Page 2 of 5 FirstFirst 1234 ... LastLast
Results 11 to 20 of 43
Like Tree13Likes

Thread: Drive system help

  1. #11
    AustinPSD's Avatar
    AustinPSD is offline Super Moderator
    Points: 56,828, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 2.0%
    Achievements:
    200+ Posts Achievement!First 1000 Experience PointsGot three Friends20+ Friends Achievement!5+ Referrals Achievement!
    Join Date
    Sep 2009
    Location
    McDonald Observatory, Mt. Locke
    Posts
    6,921
    Points
    56,828
    Level
    100
    Thanks
    743
    Thanked 5,863x 3,113 Posts
    Blog Entries
    1

    Default



    An Introduction to Drive Systems for German Equatorial Mounts (GEM) - Basic Issues & Considerations

    This technical note is intended to supply basic information regarding sidereal rate motor drive/clock drive systems applicable to German Equatorial Mounts (GEM) and variants, including equatorial fork mounts.

    In general, it is desirable to motorize a telescope mount for a number of reasons:

    - to allow the mount to move the telescope it carries to automatically track the apparent rotation of the stars
    - to support computer-controlled, automated pointing of the telescope at a specific celestial coordinate or object
    - to allow long-exposure astrophotography (imaging) using film, CCD or CMOS based imagers
    - for supporting one or more of these functions

    A GEM has two axes; the Right Ascension (RA) axis and Declination (DEC) axis. The DEC axis is the simplest in operation, this axis of motion allows the mount to point the telescope in the altitude dimension. The DEC axis is driven during pointing operations, and driven for brief intervals during declination corrections, typically by an observer who is manually correcting the mount/telescope tracking manually through use of an off-axis guider, or automatically by a CCD camera and computer/controller system that supervises the guiding function. During normal operation, the DEC axis is not in constant motion, in contrast to the drive on the RA axis.

    The RA axis is in constant operation during tracking. This axis moves the telescope in the equatorial direction, to compensate, or track the apparent motion of the stars relative to the fixed position of the telescope/mount and observer on Earth. There are typically at least two drive rates, or "speeds" on the RA axis, usually "slow" and "fast", although most drive systems support more than two ( 1/2X, 1X, 2X, 4X) speeds. The 1X "speed" is the normal, or "slow" motion drive rate on the RA axis, also known as the sidereal rate.

    Motor driven mounts typically incorporate a hand-held controller used to provide directional control, speed control, and perhaps other functions to manage the RA and DEC axis drive systems. Mounts intended for long-exposure astrophotography usually include auto-guider interfaces, the de-facto standard is known as ST-4, initially developed and marketed by Santa Barbara Instruments Group (SBIG) for their line of CCD imaging and guiding cameras. Advanced functions may also include GPS systems or GPS interfaces, allowing the mount to determine its spatial and temporal location (latitude, longitude, and time), an electronic compass (to assist in aligning the mount to celestial north, also known as Polar Alignment), interfaces for object coordinates (GOTO capability), interfaces for planetarium software (GOTO and pointing assistance), Periodic Error Correction (PEC), mount and other status indication for interfacing with an observatory control system, etc.

    A basic mount for visual observation will typically include the sidereal rate clock drive for at least the RA axis, usually a motor drive for the DEC axis, and a hand-controller to operate the RA and DEC axes.

    A more advanced mount for imaging use will include the aforementioned functions, along with an ST-4 or other auto-guider interface, as well as support for PEC.

    Primary Drive Types:

    The primary drive includes the drive motor(s), drive gearing, including any intermediate or final drive reduction gearing used to provide smooth rotation of the RA and DEC drive shafts.

    There are numerous mechanical drive systems ranging from very simple to very complex, including worm and worm wheel (Byers Type), roller drives, roller/belt drives, reduction gear trains, and so on. This technical note will examine the Byers-type, or worm gear/worm wheel drive system.

    Some authors refer to the worm wheel as "worm gear", "wheel", or "segment wheel", and the worm gear as "worm". For this technical note, the worm gear will always refer to the "worm", or spiral-cut worm gear, or worm shaft. The worm wheel always refers to the large spur-cut gear driven by the worm gear, which in turn drives either the RA or DEC shaft.

