Scope Hits EQ-1 mount Motor

[steelfixer]

Can I offer you a far simpler solution to your problem.

Remove the scope and the rings.

Make your self a spacer block that goes between the rings and the dovetail bar that is large enough so the scope clears the motor.

Move the counter weight out along the bar to allow for the imbalance you have now created by moving the scope out.

Problem solved.

If you do not have the means to do this drop me a pm and I will make you one.

Graham.

[JamesF]

I was wondering if that might work. A handful of washers might be suitable for a proof-of-concept?

James

[Mr TamiyaCowboy]

Had a look.

big problem if i extend the dovetail with shimming. balance bar is two short i am already at max weight length and scope is just balanced when holding the dslr and adapter.

i think a flexi shaft is the way to go.

the coupler connected to the ra worm shaft i max setting. only way to bring the motor closer to the mount , is to cut off nearly all the worm shaft on the motor side and then grind out a flat spot.

flexi drive is a more simple idea with a direct coupling to the ra worm shaft and motor. acting like a slow mo control rod but better quality and more flex. would also allow a second motor to be fitted to the Dec.

am looking to convert this mount to hold the Skywatcher heritage 76mm for short range solar/lunar imaging. and as the mount is lightweight will be used mostly on calm summer evenings/days.

i am already looking to purchase a SW Syntrek AZ auto-tracking and modding it to fully goto/notebook driven

[themos]

My suggestion doesn't work?

http://stargazerslounge.com/2265282-post13.html

[Mr TamiyaCowboy]

My suggestion doesn't work?

http://stargazerslounge.com/2265282-post13.html

when scope is flipped either dec nut smashes ra drive shaft. or the scope crashes the motor.

only other way is a smaller scope tube hence the 76mm short dobson tube.

going to remove tube and find out what the exact problem is ( RA drive shaft is to long and the motor housing to bulky), then go about working a fix. but for time being a flexi drive is a cheap fix.

[themos]

when scope is flipped either dec nut smashes ra drive shaft. or the scope crashes the motor.

i don't get it: As your photo shows, the only problem is the dec nut. Loosen the Dec clutch and rotate so that the tube goes back to front and then the dec nut will be on top and won't hit the ra drive shaft. That is how it was designed to be.

[Mr TamiyaCowboy]

i don't get it: As your photo shows, the only problem is the dec nut. Loosen the Dec clutch and rotate so that the tube goes back to front and then the dec nut will be on top and won't hit the ra drive shaft. That is how it was designed to be.

but then how do i use the dec slow mo control. now i have to reach infront of the telescopes aperture to adjust the dec . if i stand the other side my crown jewels get squashed/clanged by the counterwieght and bar

it now sits right under the front of the tube. the Dec control on the EQ1 can only be used on one side of the dec worm shaft. it is not like the ra where you can swap it over from left to right.

[themos]

First off, you rarely need to use the Dec slow motion control, it's there for centering an object or doing star hopping. Secondly, you rotate the tube in its cradle so that the eyepiece is always pointing away from the tripod. The Dec control stalk should end up "behind" the tube from where you are, pointing towards the aperture. I just reach over or under the tube to use it, I never have to block the aperture to do so.

[themos]

Have a look at the EQ1-reflector on the left in this video.

[Mr TamiyaCowboy]

i see what you mean thermos.

i could run like that but think it would confuse the godson when he comes to stargaze, hence trying to keep things the right way. less confusing for him and easy for me.

i think a shifty flex drive should do for the time being, then gives me time to work out a full fix. would be nice to let him have the mount and scope as a christmas/birthday gift. .

would be nice for it to be motor driven. so he can plug a modded PS3 cam into the scope and use the PS3 to take shots. i was thinking low motors give weight to an already wobbly mount. flexi cables would take away the scope crash problem, and can be routed so they have minimal chance of tangling up.

i should have mentioned both me and godson/niece use the scope

[themos]

Ok, go for a different solution if you like the sound of it. I just wanted others who read the thread to be aware of the possibilities. The "economy" drive is only good for keeping objects in the view for a while, it's no good for astrophotography at such focal lengths for anything more than 1/10 second or so.

[Mr TamiyaCowboy]

Coming back to this.

i have just got myself an arduino Uno board. and have been thinking. is it possible to use the arduino to control the RA motor.

the motor has a PCB ( yellow creame) with a small chip, couple of switches and the motor soldered direct to the board, and the motor output shaft is then fitted to a gearing system and then to a final output shaft.

could i remove board, jack into the chip and control everything via arduino ? if the pcb has a chip then surely is is a logic motor drive ?

would it be possible to use a second motor drive, de-house it, mount to the Dec worm shaft. then have arduino run both RA/Dec, maybe using stellarium as the controller ?

any ideas help and/or links would be amazing. i am a total newbie to electronics but looks and sounds a more cheaper way for a goto eq1

[JamesF]

Search the DIY board for something like "arduino nano handset" and see what turns up. I have a nagging feeling someone has done some technological magic involving handsets and guiding etc., but I can't recall who or what right now.

