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  1. #91
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    Quote Originally Posted by RayG View Post
    I've looked at Fusion 360, I'm not totally comfortable with subscription software. Josh uses Solidworks, Matthew ( my oldest son ) uses Rhino/Grasshopper, I think I'll have another look at the CAM facilities availiable in Fusion 360.

    Although once you have the G code, there is often a bit of tweaking whatever the system.

    Ray
    Oh yeah I hear you, I loathe software subscriptions, especially the typical $10-15 per month type. It's small enough that it's tempting to get sucked in and not to worry too much about it, but easy to let the number of subscriptions blow out, next thing you're dropping 100 bucks a month on software and/or services. Unfortunately these days that's just the way it is. Obviously deliberately as it's a good business model for the providers. Personally I don't need, or even want, the latest version of software, so I'd much prefer to buy the software and hang on to it for 5 or even 10 years. Clearly they'd rather bleed us a small amount each month indefinitely.

    I don't follow Rhino anymore as I was on the Beta program and stopped using it before the beta was completed. As I said it just wasn't a good fit for me so let it go. However a seat on SW is around A$5K now IIRC and the subscription about A$2K per year. Those I know who run SW say you basically need to have the subscription. That's a heck of a lot of beer tokens in my book. Before F360 came along I seriously looked at it (it was slightly cheaper and less options then) and was literally sweating. I knew I needed a good CAD program but it was a LOT of money. Luckily I found F360 as I just couldn't justify that sort of money. The student version of SW turns into a pumpkin in January each year, so that was no good, and I'm just not interested in stealing a copy. Yes stolen versions would be freely available to me to pick up on a trip away, but I'm just not going to sponsor that type of crap, particularly when Autodesk are making F360 available so generously.

    Yes the F360 CAM is the full HSMWorks kernel so 5 axis all singing all dancing, VERY powerful. I'm not sure what sort of "tweaking" of the G code you might be doing Ray? Occasionally you might go in and change some parameter in the code, but I would think that would be the exception rather than the norm these days, and any fiddling would be done in CAM. I don't run a CNC machine so maybe it's different, but from what I've seen of those who do, they don't mess too much with G code. CAM yes, it's super important to get that all right. The equivalent of CAM in 3D printing is the slicer. It works identically but in addition to the tool path slices the model. I have some batch G code I load at the beginning and end of the prints (just to position the table etc etc) but I only wrote it once and then it just gets automatically loaded when the model is sliced.

    Yes, parametric drawing is one (well two) of those buzz words isn’t it. It’s everything already said, but what it excels at is you can control how the whole part is related to itself by setting parameters as you create it.
    Ah ok, if that's what you mean by parametric, then no, I don't normally model that way. The software is parametric in terms of any changes following through and maintaining their relationship (unless specified otherwise), but I don't normally specify one dimension for example in relation to another. It's definitely possible and I might occasionally do it if, say I didn't know a dimension but knew it was a relationship to another (say 10 mm bigger, twice the size, etc). Then yes it's very easy to do that and when dimensioning you just insert it as a relationship. But I think it would be very unusual, or just plain weird, to do that for the whole model. Normally you'd just directly specify the dimension for each feature. If you need to maintain a specific parameter when making parametric changes, then you'd constrain the key part of that feature in absolute terms or constrain it in relation to something else. That's in fact typically the norm and F360 is smart enough to automatically insert some constraints to maintain the deign intent. So as a simple example you may model a cube with equal sides, and the model would then be parametric by default, yet maintain its design intent as a cube with right angle sides.

    Something I don't think has been mentioned is the increasing sophistication of paramaterized models available on the internet.
    That's a very good point Bob. For those who may not be aware of the significance of what Bob mentioned, 3D models are normally saved as STL (stereo lithography) files which are meshes made up of triangles. Because they're a surface (think of it as a skin) and not a solid model, they can't be manipulated in 3D CAD software. Yet there are probably millions of STL files out in the public domain. You'd think it would be easy just to convert it back to a solid model, but (for various reasons that aren't important here) it's actually really hard to do that properly. Some of the gaming/artsy apps could kinda, sorta, not really very well manipulate them, but not in a really strict engineering sense when you need to maintain precision. So let's say you come across an STL file on Thingiverse, download it and decide it's almost what you need but you'd like to change a few things. Well you're basically S.O.L. if it's an STL. Not quite, but it's a tough gig to make serious engineering changes from there. At one stage I wanted a new extruder for my printer, so found a model I liked but it didn't fit my machine in a few areas. I finished up having to remodel the whole thing in CAD just to be able to get all the required changes. PIA central! What Bob is referring to are models where you can make the changes online and then just download the model with those changes incorporated. So let's say it was a model of a hinge and you wanted it longer and a bit narrower than the model, just pop those requirements in and the model will change accordingly, all online.

