# Tag Info

18

AutoCAD is a computerised drafting package that lets people draw pictures. Mechanical engineering is more than just knowing how to draw pictures in two or three dimensions. Amongst other things, mechanical engineers are required to know about: Strength of materials Energy Power Torque Stresses Bending moments Couples Torsion Efficiency Thermodynamics Heat ...

10

3D printing bores/holes is inherently and wildly inaccurate. You can continuously tweak the model, material, and print configurations to get better results, but for best results, in my experience, redraw the hole to a slightly smaller size than your target and reprint. Then, after printing, use a drill to get the size and geometry more precise. For your ...

8

No. AutoCAD isn't going to teach you mechanical engineering any more than a compiler will teach you software engineering. You have to actually learn some things, then you will pick up experience by doing. Also AutoCAD is a tool for describing mechanical parts in machine-readable form. It's not going to design a part for you, or teach you how. Without a ...

7

A clamp and strain relief are used all over the place. You'll see this everywhere from domestic electrical plugs to the cable exit of power tools. The choice of cable and sheath/insulation is a factor too. For example, vehicle power cables are designed to handle vibrations (but also high temperature and to be light weight, so maybe not the perfect ...

6

To make the lid fit on reliably with as tight as possible, the only difference you need in the box and lid dimensions is the resolution of the 3-D printer. You need to account for manufacturing inaccuracies and inconsistencies. Rapid prototyping is very reliable and not subject to the same issues as machining like tool wear and fixturing issues, but no part ...

6

Pitch diameter is the diameter of the pitch circle described by the mid point of the length of the teeth around the gear, as shown in this diagram: The pitch circle defines the point where the teeth of two gears meet: Let's say you have two gears, each with a respective pitch circle diameter of $d_1$ and $d_2$. The distance between the two gear centers, $C$...

5

Double nutting can be an easy option for this. I was about to describe it myself, but these folks do a great job. This image, from the article, models the forces that do the job. Take note of the contact surfaces between the threading of the bolt, in the top vs. bottom nut:

5

As Fred alluded to in the above post, mechanical engineering is a vast topic. It takes time and commitment to become a mechanical engineer. Also AutoCAD or 3D-printing alone is not mechanical engineering. AutoCAD and 3D-printers are tools used by mechanical engineers. By the way, there are few good self-taught mechanical engineers. Following a four-year ...

5

First, to counter what some people are saying about printed metals, selective laser sintering can produce parts that are as thermally conductive as their base metals. They are limited only by porosity, and state of the art machines can produce fully-dense (zero porosity) metal parts. Second, you probably don't need to take radiation into account because ...

5

This type of feature is typically called a "loft", but I would caution you that this should be used only if needed. Lofted features will cost you a lot of money if you try to get them machined. If you're going with 3d printing it doesn't matter too much (complexity is free). That said, here's some pictures of before: And after a "loft" command: When you ...

5

As indeed answered by Greenonline, the centre distance is the average of the pitch diameters of the two meshing gears, but this is only strictly true when the gears are operating at standard centre distances, i.e. where the pitch circles are tangent to one another. There are indeed cases where two gears can be operating at non-standard centre distances, and ...

5

This is called a buildplate :)

4

3D prints are weak in the direction of each layers plane. You could try to make the part in a different orientation. Second thing to try is to use a coarser print. My friend tested mechanical properties of different 3D prints and concluded that the printers were worse the smaller the layer size was. Even materials that technically better didnt do well in a ...

4

There are a number of practical processes for 3D printing in metals using various powder sintering techniques as described in other answers. However it is difficult to use the sort of direct extrusion processes that you see with plastics because most metal alloys don't have the same sort of viscous, self adhesive phase that thermoplastics do. Most molten ...

4

Metals are used. Albeit, in machines that are much more expensive and complex than your run of the mill FDM style machines that you're likely referring to. The main reason you don't see many or any metal printers(SLS) and DMLS are likely due to patents and costs. They use lasers and special powdered materials with a binding material them. See Wikipedia ...

4

A replicator is a very long way from 3D printing. Although 3D printing is often endowed in the media with quasi magical properties all it really is is multi axis CNC extrusion and not fundamentally different from any other CNC manufacturing process. The key thing about the replicators in star Trek is that they can produce any material on demand from energy/...

