Questions tagged [threads]

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What is percent of thread depth when it comes to screws?

What, geometrically, is meant by percent thread depth? And, what would constitute 100% thread depth? I have been trying to derive the equation for thread percentage in the textbook Machine Tool ...
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1 answer
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What is difference between two Thread Forming Taps?

What is difference between Thread Forming Taps: 1/4-20 UNC GH6 and 1/4-20 UNC-2B HSS Right Hand Taps?
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1 answer
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watches: screw-down crown, gaskets, and what else?

I recently learned that some watches have a "screw-down crown", which to my understanding is made with a threaded crown stem that tightens into a threaded watch case. This seems ...
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1 answer
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Can you explain mathematical and mechanics formulation of equation in Junker 1969 paper on self-loosening of fastener by vibration?

Can you help me to understand how the first equation in the paper 'New Criteria for Self-Loosening of Fasteners Under Vibration' by GH Junker, 1969 is derived? I'm not able to understand the ...
1 vote
1 answer
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How can high-precision screw threads be made on a lathe using a less-precise leadscrew?

Motivation I am interested in how high-precision screw threads can be made from lower precision parts. As I understand it, one can make threads on a lathe in the following way: The workpiece is ...
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2 answers
110 views

Pull out force for a 5/8" tapped bolt

I am looking for the pull out force on a 5/8" bolt tapped into 1/4" thick tube steel. Does the thickness of the steel need to match or be greater then the bolt diameter?
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3 answers
91 views

Is it possible to tap a hole partially through a 3mm aluminium sheet?

I would like to secure components to an aluminium sheet that is 3mm thick. Ideally I do not want to drill holes all the way through the sheet because it is important that a seal is maintained. I am ...
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Are there conventions for clearance in Whitworth thread forms?

Are there are any conventions for the clearance between the internal and external threads of BSW and BSF threads, or other threads using the Whitworth thread form? Is the clearance achieved by ...
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1 answer
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Unable to understand minimum length of engagement for bolts

I've attached a snap of the part I'm unable to understand Machinery's Handbook 29th Edition. Here's a link to the ebook as well https://www.vtc1.org/cms/lib/PA03000913/Centricity/Domain/21/Machinerys%...
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1 vote
1 answer
135 views

Aluminium Bolt in Titanium Casing: Any Dangers of (Contact-)Corrosion?

Assumed we have a fuel flask that is made of titanium. The bottle will be filled with white gasoline when used. At the bottleneck there is a standardized thread manufactured into the titanium. Are ...
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-1 votes
1 answer
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Safety of fiberglass, cloth

Is there a way to make fiberglass so safe that it can be used for everyday clothes? From what I've found glass fibers are itchy when thick, so reducing their diameter helps make them soft on touch. ...
1 vote
3 answers
196 views

Does lead screw's thread have to be trapezoidal?

I want to move a small tool table/bed linearly, so I'm designing its mechanism. Fairly simple, it's going to have 2 rails and a lead screw. Browsing the web I find that locally the shortest ...
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536 views

Maximum strength size thread for aluminium sheet per thickness

Is there a rule of thumb, or a table which helps one determine what is the maximum strength thread size to use for aluminium sheet? I am interested in threading 3mm, and 2mm thick sheet aluminium. I ...
2 votes
3 answers
395 views

Bi-directional gearbox

I want to design and create a gearbox that allows an input shaft to be continuously rotating in one direction, while the output shaft rotates one full turn in the same direction but then half a turn ...
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1 answer
278 views

What is the contact area between threads and how does it change?

"https://www.youtube.com/watch?v=3l6EcBg9EPA" [@24:30 - 25:10] He says something about the load of a threaded interface being on only one small part of the spiral. To me this seems a bit odd ...
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2 answers
187 views

Securing aluminum angle to steel tubing without through-bolts

Overview I'm planning a rack for solar panels on the roof of a cargo trailer. I will mount the panels to a pair of 15 series 80/20 aluminum extrusion rails. I will mount the rails to the roof of the ...
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2 answers
39 views

Using a Threaded Rod and Internally Threaded Tube as a Piston Pump

Im looking for a low cost, high pressure pump with good flow/pressure control for an espresso machine (a lot to ask, I know). My first thought was using a screw-driven piston. This will work, but Im ...
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5 answers
4k views

Why do you need helicoil if you can just use a tap?

