10” Equatorial Platform for Dummies

[westmarch]

After good advice on equatorial platforms from Moonshane and reading his trial and error progress to mastery, I finally took the plunge.  

I lost the plot on how to work out the centre of gravity of my setup - see the last pic and you will understand why! - and assumed that the design would cope with common commercial 10” Dobs. (Don’t try this at home with a home build, bespoke Dob!)

I opted for Reiner Vogel’s  excellent design for a VNS (Vertical North Segment) platform, mainly because I lack the trigonometry to calculate my own curve for the bearing and he has templates for various latitudes.  The thin aluminium arc also worked for me since it only needed a hacksaw and I also lack the woodworking skills (and equipment) to cut the inclined woden arc required for a circular segment design.

Reiner’s general VNS guidance:

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

Specific design for the smaller platform:  

http://www.reinervogel.net/Plattform/Vorlage Plattform 14 hoch.pdf

I dispensed with the need to have the upper platform as the Dob’s turntable base and just sat my Dob on it.

I couldn’t cope with the electronics and so am indebted to Nick Hill’s design for a motor - he just bought a direct drive EQ1 9v DC motor, widely available commercially from Celestron, Meade, etc. designed to move a telescope rig at equatorial speeds.

Some plywood and a saw had the bases constructed.  Four 18mm pillow bearings and a length of 18mm steel shaft, an aluminium plate for the curves, aluminium right angle brackets for the attachments and an aluminium block for the pivot bearing were all that was needed.  (Isn’t ebay a marvellous thing!) Oh, and various screws, nuts and bolts.

In all, it’s cost me £85 but you could save £15 on the motor if you got a standard EQ1 motor (they are all made in China and it looks identical but without the Meade/Celestron trade mark on it.)

Haven’t had a clear night since finishing it but the motor is moving the platform, the stops prevent it from coming off the bearings and the Dob azimuth brake is able to cope with maximum tilt.

Oh for a clear night to try it out! ?

John

 

 

 

 

Edited June 2, 2018 by westmarch

[Paz]

Well done, that looks great. I bought a second hand eq platform and  saved a lot in doing so but yours has cost half what I got mine for.

Edited June 2, 2018 by Paz

[pipnina]

Being held down by gravity alone, I would be mortified at the thought of mine tipping over since we're at 51-56 degrees north in the uk!

You seem to have done a splendid job of it though. You'd think it was off-the-shelf by Meade, made specifically for that scope!

[westmarch]

4 minutes ago, pipnina said:

Being held down by gravity alone, I would be mortified at the thought of mine tipping over since we're at 51-56 degrees north in the uk!

You seem to have done a splendid job of it though. You'd think it was off-the-shelf by Meade, made specifically for that scope!

The recesses in the upper platform grip the feet of the Dob and even hefty pushing, at maximum tilt doesn’t shift it. It’s good for Yorkshire but Shetland might be a different story!

[N3ptune]

Inspiring work, your platform is simple and it looks very good too. (paint matching your telescope)

Thanks for sharing this awesome work!? I keep it has an example for my own equatorial platform project one day.

Edited June 2, 2018 by N3ptune

[westmarch]

OK. Finally got out last night to test the platform with my 10” Dob.  I wanted to observe Jupiter and lined the platform up pointing roughly magnetic north and levelled using the iPhone app.   It was a revelation!  The platform averaged a 25 min cycle before hitting the stop and requiring resetting. The image initially drifted slightly to the left but a simple adjustment on the EQ1 motor dial had it holding Jupiter steady in a x2 Barlowed, 12.4 Plossl at mag x200 with Afov 14.6’.

Despite some initial high haze, I had some superb views of Jupiter, using a Meade #38A Dark Blue filter.    

N and S Equatorial zones distinct with whorls evident on both,  S Polar Region distinct from white S S Temperate Zone.   Narrow, dark, S Temperate Belt visible clearly against white of S Temperate and S Tropical Zone. 

Transit of Europa viewed. Shadow very distinct in the N Polar Region and following the moon's transit by a Jovian hemisphere.  The white disc of Europa only visible as it approached  the edge of the Jovian disc.

