knowing how to use a tool is knowing how to set up the necessary construction elements to make the tool work. The other function is to establish the tangent at the midpoint to be the same for both the larger and smaller edge radii so that the transition is seamless. This is also why I prefer to do most of my work in 2d first, then bring it into 3d later. You can be very, very specific about the shapes at the 2d level.

    I think that if I were producing these drawings to be 100% accurate of what the components the ski or snowboard are made of, there would just be more extrusions of the profile to create the layers within. There would also be some work to do extracting the model edges (lines, not ski edges) so that you could run a profile down the edge to create the actual ski "edge" (as in the metal edge). This could then be subtracted from the ski/snowboard with the CTRL key down to keep the part that is used for the subtraction. Long story kinda short, you could model the ski/board to be a very realistic representation of the product which could be used for generating a 3d mold or form, then in something like Bonzai you could unroll it down to the flat components for CNC production of flat parts to match. I'm obviously not an expert on that process, whatever it is, but I suspect a combination of 3d and flattened 3d parts would be most useful, which is why I think Bonzai 3d or Rhino might be the best fit for that kind of product if you are doing this regularly. Regardless of the specific CAD system, my thought process and the steps I would follow would be the same in any case.



  16. #36
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    I'm really glad your in the forum mmoe! Thanks.



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    Second that.

    Luke

    "All I'm trying to find out is the fellow's name on first base" -- Lou Costello


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    I'm a little late to the party, but to add a little to what tlharris said about AutoCAD.
    If you plan on doing 3d modelling in AutoCAD for machining, stick to basic solids and meshes.
    In the last few years, AutoCAD's 3D functionality has increased exponentially. To do this, they've added a large number of new entity types. My guess is that few if any CAM programs can read these entity types. Even before the complexity of AutoCAD increased, it was always very important to know what types of entities AutoCAD was exporting, if you wanted your CAM program to be able to read them. With newer versions this is far more important, and probably requires you to be extremely knowledgeable about not just how to model in AutoCAD, but understanding how it handles entities internally, so that you can convert them to entities usable by other programs.
    While AutoCAD is now capable of modeling just about anything, it can come at the price of tremendous complexity.

    Gerry

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    Default Re: BobCAD 3D Core help

    Quote Originally Posted by mmoe View Post
    The use of mirroring the circles around the common mid-point of the ski (which you could place where ever you design it to be) is to facilitate two things. The first is to give the "circle tangent to three entities" function three things to be tangent to that set the correct radius. Part of knowing how to use a tool is knowing how to set up the necessary construction elements to make the tool work. The other function is to establish the tangent at the midpoint to be the same for both the larger and smaller edge radii so that the transition is seamless. This is also why I prefer to do most of my work in 2d first, then bring it into 3d later. You can be very, very specific about the shapes at the 2d level.
    Hey Mmoe,
    I’m revisiting this again. (for some reason I can’t access this page on my MAC anymore, so I have to respond at work). I’m doing the 14 day trial of ViaCAD and almost replicated your process. The only issue I’m having is when I do the three point circle tangent my large circle line doesn’t “link” to the three tangent points. Sometimes the middle of the circle will link but the two others will not. I tried the three point ark tangent and experienced the same results; the lines were slightly closer but still not connected to the tangent point. So… what am I doing wrong? I was wondering if there was a setting in preferences that improves the accuracy or perhaps I’m not selecting the correct tangent point of the three circles. Any help is always appreciated. Cheers.



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    Default Re: BobCAD 3D Core help

    I think I understand what you are talking about. In Viacad, it is sometimes the case that entities that should be connected appear to have a gap between them. To some degree, this can be fixed in settings, but in other cases it will just always appear that way even though it is actually correct. First, to help mitigate bad display you will have to increase your resolution for the display. Sometimes the display is shown in more of a rough manner, and the fact that they don't appear to connect does not properly represent the reality of the drawing. If you go to "File -> Preferences" and then go to the "Display" settings, you can set the resolution of each entity type. First you must select the entity type in the top drop down menu, then you can select and setup the resolution to "Super Fine". Once you have done so for one entity type, go to the next entity type in the first drop down and change the resolution for that as well. Each entity type can be configured independently, so you have to do them all if you want the most accurate display of the drawing.

    Once you have done that, select the "Units" portion of the Preferences and set the decimal places to the maximum. I work in MM, not inches, so this is 8 decimal places. I'm not sure what the max is for inches, but it's probably the same. After you have the Units configured, then select the "Custom Resolution" portion of the Preferences and set it to "Super Fine". You can then set up the Curve Angle and Facet Angle to "2.0" in each, which seems to be the finest setting possible.

    In your drawing, everything that you have already done will be set to the default resolution you had prior to these changes. Any new entities will be made with the new settings, but you will want the old ones to be updated as well. To do this, you need to select all the entities (zoom out and draw a window around everything), then go to your "Inspector" window and go to "Object Properties" (top left button in the window), followed by selecting the "Attributes" tab. In that tab, you can now set the resolution for the selected entities to "Super Fine". Generally speaking, you should have the inspector window open and to the side of your screen at all times, since you will typically access the functions of that window frequently. I also like to keep the "Concept Explorer" window open at all times, which has your layer manager and access to the parametric function of Viacad. The "Snaps" window is also useful to tuck out of the way at the side of your screen (I use the "Workplane" setting off and on when drawing splines to prevent them from going in the Z direction by accident). These windows can be made visible and accessible in the "Window" tab of Viacad.

    Even when you have the settings at their maximum value, sometimes circles don't seem to connect to their adjacent entities like they should. In my experience, this is visual only and in actuality they are tangent, it just doesn't look like it when you zoom in. This is one of my few complaints about Viacad, but eventually you figure out how to distinguish between bad display and incorrect geometry. I believe that the latest version of Viacad is taking a different approach to 2d entity display, but it may take another version before the changes translate to better display of this particular issue. Most of the time, the geometry is close enough that it looks right unless you zoom WAY in. If you still have problems, try to post a screen capture of the problem or upload a ZIP file of the drawing and I'll have a look.



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