Johnson Level 40-6912 User Manual

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22X Builder’s Transit Level

Model No. 40-6910

Instruction Manual

Congratulations on your choice of this 22X Builder’s Transit Level. We
suggest you read this instruction manual thoroughly before using
the instrument. Save this instruction manual for future use.

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Table of Contents

1. Kit Contents

2. Features and Functions

3. Location of Parts/Components

4. Operating Instructions

5. Calibration

6. Technical Specifications

7. Care and Handling

8. Product Warranty

9. Product Registration

10. Accessories

1. Kit Contents

Description Qty.

22X Builder’s Transit Level 1
Instruction Manual with Warranty Card 1
Hard-Shell Carrying Case 1

2. Features and Functions

• Horizontal Circle - Graduated to single degrees and reads by
vernier direct to 15 minutes

• Vertical Arc - Reads to degrees 45-0-45º

• Horizontal Tangent Screw & Vertical Lock & Tangent Screw ­For precise movement control.

• Built-in Sunshade - For clear sighting

• Top Mounted Leveling Vial - For effortless viewing

• Large Leveling Screws - Easy to turn

• Versatile - Ideal for leveling foundations, driveways, patios,
floors, for grading street, curbs ditches for aligning fences; or
any other light construction job.

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3. Location of Part/Components

Focusing knob

Lock Lever

Vertical arc

Vertical vernier

Horizontal vernier

Vertical
tangent knob

Vertical lock knob

Leveling Vial

Eyepiece

Horizontal graduated
circle

Horizontal
tangent knob

Base

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Telescope
objective lens

Leveling screw

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4. Operating Instructions

IMPORTANT: It is the responsibility of the user to verify the

calibration of the instrument before each use.

Set-Up the instrument on the tripod

When setting up the tripod, make sure the three tripod points are firmly
into the ground and the top of the tripod head is as level as possible.
Adjust the height of the tripod to a comfortable viewing height, and
secure the retractable legs. Attach the instrument to the tripod head
with the center screw and tighten securely as shown in figure below.

Leveling

Mount the instrument on the tripod, lock the
telescope in place with the lock lever and line
up the telescope vial in position #1 as shown.
Then grasp screws A & B so that both thumbs
are moving in opposite directions, either
toward each other or away from each other.
Note that the bubble moves in the same
direction as your left thumb.

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Keep about half the length engaged. When the bubble is centered in posi­tion #1, turn the instrument and observe the vial in position #2. Now cen­ter the bubble in position #2 using only screw C. The instrument should
now be leveled, but to be certain, double-check. Rotate the instrument
180º so the vial is reversed. If the bubble will not center when reversed,
follow adjustment procedure outlined under “Bubble Adjustments.”

Aiming and Focusing

Rotate the instrument by hand to aim the telescope to the far object.
Rotate the focusing knob until the object can be observed clearly.
Rotate the horizontal tangent knob, to place the vertical cross hairs
on the object.

Reading the Vernier

The vernier is actually a double
vernier, that is, two verniers in
one. This makes it possible to
read any angle turned by the
telescope, whether to the right
or to the left. For example,
consider that you have turned
an angle to the left (counter­clockwise) after first having set the circle to read 0º. Refer to the
bottom figure, this is what your vernier looks like after having turned
the angle.

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In the illustration to the right, the index
has passed the 44 degree line but has
not gone as far as the 45 degree line.
In this case, the third vernier line from
the index is lined up with one of the
lines on the circle. Since each vernier
line represents 15 minutes add 45 minutes to the 44 degree reading
(3 times 15 minutes equals 45 minutes). Therefore our exact reading
is 44 degrees, 45 minutes (44º45’).

The Vertical Vernier.

In reading the vertical vernier, the principle is exactly the same as the
horizontal vernier. Note however, that the vernier is below the circle
portion rather than inside as in the case of the horizontal. One other
minor difference is that you will read angles up or down rather than
left or right. Here again is a double vernier. The right hand side
reads angles of elevation (up) and the left hand side reads angles of
declination (down). These are the only differences between the
horizontal and vertical verniers.

5. Calibration

5.1 Bubble adjustment

If the telescope bubble does not
remain centered after having
leveled the instrument, and
reversed the telescope end for
end (180º) (as described under the Leveling section) the need for
adjustment is indicated. Use a 3mm hex key.

