Equatorial Platform for Dobs in Oz?

[ZeroID (Brent)]

There are several threads on EQ Platforms including pics and designs over at CloudyNights made by amateurs. Some very accurate work required but it's certainly feasible.

[skies2clear]

Thanks to everyone for their comments so far.

I don't see any problem using a well designed platform for any of my Dobs, both home made and commercial. In fact, I'd point more of the issues at the ability of the platform to do the job than the Azimuth bearing of my Dobs mounts to be a problem.

Had a look at the Equatorial Platforms site thanks Mark. Look nice and with exchange rate probably the best time to consider buying, but still will cost a bit when shipping is included, and some GST/customs expenses.

As some of the guys here have said, there are plenty of decent photos taken using these platforms. Actually, I am more interested at this point in time just to track an object so I don't have to keep nudging the thing and get the most out of the view. However, down the track, it would be nice to have the option of tracking accurately enough to do long exposure photography.

I will also check out Telescope and Astronomy to see if there is any progress there.

Thanks for the comments about different mount types. eg split ring, but the Equatorial Platform should be able to be configured to use with a reasonable size range of Dob telescopes, so would seem to be a reasonably flexible approach. Being able to adjust +/- a few degrees for lattitude would seem enough, unless I think of dragging it up north which isn't likely to happen.

If I build one, it will have to be strong, stable and not too heavy. Is that asking too much oh, and cheap! Well, looks like I need to research it more and look into building one. CN here I come!

Barry mentioned about the cost to fabricate a proper mount, but fortunately for me, my time doesn't cost me $150/hr. But if someone else wants me to build one, then, yeh, I'll charge them $150/hr. I'm an amateur, at least at these things, so I would gladly help someone else for free.

Nick

[Satchmo]

Nick

If you are only after tracking and you own an Argo Navis you can't go past the Servocat- they make a model to fit Meade 16" ( It can be adapted to other similar dobsonians only USD $1099) . It will have the advantage of scope not tilting over as it tracks and also will GOTO.

http://www.stellarcat.com/Pages/servocatjr.html

[ZeroID (Brent)]

Nick,
What latitude are you at ?
I'm interested in a platform myself later on. I'm in NZ at lat 37.43 (Auckland) and if you build one I'd be interested in seeing how you go. If you are planning on using small stepper motor(s) I might be able to help with cheap/free hardware. Keep it in mind anyway.

Good luck

[skies2clear]

Originally Posted by Satchmo

Nick

If you are only after tracking and you own an Argo Navis you can't go past the Servocat- they make a model to fit Meade 16" ( It can be adapted to other similar dobsonians only USD $1099) . It will have the advantage of scope not tilting over as it tracks and also will GOTO.

http://www.stellarcat.com/Pages/servocatjr.html

Hi Mark,

I had no idea Servocat could come in around that price. I thought they would run into the $$$$'s!! Thanks, I'll look into this idea too as I have 2 ArgoNavis units. Not sure if the Meade 16" version could be adapted to a Kriege style Dob?

Cheers
Nick

[skies2clear]

Originally Posted by ZeroID

Nick,
What latitude are you at ?
I'm interested in a platform myself later on. I'm in NZ at lat 37.43 (Auckland) and if you build one I'd be interested in seeing how you go. If you are planning on using small stepper motor(s) I might be able to help with cheap/free hardware. Keep it in mind anyway.

Good luck

Thanks Brent,

Adelaide is about 34 deg I think. I have a lot of hardware sitting around too that could be put into action, but probably don't have enough for the reduction drive mechanism. I'll keep it in mind,

Thanks

[skies2clear]

Mark, StellarCAT offer the option of having all the mechanics available as a package, minus the electronics (controller) to save some money if wanting it fitted to a second, etc, telescope. This makes it rather interesting!

[Satchmo]

Cool- you could Servocat all your scopes.

Theres another option I've been thinking about lately to track a mid size dob-and I don't have ( nor really need ) an ArgoNavis.

The Skywatcher GOTO dobs all have identical looking tracking system bolted on ( need to study this further ). With an 8" GOTO I could strip off the GOTO/Tracking system for use on a larger scope and still have a push around dob for fun all for $1000.

