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Marking the workpiece
According to the measures in the technical drawing the marking is transmitted by a pencil and a marking gauge onto the piece of work. Thereafter the bore centre is prepunched to achieve an accurate placing of the drill point.
Figure 9 - Marking and
punching the bore centre
Selecting and clamping the drill
According to the type of the bore and the material the suitable drill shall be clamped.
Pay attention to a firm clamping of the drill!
Clamping or placing of the piece of work
Smaller workpieces are fastened on the machine table to avoid a snatching up or a twisting during drilling. Large workpieces are placed on the machine table and held by an assistant.
To avoid fraying out of wood fibres on the off-side of the bore a solid wood support should be placed under the workpiece.
In any case the workpiece should be secured against snatching up or twisting!
The prepunched bore centre must be adjusted exactly under the drill point.
Figure 10 - Adjusting the bore
centre under the drill point
1 drill, 2 workpiece, 3 solid wood support, 4 machine table
Carrying out the bore
Switching on the machine the drill is put into revolving movement. Now the drill is pressed on the workpiece by the feed lever. After having finished drilling the machine should be switched off.
Pay attention to a good chip flow during drilling!
Only sharp drilling tools should be applied!
Why are bore centres
prepunched?
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What should be paid attention to when placing the workpiece on
the machine
table?
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How can fraying out of wood fibres on the off-side of the bore
be
avoided?
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Checking the bore
After drilling the dimensional stability of the bore, its
diameter and depth as well as the quality of the bore edges are checked. Wood
particles and unclean bore edges are faults which must be eliminated. In that
case the bore should be countersunk
slightly.
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