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Author Topic: Goto Inaccuracy, Missed Steps?  (Read 3513 times)

cuivenion

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Goto Inaccuracy, Missed Steps?
« on: March 09, 2017, 01:40:25 »

Hi. When using my Vixen GP tonight the gotos were way out and got worse the further the stars were from each other. I caught a few dull, quiet thump sounds coming from the motors while slewing. Only a few per slew. Normally when using goto my stars will be on the chip after my alignment, not dead center but near.

Now they're not on the chip and a spiral search won't find them. I've not noticed the thump noise before, could it be the belt slipping or the motor missing steps?

I do have the dec and RA quite tight to keep the backlash at a minimum. Could it be that I have it too tight?
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Zh

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Re: Goto Inaccuracy, Missed Steps?
« Reply #1 on: March 09, 2017, 08:26:33 »

This is with new beta firmware?
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cuivenion

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Re: Goto Inaccuracy, Missed Steps?
« Reply #2 on: March 09, 2017, 11:26:52 »

Yes, but I reloaded the old firmware and I was still having problems.
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cuivenion

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Re: Goto Inaccuracy, Missed Steps?
« Reply #3 on: March 15, 2017, 13:07:09 »

After a bit of indoor testing I reckon I had things too tight to avoid backlash. I've re-adjusted and am waiting for a clear night to test it out.
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TCWORLD

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Re: Goto Inaccuracy, Missed Steps?
« Reply #4 on: March 15, 2017, 16:16:44 »

It's quite possible if things are too tight or the motors are underpowered that you could be skipping steps and hence loosing accuracy.
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Tom Carpenter (AstroEQ)

cuivenion

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Re: Goto Inaccuracy, Missed Steps?
« Reply #5 on: March 16, 2017, 01:23:36 »

I could probably do with new motors these are the ones I have at the moment:

http://www.ebay.co.uk/itm/Nema-14-Stepper-Motor-1-8deg-Bipolar-0-5A-23Ncm-32-6oz-in-35x35x42mm-4-wires-DIY-/121684006515?hash=item1c54ee9673:g:35sAAOSw-vlVjiyC

If someone could recommend some more powerful ones that'd be great. I'm not really sure how to compare different motors. The RA was making terrible noises tonight when the mount went near the zenith. It always seems to perform great when I test it indoors and then something goes wrong outside >:(.

It's definitely mechanical, I'lljust have to try re adjusting again. The dec was fine. Just have to fine tune the RA now.
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