Using clocks for drives

[Luke Inup]

Quick questions:

Would a good electric clock be strong enough to drive an equatorial mount? (An EQ drive is just a clock is it not?)

Thanks in Anticipation

JonJon

[ronin]

You have to drive the scope weight, the counter balance weights, the mount casing and everything and there is friction involved.

So scope say 5kg, counter weights say 3kg, general mounts casing say 1kg. So 9kg at present, add in friction.

Agreed that they should be balanced, just they never are perfectly, however they still have to be moved so you have to get the whole mass up to speed, then maintain it

You will need a fairly big clock motor.

[brantuk]

Big Ben maybe? lol

[Bazzaar]

Clocks used to be used 100+ years ago. Or more correctly, clockwork drives were used.

There is absolutely no reason to use them today, electric motors are vastly superior.

Regards

Barry

[nightvision]

Large clockwork mechanics were used decades ago, a friend made a tracking mount from a wind-up clock back in 1968. Took some great lunar and wide-field shots.

[Bizibilder]

The sorts of clocks used to drive mounts were similar to "Church Tower" clocks - capable of holding a three foot long minute hand still on a windy day!! Modern electric clocks have (or use) virtually no power at all - although you could use a modern clock to be "master" of some other mechanism.

By the way - modern household clocks and watches are not particularly accurate - far less so than a reasonably good quality clockwork clock. I have made several clock movements (my other hobby) and all have been capable of better than one second per week.

[Telrad]

There's a good example of a Clock Drive at Aldershot Obs

[Si W]

Also depends on what you are tracking, Solar, Luna, or Siderial, all different rates, so three clocks rolled into one.

[Luke Inup]

Okay... Thanks folks.. Back to the drawing board then!

I had heard of the accuracy problem with small clocks. Which is why I use a clockwork, Half-Hunter, as my personal timepiece.

reminds me:

I was standing beneath the Chamberlain Clock in Hockley, Birmingham one day in 1965, when some old chap suddenly darted into the road and started traffic dodging. He came up to me and said, 'Excuse me. Can you tell me the time please!'

Honest!

[skinnyonce]

I'm going to have a go at using one of these for my eq-2-3 mount and use my 90mm mak and 450 canon dslr as astro picture taking tool and or wide field with the 28mm canon lens which ever gets the best results

AMERICAN DJ M1RPM MIRROR DISCO BALL ELECTRIC MOTOR 1RPM | eBay

[virtualpilot45]

If there was a perfect balance between the c/ws and the scope, shouldn't the friction be negligible? Or is this my inadequate knowledge of physics?

[Bizibilder]

The Disco ball won't be 1rpm in the UK - we are 50Hz supply and the states is 60Hz so it will run about 20% slow. That is if it will run on 240v as the states is 120v.

[Peter Drew]

Don't forget that for tracking, your clock would need to run at i rev per day to be anything like a sidereal drive, they wouldn't have enough "grunt" to overcome the inertia of the mount and telescope. If my memory serves me correctly, I think that clock drives used to drive on the escapement principle where the fall of a weight, governed by the clock, provided the motive force.

[Telrad]

If there was a perfect balance between the c/ws and the scope, shouldn't the friction be negligible? Or is this my inadequate knowledge of physics?

Even professional observatories have clock drive errors on the order of 0.1 arcsecond per second apparently.

[Moonshane]

I have made an equatorial platform using a 12v DC 4 rpm motor controlled via a PWM controller and driving an M10 threaded rod. not very practical for a telescope mount on a tripod but just mentioned it as there's always more than one way to skin a cat. with the rod I am using and the arc or the mount based on my latitude etc, a turn of about 2rpm tracks at high magnification.

[ollypenrice]

The sidereal day is about 4 minutes shorter than the mean solar, remember. Well balanced mounts don't need much power - I read that the motor driving the 200 inch Palomar is about the equivalent of a domestic hairdrier motor - but that is still more than my watch!

Olly

[steelfixer]

Luke.

If you want a better alternative try using the stepper motor from a printer.

You can use the circuit board from the printer to drive it and control the whole thing from a computer using a USB lead.You will need to be able to control the revolutions of the motor but there are plenty of free stuff on the net.

I am using the same principle on my scope only I am using Nema 23 stepper motors for the axis drives and a printer stepper motor for the focus.

I drive the whole setup using the Mach 3 CNC milling programme.

Reason for the large stepper motors is I converted my small mill to CNC a couple of years back but I think the telescope is far more important than the mill.

If you want to go even further you can add a gearbox.

My new project is to build a new mount using my motors but to run them through a 3000 to 1 reduction gearbox.This way the motors can run to thier full power and smoothness and still track to a very fine tollerance.

Just a thought.

graham

[Luke Inup]

Thanks folks..

It seems I started a thread then!

A happy development though. My daughter has offered me semi-permanent loan of her 3.75" refractor. (Well I did buy it for her in the first place!)

It doesn't have a drive, but daughter tells me the mounting is upgradeable and I could buy the proper accessory. Perhaps I will take up her offer for the easiest solution.

As the instrument obviously isn't mine, when I later return it, then being the generous type, I'll leave the motor fitted!

(IHmmmm! I am wondering about her motivation for offering me the loan...)

Regards

Jon

[buckie bill]

Hi there. I have an EQ3 mount and as light pollution makes observing at home difficult have to go well away from source of electricity to use scope.

I have also obtained a former street light timing clock.

Is there any way to adapt to drive the mount? Any websites to look at. Help please!!!