Jackhammer,Demolition Breaker

Table of contents for this jackhammer page. Some safety points. | Makita HM 1303 Electric Demolition Breaker | Tools, bits, sharpening | Actual use tips | Air operated breakers

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Some safety points.

Please, don't skip over this section.
Wear your safety gear when using these tools.

• Minimum of good boots, gloves,  goggles and ear muffs.  Stout clothing helps too.
• The bits get very hot in operation so use caution handling them.
• The rest of the machine can get quite warm also. Particularly the air operated ones.
• Depending on what you are digging or breaking it can get dusty too.  So wear a mask.

It is a real pain wearing all this safety gear, and many times I see guys working without it because it is more comfortable that way.  Don't do it.

Apart from the obvious benefit of saving you from serious injury, safety gear saves you from heaps of minor irritations during the working day.

I know from personal experience that if I don't wear my ear muffs, or ear plugs when using a noisy machine, I will feel far more tired at the end of the day, and probably have a headache as well.
Nothing to do with the work, just the noise.

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Makita HM 1303 Electric Demolition Breaker

Jackhammer - Makita demolition breaker

This is my electric jack hammer, or demolition breaker as Makita calls it, that runs off ordinary household power.  I always run it off a 15amp outlet and the shortest 15amp lead possible.

I use it for concrete breaking  and just about any sort of digging, harder than sand.

With the spade bit in you can really loosen up the ground a lot easier than say a pick and shovel or a crowbar.

Sometimes when auguring foundation holes with say a Bobcat a quick rattle with the jackhammer helps him to bite through a hard patch.

It draws 1300W and weighs about 19 kilo with a point in it. Use ear,eye and foot protection always. Mostly I wear leather gloves. I've a couple of pointed bits for it, a chisel bit and a spade bit. They are 25mm (1")dia. It's not the biggest demolition breaker you can get, Kango do one that uses standard inch and a quarter dia. bits.

The thing about selecting a concrete breaker for a particular job is that it is the weight of the machine that does the work. You shouldn't have to push down on it too much. Smaller machines for smaller jobs.

Of course there are exceptions, I have used ones as big as this for cutting holes through  concrete walls. Supporting it with a rope from above. Two men pushing like hell. Far more punch for a hard job. A size a bit smaller than this one can be hand held to punch out brickwork, or even reinforced blockwork OK.

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Tools, bits, sharpening

In my civil contracting days I ran a few air jackhammers, and to sharpen the bits I took them into our local spring works.  They had a forge and did blacksmith type work.  They brought the bits back to new condition.

I have when stuck, sharpened them (after a fashion) with an angle grinder.  A slow and tedious job.

If you are hiring always get bits with sharp points, and try to get a couple extra for when you wear them down.

Depending on what you are cutting, you can get clay spades (curved), straight spades, chisel points and moil points. If I am hiring, and I assume easy going, I like clay spades, but always get at least one point for unexpectedly hard sections.

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Actual use of a jackhammer

If you are starting to break up a section of concrete or dig a hole in rock, be aware that it is always easier to split of a bit at an edge.  If it is very hard, do only a small bit at a time, until you create an edge.

If you are starting off in the middle of a slab, chip away breaking out small bits in a small area.  What you are trying to do is get through to the earth below.  This is the hard bit. When you have got through, It will get a lot easier.  Always split into the hole and work back from it.

Most people when first using a jackhammer only do half a job. The illustration below shows a slab of concrete about to be broken up.

Jackhammer - Using the tool.

In example "A" the operator has given it a rattle close to the edge and split a lump of concrete off. Good so far, then the novice usually pulls the bit out and splits a bit more off close by. I've seen large areas done like this and then the guys start struggling with a pick and shovel to get it out of the ground

Jackhammer - As large as they go, a Bosch with standard sized 1 1/4" tools.

What you should do after each bite is use the jackhammer as a crow bar to lever up and loosen the concrete (or rock or clay etc.) as in sketch "B". This makes it a lot easier to shovel out of the way.

