Motorised GEM

supernova1965 (Warren) · #1 10-01-2011, 06:49 PM

Hi all I have an electician who owes me a favour for fixing his computer does anyone have or know where I can get plans to motorise a GEM for short tracking photography using a Meade LPI on the ascotron listed in my signature.

mswhin63 (Malcolm) · #2 10-01-2011, 07:51 PM

Hi Warren,

There are already some off the shelf motors, a simple on is the Celstron and just modify a bracket to suit.

http://www.celestron.com/c3/product....=44&ProdID=518

If I was to go for this motor again I would change the control to a 10 turn similar to what I have done on my current EQ3. This is the most common.
I used to have one but I raided it early and since then I have placed another motor.

So far I only go 55mm and working my way up to about 300 or 600mm FL before considering getting a guided or high end mount.

supernova1965 (Warren) · #3 10-01-2011, 08:00 PM

Hi Malcolm,

Thanks for your reply

This project is a on the cheap project as money is short and I plan to source all the parts from the recycle center and my mate is going to do the electrical work in payment for his computer repair so I need some plans so we know what we are doing. This is the only way I can get a motorised mount it's the way I like to do it the barter system works well. I am hoping for it to be powered by a car battery. Do you need to have motors for both the hand controls I haven't learnt how to use the GEM yet so I am a real noob so be gentle

mswhin63 (Malcolm) · #4 10-01-2011, 09:26 PM

I am unable to find any plans, mine was knocked in 30 minutes by raiding my DOB EQ platform motor.

1) In short you will need a Motor preferably 6mm shaft. Motor needs to run between 1 or 1/2RPM at the final stage. Sometime you need to add gearing to get the speed.

2) Bend a bracket to fit the motor onto it. and tie it to a fixed part of the mount.

3) Coupler - joins the motor to the EQ platform shaft after removing the adjustment rod. Costs around $12 ready made, or drill a hole of the right size through the centre of a metal rod.

3) Motor speed controller to raise an lower the speed of the motor. I use a PWM servo controller which I initially used on my DOB. I removed it as I am altering it to Stepper Motor.

1/2 RPM motors are difficult to get. available mostly overseas.

Sometimes it is worth just to buy the parts, some are quite cheap. Really for a computer repair should be able to buy and knock up 2 or 3 of these for you.

I personally would modify the Celestron system next time by changing the control.

supernova1965 (Warren) · #5 10-01-2011, 09:32 PM

Thanks I had another look at the link you provided and they are not that expensive I thought they would be more. So do you only need one what about the other axis

mswhin63 (Malcolm) · #6 11-01-2011, 02:32 AM

The mount you have looks like an EQ1 or 2 so a second axis control is not going to make a difference. EQ4 and above have dual axis for finer control, and usually connects to a handheld or computer control.

EQ1 to EQ3 can take photos but are nowhere near a good as a EQ4 and above.

For me I have been doing wide angle shot using a 55m lense on a Camera and planets are quite easy on these mounts but really long exposures may prove difficult but not be impossible. I am working on improving stability and managed to get some wide-field view captured tonight will process them tomorrow. Precision is the key.

I will get a 200mm lense hopefully soon and will try to get further narrower field captures on this mount.