Monarch Instrument POCKET-TACH 100 - Manual (Page 6)

CONTACT MEASUREMENTS
(Rotational Speed or Surface Speed)
POCKET-TACH can measure rotational speed by directly contacting a ro-
tating shaft or surface speed such as a moving belt or web. Contact mea-
surements require the use of the CTA-1 Contact Tip Assembly. CTA-1 is
attached to the lower side of POCKET-TACH with two Nylatch
® fasteners
which lock into mounting holes in the bottom of the instrument.
Attaching the Contact Tip Assembly (see Figure 1)
To assemble:
1. Pull back on the grips on the two Nylatch ® fasteners on the
Contact Tip Assembly to insure they are in the released (pulled
out) position.
CAUTION: Do not attempt to pull them beyond the unlocked
position (loose feel).
2. Insert the sight bars on POCKET-TACH into the correspond-
ing notch in the top of the Contact Tip Assembly (above the
window exposing the shaft).
Shaft
Contact Tip Assembly
Insert sight bars
into notch
POCKET-TACH 100
Nylatch® fastener
Figure 1 Attaching the Contact Tip Assembly
3
Notch
3. Push the Contact Tip Assembly flush against POCKET-
TACH so that the fasteners fit into the two mounting holes
on the underside of POCKET-TACH.
4. Secure the tip assembly by firmly pushing both Nylatch ®
fasteners until they snap securely in place.
5. Select either a convex or concave tip appropriate for the mea-
surement to be made and install it firmly on the shaft exten-
sion of the CTA-1.
NOTE: The rubber tips are keyed to mate with the shaft. En-
sure the surfaces mate correctly.
Contact Tip Selection
For rotational speed measurements, use the convex (conical) tip for
shafts equipped with a turned center. Use the concave (inverted coni-
cal) tip for smaller diameter shafts.
For surface speed measurements, use only the concave tip.
Making Contact Measurements
WARNINGS: Making measurements in direct contact with rotat-
ing equipment can be dangerous. Keep the hand
holding the instrument well behind the back edge of
the Contact Tip Assembly. Do not use this instru-
ment for contact measurements that exceed
20,000 RPM or 20,000 IPM.
To make a measurement:
1. Start the moving object to be measured.
2. For rotational speed measurements, carefully contact
the appropriate tip (convex or concave, see section 4.2
Tip Selection) against the axial end of the rotating shaft.
4