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c8 repair – RA lock position June 1, 2009

Posted by aquillam in Astronomy, telescope maintanance.
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This post is one in a series about C8 repair and maintenance.  You should see the introduction and disclaimers before trying anything here.

When mounted on an equatorial wedge, the telescope rotates in right ascension (RA) and declination (dec). The telescope needs to move freely to align it, but once aligned, you don’t want it to move too easily, so there are locks in both directions.  There are also fine motion controls for both directions. Below are instructions for adjusting the RA lock.  You might also want to check out the instructions for opening the base, dec fine adjustment, and the dec lock.

RA lock in unlocked position

RA lock in unlocked position

The RA lock is on the base, just above the fine adjustment knob. The open position is to the right (see image)

The fully locked position is to the left. Note that the telescope will not be immobile: you can still force it to move when locked.  However, this WILL damage the lock if done repeatedly.

Ideally, the lock will be snug when it is almost all the way left (see image below.)  This allows the lock to be fully engaged when pushed all the way over, but prevents overtightening, which can damage the lock.

RA lock in snug position

RA lock in snug position

To adjust the position, first remove the lock lever by loosening the set-screw(s). There may be two set screws, like the one in the picture below, or only one.

Removing the RA lock lever

Removing the RA lock lever

Use a regular screwdriver to tighten the lock, then back off until it is just snug.RA_lockAdj2

Replace the lever in the “snug” position.  If there are 2 set screws, be sure to tighten them both.

Lock and unlock the RA lock a couple times to make sure it is locking and unlocking at the positions you want.RA_locked

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