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lux eterna

Backlash Killer

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Hi all,

Pretty often I read about people having issues that may be related to backlash in DEC or RA, and I would like to offer a very simple and effective cure for it. I have done it on my HEQ5 Pro but surely it can be modified for any mount that needs it. With this simple fix, I can live with a rather big backlash (with no risk for binding in freezing temperatures).

For DEC, I always balance carefully (neither front nor back heavy). Then I stretch the coil spring until it has a small impact on the DEC balance (and later in the evening I eventually forget about loosening it when I slew away... so you will need some replacement springs. It took maybe 10+ of such mistakes until I stopped forgetting...). The bracket is only attached with double sided tape (on three sides), but the black maintenance plug (not original) also supports it.

7.jpg.3473f7ff17b51002432e4c00e61e12c2.jpg

 

RA is usually OK with just the standard method "East Heavy", but occationally the scope is poing due west or east (counterweights pointing north) and then there is no "East Heavy" impact. That is when I use this:

6.thumb.jpg.2eaf27d5d5f83e6d668cfb6262a5d53f.jpg

It´s a little hard to see in the pictures, but I get a momentum in RA (in reverse to tracking direction) when I tighten the string. Now, I happen to have the Rowan belt mod which includes a thick nylon spacer inside the gear cover, and that is a good thing here because it adds to the momentum. I usually hook it up an hour or two before the CW bar points due north. Then when it has well past north I will stop the camera, remove the backlash killer and re-adjust "East Heavy".

EDIT:  (Sorry, English is my second language...)  Should be a torque, not momentum.

Ragnar

 

Edited by lux eterna
Language issue
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