Questions tagged [threads]

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11
votes
5answers
11k views

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: ...
10
votes
2answers
431 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 ...
8
votes
1answer
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. ...
6
votes
7answers
4k 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 ...
6
votes
2answers
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 ...
6
votes
1answer
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 ...
6
votes
1answer
628 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 ...
5
votes
2answers
145 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 ...
5
votes
2answers
6k 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 $27$ ...
5
votes
3answers
209 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 ...
4
votes
1answer
198 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 ...
3
votes
3answers
111 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 ...
3
votes
3answers
3k 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 ...
3
votes
1answer
5k 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 ...
3
votes
3answers
615 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 ...
3
votes
1answer
53 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 ...
3
votes
0answers
58 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), ...
2
votes
2answers
731 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 ...
2
votes
3answers
125 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 ...
2
votes
2answers
2k 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 ...
2
votes
1answer
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 ...
2
votes
0answers
115 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 ...
2
votes
0answers
153 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(\...
2
votes
0answers
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? ...
2
votes
0answers
169 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 ...
1
vote
1answer
75 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 ...
1
vote
2answers
312 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 ...
1
vote
1answer
211 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. ...
1
vote
3answers
42 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 ...
1
vote
1answer
84 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. ...
1
vote
2answers
9k 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 ...
1
vote
1answer
264 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 ...
1
vote
1answer
303 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 ...
1
vote
1answer
158 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 ...
1
vote
1answer
81 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 ...
1
vote
1answer
499 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 ...
1
vote
1answer
529 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 ...
1
vote
0answers
12 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 ...
1
vote
0answers
40 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 ...
1
vote
0answers
93 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 ...
1
vote
1answer
104 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 ...
0
votes
5answers
92 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 ...
0
votes
2answers
313 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 ...
0
votes
2answers
66 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 ...
0
votes
2answers
24 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 ...
0
votes
1answer
79 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. ...
0
votes
1answer
21 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 ...
0
votes
1answer
48 views

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 ...
0
votes
1answer
76 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
2answers
128 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 ...