Questions tagged [machine-design]

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11
votes
9answers
2k views

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 ...
10
votes
2answers
4k views

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, ...
3
votes
3answers
378 views

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?
3
votes
1answer
29 views

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 ...
3
votes
1answer
184 views

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 ...
2
votes
4answers
321 views

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 ...
2
votes
1answer
128 views

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 ...
2
votes
2answers
49 views

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% ...
2
votes
1answer
31 views

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 ...
2
votes
1answer
145 views

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 ...
2
votes
0answers
47 views

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 ...
1
vote
3answers
73 views

Mechanical Engineering: How To Amplify Kinetic Energy In Axial Rotational Gear Machinery? [closed]

When I originally posted this question 2021-04-08, I was inspired by pulley physics, especially after viewing these videos at this link and this link and this link. It is not necessary to go to these ...
1
vote
2answers
58 views

What does it mean for a machine design to be "kinematic"?

I've seen the term "kinematic" used qualitatively to describe machines several times in books and on YouTube. I think I understand what kinematics is as a study, but I'm not sure what people ...
1
vote
1answer
67 views

Bending moment when there are no constraints

I faced this problem in an old book (Hall Allen S., Theory and Problems of Machine Design; 1961) The answer according to the book is 592 [in.lb], but I think the bending moment should be 0 because ...
1
vote
2answers
88 views

Velocity or Speed Ratios in Gears and Gear Trains

I have seen the different definitions of the velocity ratio for Gears and Gear trains. I have referred a book called Theory of machines by S. S. Ratan. In that book the definitions are as following: ...
1
vote
3answers
44 views

static friction of gear pair

Im working on a project that has gearing system integrated. From my simulation results im dealing with a relatively small amount of input force at the gearbox and would like to know if the force would ...
1
vote
1answer
54 views

Sleeve and cotter joint

What does 0.1D signify in this cotter joint. I meant is it denotes spacing between pin and hole. I am new to machine drawing , kindly let me know. Thanks in advance
1
vote
1answer
51 views

What would be the best mechanism to rotate a plate from 0 to 15 degrees?

I'm designing a machine in a small university project that change position of a two-state gate. The two states shown in the Figure below are 0 and 17 degrees of elevation, correspondingly. The ...
1
vote
1answer
39 views

Reading Motor Datasheet

I'm doing my first machine design for a project and I have a Honda GX160 combustion motor which has the following specs for power and speed: I'd like to use 0.24 HP at 2000 rpm. Is this possible? Or ...
1
vote
2answers
45 views

In an open belt drive, which angle of wrap should be taken for calculating tension in the belt?

An open belt drive with flat belt has different angle of wrap on the larger and smaller pulley. I have to calculate a tension in the pulley. We generally use the formulae Here θ is the angle of wrap. ...
1
vote
1answer
223 views

How can I decrease strip tension with bridle rolls in tension leveller? How can I find total elongation after the strip exits initial bridle rolls?

I'm working on a tension leveller design which consists of 3 main sections. These are Input Bridle Rolls Zone: Increase the strip tension coming out of the decoiler. Leveller Zone: Strip goes through ...
1
vote
1answer
70 views

I need help identifying a special kind of coupling

I found this switchable coupling in Rollof/Matek machine elements, i have never seen this kind of coupling before. According to the dutch edition its name is: Tweevlakskoppeling Which literally ...
1
vote
0answers
18 views

Sign convention for angular velocities in 3D gear train

Consider a Humpage gear train shown above. We are viewing the gear train from right and gear B is rotating in clockwise direction. If we consider clockwise direction as positive what will be the sign ...
1
vote
0answers
39 views

Can a semi-conductor cooler be powerful enough for a room? [duplicate]

I see semiconductors used for small fridges. I cannot find one large enough to cool a room (in place of a conventional Freon based, window air-conditioner). What engineering problems might a up scaled ...
1
vote
0answers
27 views

How to determine minimum aluminum t-slot profile type for frame?

For a frame with dimensions 1000x1000x400, I am determining which T-slot extrusion type will be strong enough. I am considering both 30-6060 (30 series I-type, metric) and 20-4040 (20 series I-type, ...
1
vote
1answer
49 views

Applying ISO fits to radial bearings

Do you need to take the bearing size tolerance into account when creating the tolerances for the mating hole/shaft when using ISO 286 tolerances? For example, a 125 mm OD bearing with a desired H7 ...
1
vote
0answers
50 views

Design a Jig and Fixture for 3-axis CNC Milling Machine

Newbie Here!!! This is my assignment task. I am required to design a Jig and Fixture for 3-axis CNC Milling Machine. The workpiece will be a simple aluminium block and it will be cut and shaped into a ...
1
vote
1answer
46 views

A device to provide real-time proportional resistance to variable force

I'm considering a potential product but I'm not sure about the core technology I'd need. The fundamental idea is that there would be a cable (or something similar) that would be pulled. But as it ...
1
vote
0answers
66 views

Springs on a pulley... When to use?

