EQ Platform for 12+" DOBs , easy .. includes 8,10". With plans & video

[PeterStudz]

20 minutes ago, bosun21 said:

The South pivot point is far better if it is metal to metal as metal to wood will introduce a degree of stiction. David used a male pin on the top and a female recessed part on the bottom. They were bought as a pair but I have no idea what they are called.

Indeed, that similar to what I have on my homemade platform. For me the male pin is a dome nut fasten to a bolt. The female recessed part is a couple of large penny washers glued together. 

Edited June 5 by PeterStudz

[PeterStudz]

I’m the opposite. I enjoy taking something complex and making it simple. Anyone can make something that’s complicated. Simplifying is much more of a challenge.

I use to work in web development. We had a team of people whose job it was to make things as simple as possible - it was far from easy or simple!

The original design was for a 10” Dob. Clearly it works and works well. There are people who use similar friction designs with the same single motor and they are working well on 12” Dobs. So it can be done.

One of the best things about this EQ platform is that it uses a simple cheap motor drive that can be bolted on without modification. However, the motor is tiny and has plastic gears. It’s made for small telescopes of a few KG that sit on an equally tiny EQ1/2. The fact it can drive something as large as a 12” Dob is quite a thing. 

And there’s another big advantage with a friction design - there’s a simple built in failsafe. It’s all too easy (I’d say unavoidable in practice) to sometimes push the unit against the drive. With a friction drive it just slips, saving gears and motor. With plastic gears plus a direct drive you risk stripping gears and/or damaging the tiny motor.

There are other friction designs that work and work well with even bigger Dobs. The difference is often in the motor. Here It’s often custom made, more substantial and with metal gears. If your Dob is so big/heavy that the little EQ1 drive is struggling and slipping it might be a sign that the EQ1 drive has reached its limit. 

Edited June 5 by PeterStudz

[AstralFields]

27 minutes ago, bosun21 said:

The South pivot point is far better if it is metal to metal as metal to wood will introduce a degree of stiction. David used a male pin on the top and a female recessed part on the bottom. They were bought as a pair but I have no idea what they are called.

In theory perhaps.. in practice I assure you the metal to wood is absolutely fine and negligible compared to the other huge forces.involved.. namely the lifting of the dob at the deep end of the start of the segment.

I wouldn't bother coming up with anything fancy on that side. 

And if you feel otherwise you can just add something slippery at the bottom of the hole at the pivot.

Edited June 5 by AstralFields

[PeterStudz]

51 minutes ago, bosun21 said:

My EQ platform made by the late David Lukehurst only used one motor. It was his larger size platform for my 12" SL dobsonian. The shaft was belt driven and used a knurled brass shaft which provided ample traction. I never experienced any slippage whatsoever whilst in use.

I looked at that quite closely when I made mine. It still has segments which are driven by friction. The examples I saw had one motor, but they were a little more than a bolted on EQ1 motor drive. 

Whatever, from what I gather one of the best EQ platforms out there. 

[PeterStudz]

3 minutes ago, AstralFields said:

In theory perhaps.. in practice I assure you the metal to wood is absolutely fine and negligible compared to the other huge forces.involved.. namely the lifting of the dob at the deep end of the start of the segment.

I wouldn't bother coming up with anything fancy on that side. 

And if you feel otherwise you can just add something slippery at the bottom of the hole at the pivot.

It might well be perfectly fine. Although it might also wear a bit too much over time. Even my steel washer has a small amount of wear after 2 yrs of use. Mind, wood etc is easy to replace if it does wear.

[AstralFields]

2 minutes ago, PeterStudz said:

It might well be perfectly fine. Although it might also wear a bit too much over time. Even my steel washer has a small amount of wear after 2 yrs of use. Mind, wood etc is easy to replace if it does wear.

As seen in the video I have plenty of replacement parts 😅

Also I plan to use it like ten times per year to image the planets and the moon.

It may seem ironic but I am not a fan of motorized telescopes. 😉

[PeterStudz]

14 minutes ago, AstralFields said:

As seen in the video I have plenty of replacement parts 😅

Also I plan to use it like ten times per year to image the planets and the moon.

It may seem ironic but I am not a fan of motorized telescopes. 😉

Here in the UK 10 times is about 2 years - we don’t get many clear nights - apparently!

It’s really cool seeing the likes of Mars at high magnification just hanging there in the middle of the eyepiece. And just being able to push around the Dob as normal. I can well remember observing Saturn, going in to make a coffee and when I came back out it was still there in the eyepiece. 

[Ratlet]

The thing I like about the EQ platforms is that at year the idea is pretty simple and you can approach it so many different ways and different solutions to problems.

You could spend weeks hunting down where excess stiction/friction is creeping in, changing parts etc.  or you could put a second motor in and get out and observe.

I've used CAD to design mine (if you are careful in CAD you can design the platform without any maths which suits me fine).

I think David Lukehursts platforms are near works of art.  The man was a watchmaker of eq platforms.

[PeterStudz]

46 minutes ago, Ratlet said:

 

You could spend weeks hunting down where excess stiction/friction is creeping in, changing parts etc.  or you could put a second motor in and get out and observe.