I'm new to thread repairs and I was just wondering when using a helicoil, why does the helicoil need to be inserted if you have already tapped the new threads into a hole? Can't you just put a bolt in ...
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1 answer
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What is the correct method to remove or tighten this splined "nut"?

This photo shows the input shaft of an air compressor head. The splined cog-looking disc around the shaft is actually a sort of threaded nut which screws into the larger disc around it. It serves to ...
1 vote
2 answers
873 views

How do british standard pipe parallel (BSPP) (G) threads seal?

I realize that there must be some sort of o-ring, gasket, or washer, but from an engineering standpoint it is not clear how to know what fitting will seal to what without having the parts in front of ...
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2 votes
2 answers
4k views

M# Screw mm per turn?

So is there a standard rule of thumb, or equation about the distance the end of a screw will travel per rotation? Conversely, how many turns it will take to travel a specific distance? Say I have an ...
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1 vote
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How to repair stripped, leaky pneumatic fitting?

I have a pneumatic cylinder with a stripped fitting, which causes a slow leak. I took it to a machine shop and he tried to re-thread it but there wasn't enough good metal left to get a good thread. He ...
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0 votes
1 answer
132 views

how does this z-axis micro-adjust lead-screw design work

The picture (which I found on the web without any accompanying explanatory text) shows a home-made z-axis micro-adjust lead-screw add-on to the vertical milling attachment of a vintage hobbyist lathe. ...
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1 vote
1 answer
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threading a compression clamp

I'm not an engineer, just a novice hobbyist, so I'm not sure my terminology "compression clamp" is correct, but I'm attaching a drawing showing what I'm trying to accomplish. This plate will be ...
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M thread as leadscrew

Hello I was searching net but can find information. I am doing a hobbyist project. I would like use shaft with metric triangular thread as a leadscrew. Can I do that? I know ACME will be loads better ...
6 votes
7 answers
5k views

Fixing a blind bolt hole when the first 2-3 threads are ruined?

One of my suspension bolts came undone while I was mountain biking recently, sadly I didn't notice. I landed a big drop with only 2-3 threads left engaged, and unsurprisingly it's ruined them. The ...
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1 answer
83 views

identify shackle or swivel tensioner mechanism

What is this called? I would say it is a shackle or I suppose, a turnbuckle, but it appears to have a right threaded rod on both sides and right threaded free nuts inside. I would just say it's a ...
0 votes
2 answers
134 views

Straight Pipe Thread

Is there any National Pipe Thread Straight (non-tapered, requires O-ring or compression olive) that is compatible, even loosely, with a machine thread threaded rod? I want to put a reducer on the end ...
1 vote
1 answer
97 views

Is there a rule of thumb to construe a screw

When your first idea is drafted you calculate which forces/pressures and so on are working on your system. And then you break the forces down into the single screws which are built in your device. ...
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4 votes
0 answers
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Thread identification

I am having a very difficult time identifying this thread. This part is a plug that I am trying to replace because the threads were stripped. The best fit for pitch is 11 threads per inch (imperial), ...
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0 answers
69 views

Screw Cap design for high pressure surge vessel

I'm designing a pressure vessel with a relatively large cap that provides access into the vessel, what recommended thread specifications is needed to maximized locking and safety against faliure or ...
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1 vote
0 answers
47 views

Decision criterion if bolted joints are loaded concentrically or eccentrically

When dimensioning bolts I have to decide if the applied load is concentrically or eccentrically to the bolt axis (according to VDI 2230 but I think in other approaches too). But how do I decide and ...
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1 vote
0 answers
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Calculating the lifting force $F_{Kab}$ with SolidWorks – according to VDI 2230

I’m not sure if my procedure to simulate the lifting force $F_{Kab}$ is correct. So I illustrate my way how to get the lifting force $F_{Kab}$ using SolidWorks and the simulation tool. I hope you can ...
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1 vote
1 answer
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Tapped thread maximum load

I am building a stair from aluminium to go to my basement, the stair sides-plates are made from 10mm thick aluminium AWS 5454. I am planning to tap M10 thread into this plate. To avoid the step ...
2 votes
0 answers
166 views

Calculation of critical internal thread according to VDI 2230 Part 1

I’m doing a “Systematic calculation of highly stressed bolted joints – Joints with cylindrical bolt“ according to VDI 2230 Part 1. In step of calculation R11 “minimum length of engagement”, when my ...
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0 votes
2 answers
129 views

What is the justification for left-hand threads?