I saw a machine that fed a sheet of laminate through some rollers. The motor had a pulley attached to its shaft, and a spring connected to the pulley. Why not use a belt? Wouldnt the spring make it ...
0
votes
2answers
103 views

Where water goes in split air conditioner system in "dry" mode?

In split air conditioners, there are two tubes connecting the indoor unit and the outdoor unit. According to the generic schematics I find online (like this one), they are part of the closed circuit ...
0
votes
1answer
51 views

What is this strange nut and what to do with it

I bought a cheap version of this machine, because all decent ones had costs of hundreds of dollars of transport to my region. The machine seems to be made of solid parts, but is really badly assembled....
0
votes
2answers
54 views

Can stainless steel be used in continuous high temperature environment (500°C to 850°C)

Can i use stainless steel as a furnace roof. Furnace temperature will be max upto 850°C. If so which ss grade will be the best in this situation. Thanks
0
votes
1answer
31 views

Shape of the shaft of knurling device

I'm trying to design and simulate a simple knurling device. The shaft ( blue part ) has a flat surface at the other end, where the small grey pin connect the green body to the shaft. I guess you can ...
0
votes
2answers
70 views

Looking for dropping servo mechanism idea

My friend and I have an idea to make prototype of vending machine. We need suggestions for making strong dropping mechanism. The idea is: The user orders X item. Let's take a can of cola for example. ...
0
votes
2answers
62 views

How to measure a dovetail slot and it's mating component?

I have had some trouble determining the best way to measure a dovetail slot and it's mating component. The parts have some difficulty mating occasionally, and our QC department is having trouble ...
0
votes
1answer
73 views

Adding the effects of two rods to move a single rod

I have to deal with a situation where I have two parallel and completely independent rods whose motion is dependent only on external inputs, and I want to add up the lengths traveled by each rod. My ...
0
votes
1answer
64 views

What type of electrical machine component for counting time?

I am looking for the proper piece of hardware to do what I'm looking for on my current prototype machine build. I want a timer to begin counting upwards in seconds when a switch is activated, and ...
0
votes
2answers
63 views

How do I read this schematic drawing notation for a drill hole?

It's for an NX part. I can't figure out the depths and such. I just know the placement of the 4 holes and that the diameters are 10 mm each.
0
votes
2answers
47 views

3D linkage design - terminology

I am designing an animatronic head, which has five degrees of freedom: pitch, roll and yaw for the head part, and pitch and yaw for the neck part. However, the yaw movements for the head and neck are ...
0
votes
2answers
45 views

Gear configuration for a legged hexapod

I have an assignment for my Mobile Robotics course to design the drive mechanism for a legged hexapod and demonstrate its gait in motion. The idea is to design the hexapod as per the following ...
0
votes
2answers
44 views

What is the name for a low pressure, low volume air reservoir?

I'm working on a project that requires very precise, but low pressure controls. I'm using a pump to charge a chamber to <15kPa, then a manifold of proportional valves to control output pressures ...
0
votes
1answer
127 views

Any books about design of complex machines? [closed]

I'm familiar with several books that deal with the analysis and design of simple mechanisms (such as Norton's Design of Machinery), including four-bar linkages, gear trains and cams. There are also ...
0
votes
3answers
43 views

Can tubes for fits & tolerance be purchased or only manufactured?

I'm currently designing a steel structure for a gym machine. I want to assemble two rectangular tubes, one being able to slide inside the other, for height adjusting. I intend to use a spring ball pop ...
0
votes
1answer
23 views

How to find a reference line for " Form Tolerances"?

In my project I have to choose a form tolerances ( parallelism ) between the handle ( purple part ) and the part that sits inside it ( the grey part ), where the two parts slide on each other. But I ...
0
votes
1answer
39 views

Safety types and definition [closed]

I am searching for some Engineering terms but couldn't find any of the definition. Direct safety Indirect safety Warnings Thank you in advance
0
votes
1answer
62 views

Is there any way to conserve energy for the following scenario of lifting weight?

A pulley can be used to provide mechanical advantage while lifting weight. Suppose a combination pulley is made such that in order to lift something four times heavier, one can use the same force but ...
0
votes
2answers
265 views

What kind of mechanism can be used to rotate a part in 180 degrees (Ψ (yaw)) and 30degrees in 𝜃 (pitch) direction?

Let's say we have a flat object. We are asked to create some mechanism so that the part can rotate in the shown angles above. What mechanisms can be used?
0
votes
1answer
51 views

What are the different methods to join 2 parts so that one can rotate 180 degrees around the other?

Let's say we have one simple box and its bottom has been cut in a circular shape. We want to attach another box to this box that can rotate 180deg around the first one. What mechanism can be used to ...
0
votes
1answer
436 views

How to choose between two possible arrangements of tapered roller bearings?

I don't know how to decide between the $X$ and $O$ arrangement, i don't have any specific example at this moment, but i want to know. Catalogues offer only some basic calculations. I'm not quite sure ...
0
votes
1answer
22 views

Motor For powered adult swing

I'm trying to design a powered swing for adults (similar to a baby swing, but scaled up). Am I right in assuming that this is functionally a pendulum and the power required is (0.5)mgsin(t)? How ...