19
Overhead drilling
!
You must install a water extracting device.
!
Connect a wet vacuum cleaner to the extracting device and switch it on.
!
Open the water supply and make sure that the water reaches the seg-
ments before you start drilling.
When drilling overhead take special care that no water gets into the tool. In case
you notice during drilling, that the advance speed decreases considerably, that
you have to increase pressure and that the water emerging out of the bore hole
is clear and mixed with metal splinters, you have probably hit reinforcement iron.
Reduce the pressure on the drill bit and switch to the next lower gear if possible
so that you may cut through the reinforcement without problems.
Once it is cut through, you may increase pressure and speed.
Extension of the drill bit
In case you have to drill deeper than the working length of the drill bit permits:
!
At the outset, drill only as deep as the working length permits.
!
Remove the drill bit and take the drill core out of the drilled hole without
moving the core drilling installation.
!
Put the drill bit back into the drilled hole.
Install an appropriate extension between drill bit and motor. If the drill bit holding
fixture is 1¼ “ do not forget the copper rings to facilitate the loosening of the drill
bit.
In case that a diamond segment, parts of the reinforcement or similar loosens
during drilling and the drill bit thereby gets jammed, stop working on this bore
hole and drill a hole with the same centre and a 15 to 20 mm greater diameter.
Do not try to finish drilling with a different bit of the same diameter!
After you have finished drilling:
!
Pull the drill bit out of the bore hole.
!
Switch the motor off.
!
Close the water supply.
Breaking of a segment
After drilling