James

[Mr TamiyaCowboy]

did a couple, and came up with guiding a eq1 also motorized focuser.

i am not sure if it will work, motor is a stock DC job pos/neg wires only, no sensor /data wire. can say these boards are made so cheap that the chips have no ID on them, or if they have its marked with invisable ink lol.

hmm maybe time for an AB hunt for a cheap motordrive i can pull apart, this one cost me £25 from wex. but every 5 mins i keep looking at it and then the soldering iron :s

[themos]

That was me that did an autoguiding conversion to the EQ1 mount. But the mod doesn't use this "economy" motor but the more expensive one with the separate handset, and it's only in RA. The modification does not provide GoTo functionality as the mechanics of the mount are just not good enough for that, I think. But it can provide the "nudging" necessary to counter the huge periodic error (220 arcseconds) of the EQ1 gearing. The ecomomy motor is regulated by a resistor and is not stable enough in its tracking operation, in my view. I also implemented an Arduino based, stepper motor focuser (with ASCOM driver).

[Mr TamiyaCowboy]

yes themos

i been reading your threads and trying to work out how it all works ( total electronics newbie).

i was thinking of using the arduino as the main board. having motors plug into mainboard and that does the brain stuff. the pc just tells the arduino what to do ( ra point here dec move there ).

how would make the motor more trackable ? replace the resistors with ? but keep the gearbox and motor the same, just a better driver system

also i would fix it to solar sidereal, so mount could be dedicated to the heritage 76mm dob remounted to the eq1

i wish i listened more at school now, i can picture everything in 3 dimensions in my head ,but just unable to put it into real life.

[themos]

The best way to learn is to just start doing stuff! I scavenged some stepper motors from old flat-bed scanners and printers. I then assembled the simplest circuit to drive a unipolar stepper, like this, have a look here http://www.arduino.cc/en/Tutorial/MotorKnob

When you play with these things, always look out for short circuits that might blow the Arduino ports and read the specs on the motor regarding maximum voltage and current. I got those by googling the model number written on the stepper. You can find 12 Volt ones or 6Volt ones or 3V ones, etc. The power for the motor comes from a separate supply, not the Arduino.

For the "economy" drive, I don't know how to regulate it with an Arduino yet. I suspect it's not worth doing. The more expensive drive is not THAT expensive (£59.99, http://www.green-witch.com/acatalog/OV_Motor_Drives.html)

What I understand is it's quite easy to make the motor track at sidereal rate (you stabilise the pulses with a crystal oscillator, essentially) and also quite easy to correct for autoguiding (you make the Arduino "push the button" for a fraction of a second) but it's very difficult making a GoTo system as there are all kinds of manufacturing errors to take into account and correct in software.

[Mr TamiyaCowboy]

getting my head rounds things.

learnt to make the led flash, next is to grab a motor shield or two.

am not sure if i should go with a 6v stepper or 12v stepper, i would like one for the RA drive and another to make a focuser control.

No more goto ideas, as you have said thermos it is highly technical an likes, so a standard RA tracking would be cool. will use a maplins gearbox to power the focuser. the stepper will be mounted behind the RA worm drive holder out of the way. will just drop a spur and pinion gear onto the motor shaft and worm shaft. to keep the input and outputs as 1:1

is a long road without any knowledge of electronics, man i was like a kiddy when i made the led flash on and off lol. thank you thermos for the diagram, decided i would be safer getting the motor shields ( do i need crystals for them with steppers), not keen on the idea of blowing/smoking up the arduino

Arc second : do i get better than 220 arc seconds using gearing system, or do i just tell motor to stop once in a while and move back a step to correct for it.

[themos]

A 6V stepper would be easier to power with AA cells but might draw more current than you can easily handle with the cheapest components. I settled on a 12V stepper that drew about a quarter of an Amp on each coil.

http://www.datasheetcatalog.org/datasheets/90/502505_DS.pdf

It came with its own gearbox (I pulled it from a scanner) so it could produce a good amount of torque. I tend to leave the stepper energised after I have achieved focus the better to grip the focuser and not allow any drift due to camera weight. If you use the half-step technique, that means you are feeding up to 2 coils at a time so I could be using 500mAh of charge every hour. Rechargeable batteries hold about 2500mAh.

Now, a quarter of an amp is already more than the Arduino pins can handle (and that's only at 5V anyway) so I knew I would need the Darlington chip that can switch up to half an Amp.

If you manage to burn the Darlington or the Arduino output pins, you can replace these quite cheaply (a couple of pounds?). You only need to swap the ATmega chip, not the whole Arduino. For the focuser, you don't really need the motor shield as you don't care about having a uniform rate.

I can send you the Arduino "sketch" that I used to drive the Darlington and unipolar stepper, it doesn't use a motor shield.

I can't advise on making one for RA tracking as I haven't made one myself. I think someone else on SGL has had a go. I don't know if they use a crystal, I guess they probably do. I consider that an advanced project, in terms of difficulty.

The only way to reduce the 220 arc second error that I know of is to use a guide camera and some software like PHD to send corrections to whatever is doing the tracking. As the tracking requires motor steps all the time, it's usually a question of either holding off on the next step ( to slow down ) or adding an extra step ( to speed up ). You never need to "go backwards", as you do for DEC guiding.

[Mr TamiyaCowboy]

thank you thermos.

found a dual stepper shield for the arduino not cheap but £34 is better than £50 two arduino (original) shields.

the focuser is only holding a webcam so maybe i can get away with lower mah drain using less power on with focuser motor.

i also had another idea, using a spare/parts goto/az track mainboard, popping two of those 6v steppers in, all i would need to do is make up a control box to jack into the mainboard ( arduino nano to send and a couple switches)