10” Equatorial Platform for Dummies

[AstralFields]

Also to come back to the printable segments shared in this thread. They are incorrect for all the latitudes. Seems like Reiner has counted with a tilt degree for the segments of 15 degrees but in the plans it is 20 degrees. For some of the latitudes he did not apply the segment tilt at all, making the error bigger.

In practical terms this will induce some errors necessitating to change the speed of the motor during the tracking and some minor drift.

After I fixed it for my latitude, the difference between 15 degree tilt or 20 degree tilt is obvious

Sorry for the bad news to everybody who printed the segments for their platform. On the bright side, I guess they can be easily replaced. I may create a fixed version after I finish my platform for all latitudes as it is pretty easy using Libre Office - Draw

 

Another mistake I have noticed in this thread, people have printed the segments at the wrong scale. Somebody asked about this and someone else took a picture of a ruler over the segment. When you open them in Libre - Draw using the in-app rulers for the page, it is clear how big they should be. One can even draw a simple line and see exactly to mm how long the segment should be.

This is likely induced by the incorrect handling of PDR printing by the printer and some auto-scaling stuff going on due to printer margins.

To avoid, it is best to import the plans in Libre Office - Draw. Fix the segments there and print the segment directly from the app.

In order to perform the fix, one may need to temporarily increase the page size to 100x100cm as the ellipse creating the segments is that big.

The exact dimensions of the segments are very important because the distance in the plans is fixed at 244mm between them (meaning they should be at a specific size). Again all of this can be verified in Draw.

Not having them exact is again inducing minor errors in the system.

Edited April 13 by AstralFields

[PeterStudz]

@AstralFields, interesting… thanks for this. Although after using my EQ platform extensively for almost about 19 months it’s more than accurate enough for me. Eg I can view targets like Mars at high magnification (x375 which is about as far as seeing & my 8” Dob will go), then pop inside for a short break, make a coffee, come back and Mars is still well within the FOV. I’ve even used it for simple imagining.

As you say, it’s easy to make new segments, but I don’t think it’s worth fiddling with… if it works don’t touch it!

Edited April 13 by PeterStudz

[AstralFields]

Yeah .. To put things into context, the errors I am speaking of are like 1 degree per hour of tracking.. pretty minor but worth sharing for any new buiders.

[PeterStudz]

12 minutes ago, AstralFields said:

Yeah .. To put things into context, the errors I am speaking of are like 1 degree per hour of tracking.. pretty minor but worth sharing for any new buiders.

This is true.

Might be worth pointing out but I think that there are other errors that are more significant than this. Although for practical visual purposes they probably don’t matter. 

Eg the EQ1/2 motor drive. I love its simplicity but its speed isn’t always constant - you can see this for yourself by placing a voltmeter over the motor terminals. I have one as a permanent fixture that I can switch on/off. For practical purposes it doesn’t matter but it will create drift. And some of these little cheap drives are better than others. Bit of pot luck there.

Balance... Recently I took my magnetic balance weight off the end of my Dob and placed it onto the ground board for convenience. This just happened to be directly opposite the drive segment. Although weighing just 600g this was enough to cause my platform to slip to such an extent that it was no longer working properly. It took me ages to work out what was going on! 

[westmarch]

On 13/04/2024 at 10:27, AstralFields said:

Also to come back to the printable segments shared in this thread. They are incorrect for all the latitudes. Seems like Reiner has counted with a tilt degree for the segments of 15 degrees but in the plans it is 20 degrees. For some of the latitudes he did not apply the segment tilt at all, making the error bigger.

In practical terms this will induce some errors necessitating to change the speed of the motor during the tracking and some minor drift.

After I fixed it for my latitude, the difference between 15 degree tilt or 20 degree tilt is obvious

Sorry for the bad news to everybody who printed the segments for their platform. On the bright side, I guess they can be easily replaced. I may create a fixed version after I finish my platform for all latitudes as it is pretty easy using Libre Office - Draw

 

Another mistake I have noticed in this thread, people have printed the segments at the wrong scale. Somebody asked about this and someone else took a picture of a ruler over the segment. When you open them in Libre - Draw using the in-app rulers for the page, it is clear how big they should be. One can even draw a simple line and see exactly to mm how long the segment should be.

This is likely induced by the incorrect handling of PDR printing by the printer and some auto-scaling stuff going on due to printer margins.

To avoid, it is best to import the plans in Libre Office - Draw. Fix the segments there and print the segment directly from the app.

