Questions tagged [threads]

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12 votes
5 answers
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Why are most standard bolt threads single start?

When looking at thread descriptions, one of the basic properties is always the number of thread starts. As far as I could tell, all of the major standard bolt threads are single-start. This includes: ...
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10 votes
2 answers
483 views

Are threads machined from high tensile steel more susceptible to damage?

I have an ASTM A311-04 1.25" diameter round 1050 steel bar that exhibits a tensile strength reading of 155,227 PSI. Normally, we receive material in the 13-133,000 PSI range. The bar is machined to a ...
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8 votes
1 answer
3k views

Can nuts safely be removed from bolts where the threads have been intentionally damaged?

On old bridge plans I have occasionally seen a note to "burr threads after installation". This was done to keep the nuts of bolted connection from loosening all the way and falling off of the bolt. ...
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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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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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  • 201
6 votes
1 answer
3k views

Is the tolerance of pitch of a thread standarized?

As I was browsing ISO 965-1 it defines tolerances on a plenty of variables regarding metric threads, but it gives the pitch of the thread as a simple number from an allowed set ( 3 – 2 – 1,5 – 1– 0,75 ...
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  • 6,133
6 votes
1 answer
1k views

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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  • 373
5 votes
2 answers
154 views

How to let a "screw" leave and reenter a thread

The setup Consider a cylinder inside another cylinder (placed with their symmetry axis horizontal). The inner cylinder is about Ø100 mm in diameter and a centimeter or two in lenght/thickness. On ...
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  • 163
5 votes
2 answers
7k views

What does "28" and "27" mean on my metric thread pitch gauge?

I have a metric thread pitch gauge that came in a tap and die set, it has pitches like $0.75$, $0.8$, $1.25$, etc. which is the distance between each thread. However there are two gauges that say $27$ ...
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  • 5,940
5 votes
3 answers
239 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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  • 373
4 votes
1 answer
248 views

British tapered pipe thread; Wall thickness? & Thread designation tpd?

I have to draw two custom pipes, 1 1/4" & 2", with on one end male tapered pipe thread and on the other end parallel pipe thread. The connections are Parallel female thread with a tapered male ...
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4 votes
0 answers
66 views

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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3 votes
3 answers
119 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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  • 201
3 votes
3 answers
4k views

Hand thread taps for stainless steel

I'm finding myself doing quite a lot of thread cutting in stainless steel lately, particularly 304 and 316, often these are moderately deep threads ~ 25 mm or so and at M12 it is becoming a bit of a ...
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3 votes
1 answer
6k views

Calculating Load Inertia in a Leadscrew System

Three common terms used in leadscrews are lead, # of starts, pitch. There definitions are usually as follows: Lead usually refers to the amount of linear travel when the leadscrew turns one ...
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  • 133
3 votes
3 answers
660 views

Measuring pipe bolt torque without a torque wrench

I've had trouble with leaky pipe flanges, since my flanges are made of plastic. The problem comes down to the fact that sealing a flange is based on torque. Torque relies on bolt friction, which can ...
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  • 5,323
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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  • 31
2 votes
2 answers
3k 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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  • 121
2 votes
3 answers
324 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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  • 43
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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  • 1,806
2 votes
2 answers
637 views

In what context is 50 threads per inch common?

I recently found a loupe with a thread pitch reticle displaying common UTS thread pitches... except that rather than 40, 48, or 56 it has a 50. What would this be used for? It doesn't appear to date ...
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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 ...
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2 votes
0 answers
155 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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  • 278
2 votes
0 answers
214 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(\...
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2 votes
0 answers
66 views

What is the load response of a threaded fastener?

Due to the fact that pipe flanges rely on bolts, and bolts rely on friction, it seems obvious to me that in deflecting to meet the load, the nut will immeasurably turn. So my question is - how much? ...
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  • 5,323
2 votes
0 answers
175 views

Thread-locking on AISC Clevises

I have a project that includes some standard AISC clevises on threaded rods in pure tension. I am trying to find guidance on how best to address the possibility that the rod could rotate with respect ...
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  • 4,501
1 vote
3 answers
158 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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1 vote
1 answer
81 views

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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  • 185
1 vote
1 answer
127 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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  • 135
1 vote
2 answers
416 views

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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  • 429
1 vote
1 answer
324 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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  • 21
1 vote
3 answers
46 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 ...
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1 vote
1 answer
96 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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  • 278
1 vote
2 answers
12k views

Optimal tightening torque for a SS screw on an aluminium threaded hole

As in the title, I need some indication about the optimal tightening torque to choose when screwing in a SS screw (A2-70, say) into an aluminium threaded hole. In particular, I am concerned with ...
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  • 111
1 vote
1 answer
292 views

Compute compressive forces necessary for thread rolling

Is there a mathematical method or reference source/handbook for computing the compressive forces necessary for thread rolling? I realize I could use FEM, but that is a lot of work, so I am hoping to ...
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  • 1,605
1 vote
1 answer
317 views

Flat Head Machine Screws with Undersized Threads

I am in search of a flat head machine screws with an 82 degree countersink that have 1/4-20 UNC thread, but have a countersunk head that is characteristic of a 5/16-18 standard screw. That is, I want ...
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  • 4,501
1 vote
1 answer
75 views

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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1 vote
1 answer
87 views

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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  • 11
1 vote
1 answer
574 views

How to find the minimum shear area of a rectangular thread

I am trying to find a method of calculating the minimum shear area of the following rectangular thread form. It is a 4.125" square thread, 8 T.P.I., straight, right-hand thread. The thread is loaded ...
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1 vote
0 answers
18 views

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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  • 111
1 vote
0 answers
46 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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  • 278
1 vote
0 answers
106 views

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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  • 278
1 vote
2 answers
672 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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  • 7,489
1 vote
1 answer
130 views

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 ...
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0 votes
5 answers
3k 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
0 votes
1 answer
62 views

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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  • 37
0 votes
2 answers
477 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 ...
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0 votes
3 answers
67 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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  • 103
0 votes
2 answers
154 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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  • 103
0 votes
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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