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

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 ...
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9 votes
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What is the name for a bolt hole with a slot that allows the bolt to be inserted or removed when the nut is loose?

I would call that a 'key hole'.
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9 votes
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Many small bolts, or few large bolts?

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 ...
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  • 4,501
9 votes
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Can nuts safely be removed from bolts where the threads have been intentionally damaged?

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 ...
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9 votes

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

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 ...
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9 votes
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Are M8 screws double the size of M4 screws?

The ISO metric bolt has its diameter as the numeral part of the name. So M8 has a diameter of 8mm compared to that of the M4 bolt. So far scaling would make sense. However, the pitch of them is not ...
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  • 20.9k
8 votes
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What bolts should I specify with Weathering Steel?

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 ...
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  • 10.6k
7 votes

Many small bolts, or few large bolts?

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 ...
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7 votes
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What method can I use to make a pivot point in an aluminum linkage?

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 ...
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7 votes

How to make screws stay tight under high vibration?

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 ...
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  • 12.5k
6 votes
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What causes a fastener to lock?

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.
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  • 6,113
5 votes

What method can I use to make a pivot point in an aluminum linkage?

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 ...
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5 votes

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

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 ...
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  • 51
4 votes

Are standard structural bolts acceptable for all cold climates?

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 ...
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4 votes

Do bolts become tighter or looser at cryogenic temperature?

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 ...
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  • 12.5k
4 votes

What causes a fastener to lock?

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 ...
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3 votes
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Convert translational stiffness to rotational stiffness of a screw

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 $\...
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3 votes
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How to determine the number of effective anchors in a base plate?

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 ...
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3 votes

How is a self-locking hex nut (ISO 7040) used?

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 ...
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  • 31
3 votes

What bolts should I specify with Weathering Steel?

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.
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3 votes
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Correct term for non-countersunk flat hex screw/ bolt?

I would call that a wafer head machine screw.
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3 votes

Can I use a wooden flat screw head with a washer to mimick a pan head screw?

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 ...
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  • 6,092
3 votes

Can I use a wooden flat screw head with a washer to mimick a pan head screw?

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 ...
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3 votes
Accepted

What does P0.35 stand for in a Tech drawing for a Bolt

I would go with Pitch of 0.35mm ie 1 turn advances by 0.35mm A view of the drawing may clarify this.
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  • 13.6k
3 votes

What causes a fastener to lock?

A standard bolt will stretch when tightened. This stretching increases force on the threads of both the bolt and hole and thus increases the force required to overcome static friction and loosen the ...
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3 votes

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

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 ...
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  • 197
3 votes

What is the purpose of drilled washers?

Depending on the size and thickness these could be spacers. One example is their use on cars to increase the track. They can also be designed as flexible drive plates between a motor and gearbox for ...
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  • 13.6k
2 votes

What bolts should I specify with Weathering Steel?

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, ...
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2 votes

What bolts should I specify with Weathering Steel?

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).
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  • 3,145
2 votes
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Are stress concentrations a concern when replacing rivets with high strength bolts?

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 ...
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  • 4,501

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