Hot answers tagged

10

I'm not a machinist, but I've tapped a few holes in my time. In my experience a tapered tap will handle this problem as the taper will reach down to the good threads and self align. Use some oil with the tap. I looked at your link and that tap doesn't have much taper so perhaps a more tapered tap might help if you have problems. There are any number of ...


9

I would call that a 'key hole'.


9

I asked a friend who is a highly competent EE by day - but who restores super sized steam engines by night and collects olde heavy metal engines etc and has much experience with old large corroded items. His comments: It really depends on the specific situation. For mild steel bolts in good condition which have not been too excessively deformed, and where ...


9

The product that you're describing (an 'expanding tap') doesn't exist, unfortunately. I had a similar problem a few years back, and actually built my own out of a Sleeve anchor, like the one pictured below. As you tighten the nut, it pulls a tapered cone inwards, pushing the sleeve apart. I loosened the nut until the sides were parallel, shaved down the ...


8

It's really not as simple as a rule of thumb - there are a lot of factors in each application. I'm going to assume that your bolt application is a fairly traditional situation where you are bolting one piece of material to another (one shear plane) not a more complex sandwich (Isolation pads, transition plates, etc.) In most bolted connections, the bolts ...


8

For structural applications (in the US), the most common bolt for weathering steel is ASTM A 325 Type 3. Type 1 is a plain steel bolt that can be galvanized, but in this situation the zinc in the galvanizing will quickly be used trying to protect the rest of the structure. Update for British bolts Interestingly, the only option for UK seems to be to get ...


7

There are a few principal advantages to having more bolts. The first is that the loads are more evenly distributed, especially when the rigidity of the fixture itself is a bit marginal and when it is important to ensure that no separation occurs eg in flange joints of high pressure fluid systems. Secondly having more bolts for the same nominal load ...


6

There are several ways you might try to fix this, for example. Don't use screws. Put some studs into the screw holes in the motor and fix them permanently (like the studs that hold the wheels onto a car). Then you can attach the studs to the mounting plate (or the skateboard frame) with nuts and shakeproof washers. Ignore the screw fixings, and run long ...


6

You can use a sort of "double diameter washer". I've made that name up, but I am pretty sure such a device exists: That's a cross section of one of your linkages. The white things are the aluminum pieces, the grey one is the screw, the yellow is the nut while the red is the "double diameter washer". If you can found some washer that is ...


5

Oxidation, dried lubricant, contaminants, rust - all that acts as a layer of glue binding the elements. As you apply a firm torque, you snap that bond. It takes a considerable time to re-form.


5

You could drill out the hole to remove the munged threads down to the remaining good threads. This should make it easier for the tap to get into the thread grove correctly. Another thought would be to grind out the damaged threads if you could get a small cylindrical grinder. (Thinking Dremel tool here)


4

To answer your question bluntly, yes, the cold can be a concern for standard structural bolts, because the cold can be a concern for just about any metal or plastic. I can give some insight into why the cold is a factor, but I want to be clear that I can't make a recommendation on acceptable temperature ranges for the standard bolts, so if you can't find ...


4

The bolt tension could increase, decrease, or stay the same. It depends on the thermal stress distribution in the whole structure, which is likely to be eventually supported by something that remains at (approximately) room temperature. This is essentially the same situation as any bolted joint that will carry a load. The "pre-stress" put into the bolts by ...


3

The translational stiffness is written as $$ k_l = \frac{A\,E}{\ell},$$ where the stiffness $k_l$ is in $\left[\frac{N}{m}\right]$, the area $A$ is in $\left[m^2\right]$, the young's modulus is in $\left[\frac{N}{m^2}\right]$ and the length $\ell$ is in $\left[m\right]$. $$\,$$ The rotational stiffness is written as $$ k_r = \frac{G\,J}{\ell},$$ where the ...