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With an adjusting screw “A” facing to the right
of the bubble and with telescope directly in
line with two of the three leveling screws,

Bubble
level
screws

note to which side the bubble is off. If to the
left, loosen screw “B” and tighten screw “A”
very slightly to remove ONE-HALF the error.
Remove the other half of the error with the two level screws in line
with the telescope. If the bubble is still not exactly centered, repeat
the procedure. If bubble is off to the right, loosen screw “A” and
tighten screw “B”. Otherwise the procedure is identical.

5.2 Instrument accuracy check

Set up the instrument in an area that is as level as possible and which is
about 220 ft. long. Place two matching level rods about 200 ft. apart
with the faces toward each other. Position and level the instrument so
that the distance from the instrument to each rod is the same. (Fig. 1)

Fig. 1

Fig. 2

Take a reading on each rod with the instrument. Note the difference
and record them. Next, move the instrument to another point in line with
the two level rods as shown in Fig. 2. Level the instrument and take
readings on the two level rods. The difference should be the same
(A-A should equal B-B). The difference between A-A and B-B is
the instrument error at 200 feet.

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5.3 Instrument accuracy adjustment

If the error is more than 3/16” at 100’, it is
necessary to adjust the instrument.
When adjusting the instrument:

1. Remove rubber cover to expose the two
calibration set screws.

Using a 1.5mm Allen wrench, loosen the two calibration set screws.

2.

3. Rotate the eyepiece seat to make the crosshair center in the reticle of
instrument on the same level with a known reference point. Then
rotate the eyepiece tube to make the horizontal hair on the reticle of
instrument level by using a known level reference point.

4. Tighten the two set screws and restore rubber cover to its original
position.

5.4 Setting Points in Line with use of transit-level

Points A and B are two points which are on a line. Center and level your
instrument over point A; sight on point B. Bring vertical hair exactly on
point B by means of the tangent screw. A pencil held vertically at B is
useful to show this point. Depress the telescope to set points between A
and B on line.

Eyepiece seat

Set Screws

Eyepiece tube

If the top of a stake cannot be seen, when you come to set point C, sight
with the aid of a plumb bob: first, to find where to drive the stake, and
secondly, to note the point on the top of the stake. If it is necessary to
continue this line beyond point C, center and level your instrument over
point B, sight point C and continue this procedure.

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5.5 Determining difference in elevation
Measuring a difference in elevation from one set-up

To find the difference of elevation between two points which can be
observed from one position, set up and level your instrument about
midway between these points. Be sure that a leveling rod held on
both opposite points can be read when your telescope is level. Each
point should not be greater than 150 to 200 feet away from the
instrument or you may have difficulty reading the rods. The height of
the line of sight (horizontal crosshair) above or below each of the
points is found by reading the rod.

A line of sight 69 inches above A and 40 inches above B is shown
above. Therefore, B is higher than A by 29 inches.

Suppose one of your points is below the line of sight and the other
above (Fig. B), C is 4 feet 6-1/2 inches below the line of sight, and
point D, the underside of a floor beam is 7 feet 9-3/8 inches above
the line of sight (the latter reading having been obtained by holding
the rod upside down with the foot of the rod against the beam). D is
then higher than C by an amount equal to 4 feet 6-1/2 inches plus 7
feet 9-3/8 inches, or a total of 12 feet 3-7/8 inches.

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5.6 Measure the difference in elevation requiring more than

one set-up

If two points are either too far apart or at too great a difference of
elevation to be observed from one set-up, the procedure shown below
is recommended. This example assumes that you want to find the
difference in elevation between points A and D. To make the finding of
this difference simple, use the convenient terms plus (+) sight and
minus (-) sight and carry the readings at each set-up as shown.

The difference of elevation between D and A is found by taking the
difference between the sum of the plus sights and the sum of the
minus sights. If the sum of the plus sights is larger, the final point is
higher than the starting point. If the sum of the minus sights is larger,
the final point is lower than than the starting point.

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5.7 Stadia Distance Measuring

Distance measuring can be done using the stadia hairs of the reticle.

The distance between the upper stadia hair and the lower stadia hair is
set at a 1:100 ration. So if the difference is 1 foot, the person holding
the grade rod is 100 feet away from the instrument.

5.8 Measuring Horizontal Angles

To measure or lay out an angle, set the instrument over a point and
level it up. Use a plumb bob with about six feet of string. Attach the
plumb bob string to the hook under the instrument by means of a large
loop fastened by a slipknot and adjust the plumb bob until it is clear of
the ground point. By shifting the entire instrument, set the tripod
(keeping tripod head as level as possible by estimation) so that the
plumb bob appears to be over the ground point. Next, press the legs of
the tripod into the ground and lower the plumb bob until its point is
about one-quarter inch above the point on the ground. The final
centering of the instrument can be made by loosening the tripod center
bolt and slowly shift the instrument until the plumb bob is directly over
the point on the ground. Then retighten the tripod center bolt and
re-level the instrument.

