In June 2021, we received a phonecall from a customer who purchased a Magnum 5 Hydraulic Handheld Core Drill over 20 years ago and hes only crossed threaded the shaft and can we help him.
It was great to hear what else he said about our Magnum machines:-
"This machine has been in almost continuous daily use and it's a marvellous piece of kit that's done everthing we've ever asked it to do!"
Magnum handheld hydraulic core drills are limited to a Maximum hydraulic flow of 20ltr per minute and maximum 150bar
So if your intentions are to use this type of hydraulic powertool from a power source that is rated above 20ltrs per min and 150bar, you will need to reduce the flow and pressure accordingly.
Even small mini diggers might produce 23ltrs/min at 180bar, this is still too much and could cause some internal damage to the Magnum.
Using an Oil-flow limiter will control the maximum hydraulic oil flow and pressure to a safe and suitable level.
Flow & Pressure Limiting Control  shown in the middle of the image above.
*A hydraulic extension hose maybe required to connect the divider to the hydraulic tool.
There is an optimum speed of rotation for a given diameter of core barrel. However, this optimum speed is also dependant on the material being drilled.
The optimum speed for a given diameter of core barrel will be different when used in asphalt than it is when used in concrete.
Speeds and feeds
Asphalt 6 metres/sec.
Concrete 3 metres/sec.
If you are drilling a 107mm diameter core barrel through concrete you would need the following calculations for optimum coring performance
An 107mm barrel circumference is 335.98mm (π x Diameter)
we know that 1m = 1000mm
So with one complete rotation of the barrel we know that it will travel 335.98mm, but we need to be traveling at 3m (3000mm) and at every second for concrete.
3000mm divided by 335.98mm = 8.929102922 which we can round off to 9
so the barrel needs to be rotated just slighly less than 9 times in order to travel 3000mm (3m) and every second if we want the best performance in concrete.
we also know that theres 60 second in 1 min, and we need to be able to rotate the 107mm diameter barrel 9 times every second
60 x 9 = 540
So the optimum for this 107mm barrel in concrete is 540 RPM
Our Magnum 5+ Handheld Hydraulic core drill is perfect as it runs a 600 RPM at 20/ltrs per min
If the core bit is rotated too quickly the core bit will stop cutting after the barrel has reached a depth of more than 50mm. The core barrel stops cutting because whilst the diamonds have fractured down the matrix surface material (segment bond) has not worn away, so the new layer of diamonds have not been exposed to the cutting surface. This is known as 'Glazing".
A nicely ‘Dressed’ segment
Rotation of barrel ------->
A nicely dressed diamond segment showing diamonds standing proud of the matrix with supporting tails of metal behind each diamond. NB The tails will point opposite to the direction to rotation.
A badly ‘Glazed’ segment
Rotation of barrel ------->
A segment showing only a few diamonds standing proud of the surface. Most of the remaining diamonds are not proud and therefore not cutting.
Many of our customers in the UK and overseas are using our machines for the core sampling sector of the market. Obtaining core samples from roads at measured intervals, which are then sent to be examined by test laboratories which helps then evaluate the state of the road construction.
Common core sample diameters:
100mm (107mm x 450mm diamond core barrel)
150mm (158mm x 450mm diamond core barrel)
Using a core extractor to easily lift out the cleanly cut core sample, leaving you with a 107mm or a 158mm hole which needs to be made safe, and filled back up with the correct specification class of material and sealed, this is known in the industry as "Back filling" and many consider this to be an art in itself.
A hydraulic breaker or a tamper fitted with a stem and tamper pad you are able to fill the void with the best graded material.
we highly recommend the lightweight LH11 hammer by Atlas Copco for this kind of job.
At Xcalibre we set to work to design and manufature these tamper pad diamteres, as we noticed that these were absent in the market place.
We now produce and stock 100mm diameter and 150mm diameter tamper pads.
So by matching the diameter of the tamper pad to the hole size, you will reduce the time back filling and in turn save you money.
COVID-19 poses a bunch of challenges for the world right now and we must all work together to help by following World Health Organisations and your own government's guidelines.
More information is available on the World Health Organisation website here https://www.who.int/
Xcalibre are proud to know that our equipment is used and trusted in the telecommunications, construction & aviation industries to support national infrastructure.