Equatorial Platform for Dobs in Oz?

[skies2clear]

Hi all,
would like to ask you knowledgable people if there is anyone here in Australia that builds Equatorial Platforms? Oh, and sells them!

Life's so busy these days I'm reluctant to have a go myself, but it's not totally out of the question.

Ideally it could be used with a Dob up to 16".

Thankyou in advance.

PS if there is no one in Oz, then I would consider any info on products from o/seas too, if they are good value pricewise.

Nick

[jenchris]

I've not heard of one - but one may exist.

@34 South, it's going to lean a bit - is your dob bearing gravity or held in by springs? Wouldn't want it to fall out when you pushed it round!!

[mental4astro]

Hi Nick,

Funny you should pose this question. I'm considering making one for my 17.5" dobbie. Won't be until the new year though. If you do go DIY, I'd be happy to push ideas & suggestions too. I've got a few other projects to clear before then too...

[skies2clear]

Jennifer, the Dob bearings are gravity, but the top plate of these platforms sit reasonably flat apart from some tilt while in normal operation, irrespective of observers lattitude.

Alex, happy to exchange some ideas, but I must admit I haven't researched it enough yet to offer much at this point in time. From what I have seen of commercial products from the US, it will be a LOT cheaper to DIY.

[iceman]

There used to be a great maker in the US which is where I got mine originally (many years ago) but he's since stopped making them.

Not sure who else makes them these days.

[jenchris]

Pardon me being a bit thick, I thought the idea of an equatorial platform was to cant the base to make it point to the pole - which would be something like 34 degrees off horizontal in Adelaide.

[mch62]

Hi also have a google on split ring mounts. I am doing one for my 18". These can be quiet portable and easy to mod a dob to suit and if done properly will not add a lot of overall hight to the scope and can be adjustable for a range of latitudes. They are in a way similar to a platform and many profesional observatories use this type.eg (Anglo Australian siding springs)
Stellar cat drives will function very well with this type of mount.
Mark:thumbsup:

[mswhin63]

I will be making these due to the success of my prototype, but I am redesigning it slightly to make adjustment easier and making it more streamline.

Obviously I will have the plans for the 12" factory immediately but hope to come up with a standard dimension when asked for things like location etc and centre of gravity of the scope.

One of the problems especially with a 12" is that finer adjustments require moving the mount a few degrees side to side and up and down. This is the major re-design of the mount and not aware of anything of it type seen. I am also considering a low cost Fork mount for smaller DOB as well. I have an idea but wont run it till I have completed the final EQ Platform design.

I am also look at a kit package making it cheaper for delivery as well.

Cheers

[Blue Skies]

No, not at all. What does vary (and I'm writing from memory here, as I did look into them at one point) is the arc it travels - I'm not sure I'm explaining it right. You build them to suit a particular latitude and they don't take well to travelling north or south of the original specs all that well, although someone was making adjustable ones at one point, sort of +/- 5 degrees. Have a look around at some DYI plans and they should explain how it's worked out.

[mswhin63]

EQ platforms are made for particular locations but there is a small amount of variation available. Currently it is difficult to adjust but possible.

There is another somewhere that adjust in 10 deg increments about $1-1500.00 US. This method is extremely complex to make and not for the DIY'er and made from ally

I will be looking at a generic platform with interchangle radius. This will be after making base and platform templates first.

[netwolf]

Matt from Telescope and Astronomy was looking at this some tima ago. I know he did have a prototype made but I am not sure how much further it got than that. Might be worthwhile to ring and ask him.

[Barrykgerdes]

Hi

Making or buying an equatorial platform for an existing commercial dobsonian is not a viable project. Principally because the azimuth bearing needs to be on a flat surface to make it reasonably stable. It is not designed to be an "RA" shaft as it has no longitudinal or side thrust support.

However it is quite possible to make a support for an existing dobsinian OTA that can allow it to operate as an equatorial mounted telescope. Doing this commercially however would not be a commercially viable project because of the wide variation in the available OTA's and a suitable "box" would cost as much to produce as a standard equatorial head of the type that are available.

Barry

[omnivorr]

Barry, the Az bearing becomes the Dec axis, the EQ platform performs the RA function....