To measure horizontal angles, such as FIG (Fig. 8), center and level your

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instrument over point F in accordance with previous instructions.

Rotate the instrument until point E is nearly in line with the vertical
crosshair. Turn tangent screw until vertical crosshair is on point E. By
hand set the horizontal circle to read zero. Swing the telescope
toward point G until the vertical crosshair is exactly on point G. Your
instrument is furnished with a vernier and you will be able to read the
angle closer than a single degree. The use of a vernier is explained
earlier in this manual.

Fig. 8

Fig. 9

In layout work, it is frequently necessary to set off an angle, usually
90º. Assume that the 90º angle HIJ is to be laid off and points H and I
are shown (Fig. 9). Therefore, J is the point you are to set.

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6. Technical Specifications

Telescope Erect
Magnification 22X
Leveling accuracy ± 3/16"/100 ft. (±5mm/30m)
Working range Up to 200’ (60m)
Minimum focus 4’ (1.2m)
Clear objective aperture 22mm
Field of view ± 2’/100 ft. (±0.6m/30m)
Number of lenses 5
Level vial 4’ per 2mm
Graduation diameter 110mm

Horizontal circle:
Graduations 1º
Number Each 10º, 0-90-0º
Vernier Double direct to 15 min.

Vertical arc:
Graduations 1º
Number Each 10º, 45-0-45º

Weight 2.204 lbs (1kg)
Center screw thread 5/8" - 11

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7. Care and Handling

Care must be taken to maintain the accuracy of the instrument.

• After each use, the instrument should be wiped clean and kept in

its carrying case.

• Remove dust from the lenses with a soft brush or a nonabrasive
wipe. Never tough the lenses with your fingers.

• Store the instrument in a dust-free area with low humidity.

8. Product Warranty

Johnson Level & Tool offers a three year limited warranty on each of its
products. You can obtain a copy of the limited warranty for a Johnson
Level & Tool product by contacting Johnson Level & Tool's Customer
Service Department, as provided below, or by visiting our web site at
www.johnsonlevel.com. The limited warranty for each product
contains various limitations and exclusions.

Do not return this product to the store/retailer or place of purchase.
Non-warranty repairs and course calibration must be done by an
authorized Johnson
warranty, if applicable, will be void and there will be NO WARRANTY.
Contact one of our service centers for all non-warranty repairs.
A list of service centers can be found on our web site at
www.johnsonlevel.com or by calling our Customer Service
Department. Contact our Customer Service Department for Return
Material Authorization (RMA) for warranty repairs (manufacturing
defects only). Proof of purchase is required.

®

service center or Johnson Level & Tool's limited

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NOTE: The user is responsible for the proper use and care of the prod­uct. It is the responsibility of the user to verify the calibration of the instru­ment before each use.

For further assistance, or if you experience problems with this product
that are not addressed in this instruction manual, please contact our
Customer Service Dept.

In the U.S., contact Johnson Level & Tool’s Customer Service
Department at 888-9-LEVELS.

In Canada, contact Johnson Level & Tool’s Customer Service
Department at 800-346-6682.

9. Product Registration

Enclosed with this instruction manual you will find a warranty
registration card to be completed for your product. You will need to
locate the serial number for your product that is located on the bottom
of the unit. PLEASE NOTE THAT IN ADDITION TO ANY OTHER

LIMITATIONS OR CONDITIONS OF JOHNSON LEVEL & TOOL'S
LIMITED WARRANTY, JOHNSON LEVEL & TOOL MUST HAVE
RECEIVED YOUR PROPERLY COMPLETED WARRANTY CARD AND
PROOF OF PURCHASE WITHIN 30 DAYS OF YOUR PURCHASE OF
THE PRODUCT OR ANY LIMITED WARRANTY THAT MAY APPLY

SHALL NOT APPLY AND THERE SHALL BE NO WARRANTY.

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10. Accessories

Johnson®accessories are available for purchase through authorized

®

Johnson
applicable limited warranty and there will be NO WARRANTY. If you need
any assistance in locating any accessories, please contact our
Customer Service Department.

In the U.S., contact Johnson Level & Tool’s Customer Service
Department at 888-9-LEVELS.

In Canada, contact Johnson Level & Tool’s Customer Service
Department at 800-346-6682.

dealers. Use of non-Johnson®accessories will void any

16 ©2013 Johnson Level & Tool - Rev. 2