[Visionoz (Bill)]

Recently Stacey (sasup) posted about "Servo-catting" his 12" LB - see here:
http://www.iceinspace.com.au/forum/s...ad.php?t=66867

I did once consider doing the same for my 12" SW FlexDob (besides not having the time to do it myself and having found that I had to mod the baseboard and also the alt bearings/mount etc, too much mucking around) but have since gotten tube-rings and Losmandy-style D-dovetail bar for it instead and have mounted it on my EQ6 Pro as well as G11 - works OK but very "scary" action when slewing as I think it might just fall off the mount one night in the dark or strip the gears off the motors!!

HTH
Cheers
Bill

[skies2clear]

Originally Posted by Satchmo

Cool- you could Servocat all your scopes.

Theres another option I've been thinking about lately to track a mid size dob-and I don't have ( nor really need ) an ArgoNavis.

The Skywatcher GOTO dobs all have identical looking tracking system bolted on ( need to study this further ). With an 8" GOTO I could strip off the GOTO/Tracking system for use on a larger scope and still have a push around dob for fun all for $1000.

Interesting thought Mark.

I notice you can buy the mount as an upgrade, but it's a bit xpensive compared to a whole scope. Your option sounds more feasible. Unless something second hand comes up. They have both a basic Tracking setup or more sophisticated GOTO, with a controller.

[skies2clear]

Originally Posted by Visionoz

Recently Stacey (sasup) posted about "Servo-catting" his 12" LB - see here:
http://www.iceinspace.com.au/forum/s...ad.php?t=66867

I did once consider doing the same for my 12" SW FlexDob (besides not having the time to do it myself and having found that I had to mod the baseboard and also the alt bearings/mount etc, too much mucking around) but have since gotten tube-rings and Losmandy-style D-dovetail bar for it instead and have mounted it on my EQ6 Pro as well as G11 - works OK but very "scary" action when slewing as I think it might just fall off the mount one night in the dark or strip the gears off the motors!!

HTH
Cheers
Bill

Bill, I know what you mean. The Alt bearings/axis are the biggest hassle to overcome on that kind of Dob mount (Skywatcher/Saxon).

As I mentioned before, SW do an upgrade Goto mount for these, but it's a bit pricey.

I must read that thread you quoted..thanks.

Cheers
Nick

[GraemeT (Graeme)]

The idea of an equatorial platform has been intriguing me for some time. The idea ofplanetary viewing without nudging the dob every 5 seconds was appealing, so I decided to have a go. My first attempt was finished a week ago and it worked, but there were some improvements needed that required minor redesigning, mainly to decrease vibration. These are currently being addressed. The cost has been minimal, bearings approx $30, salvaged steppermotor and belt from a scanner on council cleanup $nix, a kit controller from Jaycar $21, and bits of scrap metal, timber and ply.
Lots of fun nutting out the design and a huge thrill when I could watch Jupiter for 10 minutes without touching the scope. The maximum drive time is just over an hour before resetting.

[jenchris (Jennifer)]

That is so cool!

[ausastronomer (John Bambury)]

Originally Posted by skies2clear

Hi Mark,

I had no idea Servocat could come in around that price. I thought they would run into the $$$$'s!! Thanks, I'll look into this idea too as I have 2 ArgoNavis units. Not sure if the Meade 16" version could be adapted to a Kriege style Dob?

Cheers
Nick

Hi Nick,

Do you want this for visual use, or imaging or both? If its for visual use only the servocat is an absolute no brainer for a lot of reasons IMO. If imaging is involved it does get a bit more complicated. Having two scopes with Argo Navis and Servocat and having watched Mike Salway spend an eternity getting his scope set up properly on the eq platform for imaging purposes, I can tell you that I will never own an eq platform. Mike subsequently sold his eq platform (which was superbly made I might add) and put the OTA on an EQ mount.

Cheers,
John B

[ZeroID (Brent)]

Originally Posted by GraemeT

The idea of an equatorial platform has been intriguing me for some time. The idea ofplanetary viewing without nudging the dob every 5 seconds was appealing, so I decided to have a go. My first attempt was finished a week ago and it worked, but there were some improvements needed that required minor redesigning, mainly to decrease vibration. These are currently being addressed. The cost has been minimal, bearings approx $30, salvaged steppermotor and belt from a scanner on council cleanup $nix, a kit controller from Jaycar $21, and bits of scrap metal, timber and ply.
Lots of fun nutting out the design and a huge thrill when I could watch Jupiter for 10 minutes without touching the scope. The maximum drive time is just over an hour before resetting.

