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1500 questions
5
votes
1 answer
Lug bolts - fully threaded or partially threaded?
Background to the question: We have been importing lug bolts under a certain tariff heading which is under dispute :
The crux of the question is whether the lug bolt ( which we have ascertained is in fact a screw ) is deemed to be fully threaded or…
Warren
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5
votes
2 answers
Lifting a cabinet using actuators or scissor lift
Disclaimer: I am not an engineer - just a DIY guy looking for some advice or help please, so please forgive me if I use incorrect terminology :)
I am building a cabinet that has a hidden inner cabinet that is meant to rise up out of the former. The…
maGz
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5
votes
7 answers
Can I use AutoCAD to learn mechanical engineering by DOING (like programming)?
I would like to learn mechanical engineering as a side project. But, I would like to learn in a way similar to programming. Learn by doing.
Of course I understand I can't build things automatically just yet as I have no 3D-printer and they aren't…
MechLearner99
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5
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1 answer
What is the script function to select Solid Body in ANSYS Design Modeler?
I need to select a solid body in ANSYS Design Modeler, with script, in a design with multiples bodies. With the following command I select all the solid bodies, but this is not what I need.
ag.bodyPick;
ag.gui.SelectAll();
I'm creating a script to…
efirvida
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5
votes
3 answers
What would happen if we tried to run a motor in space when it is not attached to anything to provide support to it?
I know that when a motor runs it generates torque and that torque can be used to do useful work. On the other hand, the motor needs strong support that absorbs the reaction torque. In our case let us assume that that support is provided by a…
Edgar
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5
votes
6 answers
Engineering calculations in a tool that will handle units
I know Mathcad handles units along with numbers which makes it easier to avoid errors by tracking units the way we would by hand.
e.g. 250 kW + 500 W
I just wanted to compare tools before I switch to Mathcad. Are there any other tools people are…
curious_cat
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5
votes
1 answer
Rover Wheels: Convex or Flat?
I was comparing the wheels of the Curiosity rover and the Perseverance rover and noticed that the latter had a very flat cylindrical design as compared to the former.
This got me thinking about which wheel profile was sturdier. That got me thinking…
William R. Ebenezer
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5
votes
1 answer
Why would a specfication for a motor require that overtemperature protection be realized by modeling heat generation and not with an embedded sensor?
I'm reading the procurement documents for the R211 railcar contract, which is for electric multiple unit subway cars designed for rapid transit applications in New York City. The railcar's propulsion is specified to use AC induction motors powered…
nanofarad
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5
votes
2 answers
Non-toxic material for deformable wire/rod without work hardening
I am looking for a non-toxic material for a wire/rod that allows room temperature deformations without work hardening.
Example uses are semi-rigid cables that one can bend and that hold their shape afterwards or snake-like cellphone holders like the…
Mathias Schultz
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5
votes
4 answers
Why do rechargeable Lithium Ion & Lithium Polymer batteries explode or catch fire?
There are many Lithium Ion and Lithium Polymer rechargeable battery related accidents. Are some of these accidents are battery design related? Are some of them misuse of rechargeable batteries.
What is the chemical composition of Lithium Ion and…
Mahendra Gunawardena
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5
votes
1 answer
Is it possible to modify a home gutter to absorb sufficient solar energy to melt ice?
This is related to the question Will dark gutters stay ice free better than light colored gutters? The current consensus seems to be that the mass of the gutters and limited light may make simply painting them black insufficient.
In my particular…
James Jenkins
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5
votes
4 answers
Why Nusselt number for laminar flow in a pipe is independent of Reynolds number
I understand that for fully developed flow inside a tube (with constant properties), Nusselt number doesn’t change in axial direction but it is surprising that it is also independent of Reynolds number which means that the rate of heat transfer (for…
moeinSj
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5
votes
2 answers
Typical flatness of Portland cement
Does anyone have a feel for the flatness of Portland Cement when poured in a standard/typical way? Say, for example, that I wanted to pour a cement "cube" (20"x 18"x 19.25") in a mold. How flat would the top surface be without any special…
willpower2727
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5
votes
3 answers
Help with closed loop heat controller (for a non engineer)
I am interested in setting up a controller which can modulate the output of 2 hotpads based on input from an infrared thermometer. The hotpads have their own dials, but I am considering controlling them by voltage instead. So my question is, what is…
Ryan
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5
votes
1 answer
Why is there this perforated pipe inside this vertical construction joint in a reinforced concrete wall?
The picture below shows a veritcal construction joint of an approximately 50 years old reinforced concrete industrial structure. The expansion joint was likely originally sealed with a flexcell which due to age and water ingress has deterioriated…
egg
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