In order to perform the fix, one may need to temporarily increase the page size to 100x100cm as the ellipse creating the segments is that big.

The exact dimensions of the segments are very important because the distance in the plans is fixed at 244mm between them (meaning they should be at a specific size). Again all of this can be verified in Draw.

Not having them exact is again inducing minor errors in the system.

I think Peter has summed it up nicely. The platform is for visual not AP so slight drift is not a problem, particularly with wide field EPs. 

Hopefully the thread title keeps it clear that this is a low tech, inexpensive solution aimed at those with limited DIY skills.  Anything more really requires more outlay and/or knowledge and skills. 
 

John

[AstralFields]

Almost there. There have definitely been some lessons learned along the way. 

1) Don't use any drill adapters to cut wood. The damn thing broke 80% along the way and I am having to cut the rest manually. Just get a small hand held wood cutter. I probably will for my 12" DOB version.

2) Use plywood. The type of wood I am using is not the ideal, the top board broke in two so I had to patch it up. It will likely add a bit of bounciness to the system but shouldn't be too drastic. I can always replace it later on with plywood.

3) Don't store your only 9V battery in a box full of metal parts. Few days later - voltage ZERO. Just when I was going to turn on the platform for the very first time.

4) Aluminum is a tough nut. Not all Aluminums are alike. I was going to use a 3mm bar to cover the segments but that thing was tough to cut. I even gave up of putting it under the pivot. I am just going to hollow out a small hole in the wood. So I just made the segments out of wood and put some rubber on top of them to cushion the roll.

All in all, few cosmetic cuts remaining but it really came along very well. Maybe Thursday I will get to test it on the Moon.

Edited April 17 by AstralFields

[AstralFields]

Mission Accomplished.

As they say, pictures speak louder than words. This is M3 with a more or less OK alignment. I don't have a proper DSO camera so this was with my cellphone through a 15mm eyepiece on my 8" DOB .. 80x magnification.

the Aluminum segments that you find in most plans are definitely not needed. Wood is a lot easier to deal with and lined with a bit of door tightening rubber it runs extremely smooth.. no jerky motions of the objects whatsoever even at 800x. There is some drift at this power, but it is smooth and mostly to not exact alignment/speed setting. I captured all of this on video of the Moon and will be compiling it into a nice 10-15 minute video of how I made the platform from start to finish with the key lessons learned.

The price tag is really small for this one, given the performance I am getting. Next time I am doing it with Plywood.

When you break it down , there are just few parts:

Plywood - about 30$

EQ 2 Motor - 37$ from Aliexpress with shipping

Wheels and pre-cut iron rod 0.8mm - 10cm long - about 10-15$

Some spherically curved bolts - 2$

Regular wood screws - 1-2$

optional:

Li-Ion rechargeable 9V batteries - about 8$ (which I bought)

A hand-held controller for the speed of the motor - they go for about 2$. I will make one as it was very frustrating having the fine tune the speed by going back and forth from the eyepiece to the motor.

All in all , a nice price tag of around 80$. A new one (albeit prettier) sells for about 500$ here with the same motor and same performance.. I may make a couple of these for a 12" DOB and sell them for 250$ each. Already two people expressed interest. It is far below my hourly wage when I count the time I need but it is fun and always nice helping out an astro buddy :).

The biggest advantage of building one your own is you get to simply make it fit your telescope exactly and you understand how it works. Also you can cut the segments exactly for your needs. By the looks of it, this one should be OK for the 12" as well , which I already have on the way.

It provides tracking for about 90 minutes, which is great and so comfortable that I found myself forgetting to reset the telescope after an hour of observation.

[PeterStudz]

@AstralFields Good to know that it all works. For a hand controller as long as you have some bits of wire you don’t even need to spend any money. Some people have separated the motor from the box (with circuit board & switches), joining the two with long wires. You can see the two separated in the Teleskop version - the motor at one end and the box with the electronics and switches at the other.

I thought of having a hand controller, but personally I haven’t found it to be a problem. I have a little volt meter across the motor terminals on my version. All I do is make sure it’s set to the correct number (for me 2.35 - 2.37 volts) at the beginning when I have to bend down anyway and keep it there. I rarely need to fiddle with it and often don’t touch the potentiometer for several sessions in a row.

Although the good thing about making your own is that you can personalise things to your taste/requirements!

