Questions tagged [mechanical]

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14 views

Euler angles from angular velocity pseudovector

According to wikipedia page https://en.wikipedia.org/wiki/Angular_velocity Euler proved that the projections of the angular velocity pseudovector on each of these three axes is the derivative of its ...
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16 views

Need new pressure switch mechanism for a 3 phase compressor using a 220V AC Drive

I've bought a vintage Quincy 216 air compressor. Actually there are duel Quincy 216's - each has a separate 3 phase motor. One motor is 1.5 HP and the other motor is 2 HP. The compressors share a ...
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4answers
76 views

When we replace supports distributed reaction by point reaction in thin beams, is that considered an application of Saint-Venant principle?

I read about Saint-Venant principle which is about the effect of replacing forces by equivalent forces system that effect on the same small region of a rigid body, all examples I come across are on ...
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20 views

backrest angle mechanism for a Cargo Bike seat [closed]

I'm looking for a joint with an integrated rotating and locking mechanism, that can hold the load of a back leaning onto it. I have attached a dirty render of the concept. Hope this will make the ...
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1answer
59 views

Max Stress on Weld

Part is welded to a plate, based on the below free body diagram how would I determine the max stress in the weld? It seems half the weld is in tension and the other half is in compression.
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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 ...
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1answer
59 views

Bushed 3" V-belt pulley with unkeyed 3/4" shaft?

Shortly I will have two 3/4" unkeyed shafts needing 3" type-A V-belt pulleys, one each. They'll each have their own motor driving them, and will need to run to 5000 RPM and possibly higher ...
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1answer
256 views

Why/when do we use a transition fit?

I'm self-learning a bit about preferred fits and tolerances and was wondering why transition fits were even a thing. Clearance fits I understand, applications where you don't want parts to touch and &...
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2answers
59 views

Heavy machinery/loader attachment with custom tube

I spotted this heavy machinery/loader attachment at a road reconstruction job site in Ontario: The device a has horizontal tube that is cut off at an angle. The tube is attached to a vertical ...
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3answers
201 views

Why does this thing that is not a screw have a screwdriver slot?

I am (partially) disassembling an old sewing machine to clean it up. While removing the bobbin winder, I found this thing that has a screwdriver slot, but it isn't a screw. This is the part: It came ...
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3answers
83 views

Inverting motor polarities automatically to close and open a door

Hi, I need to build a device that opens a chicken coop door. The idea is quite simple, a motor connected to an axle that pulls a string up just like a wench. It would be activated by a relay timer ...
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1answer
71 views

How can I measure gear efficiency?

I am doing a experiment on various gear combinations and am wondering How I can measure the efficiency (Torque loss) of each gear pair), I have a input shaft connected to the first gear and is also ...
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1answer
49 views

Why is the torque of an ICE low at low rpms?

Let us consider a basic 4-stroke single cylinder, direct port fuel injected naturally aspirated engine which is given a constant throttle. Now, why does it produce very low torque at low rpms, meaning ...
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2answers
70 views

Parallel beam load cells, force transfer and maximum load

I'm going to experiment with a parallel beam load cell like this one: https://cdn.sparkfun.com/datasheets/Sensors/ForceFlex/TAL220M4M5Update.pdf. I've read somewhere that for a setup shown on this ...
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23 views

Cargo box opening system below

I am currently trying to make a delivery drone similar to ones Amazon did. Basically the cargo box which carry the package must open to below in order to drop the package. What I want to do is exactly ...
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2answers
36 views

HPU minimum oil temperature

Two different HPU systems in different locations with slightly different oils Chevron Ranco HD 68 and HDZ 68 have the same minimum oil temperature 55. Their flash points are are 455 and 414 F ...
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1answer
75 views

Why would anyone "pull the stem out and stop the wristwatch at night or when not wearing it" in the context of mechanical watches?

I read this the other day while discussing mechanical pocket and wrist watches: Plus it is common practice to pull the stem out and stop the wristwatch at night or when not wearing it. You then have ...
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1answer
72 views

How can (many) mechanical watches keep track of the current day of the month when these vary so much over months and years?

Having dealt with dates and time in programming context for many years, I have realized what a nightmare our common calendars are, and how much they vary by the year/month/etc. Yet there are fully ...
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1answer
61 views

Dynamic model of a two-mass electric drive taking into account the Gear Ratio

Two-mass rotational system has the following form and is represented in following structural diagram. where $\tau_e$, $\omega_1$ and $J_m$ - motor torque, angular velocity and moment of inertia $\...
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2answers
91 views

Torsion of continuous vs simply supported beam [closed]

Say that I have a 2 span of continuous beam subjected to torsion, is the torsion value smaller than those 2 single span beam subjected to torsion of same value ?? I think the torsion of continuous ...
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2answers
89 views

Effect of multiple shear pins used in combination in a coupling

Does using multiple shear pins under a limiting torque case reduce the minimum required shear pin diameter for the coupling or is the complete load distributed over the shear pins regardless of the ...
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1answer
63 views

Do really "all mechanical watches need to be maintained properly"?

Somebody answered this on a different question: All mechanical watches need to be maintained properly. Every year or two they should be taken to a watchmaker for a service. This will include ...
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3answers
93 views

Are mechanical pocket watches inherently water-proof and last "forever"?

Recently, I bought a cheap (~$53) but elegant mechanical "retro pocket watch", newly made. That is, not an antique made in the 18th century or anything. So far, it's worked flawlessly and ...
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2answers
65 views

Looking for locking "lanyard" reel mechanism

I'm working on a system that requires a small cord (~3ft long) to retract up into a reel and lock in place so it cannot be pulled away from the reel. Sort of like a seatbelt mechanism after it's been ...
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56 views

Number of Kinematic Pairs

Kinematic pairs are the connection between 2 links that can have relative motion between them. But In six bar chain as shown below: There are five pairs for them to be a kinematic chain. But if I ...
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2answers
108 views

How can a mechanical pocket watch wind itself from movement, and does it really get damaged if wound "too much"?