    Just as being able to print in metal is the Holy Grail of the hardware side, being able to import STL files and manipulate them as if they're a solid model is arguably the Holy Grail of the CAD side. I understand the latest updates of F360 are getting much better at being able to do that, so I must check it out when I get time. The significance of that is that Thingiverse becomes almost like GrabCAD, only much MUCH bigger! It would mean you can grab an STL somebody has published on the public domain, change it to suit, then send it back out as an STL to print. It would save an enormous amount of time and effort for most projects, as the chances are somebody has modelled the feature you're incorporating already.

    As a side note to the above, F360 is able to grab the CAD models of most of the McMaster-Carr catalogue and drop them in the model. That's an awesome feature (it's probably in SW too, I'm not sure) and I use it a lot. So instead of modelling, say, a bunch of cap screws, you just drop in the Mcmaster CAD models into your own model.

    I printed this out just off a rough measurement a few weeks earlier.
    Wow, you're doing some awesome work there, you should be justifiably proud of the stuff you've put up. Sorry if I missed it, but what type of plastic did you print the arm in?

  2. #92
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    On reflection much of what is being discussed here possibly causes more confusion amongst those who are considering trying 3D printing as it resolves. It probably sounds a lot more complicated than it is in reality, and in fact it's (literally) child-play once you get in to it. For a better idea of real life examples of what you can expect to be able to do with 3D printing, go to Thingiverse and just browse through different things. Unfortunately the site's search function is generally rubbish, and the site itself pretty ordinary in my opinion, but with a bit of digging a general indication of what you can do should emerge. Think of Thingiverse as a library, but in this case it's of STL models instead of books. Thingiverse - Digital Designs for Physical Objects The current engine theme should be satisfied with this Chevy Camaro LS3 V8 Engine - Scale Working Model by ericthepoolboy - Thingiverse

  3. #93
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    Quote Originally Posted by Pete F View Post
    But I think it would be very unusual, or just plain weird, to do that for the whole model. Normally you'd just directly specify the dimension for each feature.
    I hope this comes across politely, but I suspect you don't fully appreciate what parametric modelling is -well certainly one of us doesn't, how about I put it that way . Honestly, the whole point of a parametric modelling program like solidworks is so you can change and design things on the fly with minimal going back and changing dimensions. Like Bob's funnel, he only designs one, and can print out any size by typing in a few numbers in the screen and he doesn't need to be a draftsman or even know the program. For every single part you build out of 3D extrusions, there will be relations added for every sketch, even if you don't add them yourself. If I do an extrusion, I'm far more likely to associate that with an existing surface or plane than to give it an actual value. In fact, if you're not doing it, and try to move your model in space to put it into another assembly, the whole thing will fall apart. For every line, cut, extrusion, you name it, the challenge is to think what is determining this feature in real life and relate it to that, try to hardly ever use hard values. You control your sketches and relationships to previous extrusions and sketches for every single sketch (Even the first one, if it is a part you are creating in an assembly). the less values you write the better, once you get your head round how it will adjust when you scale or adjust things. You need to think ahead as to how the model will be adjusted and build those relationships. Its analogous to writing hard code in programs instead of using variables - yes you can do it but your boss isn't going to be happy if someone needs to go in to the program language and change values every time there is a materials price change for instance. In Relational modelling, its even relatively common to define some of the dimensions to a scientific function, so you can animate the model and have it stretching and collapsing like a spring would for instance
    I've been doing this for years, and I've followed loads of examples in SW tutorials and on forums. Honestly, its what its all about. That's not to say that 95% of people won't hard code all those dimensions, cos how does the boss know? Well, until he says he wants those cylinders at 45 degrees apart instead of 40, and it takes you a month instead of 5 seconds.

