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A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nails into wood, to shape metal (as with a forge), or to crush rock. Hammers are used for a wide range of driving, shaping, breaking and non-destructive striking applications. Traditional disciplines include carpentry, blacksmithing, warfare, and percussive musicianship (as with a gong).
Hammering is use of a hammer in its strike capacity, as opposed to prying with an secondary claw or grappling with a secondary hook. Carpentry and blacksmithing hammers are generally wielded from a stationary stance against a stationary target as gripped and propelled with one arm, in a lengthy downward planar arc—downward to add kinetic energy to the impact—pivoting mainly around the shoulder and elbow, with a small but brisk wrist rotation shortly before impact; for extreme impact, concurrent motions of the torso and knee can lower the shoulder joint during the swing to further increase the length of the swing arc (but this is tiring). War hammers are often wielded in non-vertical planes of motion, with a far greater share of energy input provided from the legs and hips, which can also include a lunging motion, especially against moving targets. Small mallets can be swung from the wrists in a smaller motion permitting a much higher cadence of repeated strikes. Use of hammers and heavy mallets for demolition must adapt the hammer stroke to the location and orientation of the target, which can necessitate a clubbing or golfing motion with a two-handed grip.
The modern hammer head is typically made of steel which has been heat treated for hardness, and the handle (also known as a haft or helve) is typically made of wood or plastic.
Ubiquitous in framing, the claw hammer has a "claw" to pull nails out of wood, and is commonly found in an inventory of household tools in North America. Other types of hammer vary in shape, size, and structure, depending on their purposes. Hammers used in many trades include sledgehammers, mallets, and ball-peen hammers. Although most hammers are hand tools, powered hammers, such as steam hammers and trip hammers, are used to deliver forces beyond the capacity of the human arm. There are over 40 different types of hammers that have many different types of uses.For hand hammers, the grip of the shaft is an important consideration. Many forms of hammering by hand are heavy work, and perspiration can lead to slippage from the hand, turning a hammer into a dangerous or destructive uncontrolled projectile. Steel is highly elastic and transmits shock and vibration; steel is also a good conductor of heat, making it unsuitable for contact with bare skin in frigid conditions. Modern hammers with steel shafts are almost invariably clad with a synthetic polymer to improve grip, dampen vibration, and to provide thermal insulation. A suitably contoured handle is also an important aid in providing a secure grip during heavy use. Traditional wooden handles were reasonably good in all regards, but lack strength and durability compared to steel, and there are safety issues with wooden handles if the head becomes loose on the shaft.
The high elasticity of the steel head is important in energy transfer, especially when used in conjunction with an equally elastic anvil.
In terms of human physiology, many uses of the hammer involve coordinated ballistic movements under intense muscular forces which must be planned in advance at the neuromuscular level, as they occur too rapidly for conscious adjustment in flight. For this reason, accurate striking at speed requires more practice than a tapping movement to the same target area. It has been suggested that the cognitive demands for pre-planning, sequencing and accurate timing associated with the related ballistic movements of throwing, clubbing, and hammering precipitated aspects of brain evolution in early hominids.

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  1. T

    Water Hammer problem

    We have had a minor water hammer issue for years but it was never really a problem until the last year or so. It is so loud it sometimes make you jump, it's driving us crackers. It happens sometimes when we use the electric shower or washing machine but then it's not at it's worse. It never...
  2. Robcrick88

    Can you get water hammer when stopcock is off?

    Been getting water hammer everytime neighbour turns off their taps. Very loud in our house and have asked neighbour who denies hearing anything. I tried turning off my stopcock and switching off boiler for a few hours and could still hear the banging when they use their taps. Is it possible to...
  3. Chrisbarber

    Water hammer moved from washer to toilet flushing

    We recently, about 2 days ago, started getting water hammer from using the washing machine, this has been fixed by attaching an arrestor to the inlet hose which great. However we've now started getting it from the toilet completing a flush, which is upstairs and not near the washer. Is it normal...
  4. D

    House pressure reducing valve cold water hammer

    Having issues with water hammer, I have a megaflo with balanced hot / cold using a heat stadia 3 bar prv, this seems ok as getting 3 bar at taps with test gauge, the outside tap is between the house incoming stop valve and the 3 bar PRV and that is showing just over 4.5 bar. If I switch a hot...
  5. O

    Do new tap cartridges fix water hammer?