In all I got in nearly 2 hours of viewing - this is unprecedented for me on a single object. The old maxim of seeing additional detail the longer you looked is very true. A Dob, without the platform, was more an exercise in finding and identifying.  Keeping the object in the fov, loosing it and reacquiring were the next most pressing needs.   The platform  has added a whole new dimension to my observing.

John

[Stu]

What a great build John. I would love to build one myself so might take inspiration from your project. I have owned a couple in the past and find them amazing bits of kit, very simple to use but so effective. As you rightly say, you see so much more when the target remains centred and the scope steady.

[Mr niall]

Sorry to jump on an old thread - have had this book marked for ages! Can I ask about the motor - did you have to do any electronic wizardry to get it to turn at the right speed or is I think just direct drive?

[westmarch]

Hi there,

no, that’s the beauty of it.  It is calibrated to turn an equatorial mount so it is already set. There is a standard adjustment knob so you can adjust it if you find your target drifting.

This seems to be the cheapest on sale at the moment:

https://www.rothervalleyoptics.co.uk/skywatcher-ra-single-axis-economy-motor-drive-eq1.html

John

[gerardsheldon]

Thanks for the information.  This all looks so much easier than what I have read elsewhere, so I want to give a go.   I have not had a lot of experience with wood or metal.  I would be grateful if you could help me with the following questions:

   1. Does the size of the pillow bearings matter?  I can't find 18mm.  Could I go for 17mm?

   2. Did you cut the steel shaft using a hacksaw?

   3.  Can you change the speed of the motor a lot?  I have a concern that it will either go too fast or slowly and I won't be able to adjust the motor to the right speed.

Any advice would be greatly appreciated. 

Gerard

 

 

 

[westmarch]

Hi Gerard,

sorry I missed this post.  I will PM you with some information.

John

[Grumoyjock]

Loving this as I have zero technical knowledge and minimal d.i.y skills but this would be ideal for my 8" dob

[westmarch]

17 hours ago, Grumoyjock said:

Loving this as I have zero technical knowledge and minimal d.i.y skills but this would be ideal for my 8" dob

I wish you luck. My biggest problem was finding the names for the components and where to buy them, like pillow bearings,  but if you search google long enough anything is possible. 
 

John

[Grumoyjock]

6 hours ago, westmarch said:

I wish you luck. My biggest problem was finding the names for the components and where to buy them, like pillow bearings,  but if you search google long enough anything is possible. 
 

John

Hi John

what angle did you cut the aluminium if you can remember I can source the other bits n bobs but the aluminium sections are stumping me angle wise

Thanks

George

[westmarch]

Hi George,

I’m closer to N Yorks so I cut the 54 degree curve.  If you are nearer the south of W Yorks you may wish to go with the 52 degree curve.  Once I printed out the curve, you just trace it onto the aluminium and make a series of straight cuts (marked red) and then file the waste away - aluminium is relatively easy to work with. The aluminium is so thin that you just cut it at right angles.

this eBay link should help:

https://www.ebay.co.uk/itm/Aluminium-Sheet-Plate-Flat-1mm-4mm-multiple-sizes-grade-1050A-H14/283528663514?hash=item4203a011da:g:hCcAAOSwsBtaMTUF&var=584704869652

You need two rectangles of 200mm x 100mm.  If you buy the 200mm x 200mm sheet of 4mm aluminium then you can cut it in half.

John

Edited October 3, 2020 by westmarch

[Grumoyjock]

1 hour ago, westmarch said:

Hi George,

I’m closer to N Yorks so I cut the 54 degree curve.  If you are nearer the south of W Yorks you may wish to go with the 52 degree curve.  Once I printed out the curve, you just trace it onto the aluminium and make a series of straight cuts (marked red) and then file the waste away - aluminium is relatively easy to work with. The aluminium is so thin that you just cut it at right angles.

this eBay link should help:

https://www.ebay.co.uk/itm/Aluminium-Sheet-Plate-Flat-1mm-4mm-multiple-sizes-grade-1050A-H14/283528663514?hash=item4203a011da:g:hCcAAOSwsBtaMTUF&var=584704869652

You need two rectangles of 200mm x 100mm.  If you buy the 200mm x 200mm sheet of 4mm aluminium then you can cut it in half.

