Unibor EQ35 Manual
Original instructions
Apr 2020
8
9) REMEDIES FOR HOLE MAKING PROBLEMS
Problem
Cause
Remedy
1) Magnetic base
will not hold
effectively
Material being cut may be too thin for efficient
holding.
Swarf or dirt under magnet.
Irregularity on magnet contact or workpiece.
Insufficient current going to magnet during drilling
cycles.
Attach an additional piece of metal under the
magnet, or mechanically clamp magnetic base to
workpiece.
Clean magnet.
Use extreme care; file any imperfections flush to
surface.
Confirm power supply and output from control unit,
check supply cable.
2) Cutter skips
out of centre-
punch mark at
initiation of cut
Magnetic base is not holding effectively.
Worn arbor bushing and/or ejector collar.
Too much feed pressure at start of cut.
Cutter is dull, worn, chipped or incorrectly
sharpened.
Poor centre-punch mark; weak pilot spring; pilot not
centred in centre-punch mark.
Worn or bent pilot, worn pilot hole.
See causes and remedies above.
New arbor bushing is needed.
Light pressure only is needed until a groove is cut.
The groove then serves as a stabilizer.
Replace or re-sharpen. Sharpening service is
available.
Improve centre-punch and/or replace worn parts
Replace part or parts
3) Excessive
drilling pressure
required
Incorrectly re-sharpened, worn or chipped cutter.
Coming down on swarf lying on surface of
workpiece.
Swarf accumulated (packed) inside cutter.
Re-sharpen or replace.
Take care not to start a cut on swarf.
Clear cutter.
4) Excessive
cutter breakage
Steel swarf or dirt under cutter.
Incorrectly re-sharpened or worn cutter.
Cutter skipping.
Insufficient use of cutting oil or unsuitable type of
oil.
Incorrect speed
Remove cutter, clean part thoroughly and replace.
Always have a new cutter on hand to refer to for
correct tooth geometry, together with instruction
sheet.
See causes and remedies (2).
Inject oil of light viscosity into the coolant-inducing
ring and check that oil is being metered into cutter
when pilot is depressed. If not, check pilot groove
and arbor internally for dirt or apply oil externally.
(Even a small amount of oil is very effective).
Ensure correct speed is use for the cutter.
5) Excessive
cutter wear
See cause and remedy above
Incorrectly re-sharpened cutter.
Insufficient or spasmodic cutting pressure.
Refer to instructions and a new cutter for proper
tooth geometry.
Use sufficient steady pressure to slow the drill down.
This will result in optimum cutting speed and chip
load.
