Questions about or related to design.
Questions tagged [design]
586 questions
35
votes
3 answers
Why are railroad tank cars bent in the middle?
I recently noticed that the cylindrical shape of a railroad tank car is not completely straight but has a bend in the middle. The entire tank is a bit lower there. What's the reason for this bend?
This is also visible on the drawing of a DOT 117…
Lukas_Skywalker
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25
votes
3 answers
Why does this fence have a kink?
The image below shows a style of fence that I've seen frequently around train tracks. If you look closely, you will see that between the third and fifth horizontal wire from the top, the vertical wires have a kink in them where they run diagonally…
Yly
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13
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1 answer
From an engineering standpoint, what is the purpose of the indent in a coffee lid?
I've see the same lids every day but I never really thought about their construction. There is an indent in a "Solo Travel Lid" for coffee cups that is just above the hole that you drink the coffee from.
You can see the crescent shaped indent in…
ruckus
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11
votes
2 answers
Why are three way bridges rare?
It's true that most bridges are "two directional."
But three way bridges are pretty rare, globally. I can understand why there wouldn't be many for rivers, but if bridges are designed based on the lie of the surrounding ground, why wouldn't there be…
Tom Au
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10
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4 answers
Why don't motorcycles have as good a turning radius as bicycles?
The question is about why are motorcycles not manufactured with handlebars that can turn to great degrees like a bicycle. In most motorcycles, you hardly have a steering angle of about 20-30 degrees, whereas on a bicycle, you can even go beyond 90…
Siddh Aarth
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9
votes
6 answers
How to work on big CAD project in team?
I'm always confused on what is the effective way to work on CAD with multiple team members to make it efficient. So far, as I'm freshly graduated I only work on a project where I'm the only one using the CAD software. At best there's only two of us,…
el-cheapo
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9
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4 answers
What's a professional way of tracking design history in plant engineering?
If you look at the design documentation in our projects (Biogas and waste-to-energy plants), you find out what we plan to build but not what other options were considered and why they were discarded. This information rests only in the engineers…
mart
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9
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1 answer
Involute gear curve when root diameter falls below base diameter
The answer to a question on involute gear curve calculations shows how the gear tooth curve proceeds as an involute calculation from the base diameter.
If the pitch diameter is D = m.N where N is the number of teeth and m is the modulus (for metric…
carveone
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8
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2 answers
Wheelbarrow minimize wear
I have a question about the design principle. To explain my problem I made the sketch "wheelbarrow". To minimize wear, which design is preferred?
laurens van Lieshout
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8
votes
3 answers
How do I know if I need a pull up or pull down resistor for a GPIO pin?
I've seen many microcontrollers use pull up or pull down resistors either as a setting for GPIO pins or as part of the hardware.
How do I know if I need a pull up or pull down resistor for a GPIO pin and if I do, how do I know which is right for my…
Dom
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8
votes
1 answer
What IPC mechanisms exist for the i.MX 7 (or i.MX 6) multi-core processors?
I'm considering using the i.MX 7 processor for a new design. The overall architecture appears to be similar to the i.MX 6, at least from comparing the block diagrams.
What mechanisms exist for communication between the Cortex-M4 core and the…
Patrick
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8
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2 answers
SOLIDWORKS - 3D Sketch of Trombone
My task is to create a 3D Sketch of a trombone like the one below
My professor recommended defining the points 1-4 and putting a spline through them. I did that, but my resulting design looks weird. It curves inward between points 1 and 2 before…
Melanie
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8
votes
3 answers
Why raised face for mating parts?
In designing mechanical parts in an assembly, sometimes the mating surfaces are raised faces. I've been told it's to provide a better seal. However, for piping (flanges), it seems to be the consensus that a raised face flange does not provide any…
tralston
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8
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2 answers
Why do car-seats have an expiration date?
My wife and I are expecting our first child, and therefore are expecting to purchase a car seats. My wife and I have discovered that car seats have "expiration dates": a car seat, no matter how lightly used, is deemed unsuitable for use after a…
PipperChip
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7
votes
2 answers
Design of a Four-Bar Infinity Coupler Linkage
How can I control a Four-Bar Infinity Coupler such that it does not accidentally become a Paralellogram Linkage? It seems to me that, when the bars are all horizontal, gravity could change the movement of the green driven…
skibulk
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