Chris Johns
  • Member for 5 years, 11 months
  • Last seen more than a month ago
3 answers
4 votes
4k views
Why do these car headlights run on AC?
6 votes

LEDs, especially high output ones are often run off pulsed DC, this is a convenient and efficient way to control current and thus brightness, especially in a vehicle electrical system where the ...

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5 answers
9 votes
3k views
Difference in energy consumption between empty fridge and fridge filled with bottles of water
6 votes

There are two aspects to this. First if your fridge is filled with anything other than air then you will save the energy associated with cold air escaping whenever you open the door. However if ...

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1 answers
6 votes
13k views
RC car steering mechanism type
6 votes

The key feature is that the steering has Ackerman geometry This means that the steering arms coming off the back of the hubs are connected to the steering linkage at a point inboard and behind the ...

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1 answers
-3 votes
59 views
Why doesnt steel melt when pouring titanium through it
5 votes

Firstly you're mixing units The melting point of titanium is 1668C (3000F) The melting point of steel starts at around 1300C up to around 1500C depending on carbon content. For brief contact ...

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1 answers
3 votes
89 views
Gear acceleration and maintaining torque
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5 votes

Apart from frictional losses, which should be fairly low for a 1:4 ratio, the torque/speed ratio is inescapable ie if you increase the angular speed by a factor of 4 the torque must be reduced by a ...

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1 answers
-1 votes
58 views
What is this construction site jacuuzi for
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5 votes

It is likely to be tanks for drilling fluid (aka 'mud'). This is a slurry of various substances, such as bentonite clay suspended in oil or water which serves various functions. In particular it ...

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3 answers
4 votes
3k views
Reason of Using exactly 5 Wheel Studs per Wheel
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5 votes

On reason is that die cast (alloy wheels) generally have an odd number of spokes. This is because having directly opposed spokes causes problems with residual stress distribution as the casting cools ...

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1 answers
-2 votes
80 views
What would be needed to make a tesla fastest car in the world?
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5 votes

Maximum speed in a straight line is largely determined by the vehicles maximum power output compared to its drag although once you get past about 200 mph dynamic stability can start to become a ...

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1 answers
2 votes
70 views
Glass panel engineering at work
5 votes

Glass tends to contain quite a lot of residual stresses from the manufacturing process and these will tend to be concentrated near corners (depending on how the sheet was manufactured). There is also ...

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2 answers
3 votes
263 views
Why do we still scuba dive with bottled air?
5 votes

Bottled air is used for SCUBA because it is simple, reliable and relatively inexpensive and an open circuit system with a demand valve is pretty safe to use. There are closed circuit systems (...

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2 answers
5 votes
177 views
Is steel air (argon) tight?
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5 votes

Steel is routinely used for high pressure storage of industrial argon. For practical purposes it is certainly 'gas tight' although there may be a certain amount of atomic level diffusion into the ...

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1 answers
3 votes
3k views
Cleaning Shavings from Tapped Hole
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5 votes

There are a few ways to do this obviously it's easier to clean a through hole than a blind one. Run a clean second or plug tap through the hole. If you keep a tap just for this purpose it also has ...

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3 answers
2 votes
716 views
Phrase for describing a cable without a connector at the end
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5 votes

I think that 'bare end' gets the meaning across pretty well. Although in the context of a specification I would be tempted to spell out precisely that the cable is not supplied with a connector or ...

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1 answers
4 votes
4k views
Strongest brazing materials for titanium?
5 votes

To give at least some context to this. Titanium is generally considered 'exotic' for welding purposes as it is quite sensitive to both temperature change and contamination by atmospheric gasses, even ...

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4 answers
2 votes
785 views
Small bubbles on a pump discharge
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5 votes

As well as 'proper' cavitation which is a fairly high energy phenomena and certainly a concern in terms of wear on the working surfaces of the pump it is possible that pressure changes are causing ...

