TM 9-4910-579-14&P
TROUBLESHOOTING AND SERVICE TIPS
THE BORING TOOL
The tool bits used in this machine are tungsten carbide and are extremely hard and brittle. The tool should
never be lowered until it strikes the top of the cylinder to be bored and it should never be allowed to snap out
against the face of the micrometer. Rough handling in this manner may not show evidence of cracking at the
time, but as soon as the tool is put in service, a chip will fall out due to this rough handling.
If the belts on the machine become worn or oil soaked and have a tendency to slip, you will, also, find that tool
bit breakage is a problem. The feedscrew in the machine is gear driven direct from the motor and if the belt
slips under heavy cut, the feedscrew will continue to feed the tool. This extreme pressure will snap off the end
of the carbide.
Extreme overloading of the machine will, also, break the carbide tip because, if the cut is so heavy that the
machine stalls while cutting, the spring back caused by shutting off the motor or taking the machine out of gear
will snap the end from the carbide tip.
CHATTER
Chatter trouble may develop during the boring operation due to several different causes and a listing might
possibly help you to locate the cause should this trouble occur.
1
- Sleeve bearing adjustment too loose.
2
- Boring tool needs lapping or sharpening.
3
- Width of Number 2 face on boring tool too wide.
4
- Tool bit not locked securely in tool holder.
5
- Top of engine block not smooth, giving a poor clamping surface for the base of the machine.
OUT-OF-ROUND CYLINDERS
You may find that after boring a cylinder, removing the boring bar and checking the cylinder with an inside
micrometer, the bore does not check round. If this out-of-roundness shows up through the whole length of the
bore, it probably is due to overclamping of the Cylinder Boring Machine, which has distorted the block. When
the Cylinder Boring Machine clamp is released, the cylinder will return to its original position giving an out-of-
round bore.
If the out-of-round condition in the bore checks excessively at the bottom and is not apparent in the top of the
bore, this trouble is caused by an improper sleeve bearing adjustment which allows the tool to bore out-of-round
when it is boring at a position with the sleeve farthest extended from the base. It is sometimes difficult to
determine if this variation is all out-of-roundness or part taper and part out-of-roundness.
When this condition exists at the bottom of a hole, it is important that you first check the sleeve bearing
adjustment to eliminate the possibility of any out-of-roundness.
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