Today I received the mechanical pocket watch that I had recently ordered. It was this one: https://www.trendhim.se/guldfargat-mekaniskt-retro-fickur-p.html#full-gallery I find it extremely fascinating ...
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3answers
82 views

What is this mechanical pump called?

I am unable to find it again but I once heard of a type of air pump that involved a pair of offset archimedes screws inside a cylinder. The point of the device was that as the screws would turn ...
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1answer
50 views

Peltier Module Set up isn't cooling

I have set up a peltier module with an aluminium heat sink, cooling fan, 12v, 7ah battery supply and thermal paste for the purpose of cooling water. At first, it performed well. It dropped down to 3.5°...
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2answers
70 views

Professional threaded insert in plastic?

I'm getting some plastic parts (made with HDPE) CNC machined. A few of these parts require the addition of threaded inserts. I've printed the parts myself using a 3d printer and when I add the ...
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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 ...
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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 ...
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2answers
97 views

how many power stroke in 3 cylinders, 4 stroke at 3000 rpm?

According to some answers, in 3 cylinder , 4 stroke we have power stroke each 240°, as we have 1500 rev. Of 720° in this rpm, so we will have this: 1500 x 1.5 = 2250 power stroke at 3000 rpm, is it ...
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1answer
43 views

What is this object?

In framing the question, I can't be more specific as I have no idea (though a suspicion) about what this came from. I have a number of them that are several different diameters from 125mm to about ...
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24 views

Way to keep object on linear rail in the position you leave it in despite smaller external forces?

Problem: I have a rod on a linear rail system. This rod can be pushed forward or backwards. There is air blowing out of the front of the rod (~2 lbf) causing it to move to the back position by default....
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1answer
35 views

Identify bearing dimensions from its bearing number

In motors/pumps generally following bearings are used (ref: https://www.nke.at/en/bearings-applications/applications/electrical-motors): Deep groove ball bearings Cylindrical roller bearings Angular ...
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10 views

Reloading Press Powder Dispenser Pressure

Yesterday my Lee powder dispenser to my reloading press popped off gunpowder everywhere I had removed the top part of the container off and placed it back on, there is a "on" / "off&...
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1answer
65 views

Motor sizing for modelling

Im working on a headrest for a car that will electrically adjust up and down and have drawn up my plans. it now comes to the important questions, such as what motor to use. Ive been looking at motor ...
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2answers
475 views

Heat transfer Calculation, for Cooling for an aluminium box

To go into more detail, I basically have a controller and its housing is basically an aluminium box that I need to add heat sinks to. But first I need to calculate how much heat is being dissipated by ...
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26 views

Tiny sliding mechanism

I have been trying to build a sliding keyboard phone attachment for a while now, but can't seem to get anywhere. Basically, I want to combine my Moto Z Play with this cheap, generic bluetooth keyboard....
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2answers
50 views

Do you know any mechanism that can pass a thread through several holes?

Well i am stuck trying to figure out this problem, actulally i see a machine that can make it with a torus, a torus coilling machine. But that not work with a multi turus shape. I want to automate ...
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69 views

ABAQUS: How to connect a shell edge with a shell face?

I'm performing a buckling analysis of a stiffened aluminium panel. The panel and flatbar stiffener(2) is created as one 3D shell extrusion. The T-stiffener (1) is another 3D shell extrusion. How do I ...
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1answer
55 views

Specifications of Tensile Test Specimen?

I am Currently Working on Measuring Various Mechanical Properties of Metalic Materials using Universal Testing Machine (UTM) at Various Temperatures. I know that for Testing at Ambient Conditions, ...
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0answers
28 views

High articulation joints

Looking for advice or suggestions for high articulation joints (>57°) for an automotive halfshaft. Peak operating conditions are in the ballpark of ~1000RPM, ~300ft-lb torque. I've considered u-...
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0answers
41 views

Latch design for home exercise equipment [closed]

I have a latch design problem and need your help - many years in software engineering aren't helping me much here! Two pieces of 60x30mm RHS become parallel/adjacent (on the 60mm face), with a 5mm gap,...
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0answers
40 views

How can you convert 180 rotation into two separate motions?

I have a small servo that can rotate 180 degrees. I would like to get two different connected parts to move at different times, one part moving while the servo is between 0-90 degrees, the other part ...
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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 ...
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2answers
64 views

Most efficient orientation of exhaust vents on top plate of chassis for air flow with regard to heatsink fins?

I'm looking for some advice from an ME or anyone who understands heat transfer,convection, etc. I'm currently laying out in Inkscape a top panel for an audio amplifier I'm building. Now, my question ...
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1answer
38 views

Arrow on Activity (AOA) Network Diagram

I have question-related to industrial management, actually, it is a problem on arrow on activity network diagram. I tried to solve the question my self, below are the images. If I did any mistake ...
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0answers
91 views

How is motor torque related to capstan equation?

I know that capstan equation relates $T_{in}$ and $T_{out}$ as $T_{out} = T_{in}e^{u \cdot F_c}$, where $u$ is friction coefficient and $F_c$ is wrap (slip) angle. In my situation, the capstan is ...
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1answer
59 views

Is there a way to convert a short throw in one direction into a long throw in two directions

I have a motor that I have created a simple adapter for; this lets us attach any parts we might design to solve the final problem: I would like to convert the motors motion to oscillating motion in ...