John

Cheers John I'm in Wakefield and you have been a great help👍🏻

[westmarch]

Can I please point out a typo in my original post. The pillow bearings and steel shaft that I used were 8mm and NOT 18mm.

Here is where I got my pillow bearings:

https://www.amazon.co.uk/dp/B01120P4LQ/ref=cm_sw_em_r_mt_dp_6.vKFb0R54YA2?_encoding=UTF8&psc=1

Here is where the steel rod was sourced from: as

https://www.amazon.co.uk/dp/B07MV83GXB/ref=cm_sw_em_r_mt_dp_AcwKFbRG33SF5

Sorry once again for any confusion caused.

John

[markse68]

4 hours ago, westmarch said:

Can I please point out a typo in my original post. The pillow bearings and steel shaft that I used were 8mm and NOT 18mm.

I did think at the time that sounded a bit beefy!

[varius21]

Hello, I am looking into building one of these. Thank you for all the info posted above. I am curious if the aluminum will be slipping on the metallic rod... no chance for it sliding on the rod due to the weight?

[westmarch]

Hi there,

The aluminium gets good traction due mainly to the weight of the dob.  It only slips when it reaches the end of the travel and hits the stops.

John

[westmarch]

On 02/06/2018 at 22:12, westmarch said:

After good advice on equatorial platforms from Moonshane and reading his trial and error progress to mastery, I finally took the plunge.  

I lost the plot on how to work out the centre of gravity of my setup - see the last pic and you will understand why! - and assumed that the design would cope with common commercial 10” Dobs. (Don’t try this at home with a home build, bespoke Dob!)

I opted for Reiner Vogel’s  excellent design for a VNS (Vertical North Segment) platform, mainly because I lack the trigonometry to calculate my own curve for the bearing and he has templates for various latitudes.  The thin aluminium arc also worked for me since it only needed a hacksaw and I also lack the woodworking skills (and equipment) to cut the inclined woden arc required for a circular segment design.

Reiner’s general VNS guidance:

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

Specific design for the smaller platform:  

http://www.reinervogel.net/Plattform/Vorlage Plattform 14 hoch.pdf

I dispensed with the need to have the upper platform as the Dob’s turntable base and just sat my Dob on it.

I couldn’t cope with the electronics and so am indebted to Nick Hill’s design for a motor - he just bought a direct drive EQ1 9v DC motor, widely available commercially from Celestron, Meade, etc. designed to move a telescope rig at equatorial speeds.

Some plywood and a saw had the bases constructed.  Four 18mm pillow bearings and a length of 18mm steel shaft, an aluminium plate for the curves, aluminium right angle brackets for the attachments and an aluminium block for the pivot bearing were all that was needed.  (Isn’t ebay a marvellous thing!) Oh, and various screws, nuts and bolts.

In all, it’s cost me £85 but you could save £15 on the motor if you got a standard EQ1 motor (they are all made in China and it looks identical but without the Meade/Celestron trade mark on it.)

Haven’t had a clear night since finishing it but the motor is moving the platform, the stops prevent it from coming off the bearings and the Dob azimuth brake is able to cope with maximum tilt.

Oh for a clear night to try it out! ?

John

 

 

 

 

Following requests from a number of members I have attached more detailed instructions on how to build this equatorial platform. Including a correction of a typo in the original post correcting 8mm for 18mm bearings.

I hope it is of some help.

John

Equatorial Platform Basic Guidelines.pdf

[Kon]

28 minutes ago, westmarch said:

Following requests from a number of members I have attached more detailed instructions on how to build this equatorial platform. Including a correction of a typo in the original post correcting 8mm for 18mm bearings.

I hope it is of some help.

John

Fantastic, thanks for sharing with all of us! I will probably have a go at it myself. Would these dimensions also work for an 8" Dob?

[westmarch]

I have not tried it but I believe they would.

John

[starsmydest]

Thanks John for a very detailed guide, it is really nice to have the parts names and link, I agree shopping the right parts is the most tricky task in building this, until I saw you post. 

below is my build for my 200P dob sitting on, tried it last night and it was a treat with Mars! 

 Cheers

Gang

[westmarch]

Hi Gang,

A very professional build. You are obviously blessed with a level garden.  I needed the furniture levelling feet to get the whole platform level. 

John