| Established in 1952 | |
Page: 2450 |
| CMM-24 |
The Giant Metrology Tripod is shown with a Giant Ball Bar, priced separately. |
Part Number: GBB-TRI Up until now, there have been two forms of Metrology Tripods available. There is a huge lumbering steel one that is very rigid but can only be moved on rollers. There is no way to compact this giant one for storage. Then, there is the portable one that is made of lightweight but high expansion aluminum. It can be quickly folded up and carried away, but it is neither rigid nor dimensionally stable. The alternate to these is a tubular Invar® tripod that is very dimensionally stable, reasonably portable, and is made rigid through design not brute mass. The tubular Invar® has the extremely low rate of thermal expansion of .68 micro inches (.017 micrometers) per inch per degree F. which makes this tripod impervious to nominal temperature changes. The expansion of this material is one twentieth that of aluminum and one tenth that of steel. |
The all in line construction of this Tubular Invar® Metrology Tripod gives it unparalleled stability. Although its design is somewhat more intricate, than standard tripods, this design increases the stiffness by a full order of magnitude compared with the conventional out board construction. The upper ends of the six, three quarter inch (19mm) diameter Invar¨ tubes, that form the tripods legs, are rigidly glued into deep counter bores in the one and one quarter inch (31 mm) diameter hardened and lapped steel spheres. These hardened and precision lapped steel spheres are clamped, under tension, into matching spherical seats in the bottom (not on the side, as with conventional designs) of the rugged one and one half inch (38 mm) thick upper bulkhead. The lower ends of these six tubes are rigidly glued into three rugged steel blocks that form the upper end of the foot assemblies.
The lower ends of these steel blocks terminate in one and one quarter inch ( 3l mm ) diameter hardened and lapped steel spheres. These spheres have a deep; three eighths of an inch (9.5 mm) threaded hole that is used to clamp them in solid contact with the mating spherical seats in the rugged steel blocks. These are the same blocks that terminate the tubular Invar® legs. The bottom of these large diameter hardened steel spheres locate in matching spherical seats of the rugged two inch (5 l mm) diameter feet of the Tripod.
The rugged one and one half (38 mm) thick top bulkhead can be configured to hold any instrument package. This adaptation may range from kinematic couplings to hold a Giant Ball Bar (Dumbbell) to male threads to hold an Optical Level, a Jig Transit or a Theodolite.
The top bulkhead is 48 inches (1.2 meters) above the floor. The footprint of this tripod is a giant 60-inch (1.5 meters) diameter. This large circle provides excellent mechanical stability. The lower bulkhead and horizontal support structure is only slightly above the three feet to provide the maximum stiffness. The lower bulkhead provides an additional platform for location and support of a measuring machine or calibration devices. The strict in line design of the three legs and the lower horizontal support mechanism provides three distinct pockets that allow up close operation of instruments that are attached to the rugged bulkheads.
The mechanical rigidly and temperature stability of the Tripod are extremely important, because the Tripod becomes an integral part of the instrument package mounted on it.
A reasonably low weight for the Tripod is important, so that a single technician can do any repositioning required. This complete Tripod weighs in at under 40 pounds (18 KG).
The full operation of this Tripod requires no hand tools of any kind. There will be no time lost, looking for missing wrenches.
This Invar® Tripod will fold up for easy transport and compact storage. To fold up the Tripod, first remove the three hex hand knobs at the bottom that secure the legs to the horizontal struts. Now remove the three horizontal Invar® struts by unscrewing them using the large hex hand knob attached to each. Next, remove the three special plastic knobs that are screwed into the bottom surface of the upper bulkhead. Now replace them by screwing the horizontal struts in their place. These three special knobs are then used to secure the three legs of the Tripod to the side of the lower bulkhead. After folding the Tripod, the 40 pound (18 KG) device can be carried away by the center support strut.
There is a carrying handle available as an accessory. This handle, Part Number H-40, clamps onto the center Tubular Invar® strut for easier transport.
There is a secondary platform, Part Number PLT-96, available as an accessory. With this platform the overall height of the Tripod is adjustable from 50 inches (1.3 meters) all the way up to 8 feet (2.5 meters).
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Tripod shown holding 500 pounds
| Part # | Description | Price | Purchase |
| GBB | GIANT BALL BAR | $1900.00 |  |
| TRI | TRIPOD FOR GIANT BALL BAR | $1900.00 | |
| GBB-TRI | GIANT BALL BAR WITH TRIPOD | $3800.00 | |
| < CMM-23, Portable Arm CMM calibration |
http://www.precisionballs.com |
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