[Barrykgerdes]

Same problem, the Az bearing still has no support for side thrust (nor does the alt bearing). It all depends on whether you want a platform to mount a dobsonian on or build an equatorial mounted telescope out of dobsonian components.

I could build an equatorial base to mount a DOB OTA as I have a proper workshop with all the necessary facilities but it would still not be a trully practical project. In time and effort it would cost as much as Paramount.

A dobsonian mount is a great, cheap and simple method of mounting a telescope for practical viewing. But as a basis for an equatorial mounted telescope it is not practical. By the time you beef up the rotating axes you may as well have built or bought a proper mount.

(Unless you live at the south or north pole)

Barry

[Satchmo]

Nick

These guys have been making platforms since the early 1990's..

http://www.equatorialplatforms.com/compact.shtml

Barry - you are being pessemistic about the `paramount' cost of making a platform work well for imaging.

There are plenty of people doing astrophotography with Dobs on tracking platforms..

http://www.equatorialplatforms.com/images.shtml

Heres a particularly good example..see astrophotography section:
http://www.robertbrunck.com/

[Barrykgerdes]

I had a look at their "equatorial platforms". An interesting concept but they don't make the telescope into an equatorial mount. As far as I can make from the pictures they are a device to take care of field rotation on a alt/azm mount, will only be suitable for a particular location and will still need suitable drive and guiding facilities.

If you have a nice SDM or Obsession that has cost you a mint it is a practical way to use the scope for photography. But most people looking for ways to take photographs with their dobsonians are looking at the cheaper mass produced dobsonians.

As for being pessemistic about cost. Making a device from a kit or plans may be relatively cheap but designing and building from scratch is not. Try it sometime and record your time, materials, tools etc. I have designed and built many one off projects.

To give you some idea my present project is to get the Radio astronomy dish at Wiruna operational. I have had two weekends at Wiruna and need two more, travel and time at commercial rates about $2000 a trip. Work at home refurbishing parts 20 hrs at $150/hr. Investment in electronic equipment (S/H and new) and parts $3500. This effort is only a small part of the overall project. I wonder why the original project was put in the too hard box a few years ago?

Incidently you may have seen in the news the problems with the Navy's two special landing ships. I did the original investigation and quotation for the projected modifications to the communications system. We did not get the job (politics) but the firm that got the job wanted our drawings (free). Look at the mess they are in now.

Barry

[jenchris]

I hope you didn't give them what they wanted!
Local Councils are like that - you do all the work or they won't pass the designs, then they want CAD drawings for their own use for the DA - I usually send PDF :D

[Barrykgerdes]

I don't think they got them free. The big problem was that I had done similar projects on other ships (successfully) and quoted for the "known contingencies" that I knew would be present in getting the systems to work. This is what the lower quotes had no idea of or the expertise to fix. Same thing happenned with the Collins class submarines. Incidently I still have my copies of the quotes somewhere.

There is one thing I found out long ago and that was to give "people wanting your job" all the information and procedures I had. This invariably led to their disasters because there is know way I know of to publish "expertise" and you got the work anyway under your conditions.

Barry

[Geoff45]

Trust me Barry. An equatorial platform IS an equatorial mount. It just happens to be one with limited RA travel. I'll explain it to you at tonight's astroimaging meeting.
Geoff

[mswhin63]

Very simply a EQ Platform works like a EQ1 mount. I have taken a nice photo of M42 with my DOB on the EQ platform so it works for me.

Not that difficult to make so a basic system shouldn't cost a fortune to make. The distinct advantage of a EQ platform to a generic DOB ALT/AZ mount is field rotation. No need to purchace any field de-rotator.

[ZeroID]

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]

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]

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]

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]

Recently Stacey (sasup) posted about "Servo-catting" his 12" LB - see here:
http://www.iceinspace.com.au/forum/showthread.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!!:eyepop:

HTH
Cheers
Bill

[skies2clear]

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]

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]

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]

That is so cool!

[ausastronomer]

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]

TTIWWOP :D !!
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]

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]

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.

[mswhin63]

I saw the TL systems design, one of the problems with that is it compromises on the radius to achieve variable latitude. The radius they use is not interchangeable. The front and back radius are fixed and only have the angle at which you place it. That goes against the principle of the EQ platform's number one aspect. To vary the latitude the radius and the angle need to change.

