Re: RA Drift


Howard Dutton
 
Edited

On Fri, Jul 30, 2021 at 06:45 AM, Jamie Flinn wrote:
3.916667 _> 3.916....it dropped my stepsperdegree  just a smidge - it seems to have an effect - that number 3.91667 coms form a 48/12 spur gear - now I am using belt and I suspect that the tooth angle/pitch in spur gear actually has an impact that is not there with the belt (sure it has 48 teeth but not the same angles - My RA drift was enough that it needed to be reacted to which when guiding can cascade to other problems every time you must move, so trying to reduce the NEED for guide motions and it does seem to help - my gotos and platesolving are all still great...I am sure I will be tweaking further
Spur gear or timing belt.  It is a fact that the tooth counts determine the overall ratio right up to the point that the mesh of teeth/belt fails (belt rides up on top of the teeth for example.)  Sure there can be an (usually insignificantly small) higher/lower ratio with tooth form and whatever imperfections at play but it will average out to the exact ratio.

Since 48/12 = 4 that spur gear pair's average ratio is exactly 4:1 not 3.91667:1, or anything else.

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