4

One facet of this discussion which hasn't yet been discussed is 3D modelling literacy. Think for a moment about regular '2D Printers'. You may have one at home - but what do you use it for? For printing out artwork to put on your walls? Glossy photo-books for your coffee table? Magazines? Cardboard Packaging? No - mostly, you will be printing items that you ...

4

In this case its because they are emulating a bar mechanisms. This makes it possible for the designer to think of the problem in terms of revolute joints which allows them to use age old design principles with parallelograms and all. Image 1: Equivalent bar mechanism In this case the bar is rigid so the equivalent compilant needs to be rigid too. Doing it ...

3

In addition to joojaa's excellent advice, you might try reducing the height of the interference and/or increasing the length of the flexure to which it is mounted — such changes would reduce the internal stress in the plastic to manageable levels.

3

It is unlikely polymers will be an issue, but the additives used may pose problems. Polymers should have negligible volatility due to their long chain nature. Polymer additives may still pose an issue. You may need to test any particular filament material to ensure it meets your needs. Polymer Chain Mobility Polymers do not behave like small molecules in ...

3

You seem to want an a slight interference fit so the top will snugly seat into the housing. Depending on your wall thickness and size you could probably oversize the "male" portion of the cap like .002-.003" compared to the "female" dimension. That being said, and understanding that 3D printing generally cannot hold those tolerances I would try an ...

3

One thing that other people don't seem to have touched on is the utility of the simulation packaged in AutoCAD. It's a type of Finite Element Analysis, which is an incredibly useful tool, but one that must be wielded very carefully. You can model a part, load it into an FEA package, apply constraints and forces as the part would see in the real world, and ...

3

As a working professional ME with 18 years in the field, I'll tell you that there's a great deal of difference between what will work in AutoCAD (or any other such software package) and what will work in the real world. That's why we still review designs and build prototypes before going into production. I can't tell you the number of times I've had to get ...

3

It isn't open source, but for students Onshape is free. Onshape runs in the browser so it will work on pretty much any current computer regardless of operating system. It is real 3D solid modeling with good 2D drafting. I've played with it some and it works remarkably well and as CAD programs go is easy to learn. Because it is cloud based, it greatly fosters ...

3

h11 is the tolerance range. There's a standard shaft/hole chart based on dimension/tolerance. (sorry about the images, I've searched on google but cannot find everything on the same image). h11 is applied to shafts, and H11 is for holes. With your example D4h11 is Ø48mm with tolerance of -0 to -160 microns. The referenced part can be (48-0,000) = 48mm (...

3

I believe the key here is not the material, but the manufacturing method. I would not recommend a small cnc machine, which seems to be what you're considering. Those are cool and fun, but you will have to dick around with it for dozens of hours, and it may never produce good results, and if it does, it will be slow. 25 bucks a set for parts is actually quite ...

3

I would research component manufactures web sites. It is highly unlikely that you will find all the information in on location. Here our example web site links to get started. NZXT - Mini ITX Computer cases Fractal Era ITX Computer cases Mini-ITX Mainboard Specification Hydro Series™ H100i RGB PLATINUM 240mm Liquid CPU Cooler Another good place to look for ...

3

I'll start from the particular example you are asking about. It is a positional adjustment device. It is heavily used in laser optical tables to provide micrometer adjustments. And it falls in the category of compliant mechanisms like you suggest. There are a few requirements for these devices (most have been already pointed by others). IMHO, the main two ...

2

Some pointers: It's first about surface area! But don't put the fins too close together or there is not enough space for natural convection to start... I read somewhere that ~0.25" (~6 mm) is a reasonable spacing. Stainless steel is not a good choice. You want a metal with good thermal conductivity. Aluminum is just about perfect since it is also light. ...

2

I think that there's a problem with your analogy. Autocad is to engineering as is programming - to actually running your code with meaningful results. Otherwise it's just drawing. 3D printing is as the name implies, drawing. In three dimensions, rather than two. I suspect that you're looking at hobby level engineering if you're categorizing it as a "side ...

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