I am right handed so I tend to favour that side,  so if I have broken out a chunk and then want to move over a bit, I lean into the machine with my right hip and thigh and I push the weight of the machine about with the top of my thigh, taking the weight partly off my hands.

This levering the broken stuff up also makes it easier to get at any mesh or reo bar in there. Cut your reo with bolt cutters, or maybe an angle grinder with a cutting disk in it.

Break up and clean up as you go along. It gives the machine a rest now and again and a clean work area is a safer work area.

Here is a Bosch "Brute" that I hired a while back.  My Makita was just not heavy enough to punch through some really hard concrete.

It is every bit as big as the largest air operated ones.  It is very heavy and fairly hard to handle until you get used to the weight.  But.... it is this weight that does the work.

The points and chisel bits are the standard 1 1/4"  type used in air operated hammers, and the receiver locking mechanism is the same as the air operated ones use.

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Air operated breakers

I have had a question from Steve in the UK, asking if I have had any experience with the jackhammers used in road repair work.  I am putting my answer here as it could also be of use to other people who need a jackhammer, breaker, for a longer job.

Steve, I have had heaps of experience with jackhammers and rock drills.  I had a Sullair  185 CFM screw  compressor for many years.  4 cyl John Deere motor.  Beautiful piece of machinery.  I ran mostly Atlas Copco tools.

In general, air operated jackhammers run off portable air compressors.  Usually diesel driven.  Usually mounted on a trailer.  The 185 tag after the Sullair means it delivers 185 cubic feet of air per minute.  A full size jackhammer uses about 80 to 90 cfm so I could run two large ones, virtually none stop all day if I wanted to.

That is one difference between air driven and electric tools.  Longer duty cycle.  Others are  longer life for the tool, and simply, just more punch, pound for pound.

• On the inside of the compressor will be a list of daily checks, oil, water, fuel etc that you should do before you fire it up.  Read it up and do it.
• Set the machine up level.
• If the compressor shuts down on it's own, it will probably be due to an overload cutout (heat, oil pressure, filter etc.).Get assistance in this case.
• Or the obvious, it's run out of fuel.  please don't let that happen.  In a lot of diesel engines it is a pain in the bum to bleed the system of air when you they out of fuel.
• Start up with no load on the compressor.  That is, have an open air valve with nothing connected to it.
• Normally the compressor will shut down if there is no pressure in the line, it won't roar away with no load.
• The electrical cutout for this, has an override button which you have to press for a few seconds as you are starting up each time.  This will all be detailed somewhere near the start panel.
• If the machine cranks over but doesn't fire up, usually you've forgotten the override button.
• So it's check your fuel, water, oil.  Open an air valve, one thumb on the override and hit the starter.  When it fires up after it builds up to full revs, let go of the override and close the valve.  The machine will drop down to a low no load idle.

The hoses from the machine to the jackhammers will be either 3/4" or 1" thick rubber with a claw type coupling on each end.  These claw fittings need to be snapped home fully (with no pressure in the line).  It is possible to get them half way round and think they are OK.

You can be working away and all of a sudden a blast of air, and the end of the hose is lashing about.  It could give you a hell of a thump.

The coupling have provision for a spring clip to be fitted, to stop the coupling undoing accidentally.  If these are available use them, even though they are a pain to use.

Sometimes hoses just burst from old age, couplings blow off etc.  The hose goes wild.  Don't try to catch the end.  Grab the hose away from the lashing about part and fold it in half to cut off the air supply.  Then switch off the machine, or close the valve.

To change the bit, or put one in, swing the collar / retainer to a side on position.  It is spring loaded and may be stiff, if so belt it around with a hammer or a spare bit.  Make sure it is snapped back fully closed before you fire up and start work.

The actual operation of the jackhammers is simple.  There is a level on the top of one of the hand grips and if you press down it punches, ease off and it stops.

One last point, above all else, don't push the thing, let the weight of the machine do the work.

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