Edited April 18 by PeterStudz

[AstralFields]

15 hours ago, PeterStudz said:

@AstralFields Good to know that it all works. For a hand controller as long as you have some bits of wire you don’t even need to spend any money. Some people have separated the motor from the box (with circuit board & switches), joining the two with long wires. You can see the two separated in the Teleskop version - the motor at one end and the box with the electronics and switches at the other.

I thought of having a hand controller, but personally I haven’t found it to be a problem. I have a little volt meter across the motor terminals on my version. All I do is make sure it’s set to the correct number (for me 2.35 - 2.37 volts) at the beginning when I have to bend down anyway and keep it there. I rarely need to fiddle with it and often don’t touch the potentiometer for several sessions in a row.

Although the good thing about making your own is that you can personalise things to your taste/requirements!

The thing about the controller.. I already have one laying around here, got it back last year where I built my own planetary motor out of Lego (long story) .. so it is just a matter of rewiring it to the platform. I did settle down on a constant speed towards the end of the observation but it just felt like I could use some minor micro tuning of the speed back and forth.

[AstralFields]

For those who may be interested to check on how it went

 

[Buford7]

Hi everyone—I’m late to the party on this thread, but I see that it is still active.  Great work by all, and I’ve enjoyed learning what you have been trying.

I’ve been hard at work on trying to make the plan from the OP work for my Apertura 10” Dob.  Sadly, my base is slightly too large for the original plans posted here and my groundboard feet sit about 2cm centimeters outside the template on the north axis.  I’ve been scouring also through the www.reinervogel.net website referenced in the beginning, to try and work out how to make this project fit for my Dob, and trying to figure in Centre of Gravity (COG) calculations and his original measurements to see how to “stretch” this template to fit and be accurate and stable.

When designing according to Vogel’s original instructions, I am getting my South axis calculated to be underneath my Dob groundboard.  Knowing my groundboard is larger, and guessing my COG is lower than the OP template—perhaps this makes sense.  But I have not seen anyone else here with this issue and am not certain how this would affect balance and tracking.

I have thought of 3 options overall:

1)Extend the North axis base by several centimeters on both ends and build the rest of the template according to the OP plans.  Again—no idea how this would affect balance and tracking

 

2)Use my calculations from Vogel’s original plans that puts my South axis underneath my Dob and hope that works.  Also—no idea if this is safe or effective.

 

3)Reach out to the community here and get help.   I believe this will be my best bet.  I am hopeful that someone will be able to provide further direction before I put saw to wood.  Below I am including some of the parameters and measurements that I have been gathering, and I hope that will be enough to give someone who is experienced what they need to point me in the right direction.

 

Measurements:

• Outer distance from one groundboard foot to a second groundboard foot:  465mm
• Optical Tube Centre of Gravity to ground:  600mm (assumes this is from centre of the altitude axis pivots)
• Rocker Box Centre of Gravity to ground: 150mm
• Optical Tube weight:  18.63kg
• Rocker Box weight:  13.63kg
• Distance from azimuth bearing to outer side of groundboard foot:  267mm
• Calculated COG of assembled telescope:  388mm to ground
• Height of ground feet: 22mm
• My latitude is 53.5 degrees, in Sherwood Park, Alberta, Canada

Many thanks to anyone who can provide me with direction and support!

 

Thanks,

Graeme LaRue

 

[AstralFields]

The 10" DOB should be fine with the plans

Groundboard feet are 465mm apart.. the width of the platform is 490mm.. all good and the feet land at the corners. 

You are probably missing something.

If you are unsure, just build the 12" version by Reiner on his site. Iam building three of them. They are over 600mm wide.

[westmarch]

Have you considered repositioning the feet of your Dob by 2cm to fit the platform?  It’s usually a single wood screw per foot and it’s unlikely to make much difference to the COG. 
 

John

[PeterStudz]

12 minutes ago, westmarch said:

Have you considered repositioning the feet of your Dob by 2cm to fit the platform?  It’s usually a single wood screw per foot and it’s unlikely to make much difference to the COG. 
 

John

I was going to suggest similar. The base/feet were too wide on my homemade base. All I did was move them in a bit - easy as each foot had a single wood screw. 

The base overhangs the platform by a few extra cm, but it’s balanced OK so it doesn’t mater. 

[Buford7]

@AstralFieldsThe issue with feet distance is that only bottom of the board is 490mm, once you cut out the 20° angle it is now less than 490 where the Dob feet need to rest. 
 

