RobinH

thank you for replying so quickly.

To keep the best accuracy I will continue trying to mount the phone flat in line with the binoculars. It will be possible just needs a bit of experimenting to get the best position and balance.

Thank you for making your project available to everyone. 

Robin

Hi Artik,

is it possible to use astrohopper with the phone upright? I want to use it on my binoculars which are on a parallelogram mount. Its difficult to mount a phone flat while keeping it easy to view and press the screen.

thanks

Robin

I have made 4 P mounts and the designs have evolved and improved with each one. I have found that I did not need any washers and just wood on wood contact was not a problem. Sometimes too little friction allows the bins to move if the balance is not perfect.

I suggest try it with no washers then see how it feels. 

P mounts are very forgiving of imperfections, so don't over design it.

Hi Greg,  I think that using a magnetometer is likely to give problems as anything steel will distort the earths magnetic field. I made a digital setting circle for my Dob with an arduino which became unusable when I changed the alt of the scope. 

I have also made a barndoor tracker for my camera using an arduino and stepper motor. I use a compass to find aprox North. Then a wixey digital inclinometer to set the alt at my latitude. I have attached a 10mm dia tube 200mm length along my tracker hinge and use this to sight on to Polaris and fine tune alignment. 

an alternative processor is ES32, same price as arduino, very compatible and uses arduino IDE, Wifi, and fast.  The only down side is it is wider so needs 2 breadboards. 

I have used weight lifting type weights then filled the large centre hole with polymorph. when its cooled you can file it flat then drill a hole to suit. I used these for my binocular parallel mount weights. They can often be bought from charity shops or car boot sales.

Robin

The sponge is a easy and cheap fix to try .  My diy P-mount uses a  typical Dob AZ pivot with 3 teflon pads riding on a plastic surface.  It did move too easily but  tightening the central bolt fixed it. I suppose with a lazy susan there is not an equivalent bolt to tighten. 

I found that the azimuth pivot can benefit from quite a lot of friction as the arm gives lots of leverage to move to position.

I have used a very similar surveyors tripod for my P-mount and added 2mm stainless wire ropes between the legs. This stops the legs splaying out when on flat concrete, but also folds up when the tripod is folded up for storage. 

Robin

I will be trying my 10x50s on a Manfrotto 222 joystick on top of a monopod next week. Hopefully this will do the job and also be small enough to take on holiday around the north coast of Scotland in the campervan.  I normally use Helios 15x70s on a parallel mount but that combination is too big to take on holiday.

I will be using the binocular right angle adaptor fixed to a quick release plate so I can use my camera on the monopod when not using the binoculars. The manfrotto 222 has a quick release adaptor on top as standard.

Did it work ok?

The boxmount looks good, very compact.

It looks like its the proper bit.

I wonder how long before you automate it

Robin

I recommend a wide separate base like a low stool then you will not have to screw legs directly onto your dob base. I made a separate base and found it made moving the dob easier.  I found 300mm high works well for me.

if you drill shallow holes into the top of the new base in the correct place then the existing feet on the dob will locate and sit on the base very safely. 

Robin

here are a couple of photos of my home made mount. It based on a surveyors tripod shown at its lowest position. 

The hinge is shown in a closer view. This is for use when seated.

also shown is max height  over 6 foot. and minimum height lower than needed for a reclining chair. 

Let me know if you want any dimensions or details to make one.

the bins shown are 15x70 Helios 

I suggest using a  parallel mount for bins then if the beam is long enough you will be able to reach up higher than 172cm with the central post much lower. 

for use reclined you need the bins to swing in an arc horizontally at the end of the arm. This allows you to keep the chair still while being able to scan a large area of the sky. It really irritating using a P mount without this extra degree of freedom. I have used one without for a couple of years standing up which was good. I added a hinge with its axis vertical and am now able to use it when I am reclined. This is important when looking up high. I don't know who makes one as mine is homemade. 

I suggest waiting for more members to advise before buying as they are not cheap and may not do what you find that you need.  If you can do some DIY then it does not cost much.

I can post a picture tomorrow to explain what I mean.

I have now remade my barn door tracker to use the 8mm 3D printer threaded rod that you suggested May 22. It works much smoother and is the correct part to use. I found one that moves 2mm for every revolution which was twice as much as my original M6 threaded rod but it will not be difficult to change the software to suit. 

Thank you for your very helpful idea.

Robin

Hi Duncan,

how about leaving the  north  side of the roof fixed so it can act as a shield. 

Can you use an octagonal shed or turn the shed so the fixed part of the roof is  towards the offending light. 

Robin

thanks for the explanation. I am gradually getting a clearer mental image of the movement. 

Are the guiding blocks  39 degrees and flat.?  It looks very simple which is good. Lots of other eq platforms seem to have complicated guide profiles.

Will you need to pivot the motor to match the angle of the threaded rod as it moves? I know you will not run for long so maybe the belt can just twist a small amount.

I am very interested as I have been wanting to make a platform for about 4 years but other projects have got in the way and I am very slow.

Robin

Have you decided how to drive the plywood circle?  I assume that the pressure pump is what I would call a gas spring.  Could the assisting pressure pump  be mounted flat to push the top disc round rather than lift it?

I think there is a problem with the power supply as I have used the same 5v for the arduino and the stepper driver. I had noticed that an analogue input changed depending on if the motor was running so there is a problem. I will modify the power supply to make the motor run from an independent 5v supply.  I was trying to cut corners which proved to be the wrong strategy.

I have received the 8mm 3d printer threaded rod and brass nut this morning. Its much easier to turn  and I think it will be a big improvement. 

Robin

thanks for the suggestion of 3d printer rod and brass nut.  I have used a m6 threaded rod (construction type) on my barn door tracker but have been experiencing problems sometimes with the stepper motor stalling.  The 3d printer drive thread is not expensive like I had imagined so I will be changing.

Robin

Thanks Sven,

I will read  your very detailed explanation and see how I can use your ideas .

Robin

Thank you,

I have designed my barn door for a max of one hour movement. After doing a spreadsheet with lots of rows it does seem that there is only a very small speed difference at one hour. 

Robin

Hi Chriske,

do  you have any more info on your friend's  varying speed strategy that you can share? I am building a straight threaded rod barn door tracker but  have only a constant  speed on my stepper. I think that I will need to vary the speed but have not yet thought of a simple strategy to do this.

Robin

Have you seen this site?  https://sites.google.com/site/thedobsonfactory3/welcome

they don't do plans but do have a diy kit. The dobs fold up really small for transport .

Great report, so much that you saw and very interesting to read. I usually read it more than once and try pick out any of the easier possible targets for me to try.

It was very cold, so cold that it was difficult to carry on observing.  My van said -4.

Thanks for showing me the Leo Trio and how tapping the tube works. I had read about it but I could never have tried it without you finding the objects.

Imaging does make the hobby less interesting for others as the equipment is busy taking pictures. Your Dob is great for parties as you find the targets then show other people. Then on to new targets all with no electronics or software or motor/gears to go wrong.

I was able to find a few new objects with my bins, its so nice having dark skies compared with Wolverhampton.

Robin