Astronomy Hacks

Upgrade Your Dobsonian Bearings

Use Ebony Star and Teflon for butter-smooth motions.

Dobsonian telescope mounts move in altitude and azimuth on friction bearings. There are two double altitude bearings, one on each side of the telescope tube or mirror box. The scope pivots vertically from horizon to zenith on these altitude bearings, one of which is shown in Figure 3-30.

The scope rotates horizontally on one triple azimuth bearing, shown in Figure 3-31. On the left is the bottom of the circular baseboard, which is covered in Ebony Star laminate. The triangular groundboard, the top surface of which is shown on the right, has Teflon bearing pads applied directly over its feet. The two boards are loosely joined by the azimuth bolt, visible in the center of the groundboard. When the two components are assembled, the groundboard sits flat on the ground, with the baseboard above it.

When the Dobsonian scope is rotated in azimuth, the laminate surface rides on the Teflon pads, providing smooth movements.

Figure 3-30. An altitude bearing

Figure 3-31. The azimuth bearing

This arrangement seems simple enough in theory, but in practice there are three requirements for ideal Dob bearings:

• Ideal bearings have perfect friction, not too much and not too little. The friction must be low enough to allow ...