3

Nylon insert locking nuts, also called elastic stop nuts or nyloc nuts, are nuts with a plastic insert of an ID smaller than the screw to which it is applied. Nyloc nuts are useful in applications where vibration or insufficient clamping loads may cause the nut to loosen and back off. These nuts are extremely common and fairly reliable in tension, though ...


3

A shoulder bolt is a good approach in applications with light loading, but it needs to be specified such that it can be fully tightened while still allowing the necessary clearance for movement without binding. Use shims where needed. You can reduce some of the play in the joint by having the bolt threaded into one of the aluminum pieces (but still backed ...


3

WR grade bolts are available in the UK in 1/4 inch imperial size HSFG (when imported from America) and also in M24 TCB's, both of which are used regularly in bridge steelwork in the UK.


3

This report (large PDF warning) on base plate design says that the AISC Steel Design Guide I instructs the use of plate washers fillet welded to the top of the base plate, with the inner diameter of the washer being much closer to the rod diameter, to ensure initial engagement of the rod. Specifically, I found that information in Sections 2.3.2 (pp.8-10), 3....


3

I would call that a wafer head machine screw.


3

It seems reasonable to believe that the flat head (countersunk) screw would apply enough force to split the wood, hence the restriction. If you use a flat head screw and the washer prevents the countersunk portion from exerting wedge-type force on the wood, you will have accomplished the objective. Consider also that if you use a fender washer (large ...


3

If you use a washer under the head of the flat head wood screw, get you a cup washer. these are intended to let you use flat head screws as if they were pan heads. They hold the wedge profile of the flat head screw up and out of contact with the wood so it will not split the wood as you screw it in, and they hide the sharp rim of the screw head so it will ...


3

I would go with Pitch of 0.35mm ie 1 turn advances by 0.35mm A view of the drawing may clarify this.


3

Under high pressure and high heat metal bonds by a process called diffusion. Where the atoms of the two parts intersperse over time. This and oxidation, slow chemical burning of unintentional matrial and debris between the two parts, cause a strong bond that many times cuase the fastener to break before it can be removed.


3

The most common way to fix mangled threads, if they're really beyond fixing and if there's enough meat to open the hole a bit larger, is to use something like a heli-coil (aka : threaded insert). For a given thread, a helicoil will have a special oversized drill and tap which you use to clear out the mangled threads to a larger diameter and tap. After ...


2

Re-iterating some of above as manufacturer I can advise that Weathering Steel TCBs are generally available in M24 diameter only, with the following lengths: 70, 80, 90, 100, 105, 110, 120, 125, 130, 140, 150, 160, 170, 180, 190, 200, 220, and 240 mm. CSK & alternative diameters can be manufactured bespoke - dependant on quantity. Galv / Zinc Flake ...


2

I assumed you'd use normal bolts, but use a nylon washer to electrically insulate the bolt from the weathering steel (in order to avoid bi-metallic corrosion).


2

The biggest consideration is that the thread must fully engage the nylon ring. If your bolts are too short, the nylon won't do it's job by deforming to the shape of the threads. Depending on how critical your application is, in many industries they are considered single-use as the nylon gets less effective the more times the nut is installed. For very long ...


2

According to AISC J1.9 rivets can be considered as sharing the load with high strength bolts, specifically in joints designed as slip-critical as per J3. The apply this section to both new work and alterations. The commentary on this section points out that this is because the ductility of the rivets. This means that you do not need to be concerned with ...


2

I'm sure there are specific strategies relating to pipe flanges, but for the broader issue of controlling that all of your bolts are tight enough, here is some background information. When tightening bolts in any clamping application, what's really important is the total clamping force. In any simple joint, and specifically when dealing with pipe flanges, ...


2

Although i know is's not the right answer, i would like to mention that using a micrometer to measure bolt length out of nut can be helpful, because that is proportional to torque, so for same installations one can use it to check if all bolts have the same load. another option when a torque meter is not helpful is to use smart bolts. they have internal ...


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