    The simplest primary drive consists of a large toothed gear known as a worm wheel, and matching worm gear (or worm shaft, which integrates the worm gear with the shaft itself) with a typical reduction ratio of either 144:1 or 360:1.

    On the RA axis these ratios correspond to one revolution of the worm in 10 minutes (144:1) , and to one revolution in 4 minutes (360:1), which represent 1x sidereal tracking allowing the RA axis to follow the stars at the correct rate.

    Ideally, the worm wheel should the same diameter, or larger than the diameter of the main mirror or telescope aperture. A higher tooth count on the worm wheel results in overall better performance, both in terms of drive ratio reduction (minimizing the required motor torque and drive current), backlash recovery time, and periodic error.

    The worm wheel and worm gear must have a close, precision mesh. The worm gear concentricity/centering with the drive shaft must be near perfect, an in the case of a worm shaft, concentricity is generally easier to achieve because the worm and shaft are machined from one rod, and are integral on the same turning center.

    The worm gear shaft bearings must have very little, and ideally adjustable end play and pre-loading.

    The mesh precision, shaft end-play and loading all affect backlash, especially during direction changes. Some implementations use mesh adjustment mechanisms, including spring pre-loading, alignment and pressure capability to tune the mesh between the worm gear and worm wheel.

    Due to machining tolerances and precision limits, periodic errors will almost always be present, and will manifest themselves with a period of one revolution of the worm gear/shaft.

    Periodic error will show up as positive and negative corrections that are required to provide a steady drive rate and maintain accurate tracking when following the stars.

    This is purely due to mechanical machining tolerances of the worm gear, and to a lesser extent worm wheel. The periodic error can be reduced by increasing the diameter of the worm gear/shaft, because the effect of machining error and tolerance is reduced by averaging the error out over a larger travel distance.

    Commercial, off-the-shelf electronic drive systems compensate for most of this error - using a technique called Periodic Error Correction (PEC), the control system "learns" the fundamental periodic error present in the mount and load combination, and "trains" itself to automatically retard, or speed up the drive pulses to the motors to correct the error.

    Some drive systems incorporate shaft encoders, designed to create a pulse counter to keep track of the number of revolutions of the worm gear, worm wheel and their absolute position relative to an index.

    It is much preferred to fabricate a low-error, high precision drive (or buy one) than to rely purely upon control system PEC, as even with the most sophisticated and expensive drive control mechanism there is only so much correctable error that can be obtained/eliminated through the a PEC mechanism.

    The Byers-style drive mechanical components include in the simplest form a drive motor, coupled to the worm gear/worm shaft. In turn, the worm gear meshes directly with the worm wheel, through which the RA or DEC drive shaft is coupled. This approach reduces backlash by minimizing the number of gears in the reduction system, utilizing high-precision machining of the worm gear and worm wheel, and multiplies torque effectively, via the high reduction ratio of 360:1 in the best examples of this drive system.

    This also allows for a technique known as "short coupling", intended to minimize mechanical moment, torsion stresses and mechanical error by keeping the RA and DEC axes shafts to a minimum length.

    Backlash:

    Without ultra-precision machining and near zero mechanical tolerances, a drive system will exhibit backlash to some extent. Backlash occurs due to mesh errors between the worm wheel and worm gear/shaft, or in multi-gear reduction drives from the accumulated mesh and rotational error in the gears comprising the drive train.

    Backlash is most noticeable in the DEC axis, when attempting to take up accumulated "slack" in the gear train, and because of potentially frequent directional changes. It is next most noticeable in the RA axis when direction changes or corrections for PEC functions are executed, and when moving the drive opposite its normal clockwise direction of rotation. A technique for minimizing backlash in the RA direction is to always slew to objects using the same direction of rotation on that axis.

    Depending upon the drive reduction ratios, it can take from 1 (360:1) to as many as 4 (144:1) seconds to recover from accumulated backlash in the drive. A drive correction system can reduce the recovery time by temporarily speeding up the drive motor above the sidereal rate until the accumulated lash is eliminated.

