Guiding issues with DEC deviations

[Thalestris24]

This is where we all start spending your money, Al!  Don't listen to us...

lly

The dark side... The slippery slope... The Money Pit!

[almcl]

Ha ha! Think I might have to wait till we get back from the family hols in Italy next month to announce "...oh, btw a couple of large boxes should be delivered in a day or so. They'll have a replacement mount in...."

Does the EQ6 (non goto) have an ST4 port that my GPUSB interface can plug in to? That would knock £130 off the price...

The good news is that I've just been out and twiddled the allen bolts on the Dec axis gears and there's almost no discernible slop there now. Even better, Clear Outside is forecasting two nights of clear skies!

[Uranium235]

Low weight, low cost, kill flexure=OAG

Stress, shouting, swearing = OAG

[lensman57]

Thanks all for the thoughts and info.

Definitely going to tighten up the gear train - there's a bit of slop on the motor gears, as well as on the worm, so reducing that will be first task. Not using the finderscope mount but a home fabricated set of tube rings and bar, piggybacked on the OTA's mounting rings. I'll try a slight modification to these although I don't think flex has been an issue so far.

I do like Olly's idea of an elastic tie down, must have a look at that one when I've worked out which way I should go!

Hi,

The belt drive is not all that has been made out to be. The budget Synta mounts like others use a worm gear system as well as the cogs to run the mount. A belt drive conversion will only take out the slop in the cogs and the back lash in the worm gear train still remains. It does improve the pointing accuracy to some extent and will also make the mount quieter during the fast slews  so you are not at a loss with your EQ5. If you decide to take out the slop in your gears by tightening them you should still leave a very small amount of free movement between the gears. If totally tightened up the stress will eventually cause the gears to fail. You could use a small amount of high pressure grease between the gears to negate the effects of backlash and to help to make the mount sound quieter and smoother. When I had my EQ5 I found out that excessive play in the worm gear train was the main cause of getting elongated stars in particular if the polar alignment of the mount was not spot on as the guiding software was trying to correct both the RA and DEC with little success and ending up over correcting and then trying to pull it back like a YoYo.

Regards,

A.G

[kalasinman]

Stress, shouting, swearing = OAG

Not here.

[Thommy]

Be careful, though. You shouldn't tighten it too much. I'm not sure, but on the picture you posted it seems a little too tight already. There should be a little slop.

/Thommy

[ollypenrice]

I think OAGs begin as a proverbial proverbial pain and end in sweet contentment but I only undertake this journey when I have to, which is with long FL and reflectors.

Olly

[almcl]

Just to round this one off, I rebuilt the guidescope mount replacing a steel strip with a more rigid aluminium bar, remade the mounting rings and tightened up the worm gear. The resulting guide graph is a lot smoother now:

[goose35]

I had this prob last night on my first proper guiding run. I know for a fact i have dec backlash that ive tried 2 times to tune to no avail. I think a dec strip and clean is needed