|Optic-Craft Machining has developed
a completely new clock-drive that meets the exacting needs of today's
astronomical community. The operational characteristics are unique
and are not available from other drive manufacturers.
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Features and Specifications
- Drives produce one revolution in 1436.3 minutes +- 3 ARC second per
- Gear Specification
- Both 6" & 9" drives have 32 pitch main worm gear, with
companion worm. All gears are precision ground and lapped. R.M.S. lead
variation does not exceed .00007". AGMA level international standard
- Worm gear is made from high tensile strength aluminum & worm is
made of stainless steel. Secondary worm/worm gear is made of bronze
and stainless steel.
- All Worm gears are anodized a light gold color. There is no extra charge
for this service and is included within the cost of each clock drive gear
assembly. Many manufacturers charge extra for this
- Gear Mesh Load
- The worm mounting plate assembly is tension loaded to the 6"
& 9" gears. This flotation action eliminates all gear backlash
& maintains 100% tooth to tooth engagement. This is a patented mechanical
- Protective Coatings
- Use white gear grease for long term protection on gear teeth.
- Both 6" & 9" drives deliver 2060 in oz. torque at worm.
Slip clutch will manually produce 50 ft. lbs. Minimum gear train torque
at polar shaft 2200 ft. lbs.
- Worm Housing
- Housing is plate mounted. Pre-load of secondary bronze motor change
gears are established at time of manufacture. Main worm bearing blocks
are pre-lubricated and are machined to within .0003 ". Worm shaft
lateral end play is canceled by two worm shaft thrust bearings and two
thrust washer clamps and two roller bearings.
- Slip Clutch
- Clutch surface area is 70% of gear. Clutch faces are lined with pressure
pads. The material provides an excellent gripping surface. Also, a .250"
thick keyed aluminum thrust plate locks gear in place.
- Motor Speed Control
- Because of the precision of our drive assemblies, a motor speed control
is not needed. If customer prefers one, we recommend the "Accutrack"
Model 2361 which varies AC line fi-equency. 12 V. D.C. input 110-115
V. A.C. output or the "Accutrack" Model 3117 which varies
the A.C. line frequency and has both 12 V. D.C. and 110 V. A.C. input.
Output 110 V.A.C. They are available from Orion
Telescope Center. Also, for those wanting to construct their own
A.C. line frequency controls the following is available from Willmann-Bell
- For GO-TO applications, we suggest the AWR system.
Please visit their GO-TO web site for more information.
- The Back-Plate
- Worm motor assembly is screwed onto the housing surrounding the polar
shaft, on the telescope mounting. Three threaded 1/4-20 screw holes
are provided either vertically or horizontally placed, based on the
customer's need. Back plate assembly. clearance hole cannot come into
con- tact with polar shaft. State clearance hole diameter required when
order is placed within 1/16" increments.
- Slip Clutch
- Clutch is engaged by turning threaded pressure plate clockwise by
gripping one or more of the three knobs provided. This will provide
approximately 80 foot lbs. of torque. If further torque is required,
screw down each knob clockwise which allows an additional 50 to 60 foot
lbs. of clutch pressure.
Subject to Change
Always contact us
- D.P. - Diametrical Pitch
- Worm gear rate - The speed of the rotation of the worm in RPM to yield one turn of the main gear once each sideral day or once every 1436.3 minutes
- Sec. gear ratio - Input turns vs. output turns of the additional gears that match the worm rate to the input shaft which is designed for 1 RPM standard. The numbers above are approximate. (other rates are available)
- RPM - Revolutions per minute
Before purchase always verify specifications with Contact Optic-Craft
* - OPTIC-CRAFT MACHINING larger precision designed
clock drives incorporate the following features as standard equipment:
- Bore shaft sizes up to 8" I.D. at no extra cost
- All worms made from 303 stainless steel.
- All worms mounted in precision sealed taper / roller bearing housing
eliminating both radial and axial movement while affording a smooth
turn- ing action. This bearing block design is used on 16". 20"
and 24" drives.
- 600 in oz. HURST AC synchronous motor provided on all models over
9 inches in diameter.
- No assembly required. Drives incorporate unitized construction design
attaching to your mounting simply within minutes.
The nearest comparable California manufacture of clock drives charges
an additional amount for these standard OPTIC-CRAFT features and this
does not include unitized one piece construction.
** - On 20" and 24" drives customers specialized
housing and mounting plates will be considered as part of purchase price
that may deviate from OPTIC-CRAFT support plate design.
All drives are assembled with HURST synchronous hysteresis
reversible motors 110 volt 60 cycle. 220 V 50 cycle can be obtained by
using a step down transformer.
Provide The Following Dimensions When Placing An Order:
- Measure polar shaft diameter to within + .0015" of an inch. Use
- State clearance diameter of back plate hole to within 1/16 of an inch
& whether you require vertical or horizontal mounting holes.
Need 3" polar shaft length to accommodate thickness of clock-drive
- Maximum bore size available on clutch is 3.5" from 3.5"
to 5" add $45.00 to order for special machining. This applies to
6" & 9" drives only.
- Delivery - 5 to 8 weeks from receipt of order.
- Warranty - 5 years parts & labor.
- Shipping - C.O.D. United Parcel Service shipping charges only U.S.A.
& Canada. C.O.D. Air Mail only foreign orders.
Myths about Gear Specifications
There are some myths that have been communicated by advertisers
over the years that include statements like, patented production techniques
that make a drive train accurate or that aperture size & gear diameter
should be the same. The facts are all drive manufacturers must conform
to recognized machining & machine tool national standards that have
been the guideline for instrument manufacturers for more than 50 years.
If a gear is made to a A.G.M.A. standard or class 15 then that class defines
its accuracy. It is one of the few systems that the manufacturing community
recognizes. Aerospace gearing is class 14. Optic-Craft gears are class
15. Our 6.6" gear is just as accurate as our 20.0" gear. As
protection to you as a consumer, ask the manufacturer what class of gear
they produce in order to test their advertising claims.