    Also, if you don't relate dimensions to other sketches you wouldn't be able to build new parts within an assembly, which is really the most powerful part of CAD and is how they can design a whole car and it will work without anyone ever creating any kind of model of it. In an assembly, I can make those cylinders 1" taller and the model will rebuild itself and the oil line will be longer because I related it to the oil pump and the cylinder head amongst others, and not to any part of the cylinder. If I used fixed values everywhere, I'd have to change many hundreds of dimensions and it would take weeks to be honest, and would cause loads of mistakes.

  4. #94
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    Quote Originally Posted by variant22 View Post
    Obviously I'm still getting the settings dialed in for TPE. I see a lot of use for this product in the workshop when I get it printing nicely. Any type of rubber gasket, dust guards, vibration mounts and even leveling feed are things that spring to mind.
    Have I mentioned recently that I need a flexible bellows for my Tos T&C grinder?????

    PDW

  5. #95
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    Quote Originally Posted by Pete F View Post
    ... being able to import STL files and manipulate them as if they're a solid model is arguably the Holy Grail of the CAD side.
    I'm doing some SW training at the moment and one of the things that surprised me was being able to do just that. The example they used was an imported bracket and the software can move holes, change sizes and all sorts. Pity about the cost...

    Parametric seems to be used in two ways these days (bit like the term 'universal' when applied to mills). The first is being able to relate one dimension to another, typically through some form of equation, so you can preserve the golden ratio all you like in your designs while making parts bigger or smaller.
    The second way is having a dimension that can be edited after being drawn, so in AutoCAD 2000 LT (my stand-by) if I draw a circle, that's it. The only way to get a bigger circle is to delete and draw again. In SW, a circle in a sketch can be changed in size and as an added bonus, things like tangency etc can be preserved too.

    I'd love a SW license of my own but it's just too pricey. I'm now resisting making up all these 3D models while I have access and going to town on a printer.

    Michael

  6. #96
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    Quote Originally Posted by sossity View Post
    ... You control your sketches and relationships to previous extrusions and sketches for every single sketch (Even the first one, if it is a part you are creating in an assembly). the less values you write the better, once you get your head round how it will adjust when you scale or adjust things. You need to think ahead as to how the model will be adjusted and build those relationships.
    I worked in a defence organisation once where even shelling out a model to make a sheet metal bracket was forbidden. While using equations and relational dimensions is fine for the average widget maker, when you need to rigidly control configuration having models that can drastically change just by changing one dimension is not a good idea - having said that I also worked with a bunch of people who were using SW but did not fully define their work, so the part sizes effectively 'floated'. At the end of the project we had to hire a draftsman to go through and examine every sketch of every part to put in that detail so that the models could then be used by toolmakers without fear of getting the wrong thing.

    Michael

  7. #97
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    Quote Originally Posted by Michael G View Post
    While using equations and relational dimensions is fine for the average widget maker, when you need to rigidly control configuration having models that can drastically change just by changing one dimension is not a good idea
    I don't see why that might be. If you change one dimension and screw up the model is that any better? Its what mechanical engineers want, they will have brainstorm sessions and the draftsman will go off an design something like they think was wanted. I've been through the process for real with that waste management guy, its very interesting. A skilled draftsman will provide something that can then be modified with the engineer looking over his shoulder, not taking hours. With my engine as an example, marketing are going to say they want a bigger petrol tank so you need to change the angle of the cylinders. you've worked there long enough to know this happens or maybe the mechanical engineer told you to make that angle adjustable, so you can change it in 30 secs. you wouldn't make it a parameter anyone can change, but any draftsman should be able to change it and have all parts rescale themselves to fit. My example previous was extreme, you wouldn't relate the whole model to one dimension, nor would you bring out every key dimension so anyone could modify it, but there are key dimensions you will need to be able to change without redrawing every single part manually. The computer should do it for you through relations.

    regarding SW cost, you all have too many morals. I have "owned" an autocad licence for the latest version for 20 years. Do I feel bad about it? Actually no, I've made 5 employers purchase a full autocad licence for me to use. However, if I made money out of it for myself, I would feel guilty.

  8. #98
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    Quote Originally Posted by sossity View Post
    regarding SW cost, you all have too many morals. I have "owned" an autocad licence for the latest version for 20 years. Do I feel bad about it? Actually no, I've made 5 employers purchase a full autocad licence for me to use. However, if I made money out of it for myself, I would feel guilty.
    Ummm, I'm a software designer. A lot of my code is in the public domain but people pay me an annual maintenance fee for some of the stuff I've developed. I don't have *quite* the same attitude as you do.