 

Exact polar alignment is challenging to achieve with an EQ platform (in other words a pain in the…). I did it once, marked the position on my patio and never again.

Without accurate polar alignment there will always be a small amount of drift. Although for visual this is insignificant. However, any small amount of slipping, stiction, wobble, little build/segment inaccuracies etc is far outweighed by the fact it isn’t accurately polar aligned - So unless you enjoy chasing your tail you can, in practice, ignore these little imperfections and carry on observing. 

Edited June 5 by PeterStudz

[AstralFields]

50 minutes ago, Ratlet said:

You could spend weeks hunting down where excess stiction/friction is creeping in, changing parts etc.  or you could put a second motor in and get out and observe.

The only reason I would do that is for the challenge itself. Getting a design optimised so it works with the simple Celestron motor across the entire big 60+ minute segment.

Only problem is, I've had enough of a challenge on this topic and it is no longer fun  😅

It is also like a 4x4 car.. even if a front wheel drive will probably do the job.. you take a 4x4 if you want a guaranteed outdoor road trip.

And finally. An hour of my time these days is not that far from the 40$ the motor costs.. making it an easy pragmatic decision when faced with multiple hours of optimisation or just turning one more motor ON. 😉

[PeterStudz]

For an 8” to 10” Dob there’s already fantastic plans with step-by-step instructions for a simple and easy to make EQ platform on this site. Follow the instructions and you get something that works and works well. Deviate from this and you might get issues. Look through these pages and you will see plenty of others who have made this design. Some with modifications too. Eg the two motor variant has been done before, different options for a south bearing… If you are not satisfied with this and want something more complicated/different then there are a host of other designs out there on the internet. 

Having read stuff by others with more experience and having tinkered with my own platform slipping usually comes down to two things:-

You need more friction. 

Balance - the centre of mass is too far away from the polar axis. The simple platform on this site should get your centre of mass close enough for the majority of 8”-10” Dobs. For larger Dobs you probably need to calculate your centre of mass and slightly modify the design. There’s lots of information on how to do this on the internet. It’s not difficult. But you need to do this at the design stage. Once it’s built it’s too late. 

People are different and there many ways to go about building or making something. There isn’t a right/wrong way. When I built mine I closely followed the design on this site. And it was nice, but no surprise, to discover that it worked the first time I used it.

Modifications, mostly personal, were done over a period of about 1 year, in an iterative way (iterative design), mainly because I didn’t really know what I was doing and I wanted something quick and that worked. It’s the same process that I followed when I made the base for my Dob. 

Here in the UK we can get weeks on end where the sky is cloudy, so time isn’t an issue. Much of the “improvements” used bits that I already had down my shed (so were free). Here you could argue that it’s never finished, but by doing this I made something that worked and made it quick. Then slowly “improved” it when time allowed. I certainly didn’t waste any observing time at the eyepiece!

Edited June 6 by PeterStudz

[Peter25626]

Hey AstralFields, I am looking but can't seem to find the plans visible in this clip from your video. Any help finding these? Really look forward to build this! 

[Cornelius Varley]

49 minutes ago, Peter25626 said:

Hey AstralFields, I am looking but can't seem to find the plans visible in this clip from your video. Any help finding these?

The pdf file for the plans are in a link in the first post in this thread.

[AstralFields]

3 hours ago, Peter25626 said:

Hey AstralFields, I am looking but can't seem to find the plans visible in this clip from your video. Any help finding these?Really look forward to build this! 

Hello, They are in the description of both videos
 

If you would like to build your own, please follow this guide

https://drive.google.com/file/d/1Xg4LBCNtED23_Ha50-la0b70z4_xOGFb/view?usp=drive_link

You will need to install Libre Office Draw (free) to ensure printing of the segments at scale. Additionally, you could try with the PDF version:

https://drive.google.com/file/d/1vaq1xYoLOoWMC4bgHCmyJTn5w97NLlUx/view?usp=drive_link

Make sure to post some pictures here of your completed platform

Edited July 2 by AstralFields

[Peter25626]

2 hours ago, Cornelius Varley said:

The pdf file for the plans are in a link in the first post in this thread.

I see them, yet those are not the same plans as in the background of the video. I am having trouble understanding the files that are attached. For example,

What do the three coloured circles represent?

What is the 'diameter of azimuth bearing'?

 

[AstralFields]

46 minutes ago, Peter25626 said:

I see them, yet those are not the same plans as in the background of the video. I am having trouble understanding the files that are attached. For example,

What do the three coloured circles represent?

What is the 'diameter of azimuth bearing'?

 

The three colored circles represent different Dobsonian bases sizes and how they would be put on the platform with their respective circular bottoms.

You can find more of the theory here:

https://www.reinervogel.net/index_e.html?/Plattform/plattform_VNS_e.html

Edited July 3 by AstralFields

[AstralFields]

4 hours ago, Peter25626 said:

Hey AstralFields, I am looking but can't seem to find the plans visible in this clip from your video. Any help finding these? Really look forward to build this! 

The plans you see here are from this thread: They use a different design with Aluminum so I did not include them in my build.