I'm familiar with left hand threads on bicycle pedals. The action of pedaling for that side of the bike would un-thread a right-hand threaded pedal, although some people have hacked a solution. I ...
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6 votes
1 answer
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How are non-continuous internal threads plastic injection molded?

I'm trying to figure out how the heck some of these plastic bottle caps are injection molded. By having the thread on the inside of a cap, this obviously creates an undercut. Now I've watched some ...
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1 vote
1 answer
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What is this part called, and where could I get one?

I'm fairly illiterate when it comes to Engineering, so please understand I have pretty much 0 idea what I'm talking about. I'm having to build a seawater distillation device for school, and we ...
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0 votes
1 answer
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meaning of 1" baseplate fitting to mount to a standard 1" feedthrough port

I was looking at this page to figure out how I would install a manipulator onto my chamber. It says 1" baseplate fitting to mount to a standard 1" feedthrough port" So, I would have to have a ...
1 vote
1 answer
350 views

Tool Clearance at Bottom of Milled Thread

Hi, So I have a large piece that I want to thread (the entire region in blue), but I am not sure how much space to leave at the bottom for retraction of the blade (region in red), see above image. ...
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1 vote
3 answers
47 views

How to calculate properties of a thread?

I have a simple thread joint between two objects: and want to find a size of those threads so that after rotating male part it stands at the specific angle. For those who is curious I made it in ...
2 votes
1 answer
30 views

making a leak proof thread for my keychain idea

I have been designing a prototype for a keychain that sprays perfume. I have a metal keychain piece which has a female thread and the plastic sprayer screws right into it and has a male thread. I ...
0 votes
2 answers
515 views

How to indicate standard screw thread in drawing

I have no experience with actual CAD drawings and CNC machines so please forgive me if this is a really stupid question... Anyway I have a part which I have 3D printed and it contains some internal ...
2 votes
0 answers
238 views

What is the minor diameter of a thread in terms of its nominal diameter and pitch?

I'm trying to find the formula for calculating the tensile stress area of a bolt. According to page 1528 of The Machinery's Handbook (29th Ed.), that formula is given as $$ A_S=\frac{\pi}{4}\left(\...
3 votes
1 answer
54 views

What thread could this camera motor be?

Firstly, I am sorry that the title of this question isn't helpful. I have bought these motors for a project: 5V 7mm 2 Phase 4 Wire Stepper Motor I assumed that the 1.7mm diameter threaded shaft ...
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6 votes
4 answers
2k views

Why are Whitworth threads angled at 55°?

You're probably thinking, "Well.. Why not? It's gotta be something.." Right? But 55° is kind of an odd angle if you think about it.. and it does seem like a pretty specific choice considering a ...
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3 votes
3 answers
122 views

Making precise, intricate measurements

What's the best way to precisely measure intricate mechanical parts? For example, notice the tiny differences between the pitch in these two threads, and the tiny variations in external width of the ...
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2 votes
2 answers
3k views

Bicycle pump connector thread size

Does anybody know what the thread size is on a bicycle pump connector, such as this one? Note: I'm not talking about the female end that goes on the valve stem on the bike (that's a Schrader valve ...
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5 votes
3 answers
247 views

Cutting flattened out "threads" to prevent small-scale slipping

I have a product where we transmit quite a lot of shear force through a small bolted join. On our current design the contact area is about 10mm², the bolt is M2, and the force is 45N, and it works ...
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1 vote
2 answers
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Rigid tensioner/turnbuckle: One side tightens, but the other side loosens

I'm attempting to make the rigid equivelent of a gate tensioner/turnbuckle. I'm doing this for a couple of reasons: I like the idea of not fussing with cables I'm using this experience to learn about ...
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