I though about building Vogels larger one as well, or just widening the base of the 10” plan to fit my Dob better—just not sure how modifying the template affects balance, tracking time etc. 

[Buford7]

@westmarch/PeterStudz-I hadn’t though of moving the feet, so will consider that too. 
 

Are you guys getting 90min or so of tracking on this design now that you’ve had it awhile?  

With not getting into the whole COG calculations that the Vogels original plans called for—you’ve been happy with the results and not having balance issues or tracking time issues on 10” units?

[westmarch]

I average about 40 mins tracking on my platform. It actually lasts longer because I have it switched off while I am star hopping to my target and only switch it on when I am in the acquisition region.   I have not had balance issues and the recessed feet in the platform gives additional stability. On the basis that most commercial 10 inch Dobs are mechanically fairly similar, I think that it should work.

BTW Peter found a great app which cheaply does away with the star hopping bit and turns the Dob into a GoTo scope.

John

 

 

[AstralFields]

On 05/05/2024 at 23:52, Buford7 said:

@AstralFieldsThe issue with feet distance is that only bottom of the board is 490mm, once you cut out the 20° angle it is now less than 490 where the Dob feet need to rest. 
 

I though about building Vogels larger one as well, or just widening the base of the 10” plan to fit my Dob better—just not sure how modifying the template affects balance, tracking time etc. 

I think the bigger platform will be better in all regards. 10cm is a very minor difference and I wouldn't worry about it at all. If anything it should improve the balance of the whole thing.

I have the same feet distance on my 8" and I had a width of 500mm and it fit very nicely.. So you can basically settle on a width between 490mm and 600mm and take it from there.

[Buford7]

2 hours ago, AstralFields said:

I think the bigger platform will be better in all regards. 10cm is a very minor difference and I wouldn't worry about it at all. If anything it should improve the balance of the whole thing.

I have the same feet distance on my 8" and I had a width of 500mm and it fit very nicely.. So you can basically settle on a width between 490mm and 600mm and take it from there.

Yes I would agree—in fact I plotted out my scope on the larger Vogel template last night and looks like a great fit and alignment!  So between that template and John’s (original poster) excellent instructions here I am using a calculated COG of my whole setup to adjust the South pivot point which I’m hoping will enhance tracking accuracy (Sketch attached) I believe I shall proceed with this. Thank you for your thoughts!

Edited May 7 by Buford7

[Buford7]

4 hours ago, westmarch said:

I average about 40 mins tracking on my platform. It actually lasts longer because I have it switched off while I am star hopping to my target and only switch it on when I am in the acquisition region.   I have not had balance issues and the recessed feet in the platform gives additional stability. On the basis that most commercial 10 inch Dobs are mechanically fairly similar, I think that it should work.

BTW Peter found a great app which cheaply does away with the star hopping bit and turns the Dob into a GoTo scope.

John

 

 

That’s all great feedback John—I appreciate hearing more of your experience.   Tracking is going to be a wonderful addition

 

And great idea about the app—I will check it out for sure. 
 

Thank you again for starting this thread a few years back. It has stimulated a great deal of help for DIY astronomers. 

[Buford7]

On 04/08/2022 at 05:42, PeterStudz said:

Almost there. I lost some time due to holiday but once you’ve cut out the boards and aluminium arcs the whole thing quickly goes together. My Dob has a rather “solid” DIY base with large feet and I haven’t quite worked out how to secure it. But as soon as I had something that worked I could not resist giving it a go, the Dob just carefully plonked on-top. Didn’t have much time before the forecast clouds came in so I homed in on Saturn. Even at 300x (far too much for a sharp view) I could keep the planet centred. Went in to make a coffee and even after 4-5 mins Saturn (some drift of course) was still in the eyepiece. I could even make out 4 moons (a first for me), the advantage of having more time to observe before having to nudge. Now, just need to finish it off!

Nothing that different from the excellent instructions. And I have to say that @westmarch should get some sort of prize for this thread.  I know he’s taking ideas and inspiration from others but this platform is minimalistic, simple and straightforward to make that just about anyone can give it a go. All in the tradition style of the Dob. The only tools I used were a handsaw, hacksaw, electric drill, file, and some screwdrivers.

I did break a drill bit when drilling the fixing holes for the aluminium block, the end of the bit stuck fast. Cheesed off I went down the shed to see if I could find something as a substitute. In the end I used a scrap plywood block, a couple of penny washers to form a recess and a dome nut to sit on top of an M12 bolt. The dome nut is 18mm diameter which is similar to an M20 bolt with the threads filed off . Seems to work well with a smooth rotation.