Motors are subjective, I am look at high accuracy in an attempt to get really long exposure imaging.
The servo control I am using is better suited for visual and planetary imaging.

[GraemeT]

Well, last Friday saw the trial of MkII, still having a few problems with vibration wobbles but I think I've tracked down the problem to the levelling feet ont the grass, so a redesign with pointed tips rather than flat is underway. Pictures should be attached - fingers crossed.

[GraemeT]

Rewind is achieved by loosening the knurled screw and manually winding back with the crank handle on the right. The right bearing housing has a microswitch to stop the lead screw self-destructing if I forget to watch it as it reaches the end of its travel. I got about an hour out of a 2200mAH Lipo battery.

[skies2clear]

Good work Graeme! Hope the new feet sort it out as that's often the problem on soft surfaces like grass.

Malcolm's point on the TL Systems platform is taken. Didn't research it thoroughly enough.

[Visionoz]

The TL systems seemed to have had a bad rap; read a review previously - found another one cheapie which is quite impressive for the dough they're asking for - see here: http://atomicplatforms.com/pics.html

Shame that probably shipping to Oz is quite high for it

HTH
Cheers
Bill

[skies2clear]

Bill, thanks for the info on Atomic Platforms. Looked promising, but sadly would like to inform you, they are not interested in sending their product to Australia, or anywhere outside the US of A. Pity. They quoted a pretty pathetic excuse in my view, which sounded more to me like they don't know how to pack anything properly. So better left alone in that case, but thanks anyway,

Clear skies

[GraemeT]

Basic diagram:

[glend]

Just bumping this old thread back up for a re-fresh. Having looked at the Eq Platforms available for Dobs (as mentioned here originally) I am leaning towards going with the Servocat Jr and hoping it will be able to handle my 16" GSO - anyone running that configuration?

[5ash]

More like 56 degrees off horizontal to get 34 degrees pointing at the pole , quite a steep incline for a heavy 16" dob .
Philip

[Satchmo]

I know of someone pushing a 16" binocular with one - if in doubt talk to the manufacturer. It doesn't cost much more for the beefier gear box that will push a 40" - it may be wise to buy one that will drive future 'scopes as resale of accessories is always at a big loss.

[glend]

Thanks Mark, I have parked that idea for awhile. I did speak to Astro Devces and there will be no probem driving it from Sky Safari Plus. I realised my Pushto system was lighter weight, made no noise, and is much faster to target than any Goto system. The only advantage might be in tracking but not a real concern for visual use.

[Satchmo]

Hi Glen - I wouldn't understimate the power of having tracking - some say it is like adding a few inches of aperture. Having a truly still image allows your brain to really integrate the finest details properly and sort out the noise from the real photons. I had a Dob Driver on my 14" for a while and could see the benefit although it was not a system that was easy to use.

[BowenW]

I am in Adelaide, and have a DOB/EQ platform, and it has no chance in hell of falling off, I use it for 3 dobs ranging from 6" to 14" ( all use the same platform ) for some reason people seem to think that this type of platform is unstable, if you look at this image showing the range of movement you will see that the dob has no chance of falling off

http://www.equatorialplatforms.com/EQ-Plattform-1-animiert.gif

image courtesy of http://www.equatorialplatforms.com

when I constructed mine I made 3 different sets of end plates ( for my 3 regular viewing spots ) it takes all of 2 minutes to change the platform from site to site, The one I use for home is set to my exact lat of 34.7. I will take some photos when i next set it up to show it with the dob at all extremes of movement. I have in the past knocked over my EQ5 with only and 6" Newtonian on perfectly level ground, when I tripped on a power cable for the drive, I cant even make the dob unstable on the platform, as the COG is way to low. The tracking is also just as good as the EQ5, and in some cases I would have to say even better. I chuckle to myself each time people make posts about how this type of platform is unstable, when there are 30" dobs sitting on them http://www.equatorialplatforms.com/osp.corwin.jpg

as long as you plan it correctly you wont have any issues. they are not hard to make and there are plenty of resources available on the net to show you how to go about it.

for those interested in building there own check out these to sites they have all the info you need to make your own.

http://www.reinervogel.net/index_e.html?/Plattform/Planung_e.html

http://homepage.ntlworld.com/molyned/the_equatorial_platform.htm

choice is yours as to what style you build

clear skies...

B