    In general, backlash equates to a constant error in either DEC or RA upon initiating a movement or direction change on that axis. As previously mentioned, the backlash error can be minimized on the RA axis by always moving the drive on that axis in a constant direction (i.e. don't reverse the drive when slewing to an object), and in DEC by using pulse width "bump" control on the DEC axis to maintain the gear mesh in constant tension (i.e. take up the drive slack).

    Drive Rate:

    In tracking the stars, the telescope must be driven at the sidereal rate of 1436.07 minutes of arc per revolution.

    In practice, this will produce some error for long exposure photographs due to atmospheric refraction. The DEC error can be corrected by moving that axis as necessary, either by manual operation of the DEC axis while guiding, or via an auto-guider (ST-4 based) interface to the drive motor control.

    This refraction-oriented distortion/error causes the apparent position of an imaged object to be shifted towards the zenith.

    The error significance is based on the relative DEC (altitude) bearing for the object being imaged. It is greater for objects lower on the horizon, less for objects higher on the horizon or nearer the zenith.

    The normal RA drive rate corresponds to an axial movement of 15 arc-seconds per second.

    Torque Requirements:

    The available torque required to turn the DEC and RA shafts must overcome friction in the shaft bearings and related support components in the mount, as well as move the weight of the telescope on the respective axis.

    Once the mount components and telescope are rotating, especially during a fast slewing operation, considerable momentum is developed, which in turn requires sufficient torque to "brake" or stop the movement.

    In fast slewing operation, the inertial mass also means that extra torque is required from the motor to accelerate the load from its normal slow (or stopped/parked) mode.

    Additional instrument and component load on the telescope (eyepieces, cameras, spectrographs, etc.) also increase its inertial mass, as well as creating balance/counter-balance issues. These weight and balance issues must be accounted for in the overall mechanical design, as well as in computing the drive motor torque requirements.

    If the telescope and mount combination is not balanced, then gravity acts on the out-of-balance weight to produce an additional torque. In turn, this adds or subtracts to the total torque, and may lead to the condition where the total load may be too much for the motors. This effect shows up as directional stalling, where the motor can drive in one direction but stalls when driven in the other direction. In the negative case, if the drive motor cannot supply sufficient reactive torque, the mount may "overrun" in that axis.

    Drive Motors:

    There are three basic types of drive motors; Synchronous, DC, and Stepper. A fourth type, the Servo is a specialized drive motor capable of very high precision movement when coupled with an appropriate control system. With regard to this technical note, servo motor systems are outside the scope of discussion because of cost and complexity of implementation. There are some commercial systems that use low-cost servos (ex. Sidereal Technology, Sidereal Technology) however they are intended for providing drive capability to Dobsonian mounts.

    The drive motor must supply enough power to turn and accelerate the RA or DEC axis shaft, and must also provide a steady, controlled sidereal drive rate. The motors and/or control system should also provide a means of directional control, rotational speed adjustment (fine and coarse, for example to support fast slewing operation).

    The accuracy required in the drive motor, and overall drive itself is dependant on the intended use of the mount and telescope.

    For visual observing an error of 1 arcminute in 15 minutes of time is tolerable. This corresponds to about 0.5% error.

    For astrophotographic imaging use, an error of 1 arcsecond over 15 minutes of time is considered acceptable. This is less than 0.01% error and can only be achieved with high-precision machining, assembly, and a motor control system using high-precision oscillators/timing circuits. With added precision control, error rates down to 0.0022% are relatively easy to achieve.

    Whatever drive motor is chosen, it must have the capability to drive the DEC and RA axis shafts either directly, or through a reduction gear train, and for the RA axis with the required accuracy in sidereal motion. The drive motor must have sufficient torque, or be able to develop sufficient torque through the drive reduction gearing to support normal rate motion, fast slewing operation, and overcome mechanical inertia in the mount/scope combination related to balance and acceleration/braking operation.

    Stepper Motors:
    The stepper motor is a low voltage system and is relatively easy to drive and control.