I’m a veteran of the EQ1 motor drive. I had one for an EQ1 (my first telescope) and it was the best £28 I’ve spent in astronomy. It transforms the EQ1 into something useable. Although I did try and improve it by replacing the 9v battery with something with more beef and that’s rechargeable. I did find that I was going though 9v batteries far too quick and that this small battery didn’t do that well in the cold. For this I used a cheap 12v sealed lead acid battery (the type used in alarms) knocked down to 9v with an equally cheap converter. This pushes out a steady 9v almost whatever the temp and lasts an age before needing a recharge. I also added a little voltmeter over the motor terminals - the idea here (I know it’s not quite as simple) is that I could quickly dial back a motor speed that worked. Oh, also a proper size “knob” on the potentiometer. I’ll change the wiring around somewhat  but it’ll basically stay the same with a battery box on the lower board. I was also going to use a micro switch for a motor stop but playing around I felt that for security it does need some sort of physical stop. For that I just added a couple of wooden blocks and I might still add a micro switch on top of one of these.

PS - my drill can take a 25mm bit. I was wrong there! 

Hi Peter!  Love your setup here. I am doing some similar work in the next few weeks. Your upgrade knob for the potentiometer—would you let me know where you got it, or what size is needed to replace to stock knob. Love that mod and want to do the same when my EQ drive shows up. 
 

Thank you! 
Graeme

[Buford7]

I thought I should post the same question to the group as a whole that I posed to Peter yesterday—but is anyone able to check what the shaft size under the Speed Control dial is on the EQ drives you are using for your vns platforms?  Everyone seems to be using the same basic one (Celestron 93514 or equivalent) and I’d like to put a larger dial on there to make it easier to adjust in the dark. Just need to know a shaft size so I can order something from AliExpress. Thanks!

[PeterStudz]

On 07/05/2024 at 17:05, Buford7 said:

Hi Peter!  Love your setup here. I am doing some similar work in the next few weeks. Your upgrade knob for the potentiometer—would you let me know where you got it, or what size is needed to replace to stock knob. Love that mod and want to do the same when my EQ drive shows up. 
 

Thank you! 
Graeme

Hi Graeme,

I used a flange ridged coupling coupler. It doesn’t replace the knob - from memory the plastic knob is glued to the potentiometer - it just goes over it and is tightened down with grub screws. I did file down the shaft a tad so that the grub screws were as far down the original little plastic knob as possible, but it’s not necessary.

You need a coupler with a bore of 4mm. Like this…

https://www.ebay.co.uk/itm/295812217786?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=ix8MD51qSo2&sssrc=4429486&ssuid=I8jCpZsmREe&var=594047402957&widget_ver=artemis&media=COPY
 

There’s cheaper too…

https://www.ebay.co.uk/itm/174613961375?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=j52Qiqy0T9G&sssrc=4429486&ssuid=I8jCpZsmREe&var=473819681841&widget_ver=artemis&media=COPY
 

There must be other solutions but this has worked well for me.

[Buford7]

@PeterStudzAh beautiful!  I can see where that would work nicely. Thank you so much. I shall hunt this down!

Peter, I can also see some value in the little micro switch that you set up to stop the motor when it gets to the end of its range. Would you mind explaining how to wire that switch into the battery/dc converter and motor set up that you have? I can see that I might want to give that set up a try as well. 

Edited May 8 by Buford7
To ensure I am replying directly to previous comment

[PeterStudz]

On 08/05/2024 at 18:03, Buford7 said:

@PeterStudzAh beautiful!  I can see where that would work nicely. Thank you so much. I shall hunt this down!

Peter, I can also see some value in the little micro switch that you set up to stop the motor when it gets to the end of its range. Would you mind explaining how to wire that switch into the battery/dc converter and motor set up that you have? I can see that I might want to give that set up a try as well. 

I like the (much bigger) toggle switch as it’s easier to find in the dark. I use an external rechargeable battery. The EQ1/2 motor drive comes with a standard 9v dry cell connector. So I don’t need to alter the motor drive  and solder etc I’ve used another 9v connector and snapped it together, the second new connector going to the rechargeable  battery. The toggle switch has just been added in-line - leaving the  micro switch “on” all the time. I’ve added some pictures to try and illustrate my poor explanation. Hope that makes sense!