Older Equatorial Mount Conversions

Due to an increase in the popularity of converting older, heavy duty German Equatorial Mounts, a web page about the conversion process for these types of mounts follows. 
In order to have us complete a conversion for you, we must have the mount here. We can't stress this enough.  Do consider that your large mount will typically hold a 16" or larger mirror. This is up toward professional observatory class.  A few hundred dollars for shipping is not that far out of line. 
 

• The complete conversion of a GEM, with 1.5 - 2" shafts for example, will typically cost between US$1400.00 - US$2500.00. 
• Customers who already have some of the needed parts, (laptop, gears, the bare PCB, steppers etc.), will be charged less if the parts are suitable. However, we have yet to convert a large GEM for less than US$1400.00. 
• A servo version not requiring a laptop in the field can be ordered. Cost is a few hundred above the stepper system. 
• The total conversion cost depends on the gear ratio you are wanting on the scope. For visual use and short ccd work, a small 180:1 Dec. gear and the stock 180-360:1 RA gear will work great. It is a little cheaper too. Long exposure CCD work requires a little more gearing and costs a little more. (the gears cost money and the modifications to hold them in place cost money). This is assuming that you have a good 359/360:1 RA gear.
• Toothed belts and pulleys are required on all conversions to achieve the recommended arc second per microstep value for good tracking. 
• Once converted, your mount, if it is in decent mechanical shape, can easily achieve sub arc second pointing accuracy. This is verified on a recent DS-16 conversion, by the owner. 
• Astrophotography is easily accomplished using one of the large old GEM's. Periodic error for the gearing is CANCELED ENTIRELY with the use of the standard error correction routines in Mel Bartels software. This is made possible by the use of microstepping the stepper motors and special error correction routines in the software (included).
• The use of expensive gears is not necessary. We typically recommend using our own shop made worm gears. 
• Encoders are not needed on a geared GEM. The steppers are plenty accurate as they are. If you are wanting to use a second computer and another planetarium program, you can certainly add them to your mount. You can use Guide8 with the systems if you like a planetarium program. There is a page on our site that covers how that works too.
• We can deliver telescope mounts in person just about anywhere in the US. The fee for this is typically at or below what it costs to mail the scope. If you live nearby, we can show you how to operate your scope here. We now have a custom made crate for shipping to and from your location/nearby terminal. 
• There is a manual for using GEM's listed in the interactive support page.
• The typical mount needs only to have 180-360:1 gearing on each axis if you use a 400 step/.9degree stepper motor (this is what we typically use on all our conversions). Should you wish to use the mount for 'serious' astrophotography, I do recommend a 500:1 gear ratio or more on each axis. This can be achieved with a toothed belt & W/W gear system. 
• Because we use microstepping in the software, there are 40 microsteps to each full step of the motor, the need for ultra low PE gearing is no longer required. The mathematical pointing accuracy of a 400 step motor with only a 500:1 gear ratio is .162 arc seconds. You can further diminish this by adding to the gear ratio if you so desire.
• Slewing speeds will be around 3 degrees per second if you use a 360:1 gear ratio on each axis. The higher the gear ratio, the slower the slew speed. Flywheels added to the steppers can increase slewing speeds by a factor of 2.
• Since most of these mounts will be in an observatory, we do recommend using a laptop to operate the software. Most observatories are small and an added desktop/monitor will take up more space.
• Laptops can be bought from E-Bay for $50-$125 daily. Specifications and comments about the laptops can be found on our "About the Computer" page.
• You can interface scope with any program that supports LX-200 commands. It does require a null modem cable and another computer, typically a Pentium or faster.
• You must use another computer to do CCD work. Scope.exe can't be run at the same time on the same computer as a ccd program. The scope driving laptop is used real time mode via DOS. 
• Mount time away from you will be on the order of 4 weeks. We typically charge you at least half of the total cost up front, order all the parts, get most of it ready for conversion and then get the mount from you for conversion. This way we don't have mounts filling up the shop waiting on parts. You don't loose your mount for very long either.

Do keep in mind that our scope control system is extensive and has been tested and used by hundreds of scope owners of a period of many years. It is not a 'hobbled together' system that will give you problems most of the time and rarely work properly.

When a scope is properly converted, installed and the end user knows how to operate it, it's accuracy and performance will astound even the most critical observer. When you consider what others pay for something that performs only half as well, you truly do get more than you pay for with this system.