Clamshell And Rotating Ring Combinations.
For up to 12" tubes. E-mail for larger sizes and shipping estimates
About Our Ring Sets:

We offer two types of ring sets. Clamshell and Rotating Rings. This allow mounting your telescope tube without the need for drilling holes for altitude bearings, or for imaging tube assemblies that do not require altitude bearings.

The clamshell rings close securely using 2-1/2" thumbscrews (visible in the two top left images) which fit transversally though the center of one side of the top clamshell connecting set into a corresponding 1/4-20 insert in the abutting connector. Loosen the thumbscrew to move your tube forward or back, or turn for easier eyepiece position. The rotating ring is contained in a clamshell ring and is essentially the same as the clamshell, but provides easier rotation of the tube for near-effortless repositioning of the focuser for more convenient/comfortable eyepiece and finder locations. When your telescope is pointed low to the horizon, turn the eyepiece upward, when near zenith, turn the tube so your focuser is pointed toward the side where you're not leaning far over the telescope. Especially convenient with telescopes that track equatorially!

Clamshell Rings For Equatorial Heads:

Custom designed to your preferred design and dimensions. We match your dovetail plate or equatorial head hole size and center to center dimensions. Inside diameter of rings are designed to be 0.125" larger than your tube diameter, providing 0.0625" spacing for adhesive backed felt or other material to secure your tube precisely.
Clamshell Rings For Dobsonian Mounts:

Same as above,except instead of mounting plate, we add a set of bearings on the sides of the clamshell to match your mount's inside width dimensions between the side boards. Bearings can be small up to 12" O.D., or large up to 18" O.D.
Second Ring Set For Second Tube:

Available for either equatorial mounting or on Dobsonian mount, this is second set of rings attaches with four 1/4-20x1.0" socket head bolts. Note in the left photo, the left side shows one half of the front ring set removed showing a 1/4-20 threaded insert in the clamshell ring segment. The second set of smaller inside diameter ring segments bolt into the first, as shown in the right photo. In the right photo you can see the smaller diameter ring outside the larger one, at the back. Just let us know the second tube's outside circumference.
Clamshell Rings With Internal Rotating Rings:

This works for both equatorial head mounting or on a Dobsonian mount. We combine our clamshell rings, described above, with an internal rotating ring cut to fit within 0.125" of your tube, allowing you to fit to your preference with adhesive backed felt strip or other materials. The internal ring freely rotates inside the outer clamshell. A Nylon set screw through the front outer ring tightens to your preferred friction against the inner ring, or locks it completely. The inner ring rides on Teflon pads inside the back outer ring. Simple and efficient design.
Kit: All parts included, wooden parts are rough sanded with 80 grit, holes predrilled. All parts dry-fitted before shipping. Kits may be shipped worldwide. What you'll need: Philips screwdriver, sandpaper, wood glue, adhesive backed felt to line inside of rings.

Materials:
CNC precision cut 3/4" Baltic Birch plywood. Anodized heavy duty aluminum piano hinge. Steel wood screws. Clamshells open and close using a 2-1/4" thumb screw that passes through one of the top boards into a 1/4-20 brass threaded insert in the abutting board.
Type ID Clamshell Rings
Price
Kit CR Drilled for Equatorial Head Mounting.
$85.00
Kit CRSB With Small Bearings up to 12" for Dobsonians.
$95.00
Kit CRLB With Large Bearings up to 18" for Dobsonians.
$100.00
Kit CRAS Additional set of smaller diameter ring segments.
$45.00
Clamshell Rings with Internal Rotating Rings  
Kit RR Drilled for Equatorial Head Mounting. $185.00
Kit RRSB With Small Bearings up to 12" for Dobsonians. $195.00
Kit RRLB With Large Bearings up to 18" for Dobsonians. $200.00
Order:
Tube diameter:
Second tube diameter: