Unibor COMMANDO 40
Original Instructions
Nov 2019
8
9) REMEDIES FOR HOLE MAKING PROBLEMS
Problem
Cause
Remedy
1) Magnetic base
won’t 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 work-piece.
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.
Loose bolts on motor bushing support bracket, main
casting or loose gib adjusting set screws.
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
Adjust where necessary
3) Excessive
drilling pressure
required
Incorrectly re-sharpened, worn or chipped cutter.
Coming down on swarf lying on surface of workpiece.
Gib strips out of adjustment or lack of lubrication.
Swarf accumulated (packed) inside cutter.
Re-sharpen or replace.
Take care not to start a cut on swarf.
Adjust setscrews and lubricate.
Clear cutter.
4) Excessive cutter
breakage
Steel swarf or dirt under cutter.
Incorrectly re-sharpened or worn cutter.
Cutter skipping.
Slide needs adjustment.
Cutter not attached tightly to arbor.
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).
Tighten grub screws supporting the slide.
Retighten.
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 gear is used 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.
