Engineering Stack Exchange
Engineering Stack Exchange

Questions tagged [machine-design]

112 questions
11
votes
9 answers

Aluminum weight saving

"Aluminum saves weight! Its 3 times lighter than steel!" Also its 3 times weaker and 3 times softer. When comparing stiffness and strenght to weight ratio, aluminum isnt any better than steel of comparable grade. Yes, 7000 grade expensive aluminum…
Soliton
  • 119
  • 4
10
votes
3 answers

How do vending machines prevent people from stealing goods?

I never understood mechanically how a vending machine prevents people from accessing goods through the dispensing panel. From what I understand it's not a locked door that unlocks only upon payment, dispenses goods and then re-locks. In my…
Sidharth Ghoshal
  • 219
  • 2
  • 6
3
votes
2 answers

Why do pneumatic valves need both a Safety Relay and an Air Dump to be safe?

If air dumps safely release pneumatic pressure from an industrial machine when an E-Stop is pressed, why is it also standard practice to cut electrical control power from the valves with a safety relay? This would be useful if the air dump failed,…
Micah Lindstrom
  • 131
  • 3
3
votes
1 answer

What is a shaft collar called that is used to restrain a pulley?

I would like to look for a shaft collar like the one used in this photo of a cable robot: As you can see, there is a flexure that clamps the collar onto the shaft (as a shaft collar does). In addition, there are two screw holes where the collar can…
user391339
  • 249
  • 1
  • 6
3
votes
4 answers

Why one big cargo ship is more efficient than 10 or 100 smaller ships?

Given the fact that small container ships are easier to manufacture than big container ships.. then why is it considered better to build bigger ships instead of many smaller ships? And to see why manufacturing is easier at smaller scale - consider…
AIon
  • 157
  • 1
  • 7
3
votes
3 answers

What is "reversal" in mechanical engineering drawing?

I've come across these terms "reversals allowed" and "reversals not allowed" in a sample drawing while reading a GD&T course. What exactly are these terms? What do they mean?
Somanna
  • 169
  • 2
  • 6
3
votes
1 answer

What mechanism is available to rotate a metal piece on another metal piece?

I am trying to find some type of mechanism where I can have a smooth but not too stiff rotation between two metal pieces. I was thinking of putting a shoulder screw through the pieces (the pieces will be side by side) and a nut at the end. A real…
juniorsworld
  • 61
  • 3
3
votes
1 answer

What mechanism do I use for this pen-like design?

I am trying to make a pen-like product that moves out fluid from its tip for some special chores, but I am having issues about the motion of the clutch. The picture you see is a sectioned concept because my thought isn't fully fleshed out. Legend:…
juniorsworld
  • 61
  • 3
2
votes
1 answer

The generalized Lami's theorem

In statics, Lami's theorem is an equation relating the magnitudes of three coplanar, concurrent and non-collinear vectors, which keeps an object in static equilibrium, with the angles directly opposite to the corresponding vectors. According to the…
Emmanuel José García
  • 133
  • 6
2
votes
0 answers

What is the relationship for the curve of the non-involute portion of a gear (below the base circle)?

I'm in the works of writing my own gear program, but I've stumbled on something that textbooks and the internet don't seem to answer. A lot of the time, the dedendum of a gear cuts into the base circle. When this happens, the curve below the base…
Gabe Morris
  • 121
  • 2
2
votes
1 answer

designing a drill jig for manufacturing a finished product

what will be suitable drill jig for the given product? since the drill is not straight. so i'm not sure for the suitable design, kindly looking for kind help. thanks in advance! if it would have conventional product for drilling three holes, i would…
Satya
  • 432
  • 3
  • 11
2
votes
2 answers

Designing a progressive die to make a blank on a thick steel sheet

Suggest and Design a progressive die to make a blank with a 2 mm thick steel sheet as shown in Fig. The ultimate shear strength of the material is 480 MPa. Calculate press capacity assuming 75% efficiency. Like I know if we have to design a…
Rajakr
  • 328
  • 1
  • 6
2
votes
1 answer

How is the assumption that stress and strain are elastic everywhere is valid for STRESS-LIFE method for fatigue life calculation?

Stress life method is generally employed for high-cycle fatigue (HCF) applications. while HCF region is approximated by $\sigma=a(N)^b$ which gives a linear graph on log-log scale, for steels it starts from $0.9\sigma_{ut}$ up to $0.5\sigma_{ut}$. I…
huministic
  • 41
  • 3
2
votes
1 answer

Relation between links and pairs in Kinematic chain

I came across a equation for kinematic chain (for lower pairs only) : L = 2P-4 where L: Number of Links; P is the number of pairs how could this equation be derived ? EDIT: I tried putting values in the equation.Since for the pairs to be any integer…
Sankara Narayan
  • 23
  • 5
2
votes
0 answers

Differentiating between Two Orthographic Projections

I came across the infamous control handle assembly in two different books, referencing the views differently. One of the had it like the following photo The other book labelled the side view in this photo as the elevation (front view). The question…
M. Abelshafy
  • 21
  • 2
1
2 3 4 5 6 7 8