TTIWWOP !!
Some pix would be real good ! Sounds like my kind of project. I got heaps of bits left over to do weird things with. Jaycar Kit, not sure if those are available over here but can soon import something.

[GraemeT (Graeme)]

Originally Posted by ZeroID

TTIWWOP !!
Some pix would be real good ! Sounds like my kind of project. I got heaps of bits left over to do weird things with. Jaycar Kit, not sure if those are available over here but can soon import something.

The controller came with its own stepper motor in the kit, but the scanner motor was geared down which allowed the motor to run faster avoiding a jerking image. The kit has been dropped from their latest catalogue, but some branches still have stock. Ocean Controls have the K179 kit which is a stand alone which will work up to 35volts. I was using a 9v transistor radio battery, but have ordered an 11.1 volt rechargeable LiPo. The little battery was able to pull my 40 kg 8" Skywatcher collapsible dob quite easily. As long as you find the centre of gravity of the scope and its mount and design the bearing runner radii to suit, there is very little load on the motor geared for minimum speed and maximum torque. Pix wil follow but the thing is in bits at the moment while I fool around with the design.

[skies2clear]

Graeme, good on you for going ahead and building one. When you are able, I'd also like to see what you did.

John, it would be primarily for visual use. Just get sick of nudging all the time and would like to be able to concentrate on the object a lot more.
I had aspirations of using a ServoCat on 2 scopes with one controller to save some money, but the smaller Dob, a commercial 10" has a lousy altitude bearing setup so adapting a ServoCat is not that viable, without major redesign, and if that is the case, I may as well build a completely new mount to improve the whole thing.

At this stage, I have a few choices, but that could all change.

1. Still get a ServoCat for the bigger scope
2. Build an EQ platform for the 10"
3. Rebuild the 10 mount and add ServoCat
4. Use the tracking gear from a Skywatcher Goto but then I'd have another scope I don't need. Too expensive to buy a new Goto add on, and may as well go for ServoCat. Hmmm, could sell the extra scope.
5. There are probably other options like an EQ5/6 with motor drive, etc, etc.

I like the idea of building something myself though. ALways been a hands on type.

Thanks

[skies2clear]

Hey if anyone is interested. There is crowd called TL Systems in the US that sells an EQ Platform kit for around $250. You supply the wood yourself, but they supply everything else, controller electronics, motor, including plans. There is also a dual axis drive option for those into astro-photography, and a couple of other options.

Seems cheap enough! I have a preference for building and designing the whole thing myself, but, time is the big problem at present....too many things and ideas.

Anyway, I thought it might be a viable and cost effective option for those not wanting to spend big bucks. How good their platforms are I have no idea, but they claim their design can handle up to around 140 lbs in weight, and has a large range of adjustable lattitude, I think from memory from 10 to 65 deg and the motor direction is reversable, and can be used in southern lattitudes. Whether the lattitude can be adjusted within that range once built to their specs I don't know, or if it has to be built for a particular lattitude.

Clear skies.

[mswhin63 (Malcolm)]

Only 2 critical areas in the design for the Platform,
1 - The radius's although fine tuning alignment can resolve some of the minor imperfections.
2 - the Drive is the most important, getting the COG as I have found can make the drive too light which can cause minor instability or too heavy that can overload the drive. Overcompensating is quite high in cost. My current drive is servo/DC drive, but changing to Stepper in the new version to motor drive the reverse. I currently have a spring mechanism which I release to disengage the drive. I also have a remote control for the drive too.

My platform has worked well but has a few issues that I am not happy with. I am completely re-designing it to make it modular and with new methods as well. I hope to sell the parts as standard with replacement parts for variations in latitude. I am only in the design stage for this but I hope early next year I will start making some components.

[skies2clear]

I see that some have used synchronous ac motors and used variable frequency supplies to drive these with success. Also DC or Dc servo like yours Malcolm seem to be my preferred choice. I have heaps of stepper motors around the place and even have a microstep stepper controller I should put into use, but need to find a suitable reduction gearbox for this. One of the hassles of the steppers I have is they are quite substantial motors that need a bit of current to drive, so a small battery pack isn't suitable. Another thought of mine, but nothing much else to back it up with no experience, I like the idea of using 2 motors, one on each side to drive the platform. Saw this idea on Cloudy Nights under the subject of an EQ platform for $30.