# Engineering Stack Exchange Community Digest

## Top new questions this week:

### Is a single large impact better than several small impacts for breaking ice

I'm designing a device that uses impact to remove ice from sidewalks. I have a question about how to best design the impact mechanism. I can design it to deliver several light impacts or fewer harder ...

mechanical-engineering building-physics impact

### Gear profiles (involute and root) generated by power skiving

@Involutius contributed an article on the equations that describe the root profile of gears which are cut by a trapezoidal-profiled hobbing tool. From that article, I was able to do a slightly ...

gears

### How to model Motor Windings in Solidworks?

I want to model a DC motor in order to eventually do some simulations (temperature/cooling related) and I'm wondering what is the best way to model the motor windings? I've seen a few video's on how ...

### How to periodically shut down a recirculating hot water solar thermal system

I am posed with a scenario where a hot water solar thermal system has been setup. The system comprises of a cold water tank, heating arrays and then a hot water tank. The system is closed loop and ...

mechanical-engineering heat-transfer heating-systems valves heat-exchanger

### What is the minimum height of a chimney needed in a camper?

Like a lot of people nowadays, I'm fitting a log fire into the back of a camper van but can't find the minimum height above the roof for the chimney. Ideally, it should be as low as possible for ...

heating-systems building-physics fire

### Calculation for lowering temperature in a room… room-fridge with water mist?

I was looking at how the water cools my body when it evaporates off it. Then I thought the specific heat capacity could be used to calculate how much energy (i.e heat) would be taken out of a room ...

mechanical-engineering thermodynamics heat-transfer
 asked by El Flea 1 vote

### Why do recoilless rifle ammunition still have casings?

Recoiless guns have breeches that allow gas to escape out of the back of the gun. Therefore, theres no sealing action to be performed by the casing. Why is ammunition with perforated cases used, when ...

firearms
 asked by Francis L. 1 vote

## Greatest hits from previous weeks:

### LO/LC, CSO/CSC Valve Definition

Does any one here know of an authoritative source (ASME, ISA, NFPA, OSHA, etc..) that gives a definition for the following in one of their standards or codes and the number for that standard or code: ...

mechanical-engineering valves standards

### What is the meaning of vorticity and circulation?

In fluid kinematics I can't understand the meaning of these terms : vorticity and circulation. Can somebody give me a description of these terms so that a lay person can understand them easily?

fluid-mechanics

### How to reverse the direction of rotational movement on the same axis?

I want to make a "gearbox" that will transform input rotational movement to an output rotational movement with the same speed but in the different direction (clockwise / counterclockwise) on the same ...

mechanical-engineering gears

### Can wifi signal reception be improved by opening a door?

A wifi user is in a different room than the router. The computer is having a hard time connecting and receiving the wifi signal. Can the wifi signal from the router to the computer be improved by ...

signal wifi

### Is stainless steel plating possible?

Is there a method for plating steel with stainless steel? If so, is it chemical, electrical, or electrochemical? I did a quick search on the internet but was unable to find a service. I'm ...

materials steel

### What is the difference between "Crushed Stone" and "Crushed Gravel" aggregate?

Crushing Question While reading a material specification for crushed aggregate, the text mentions both "crushed stone" and "crushed gravel" are acceptable. These materials sound very similar, but ...

civil-engineering geotechnical-engineering

### How can I keep a Zippo lighter from losing fluid to evaporation or leaks?

Zippo lighters are notorious for needing regular refilling. The fuel evaporates from the cotton regularly. Some people put a bit of rubber around the seal. What atmospheric conditions keep fuel from ...

fluid-mechanics thermodynamics fire

## Can you answer these questions?

### Does this PID-like algorithm make any sense for a solar inverter?

The application I want to implement the control of a photovoltaic inverter. The goal would be to keep the consumption of a microgrid (the power absorbed from the grid) to a constant value. Notes: ...

control-engineering control-theory pid-control photovoltaics

### Shore durometer type D to brinells

I saw a video where a person was measurring hardnes of a material with Shore durometer type D and was comparing it to steel. The screen on durometer showed 96.5 HD and i was just wondering, how much ...

materials material-science
I am currently designing a symmetric parallel mechanism that can be modeled as follows: Here, $\tau^j$ denotes actuator moments and $k_i$ are torsion springs constants. For a specific point in the ...