    A stepper motor can be driven down to zero steps per second, reversed, and ramped up to high speed, in the order of 300 steps per second using relatively simple drive electronics.

    There are stepper motors with wide availability that can be driven to 10000 steps per second using more sophisticated drive electronics.

    Stepper motors are typical on most commercially available mount/drive systems.

    Synchronous (AC) Motors:
    The synchronous motor is designed to be supplied by alternating current (AC) mains systems between 120V to as much as 480V 50Hz/60Hz.

    There are several drawbacks to the use of synchronous drive motors:
    - Isolation transformers and ground-fault protection systems are generally required, as the drive components may be exposed to water during inclement weather.
    - Frequency stabilization is generally required, as there is an allowable error "tolerance" in utility/mains supplies that will affect the drive rate accuracy
    - For synchronous drive motors under high loads, torque control systems must generally be used if the mains frequencies are varied to control the motor speed
    - The use of synchronous motors places restrictions on the usable drive reduction ratios (144:1 is typical).

    Synchronous motors are rarely, if at all used on portable or small mount systems, and are more common, and appropriate for permanent observatory installations, especially where very large working loads are involved.

    DC Motors:
    A DC motor system generally has higher torque than stepper motor system, and can typically run at higher speeds during fast slewing operations.

    Motor control systems for DC drives are more complex than for stepper-based systems. The Meade LX200 is an example of a contemporary DC drive motor mount. DC systems also may emit more noise, which can be a nuisance in certain applications.

    Precision control of DC drive systems generally require shaft encoders on the motor output shaft itself, as well as on the driven RA and DEC shafts. The control systems use positional information from the encoders on the motor output shaft and other drive-train components to control speed, provide acceleration and deceleration curve data during speed changes, and compute speed related error on the RA drive for correction purposes.

    This is the end of the introductory section of this technical note. The next section will examine motor and control systems in depth, along with mechanical integration of the motor and drive into a GEM mount.
    fevil and dynamo like this.

  2. The Following 10 Users Say Thank You to AustinPSD For This Useful Post:

    admin (01-07-2010),barek (12-28-2010),dynamo (09-28-2012),jonesy311 (03-11-2012),LeFanch (10-18-2011),mikec (01-07-2010),Moonrider (01-10-2013),saturn1970 (12-04-2009),tk1138 (03-22-2011),WWPierre (01-07-2010)

  3. #12
    saturn1970's Avatar
    saturn1970 is offline Main Sequence
    Points: 9,379, Level: 67
    Level completed: 10%, Points required for next Level: 271
    Overall activity: 0%
    Achievements:
    10 Days registered365 Days+ Registered Achievement!First 1000 Experience Points750 Days+ Registered Achievement!1000 Days+ Registered Achievement!
    Join Date
    Nov 2009
    Location
    Oxford uk
    Posts
    66
    Points
    9,379
    Level
    67
    Thanks
    5
    Thanked 6x 4 Posts

    Default

    Thanks again for your help.

    This is fantastic.

    Cheers Matt

  4. #13
    saturn1970's Avatar
    saturn1970 is offline Main Sequence
    Points: 9,379, Level: 67
    Level completed: 10%, Points required for next Level: 271
    Overall activity: 0%
    Achievements:
    10 Days registered365 Days+ Registered Achievement!First 1000 Experience Points750 Days+ Registered Achievement!1000 Days+ Registered Achievement!
    Join Date
    Nov 2009
    Location
    Oxford uk
    Posts
    66
    Points
    9,379
    Level
    67
    Thanks
    5
    Thanked 6x 4 Posts

    Default

    Hi AustinPSD

    I am looking forward to your next installment - when you get a chance.

