24 hour gear for my base help see photos

[captainleeward]

The base you see below in the photos I built from scratch in my shop. I have a Zumell 8 inch telescope that fits on this base. I want to replace the main gear with one that will track the planets on time.

This configuration does not work properly.  My first try. I have a small machine shop in my garage with mill, lathe, drill press ect. I have the capability to cut gears on my rotary table and mill, I can also hob

gears on my lathe like the one you see below. The one below is an 8 inch aluminum hobbed gear it works but it goes to fast. I need the proper main gear diameter no of teeth and motor with rpm and where to buy same like ebay. I am not going to spend a lot of money as I should be able to make every thing I need.  you can see some of my projects on  homemadetools.net  under builders captainleeward.

Any help would be very appreciated   thanks for looking...Cap.

[happy-kat]

You sure have a lot of projects on there I had a quick look. I can't help with your current project hopefully someone will.

[Mick J]

Wondering if you can control the motor speed electronically,   great linked site -  will have to stay off that - 

And welcome aboard captain.

[captainleeward]

Hey Thanks guys for your thoughtful comments I shall keep serching..

[happy-kat]

You perhaps need to calculate the cogs needed for sidereal rate.  Maybe @Gina might know where to point you.

[captainleeward]

O thank you  don't know who that is?  :O)  Also see new photos.....below.

[lux eterna]

Hi Cap,

You need a mount rotational speed of roughly 360 degrees per 24 hours. So just calculate the current rotational ratio (screw axis to mount supporting plate) and see what rotational speed is needed for the motor. A stepper motor would need control electronics, but I would go for a 12V DC motor (with optional speed control with much simpler electronics). But motor speed control may not be necessary for visual use only (no astro photography).

Ragnar

[captainleeward]

Thank you so much for all your ideas I'm getting the idea now..

[lux eterna]

I just got another idea... You could try using a cordless electric screwdriver to turn the shaft. No cables needed, and adjustable speed.

Also, if you could tilt the complete setup, so the rotational axis points towards the Polaris region, the tracking precision would increase pretty much.

Ragnar

[Gina]

Yes, I was thinking of saying that.  An equatorial mount would be best - as you say - axis pointing towards Polaris.  If rotating at 15 degrees /hour your telescope will follow whatever it is set up on.  Makes observing much easier.

[captainleeward]

WOW what a bunch of really nice people in this group. I lost the information I had a few years ago but now its coming back thanks to you guys and gals  for your wonderful input .

[Rusted]

So, in summary:

The time taken for a point on the Earth to rotate once relative to the background stars is 1436 minutes [plus a few seconds.]

So the polar axis rotation required is 1/1436 rpm.

A single start worm [or threaded rod] needs a wormwheel with a number of teeth which matches the motor speed.

Say you have a 5rpm motor. 1436/5rpm = 287 teeth. For an 8rpm motor: 1436/8rpm = 180 teeth.

A vertical [azimuth] axis driven by a single speed system will be fast or slow of the stars and planets depending on the object's altitude.

The object will also rise and fall in the field of view depending on its direction relative to south. It will usually be highest to your South.

The latitude of San Diego is 32.7 degree north.

So you need to tip your whole mounting over at an angle of 32.7° to the horizontal to become an equatorial mounting.

What was your azimuth bearing now becomes the Polar Axis and it should now point at the North Pole Star called Polaris.

An equatorial mounting will follow the planets well enough with the polar axis driven at a steady 1/1436 rpm.

An equatorial mounting needs greater stiffness [than an altazimuth mounting] to avoid axles bending or bearings falling apart.