    I quite agree that individual software licences for products like Solidworks is way over the top, though. So I don't use it even though I could get a copy for the asking.

    PDW

  9. #99
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    Quote Originally Posted by sossity View Post
    ...but there are key dimensions you will need to be able to change without redrawing every single part manually.
    Yes there are dimensions that I would want to change and I have no problems in diving in and doing so where appropriate. If there were dimensions that had a relationship to other dimensions in the same part I would probably link them happily.
    The problem starts when you link say the diameter of your valve stems to the guides in the head. In a large drawing office it is possible that while you are designing the head someone else is using those valves for a larger engine. Suddenly your part changes because someone else is using/ modifying a related part.
    Proper configuration control is knowing exactly which version of a part is used on which assembly, and you can't do that if relationships exist between parts in assemblies that could be changed in an uncontrolled way.
    Don't care? Just ask NASA whether they have had any problems with configuration - for example some parts designed in metric and some in imperial.

    Quote Originally Posted by sossity View Post
    regarding SW cost, you all have too many morals.
    We are who we are.

    Michael

  10. #100
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    We arent arguing about too much here. solidworks wont let you change dimension of any part used by other assemblies without letting you know and it will ask if you want to make a copy. If you take a standard valve modelled for other engines then you wont be adding any relations to that part, its already designed. you apply relations to what makes sense and is a relationship that you want to stick with ie maybe you set the guide you are designing to that standard valve stem diameter + 0.05mm. This isnt something i invented, its what everyone does. thats not really a good example because you will already have standard valves and guides but you get the gist. As I said its actually what parametric design is.
    In autocad you can always change the size of a circle by changing that parameter. if it wont change for you then you probably have snap to selected and the diameter is snapping onto something. Because autocad has paramters is not the same as it being a parametric design tool
    i hope you'll agree autocad lt is not a parametric design tool

    Ill leave it at that, its not really possible to visualise or explain how solidworks works through a few words. you' be surprised though how it all comes together and works in a real file system because you are emulating reality but i cant explain well.

    As to we are who we are, I'm glad I never claimed I stole the software or i suspect id be in trouble.

  11. #101
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    Quote Originally Posted by sossity View Post
    As to we are who we are, I'm glad I never claimed I stole the software or i suspect id be in trouble.
    Unless you physically steal a box containing software from a shop etc you can't 'steal' software (or any digitised item like music, movies et al) anyway.

    All you are doing is making an unauthorised copy which is a violation of the owner's copyright. You haven't deprived them of the use or possession of their property, you've made a copy of it without permission.

    It's an area where the concept of 'ownership' really has to be re-evaluated.

    David Brin wrote a sci-fi novel called 'Earth' IIRC where basically unbridled copying destroyed the business models of anything capable of being digitised & copied. Creative works returned to being a craft.

    Another take is Charles Stross' novel 'Rule 34' where things like 3D printers and print files were restricted & licensed.

    Going to be an interesting ride for the foreseeable future......

    PDW

  12. #102
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    Quote Originally Posted by sossity View Post
    I hope this comes across politely, but I suspect you don't fully appreciate what parametric modelling is -well certainly one of us doesn't, how about I put it that way
    Yes you're absolutely correct, one of us is mistaken and I'm sorry to say in this instance it's not me. Michael's definition of parametric is 100% correct as it relates to this type of software and "parametric" is generally meant to mean that you can modify a value and it will change that value while maintaining the (unconstrained) relationship between that feature and the features it's associated with. CAD software that is nonparametric would require you to redraw the whole feature again and re-associate it with other features. As an example, SW and F360 are parametric, until recently AutoCAD for was not. You crossed over to confuse scaling with all of this, and that really has nothing to do with it. Because none of the relationships change, you could change the scale of a model and it wouldn't technically need to be parametric; you've just changed the scale. You're absolutely right about the relationship and I didn't suggest for a moment anything different, indeed I specifically used a cube as an example of exactly how this works. I have no idea what you're referring to in regard changing an angle taking "months", that's something I do often and it's two key strokes.

