Currently the drives exist in the following models:
RA mk III
The RA drive consists of a new shaft of 303 stainless (and optional worm if you don't want to carve apart the Meade drive entirely) mounted in the original carrier against the original wheel, a flexible beam coupler, two small flange bearings, a stub shaft of 5/16" 303 stainless, 50 tooth and 10 tooth timing belt sprockets a 200 step NEMA23 stepper, a belt and brackets, all mounted on 8 rubber isolation mounts. Most of the drive can be fabricated at home by a careful hobbyist with a drill press, vice and hand tools. Some modification of the flexible coupler **is needed, and requires a lathe or very very careful work in a drill press. Periodic error is a possible result of the drill press method but is not absolutely going to occur.
DEC mk II
This drive consists of an over the counter worm and wheel made of Brass (wheel) and Steel (worm), a 5:1 gear box, a single beam flexible coupling, a 200 step NEMA 17 stepper motor and the needed brackets. The brackets are all home fabricated and can be fabricated by the hobbyist with a drill press and a penchant for detail. Some modification of the flexible coupler ** is needed, and requires a lathe or very very careful work in a drill press. Periodic error is a possible result of the drill press method but is not absolutely going to occur.
The mk IV drive which is in the planning stages will eliminate the gearbox and use the timing belt setup like the RA drive. Either setup will work, but the gearbox version is more compact.
** This coupler can be special ordered in the proper size but will require a quantity purchase.
Notes on both drives
The drives can be made to run with smaller motors. These drives as you see them will run the scope fine with the RA 5 pounds and the DEC 3 pounds out of balance!!
Use of a super wedge requires spacing the telescope up 1 1/2 inches to provide clearance on the RA drive. I am currently trying to locate a standard wedge to confirm my feelings that no spacer will be required.
Mk IV Drives
1/04/05
During the last 3-4 months I have been quietly converting another LX50 mount. This mount incorporates some new design and noise abatement techniques. I am using NEMA17 sized steppers instead of the NEMA23's. The new steppers are also 400 step as opposed to 200. These two changes alone have reduced the bulk and current demand of the system. The gearboxes have been eliminated and replaced with several micro toothed timing belts. The entire RA drive fits inside the base casting. The only external portion of the DEC drive is a 3/8" wide timing belt running up the back side of the West fork arm.
I am waiting for the correct timing belts to arrive (est. 11/Jan/05) and subsequent clear weather for testing. The drives are strikingly quiet and smooth. An information CDROM is in the works and should be available in about 6 weeks for those who want to tackle this project and don't want to spend the time and money experimenting with mail order parts and the time delays that go with them.
Here's some teaser images of the RA drive (not fully completed):
Minus the 2 belts and one sprocket for the stepper motor. In this view the worm has not been pinned to the shaft so don't email me about the poor mesh of the gears!
Here's a couple shots of the nearly completed DEC drive. The shaft is supported by needle roller bearings and has ball bearing thrust.
Lower end of the DEC drive. Stepper is fully supported in rubber. Intermediate shaft (below) is supported with needle roller bearings also.
All that remains to finish is shortening and milling the flats on the shafts.
Here's a sample drawing from the CDROM:
Reproduction on this page of the drawing is substantially less sharp than the drawings on the CDROM.