    Hi all, We have some terrible water hammer in our house. I've had a plumber come round to try and fix it, to no avail, but I'm not convinced he chose the right course of action. He started by checking the water pressure, securing a few pipes in the roof space which was fair enough, but...
  6. D

    Water Hammer following Combi boiler installation

    Worcester Bosch Greenstar i combi installed. Since installation water hammer happens when hot taps are turned off, but only when the heating is on. Have you experienced the sam?
  7. D

    Water Hammer on washing Machine

    Have a problem with water hammer on washing machine, solved it for a bit with a mini rester been thro 2 seem to only last a year or so and expensive. So purchased a 1/2" T and a 0.16L mini expansion vessel and T what pressure should it be set at? When I first used machine it seemed ok then few...
  8. J

    Quooker water hammer

    Greetings and Merry Xmas to all Just been to an interesting callout. Quooker fusion pro3 tap recently fitted in a new kitchen on a small 2 bed mid terrace with a Ideal logic 30 combi. Customer getting the most horrendous water hammer, started the day after the "plumbers" left for xmas...
  9. M

    water hammer after flushing toilet

    Hi, I have been having water hammer after flushing toilet in the past couple of weeks. I have tried turning off the stopcock and opened all taps to drain all the water in pipes and toilet. The water hummer then fixed for a few flushes but it comes back. It's ok a few weeks ago before we fixed...
  10. M

    Water hammer ceramic disc taps

    Can you get water hammer from ceramic discs on tap valves? Have been to a job where is it sounds like its coming from there. But I know this isn't always the case. Thanks
  11. S

    Sewage smell every time neighbour flushes Saniflo and pipe hammer

    Hi, I'm hoping someone might be able to give me some advice. I'm in a semi detached, and unfortunately our neighbour's pipework all connects to ours. We've been getting a couple of issues with the plumbing ever since he put in a saniflo downstairs 5 years ago (unfortunately he is awful and can't...
  12. C

    Water Hammer

    Howdy, We have an issue with water hammer since going to a pressurised system from a gravity fed one. It occurs when the downstairs toilet or washing machine are being used - which makes sense as they are on their own loop of pipes it seems (weird extension with do it yourself plumbing it...
  13. L

    Water hammer caused possibly by cold feed crossing into hot feed

    Have a water hammer that can't get to the bottom of and have searched everywhere. Hammer occurs when hot tap 1st runs the noise comes from the hot water tank cupboard thought it was the expansion vessel so had it replace went away for a short time but returned. Had the vessel checked again and...
  14. J

    Water hammer with smart thermostatic valve

    I have gradually fitted smart TRV's to all of the radiators in our house, and in general we are very pleased with them. However, it has become apparent that quite often, when the timing makes the TRV switch off, this sets off water hammer in that radiator. This is easily fixed by running a hot...
  15. M

    Mystery water hammer

    Problem in video link View: https://youtu.be/efrhhYhhquk Does it when we turn bath taps on or shower either whilst the hot water is on or recently heated. I'm not 100% sure need to figure that out. Havent heard it do it with any other taps in the property. We have an unvented hot water...
  16. H

    Water Hammer & Bathroom fittings squealing when toilet is flushed

    I've been experiencing water hammer within the house for a couple of months now, which rattles the pipes whenever turning off a tap or an appliance cuts off its supply. I have turned the stop tap off while turning on all taps allowing the system to aerate which fixes the issue for a day or so...
  17. A

    Water hammer advice needed

    Hi I think I might have a water hammer- when I flush the toilet or close the bath/ kitchen tap too fast I hear a ‘thunk’ sound. We have a pressure limiter at the main- limits the house to 3 bar. The water softener likely takes this down a bit further. Do I need to be worried? Given the...
  18. J

    Water hammer when neighbour uses water.. Please help

    Sorry to bother but in desperate need of advice, we've suffered with water hammer issues in our council property since 12th November 2018, I share a water line with both neighbours either side of me and the main Thames line is in the street right outside my house leads to another stop tap in my...
  19. G

    Hammer arrestor on dishwasher?

    I have some severe water hammer going on. Behind the bath upstairs where I cannot access the pipes. It is is mild when a cold tap is turned off or the toilet is flushed BUT it's horrendous when the washing machine and dishwasher run. I have bought an arrestor to put on the washing machine but...
  20. H

    Bathroom sink tap squeeling & Water Hammer

    Recently I noticed the houses plumbing developing water hammer whenever shutting off any one of the taps. I have turned the stop tap off and allowed the system to drain and this fixes the issue for a day or so before it returns. I think the culprit is my toilet which seems to be constantly...