    Cheers Matt

  5. #14
    AustinPSD's Avatar
    AustinPSD is offline Super Moderator
    Points: 56,828, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 2.0%
    Achievements:
    200+ Posts Achievement!First 1000 Experience PointsGot three Friends20+ Friends Achievement!5+ Referrals Achievement!
    Join Date
    Sep 2009
    Location
    McDonald Observatory, Mt. Locke
    Posts
    6,921
    Points
    56,828
    Level
    100
    Thanks
    743
    Thanked 5,863x 3,113 Posts
    Blog Entries
    1

    Default

    Hopefully in the next couple of days - I've been working on a CAD model of a hypothetical mount along with the control system... should be worth the wait.
    CGEM 800 HD, NexGuide,
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    XT8 Limited Edition, Oberwerk BT-100, Canon 20D/20Da/T3i/60D/5D Mk III, various eyepieces, adapters, geegaws, widgets, and tiddlybits

  6. #15
    saturn1970's Avatar
    saturn1970 is offline Main Sequence
    Points: 9,379, Level: 67
    Level completed: 10%, Points required for next Level: 271
    Overall activity: 0%
    Achievements:
    10 Days registered365 Days+ Registered Achievement!First 1000 Experience Points750 Days+ Registered Achievement!1000 Days+ Registered Achievement!
    Join Date
    Nov 2009
    Location
    Oxford uk
    Posts
    66
    Points
    9,379
    Level
    67
    Thanks
    5
    Thanked 6x 4 Posts

    Default

    Great this sounds interesting

  7. #16
    mikec's Avatar
    mikec is offline Bright Giants
    Points: 10,156, Level: 69
    Level completed: 69%, Points required for next Level: 94
    Overall activity: 0%
    Achievements:
    10 Days registered200+ Posts Achievement!First 1000 Experience Points365 Days+ Registered Achievement!3 Years + Achievement
    Join Date
    Nov 2009
    Location
    Northwest Indiana
    Posts
    347
    Points
    10,156
    Level
    69
    Thanks
    156
    Thanked 101x 85 Posts

    Default

    Can't wait for part 2 Austin. Very interesting! Thank-you for taking so much time for our benefit. -Mike
    Mike
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.


    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    ED120 Refractor (fl=900mm - f/7.5) on an EQ5 mount, Zhumell Z-10
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    (fl=1250mm - f/4.92). Canon 15x50 IS Binos, Canon Rebel XI
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    (1000D),
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    Starshoot DSI II and all the accessories I can afford for now (unless you guys tell me different)
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.

  8. #17
    WWPierre's Avatar
    WWPierre is offline HYPER GIANT
    Points: 64,445, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 0%
    Achievements:
    10 Days registered3 Years + Achievement400+ Posts AchievementGhost Achievement! Averaging 5+ posts a day!1000 Days+ Registered Achievement!
    Join Date
    Jun 2009
    Location
    Squamish B.C.
    Posts
    6,948
    Points
    64,445
    Level
    100
    Thanks
    1,095
    Thanked 2,953x 1,808 Posts

    Default

    Quote Originally Posted by AustinPSD View Post
    Hopefully in the next couple of days - I've been working on a CAD model of a hypothetical mount along with the control system... should be worth the wait.
    What is your cad platform, Austin? Did you build the cad model of the scope in your sig?
    Meade 16" LightBridge; Celestron G-8N Bird-Jones/motorized EQ5;
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    127 Mak/go-to EQ5; Burgess 127f8 refractor; Sky-Watcher 5" F/5 collapsible dob; 90mm Mak/motorized EQ2; Royal Astro 76/910-GEM; Meade 60x700 refractor/alt/az; Zhumell 25x100 Coin Ops; GalilleoScope. Celestron 8mm-24mm zoom; lots of fixed EPs,some good, some..not so much. A small collection of surveying instruments; a forest of tripods; Canon Rebel Xti. Confirmed gadget junkie; Custodian of the Magnetic North Pole (Send $1.00 to Pierre each time you use a compass.)
    49-41-37.03N 123-09-29.61W Calculated magnetic declination: 17° 39' East

    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.


    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.


    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.

    We have been broadcasting our presence to the Universe for 100 years now. If there is a detachment of Galactic Pest Control within 100 light years, they are already on the way.