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2 answers
0 votes
2k views
Can anyone verify this wall thickness of a pressure cooker?
5 votes

Those figures are about right for the bare minimum wall thickness for the walls of a cylinder however, as you say, this would be inadequate in practice for a number of reasons. Safety concerns ...

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1 answers
5 votes
865 views
Why does hydrogen fuel produce less horsepower than gasoline in internal combustion engines?
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5 votes

One consideration is the relative densities of hydrocarbon fuels compared to hydrogen. If we assume that the fuels are completely vapourised in the combustion chamber then the mass of fuel depends on ...

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7 answers
4 votes
6k views
How can I cheaply drill a 0.1 mm hole in a small piece of tungsten?
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5 votes

You really need to use a dial indicator to set up a 4 jaw chuck to the sort of accuracy required for this job. This is fiddly compared to a self centering chuck but has the potential to give you ...

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2 answers
2 votes
709 views
Why no hydraulic piston gas compressors?
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5 votes

There are two aspects to this. First is that the main advantage of hydraulics is that is provides a compact means of greatly multiplying force but in compressing gasses you have to a huge amount of ...

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2 answers
4 votes
2k views
Most efficient way to build a toothpick bridge
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5 votes

As you are spanning 10 feet and the length of the toothpicks is small in comparison you have quite a lot of options in terms of the design of the structure you use. In fact one approach would be to ...

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2 answers
3 votes
211 views
Why does "Google self-driving car"'s roof camera rotate?
4 votes

That's a lidar sensor, which is making a continuous 360 degree sweep, rather than a camera which has a field of view as such. Rotating mirrors are a fundamental part of how the system works. Note ...

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2 answers
1 votes
264 views
What is the Meaning of To Warm Up an Engine?
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4 votes

The specific issue with carburettors are that they are purely mechanical devices and can't directly measure the mass flow rate of fuel they are delivering and as such are quite sensitive to ...

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1 answers
1 votes
44 views
Weird texture on faces when using Shapeoko CNC
4 votes

No milling operation will give you a perfectly flat surface. The level of finish you can achieve will depend on the capabilities of the mill itself, the tooling you use and how the tool paths are set ...

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1 answers
1 votes
113 views
Is it possible to replicate a motorcycle engine cylinder head?
4 votes

Yes it is but there a a few things you need to watch out for. You will need to allow enough excess material for any surfaces which need to be machined subsequent to casting. All castings shrink ...

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2 answers
0 votes
102 views
What are the challenges in building a 'sports car' frame and body?
4 votes

The main issue is practicality. The vast majority of car buyers have certain expectations in terms of comfort, features and interior space which are pretty much essential in their choice of vehicle. ...

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1 answers
5 votes
334 views
Proccess of a 4-wheeled vehicle taking turn
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4 votes

It depends. The driven wheels need to be connected by a differential whcih allows power to be transferred to both wheels but still allowing them to turn at different speeds. It's not that easy to ...

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6 answers
1 votes
1k views
How to create an airtight connection between Stainless Steel and PTFE?
4 votes

You're going to struggle to get a reliable gas tight fit with that design. For a start it would be better if the two connections were separate so they aren't fighting against each other in terms of ...

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3 answers
0 votes
563 views
Is a heavier car better than a lighter one?
4 votes

For any car lighter is better and this goes double for a sports car. It is true that having less weight over the drive wheels can reduce traction but the gain from less overall mass will always be ...

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1 answers
1 votes
92 views
What is the mechanism of the blades movement
Accepted answer
4 votes

One way to achieve this is by a series of 4 bar linkages The above is used for marking out equally spaced points on a line of arbitrary length. Pretty simple and elegant. By virtue of the ...

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1 answers
0 votes
69 views
Can we rotate the given white wheel?
4 votes

This sort of sliding seal is very difficult to achieve, especially when you have a square corner. Rotary engines have this problem and tend to accept a certain amount of leakage as inevitable and ...

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