    What you're referring to is "design intent" in modelling and refers to being able to make changes to a dimension (angle etc) for example but maintain the "design intent" of that feature. I must admit I must be misunderstanding what you mean (sorry for that but I've been working all night and it's been a hard few days), because it sounds as if you are suggesting you reference your whole model back to some master dimension and relate all dimensions back to that. That would be fine when creating virtual models that exist only in zeros and ones, but I would think that would be completely unrealistic in the real world. I've watched quite a few SW tutorials but can't say I'm otherwise familiar with it, however I thought it was quite similar to F360 in this regard. Nevertheless I can really only speak in regard F360 and in that CAD program the "design intent" is normally maintained by constraining the feature in relation to another feature. That way when a dimension is changed the "design intent" ie the relationship, is maintained. Choosing the appropriate constraints (and not over constraining) the model is the key to this whole malarky from my experience and was probably (and for me still is) one of the most difficult parts of successful modelling if you want the end product to be truly parametric.

    I follow a few guys on Youtube who use F360, including Autodesk themselves, and while I don't pretend for a moment to have anything like their level of proficiency, not even a small fraction of it, but I do model the same way they do. Anyway, the proof of the pudding is in the eating and from your model it's clearly working for you, so I suspect we're possibly both talking about the same thing but from different angles, and I've mistaken what you were saying. One thing that does seem apparent is that we model differently and it seems you model from solid, and I model from 2D sketches. I don't know if one way is technically "better" than the other, modelling from solid is often faster, but I think it will depend on the individual. As mentioned, Rhino seemed suited to solid modelling, while I (normally) model from sketches on planes and extrude them to solid. It's how the Autodesk F360 most often seem to do it, so I figure I mustn't be too far off the mark. That's not to suggest the sketches aren't still constrained and related to each other, and the model won't "fall apart" when moved as you suggest. If it does then it wasn't properly constrained.

    Michael I'll check with F360 to see how good it is with STL editing now. I know they made some big advances in that area about 18 months (?) ago, but just haven't tried it myself recently. I tried earlier versions and it was a disaster. I remember them making a big deal about how it can do that now, but just how good I don't personally know. I do however know there's a big demand for it with the rise of 3D printing and the proliferation of STL models, so if it's not nailed down by now I think it soon will be. Meshmixer was the program that used to be used for this type of thing. I tried it, but it wasn't for me. Again, all fine and beut if all you're doing is making virtual models for cyberspace, but not really for precise engineering applications that need to mean something in relation to the real world.

  13. #103
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    Quote Originally Posted by Michael G View Post
    Proper configuration control is knowing exactly which version of a part is used on which assembly, and you can't do that if relationships exist between parts in assemblies that could be changed in an uncontrolled way.
    Unremarkably, Michael's understanding and description of parametric modelling is spot on.

    Michael that requirement for everyone to be on the same page in relation to the design is one of the big sells Autodesk use for F360. Since it's a cloud based app, everyone automatically has the latest version. It's of no relevance to me, and many people criticise the cloud for, well being a cloud, but for big organisations it's critical.

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    Quote Originally Posted by Pete F View Post
    Yes you're absolutely correct, one of us is mistaken and I'm sorry to say in this instance it's not me.
    I have just learned I can no longer be absolutely certain of anything and its got me quite worried about my head again. After a bit of research the definition of parametric is exactly what you guys said, you can change the length of a line by changing that parameter. I was absolutely certain you could do that in autocad. AutoCAD can change lines and circles by selecting and dragging a vertex but it looks like you can't type in co-ordinates once the line is drawn. After 2010 you can switch autocad to parametric which shows how much I kept up with it. The scary thing for me is, I knew this program inside out, better than the drawing office guys, honest! I can actually visualise editing co-ordinates of lines in a parameter box, but I must be making that up. I checked and the last time I did an autocad drawing was 2013 and I'd have bet it was last year too. I had no problems then, I must still have had half a brain. This is scary stuff, with Alzheimer's you don't know your going mad, do you?

    I feel just as certain on the use of parametric design but I don't know if I can trust my head on that now either. Sorry guys, I apologies for wasting the forums time. Thanks for treating me with respect, I made a dick of myself...

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    Quote Originally Posted by sossity View Post
    ... Sorry guys, I apologies for wasting the forums time. Thanks for treating me with respect, I made a dick of myself...
    No apology necessary, you learnt something and that is never a waste of time (and through this discussion others have too).

    I would be surprised if there is not some way in AutoCAD to change dimensions by typing in exact values - after all that is the whole basis for engineering design. Imagine trying to specify a shaft diameter to fit a particular bearing if you could not.

    Michael

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