  9. #18
    AustinPSD's Avatar
    AustinPSD is offline Super Moderator
    Points: 56,828, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 2.0%
    Achievements:
    200+ Posts Achievement!First 1000 Experience PointsGot three Friends20+ Friends Achievement!5+ Referrals Achievement!
    Join Date
    Sep 2009
    Location
    McDonald Observatory, Mt. Locke
    Posts
    6,921
    Points
    56,828
    Level
    100
    Thanks
    743
    Thanked 5,863x 3,113 Posts
    Blog Entries
    1

    Default

    I use BRL-CAD:

    BRL-CAD | Open Source Solid Modeling

    The learning curve is steep, but it is open-source and has pretty rich capability.

    I used it for the CAD rendering in my signature...
    CGEM 800 HD, NexGuide,
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    XT8 Limited Edition, Oberwerk BT-100, Canon 20D/20Da/T3i/60D/5D Mk III, various eyepieces, adapters, geegaws, widgets, and tiddlybits

  10. #19
    AustinPSD's Avatar
    AustinPSD is offline Super Moderator
    Points: 56,828, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Overall activity: 2.0%
    Achievements:
    200+ Posts Achievement!First 1000 Experience PointsGot three Friends20+ Friends Achievement!5+ Referrals Achievement!
    Join Date
    Sep 2009
    Location
    McDonald Observatory, Mt. Locke
    Posts
    6,921
    Points
    56,828
    Level
    100
    Thanks
    743
    Thanked 5,863x 3,113 Posts
    Blog Entries
    1

    Default

    Just checking in - I'm running a bit behind on my planned release update of this material.

    I'm having infrastructure problems, including some cranky issues with BRL-CAD's output formatting module, related to producing printed versions of the CAD solid model and mechanical drawings for the mount. I hope to have this solved today.

    I am also waiting for a FEM run on the mount design to complete for final check data. Its just slow, as it runs as a distributed background task on my network.

    If these don't complete in a satisfactory time frame, I'll do an intermediate "punt" and publish the textual narrative tonight or tomorrow morning, and update with the verified FEM model and engineering drawings as they are available/complete.

    FWIW, the mount design is based on a pier-supported plate, short-loaded shaft and pillow-block equatorial design using Beyer's style worm-shaft/worm gear DC-stepper drives. I created the design to support a 160Kg working load (up to 80Kg of OTA/imaging gear), that is also intended to be linearly scalable up, or down for different working loads.
    Last edited by AustinPSD; 01-13-2010 at 04:33 PM. Reason: missing chunk of OP for some reason...
    CGEM 800 HD, NexGuide,
    To view links or images in signatures your post count must be 5 or greater. You currently have 0 signatures.
    XT8 Limited Edition, Oberwerk BT-100, Canon 20D/20Da/T3i/60D/5D Mk III, various eyepieces, adapters, geegaws, widgets, and tiddlybits

  11. #20
    saturn1970's Avatar
    saturn1970 is offline Main Sequence
    Points: 9,379, Level: 67
    Level completed: 10%, Points required for next Level: 271
    Overall activity: 0%
    Achievements:
    10 Days registered365 Days+ Registered Achievement!First 1000 Experience Points750 Days+ Registered Achievement!1000 Days+ Registered Achievement!
    Join Date
    Nov 2009
    Location
    Oxford uk
    Posts
    66
    Points
    9,379
    Level
    67
    Thanks
    5
    Thanked 6x 4 Posts

    Default

    Great i am looking forward to it.

    Well done on the promotion.

    Regards Matt

 

 
Page 2 of 5 FirstFirst 1234 ... LastLast

Similar Threads

  1. Replies: 1
    Last Post: 05-21-2008, 02:41 PM
  2. Replies: 0
    Last Post: 04-30-2008, 12:24 AM
  3. Using an Autostar to control a large Dob drive system .(?)
    By Gary Heath in forum Amateur Astronomy Forum
    Replies: 1
    Last Post: 11-20-2004, 12:08 PM
  4. Ion drive
    By Fred Williams in forum General Astronomy Forum
    Replies: 0
    Last Post: 08-08-2003, 04:27 PM
  5. Ion drive
    By Brandon Siegel in forum General Astronomy Forum
    Replies: 0
    Last Post: 08-07-2003, 08:14 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Powered by vBulletin® Version 4.2.0
Powered by vBulletin®
All times are GMT. The time now is 11:23 AM.