Grouting, Levelling, and Anchoring Flashcards
(34 cards)
What is the accuracy of a master precision level?
Each division is sensitive to within 0.0005 inch per foot on its main horizontal vial.
Why should the master precision level be allowed to acclimate to ambient temperature before use?
It is extremely sensitive and even minor temperature changes affect the accuracy of this level.
What is the auxiliary transverse vial on a master precision level used for?
To check that the level is positioned correctly (on the apex) when levelling a shaft.
What is the accuracy of a precision level, also known as a mechanic’s or machinist’s level?
It has a sensitivity of 0.005 inch per foot per division.
What is the longitudinal V-groove on a precision level used for?
Enables it to be used to level shafts accurately.
What is the accuracy of a bench level or carpenter’s level?
0.020 inch per foot or only 0.1 of a degree.
Is a bench level or carpenter’s level accurate enough to level most equipment?
No.
What is a plumb bob used for?
By tying the free end of the string to a bracket mounted to the top of the machine to be checked and dangling the bob on the end of the string, the side of the machine can be checked for vertical alignment (plumb).
What is one drawback to the stability of a plumb bob?
It is extremely sensitive to drafts and vibration.
How are the limitations of a plumb bob overcome by performing a wire alignment?
The plumb bob is stabilized in oil.
The limitations of a plumb bob can be overcome by using hardened steel piano wire (typically 0.020 inches diameter) with a heavy weight on the end immersed in a pail of oil.
How is an ohmmeter and inside micrometer used to check vertical alignment during a wire alignment?
An ohmmeter is connected to the wire and an inside micrometer. The ohmmeter indicates when the inside micrometer touches the wire and completes the circuit. When the readings are identical at the top and the bottom, the surface being aligned is vertical.
What is a horizontal wire alignment used for?
To check the levelness of a machine or base.
What is a horizontal wire alignment used for?
To check the levelness of a machine or base.
How does a horizontal wire alignment check for level?
The wire is tensioned by hanging a known weight over a roller at one end. Wire sag charts should be consulted to determine the amount of sag for the horizontal distance, wire size, and tension used.
For example, if the distance between wire supports is 25 feet, the sag in the wire at
4 feet 0 inch from one end is 0.012 inch. At 4 feet 6 inch from the other end, the sag is 0.013 inch. Measure the vertical distance from the wire to the machine surface and add the amount of sag from the chart to obtain a corrected vertical height. When all corrected readings are the same, the surface is level.
How does base plate mounting work?
Simple and complex rotating machinery is often assembled on skids or baseplates. These skids can be set in place on a foundation and then levelled, anchored, and grouted in place. These separate machines should then be aligned to each other.
How does sole plate mounting work?
Individual machine units may be set on heavy steel plates that have been either set into the foundation or mounted on structural steel supports. Sole plates may also be individual plates under each foot rather than one plate for the whole driver or driven.
What type of levelling feet do small lightweight equipment use?
They are often provided with levelling feet or levelling screws in the bolting flange on the equipment base, similar to those on domestic appliances such as washing machines.
When using levelling feet, how is the anchor bolt typically secured?
It is usually sealed into and anchored into the concrete pad or floor.
If the anchoring bolt is situated beside the levelling foot, what can happen to the equipment base as the anchor bolts are tightened?
Distortion of the equipment base as the anchor bolts are tightened.
How can distortions of the equipment base be avoided when using an anchoring bolt with levelling feet?
To avoid distortion, the anchor bolt can be installed through the center of a hollow levelling foot (Figure 10D) or a levelling nut and a locknut can be used on an anchor bolt (Figure 10E).
Why can some equipment not use levelling feet?
Some equipment is too heavy for levelling feet, or it vibrates so much that the levelling screws would shake loose.
How are wedges and shims used to raise and level heavy or vibrating equipment?
Wedges (Figure 11A) and jacking bolts are used to raise heavy equipment and shims (Figure 11B) are then inserted to support these machines at the correct elevation.
The wedges should then be removed and the shim grouted in place.
How are shims constructed and what are their typical sizes?
Shims are pieces of thin, flat steel that range in thickness from 0.001 up to 0.125 inches.
What size sheet brass and plastic shim stock can be used to level lightweight equipment?
Up to 0.025 inches.
