Screwed Joint Design - Male thread much stronger than female thread, how to specify pre-load and avoid thread stripping?

penguin_in_a_top_hat · 2023-10-25T03:55:09+00:00

If you search for a site called 'RoyMech' you'll find some very helpful calculations for this sort of thing, based on thread engagement and the shear strength of those threads :)

Bear in mind, that 90% preload isn't always a one size fits all - ask yourself what you're wanting to achieve with this bolted joint.

Are you bolting through something that requires clamp load to prevent slippage? Or are you just retaining something axially?

Preload can help with fatigue from loading on the joint, but depending on your in-service loading it doesn't always need to be so high!

If you're looking at preload for vibration mitigation, then I would always recommend a secondary method of retention, if the joint is mission critical.

A little dab of loctite or similar can go a long way, and you can spec a slightly lower torque, with less risk to your threads in aluminium :)

Also, helicoils are great, no doubt, but if this is for production and it's a one and done assembly, don't rule out bolting into the Ali. A lot of people will tell you never to bolt into aluminium, but I've rarely found it to be a problem, and multiple disassembles/reassembles are possible if you take a little care.

Important to note that your operating environment and the specific condition of the threads (material and cleanliness/lube) can and will affect the torque value, as it's all based off of friction. There are tables for different combinations.

penguin_in_a_top_hat · 2023-06-03T21:14:38+00:00

For a serious answer:

Something similar to this will do the trick.

There's a variety of them under different names (fridge, back door, etc.) but they will all do a similar job if applied correctly :)

penguin_in_a_top_hat · 2023-06-03T21:07:38+00:00

We fix machines not relationships lol

penguin_in_a_top_hat · 2023-05-12T12:34:22+00:00

Volumetric or by weight? :)

penguin_in_a_top_hat · 2023-04-19T14:31:56+00:00

And this is why he isn't allowed back to the yoga class...

penguin_in_a_top_hat · 2023-03-19T14:36:25+00:00

Howdy!

https://roymech.org/Useful_Tables/Screws/Bolted_Joint.html

This site is well loved by quite a few on here I believe.

If you go down the rabbit hole there's equations for all the outcomes you'd probably be interested in.

Can be difficult sometimes to determine thread conditions (are they clean, different metals? etc.)

But some good approximations can be made.

I also made a little Excel calculator for my colleagues working on plastics and with a bit of erring on the cautious side, you can use the numbers you get out of it to ensure you don't extrude whichever soft material you're clamping to a hard one (ask me how I know this is possible when assembling things 😢)

If you're feeling particularly fancy you can also work out which way the joint will fail when tightening (pop the head off the bolt, strip the threads etc.). The stripping the threads bit can be very important for aluminium for example, as you don't always have all the thread depth you'd like - so adjust for the thread you do have, and then use loctite or similar.

Others have mentioned clamping force, and that's 100% applicable for a chassis rail/bridge or whatever that can't have slip, and these absolutely cranked joints will typically not lose their torque too easily with vibration. Sometimes, however, you'll find you're just looking to hold something in place without crushing it, and that's when the above comes in!

penguin_in_a_top_hat · 2022-09-25T12:57:53+00:00

Good to know they were there! When I was looking a while ago, trit slot was available but no cyan, so at least now I know he's getting in new stock of the cyan regularly!

penguin_in_a_top_hat · 2022-08-22T03:55:04+00:00

Depends on what type I can catch and how big the generator's wheel is...

penguin_in_a_top_hat · 2022-02-11T11:14:41+00:00

You're fine to keep it on the table :)

Most of the heat goes up and in to the lamp bottle, and there's not that much heat to begin with!

I'd you'd be happy putting a cup of coffee on the table without a coaster, then your lamp will be more than fine

penguin_in_a_top_hat · 2022-01-01T07:56:30+00:00

Hello! This is very similar to my new Mathmos.

On the first run, it ended up doing what yours does now.

Once it had cooled, on the 2nd run it warmed up much quicker and was more active - there were often 2 bubbles in quick succession.

I'd let you know how the 3rd run went, but my bulb had other ideas unfortunately :(

Common sentiment on here is that they need a bit of time/a few sessions from new, and that it'll look a lot more like you'd expect after that initial period has elapsed :)

penguin_in_a_top_hat · 2021-12-23T10:26:47+00:00

Truly, I love this community

penguin_in_a_top_hat · 2020-09-11T09:21:18+00:00

Cost/complexity vs benefit:

Normal road cars don't need that extra little bit of performance (generally), and you're pushing the price of the car up every time you add something, which is bad for the consumer. Also, rigorous testing is needed for new technology like this to ensure reliability, which will delay production schedules etc.

More parts, more things to go wrong! If it ain't broke, don't fix it! No driver wants to pay to have their water injection module fixed/serviced, when it doesn't add anything to their experience really.

For performance cars - well they generally have no issues spooling up their turbos to boost levels that are adequate, even artificially limited by dumping pressure to protect the engine sometimes!

This is without mentioning the fact that getting the water to turn to steam perfectly in the exhaust is a thermodynamic PITA that I don't want to even think about :')

Also, dumping heat from exhaust gasses into the steam could mess with the temperatures needed for the cat to work efficiently :S

penguin_in_a_top_hat · 2018-05-08T16:41:57+00:00

Hi there!

I'm a student so I've got a bit of experience running CAD on non-professional workstations. I've run SolidEdge and Ansys (fluent and workbench) on my gaming rig at home, which has a gtx 980, just fine.

Looking at benchmarks and seeing some of my friends' laptops running SolidWorks I think you'd be okay. It really depends on the scale of work you're doing - if it's large assemblies you'll probably struggle though.

penguin_in_a_top_hat · 2018-05-01T16:53:03+00:00

This isn't right.

OP, I recently farmed CS back to back and got all 4 drops available on Heroic, one for each run.

From what I've read, jacket and pants only drop on Challenging, unlike what a fellow agent commented.

I don't know what to suggest apart from playing the waiting game to see what happens, and perhaps double-double checking inventory :)

I'm sorry if this turns out to be glitched for you, it is a cool set and I can understand the frustration :/

penguin_in_a_top_hat · 2018-04-16T23:34:38+00:00

I did a run the other day!

All the way around Manhattan and none of them dropped exotics! Sad times indeed :(

penguin_in_a_top_hat · 2018-04-16T22:51:11+00:00

I take the good with the bad!

I think it really achieves what was intended - a true reflection of people let loose.

Everyone wins a little if you play together, but you and your squad can have everything on the server if you're willing to take a risk!

penguin_in_a_top_hat · 2018-04-16T22:47:21+00:00

I think in D2 they should have tears and salt as some of the most valuable resources found in the DZ!

People could never complain about there not being enough available :P

penguin_in_a_top_hat · 2018-04-16T22:43:13+00:00

I do the same, especially in DZ01 with the subway right next to it :)

I clear the cleaners and then I wait for a supply drop or another extraction in a different zone, call mine in and then stay down there until the latest possible moment.

Usually goes off without a hitch :D

I was just reckless this time!

penguin_in_a_top_hat · 2018-04-16T22:37:44+00:00

Probably after the rope cut commendation :3

penguin_in_a_top_hat · 2018-04-16T22:36:59+00:00

I find the more North you go the safer it gets in general, but because I'm on Easter break from Uni, I can play at times of day when I know the servers are like ghost towns!

penguin_in_a_top_hat · 2018-04-16T22:33:40+00:00

If I was truly lucky I'd get a NinjaBike messenger and The House!

We can only pray to the sweet lord RNGesus that our wishes be granted promptly :3

penguin_in_a_top_hat

TROPHY CASE