1. THE TOP ROCKING PLATE (TRP): A triangular platform on which swivels the Dobsonian telescope. Three curved "feet" are attached to this top plate. These curved "feet", allow the top plate to rock equatorially through a 20 degree arc, corresponding to 80 minutes of tracking. 2. THE BOTTOM SUPPORT PLATE (BSP): This plate sits on the ground. Mounted to it are the two north "roller" bearings and the three south bearings which all support the top plate and allow it to rock equatorially. 3. THE DRIVE SYSTEM: This includes the motor(s) and motor controllers that allow the TRP to move in a true equatorial tracking motion over the BSP. More details and specifications of the various drive systems we offer on our Platforms can be seen in the “Platform Models” section below.
We build our Platforms in small production runs of 15-18 at a time. That way, each unit can get a lot of care and attention as it goes through more than 100 construction steps. There is no getting around it: an Equatorial Platform is a tricky device to make well. There are a multitude of bearing surfaces that all need to be lined up precisely with their respective bearings. There are quite a few angles that need to be measured and cut to high degree of accuracy. Clearances for all the parts as the Platform moves during its tracking need to be allowed for and built in. The drive controllers and motors have to be mounted to close tolerances. This is where our 18 years of experience in designing and building Platforms comes in handy! We know what works. We have a clear idea of the sequence of steps needed to produce the final product. And most importantly, we never give up seeking ways to improve the design, the appearance, and the performance of our Equatorial Platforms. As extra insurance that our customers receive a perfectly functioning Platform right out of the box, we star test and calibrate every unit before it is shipped. That’s right, no Platform is allowed to leave our hands until it has been actually used under observing conditions, even if that means delaying shipping until after a clear night. That’s part of our guarantee that you won’t be disappointed when purchasing one of our Platforms.
All of our Platforms utilize the best materials available. The wooden Platforms are manufactured from Apple-ply or Baltic Birch plywoods. Or, for those who want their Platform to match their Starmaster or Tectron telescope, then a grade A Red Oak Plywood is used. Solid hardwood rails - either Maple, Alder, or Oak - are added as stiffening members. A lot of care is taken with the finishing of the wooden Platforms, beginning with a three step sanding process. The wood is then oil stained (unless it is getting a clear finish) and finally an outdoor polyurethane is applied in several coats for a long lasting finish that matches your telescope. The Aluminum Platforms use square and rectangular aluminum tubing that is carefully cut, jigged up and welded. This makes for an extremely rigid but lightweight structure. The welds are then ground flat for a neat and seamless appearance. The final finish on the aluminum is an extremely durable, impact-resistant powder coat finish. The drive components, bearings and bearing supports are of similar high quality. We do quite a bit of the metal fabrication in-house with a 12x36 precision lathe and Bridgeport mill. The remaining metal work is contracted out to selected machine shops that have the needed specialized equipment. Many of the Platform parts, especially the bearing supports, are custom designed and machined out of heavy wall aluminum extrusions. All of the finished aluminum pieces are black anodized for durability and a pleasing appearance. All of the Platform fasteners are of stainless steel or anodized aluminum for maximum corrosion resistance. The bearings themselves - there are 5-12 in each Platform - are roller or needle bearings designed to handle many times the weight of the telescope. They make for an absolutely smooth tracking movement. What a pleasure to view an object at high power as it hangs there motionless in the center of the field!
Our wooden and our welded Aluminum Platforms come in two basic models, the Standard Single-axis and the Standard Dual-axis. Both types are similar in size and appearance. Both offer the same peerless tracking. The two models differ primarily in respect to their drive components.
The Single-axis Platform drive utilizes one stepper motor which is mounted to one of the north roller bearings. As this motor turns it causes the top rocking plate (and the telescope that sits on it) to move equatorially. A hand control with a quartz drive microprocessor allows the exact sidereal rate of tracking to be tuned in. Additionally, push buttons on the hand control offer a two-speed slew in Right Ascension for centering objects in the field of view. This whole drive system runs off of an included 12V DC rechargeable battery, perfect for use at remote dark sky sites. If you are primarily a visual viewer, then the Single-axis Platform is a perfect fit.
The Dual-axis Platform utilizes two stepper motors connected to the RA drive roller and one stepper motor connected to a DEC drive. A micro-processor mounted on the Platform controls these stepper motors. The Platform is powered by 12V DC, either by an optional built-in battery or by a user supplied power source. The included hand control allows one to fine tune the tracking rate and gives one a two-speed slew in both RA and DEC for centering objects in the field of view or on a CCD chip. You can also do auto-guiding with the Dual-axis Platform, using commonly available auto-guiding cameras. Bottom line, for those who wish to do any kind of imaging (including video viewing with a MallinCam type camera), the Dual-axis Platform, with its slew controls in both RA and DEC, is a necessity.
Setup and Use
2) Polar alignment for visual use is
easy. After the Platform is leveled, make sure its center line points
roughly toward Polaris. See the illustration at left. During the day a
compass can be used, taking care to allow for the true/magnetic north
offset for your location. Quick and accurate polar alignment can also
be done with our new
Polar Alignment Tool. For astro-imaging, more accurate polar alignment
can be achieved with the standard star-drift
method, as with any equatorial mount.
4) Now place your Dobsonian telescope on the Platform. Most of our customers have the Platform configured as a new groundboard for their telescope. The top of the Platform has a center pivot and three teflon pads to accept the rocker box of the scope (after the stock groundboard has been removed). This arrangement is very stable and keeps the eyepiece height as low as possible. However, we can also configure the Platform to accept the whole telescope with its stock groundboard. For some scopes, such as the Teleports, that is a more feasible arrangement. The larger and heavier telescopes can be brought up onto the Platform using a low set of ramps. Here is a nice illustrated story of how one of our customers gets his 20” Obsession on his Platform.
5) Now just turn on the RA drive motor (using the "off-on" switch on the control panel) and you are tracking! Grab the scope and move it, just like always. There are no clutches or levers to disengage. Wherever you point you are tracking, quietly and precisely. Break out those high power eyepieces you seldom used in the past, and get the views you should be getting. Call your friends and neighbors over - everyone gets to observe for as long as they want with no hassle. With tracking you will flat out see more - it’s like adding inches to your mirror.