[0.17] recommended strategy for modeling parts that need to be fitted to other existing objects?

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prof7bit
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[0.17] recommended strategy for modeling parts that need to be fitted to other existing objects?

Post by prof7bit »

I want to model a fan holder/duct for a cooling fan for my 3d printer. It has to fit to the fan, to the extruder mounting plate, have the right distance to the nozzle, not touch the heating block, not obstruct the cables and stay a certain height above the bed. What is the best strategy to make sure all the dimensions and angles are correct?

Should I first make rough models of the fan, the extruder mounting plate, the nozzle and the bed, position all these objects in the right places and use that as reference for modeling my fan holder around them? Should I then somehow directly use these reference objects as external references in my sketches (would I use shape binders for that?) or would I just model it, move it to the correct places (assembly2?) and only make sure by visual inspection that all parts really end up in the correct places? And if I do this should I keep the models of these reference objects in the same document or should I model them separately and (only temporarily?) import them as simple step files?

Or should I represent all the geometry of the relevant printer parts and fan parts with datum planes/lines/points and attach my fan holder to these datum objects?

What is generally the right (or recommended or most elegant) strategy or workflow to solve these kinds of problems?
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DeepSOIC
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Re: [0.17] recommended strategy for modeling parts that need to be fitted to other existing objects?

Post by DeepSOIC »

I would probably go for master sketch approach. Draw a few sketches of main projections, that outline the extruder assembly, bed, fan. The sketch doesn't need to be paddable. Then use external geometry references to these sketches when modeling the actual fan duct.
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NormandC
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Re: [0.17] recommended strategy for modeling parts that need to be fitted to other existing objects?

Post by NormandC »

prof7bit wrote: Wed Jul 26, 2017 7:55 pm Should I first make rough models of the fan, the extruder mounting plate, the nozzle and the bed, position all these objects in the right places and use that as reference for modeling my fan holder around them?
That would be my choice. For me it's a lot safer than just relying on master sketches, although nothing prevents you from using both.
prof7bit wrote: Wed Jul 26, 2017 7:55 pm Should I then somehow directly use these reference objects as external references in my sketches (would I use shape binders for that?)
Using shapebinders is a possibility.
prof7bit wrote: Wed Jul 26, 2017 7:55 pm or would I just model it, move it to the correct places (assembly2?)
To be blunt, I find that people are too hung up on the missing Assembly workbench, and too often for simple projects, Assembly2 just adds an unnecessary level of complexity. Seriously overkill for 3-4 parts!!! If you use shapebinders there will be no need; on 0.16 it would be so much easier and faster to use the Move and Rotate tools from the Draft workbench. :roll:
prof7bit wrote: Wed Jul 26, 2017 7:55 pm What is generally the right (or recommended or most elegant) strategy or workflow to solve these kinds of problems?
There is no right strategy, you will get as many recommendations as there are people. It's a matter of preference, that's all. Also add that the new PartDesign features of 0.17 are so new that none of us has much practical experience with using them.
triplus
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Re: [0.17] recommended strategy for modeling parts that need to be fitted to other existing objects?

Post by triplus »

Assembly 2 workbench has a good track record in my opinion and AFAIK it was used to build a satellite that went in space. I guess hard to argue with such reference. ;)

If you would like to achieve some cross-part reference (like expressions) you will likely need to have all parts saved in a single document for now. And for each part create a Draft Clone feature to be used in assembly after.
prof7bit
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Re: [0.17] recommended strategy for modeling parts that need to be fitted to other existing objects?

Post by prof7bit »

After playing around a bit with trying to fix the positions of datum planes with the help of sketches (and finally found a way that seems not overly complicated) I think for this specific problem I'm going to use the recommendation of master sketches and use these sketches to define datum planes for all relevant parts of my object.

First I tried to put a lot of time into modeling the lower parts of extruder and mounting plate, I began with the nozzle tip at (0, 0, 0) working my way upwards until I arrived at the mounting plate screw holes where I want to mount my fan holder. The result looks nice but it took a lot of time and I realized that all I really need from it is the exact position of these screw holes in relation to the nozzle tip and a placement for the lower duct end. The mount holes are easy but the end of my duct sketch will still be in mid air but nevertheless needs a geometric relationship with the exact nozzle position.

Earlier I tried to arrange just a bunch of datum planes by fiddling with the values in superplacement alone but yesterday the suggestion with the master sketch helped me to figure out a simple way to define a datum plane (its angle and even the translation of its origin) with just one single line in a master sketch.

I think this is the way I'm going to use to define my datum planes from now on.
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