DIY Parallelogram Binocular Mount

[tombardier]

I completed my parallelogram mount today. It's something I started when I had some time off over Christmas.  There was an initial surge of productivity, and then it languished.  I managed to get it over the line today though, and I couldn't be more pleased!  To cut a long story short, it's everything I hoped it would be.  Immersive views, in a completely relaxed position!

I started with some 1x2" oak battens, and some M8 bolts with plastic hand-tightening knobs, and also some teflon washers:

A bit of a test fitting here:

Double-hinged, because I was just making it up as I went along!

Bought two nice pieces of billet aluminium for the azimuth bearing.  120mm diameter, with 37mm depth.  I went for 120mm because it's the size of a CD, and that's the classic thing to make an azimuth bearing, using teflon discs.

I made it to fit my EQ6-R tripod

So I went ahead with the teflon/CD idea:

 

So, I got it working, but actually, it had quite a lot of lateral play, and I just didn't find it too pleasing at all, so it was back to the drawing board!  I decided to use a tapered roller bearing instead.  I had an excessive amount of material to play with, so it was no problem!

Just a video of me taking very deep cuts: https://twitter.com/tombardier/status/1489028101292142595

 

The outer race would go in after machining, but not after having cooled down.  I bought it in to the house and it dropped right in. The inner race wouldn't go on after machining, but a few minutes later it went right on.  They both fit very nicely.

And here it is, finally!

[MarkRadice]

I like that! Great job - definitely not under mounted  

What was or will be first light?

[tombardier]

9 minutes ago, MarkRadice said:

I like that! Great job - definitely not under mounted 

What was or will be first light?

Thank you!  I'm very pleased with it.  I spent some time ironing out a few teething problems this afternoon.  I increased the pre-load on the azimuth bearing, as it was just too smooth.  I found an old cast iron pulley which fits on the counterweigh bar very nicely, and gives me the perfect counterweighting in combination with just one normal 5kg counterweight.  The binocular mount arm itself was drooping a bit, so I shimmed the rear bolts holding the aluminium strip, and also shaved off some material where it had been catching.  I'll probably re-design that bit at some point anyway.  The double hinge thing is ok, but it's not as smooth in operation as the rest of it is, and it feels like it would be better to have the binos themselves able to rotate freely, rather than using the hinges.  I think the double hinge arrangement offers huge freedom of movement though.

I managed to spend some quality time with it last night, and it was lovely to use!  I can just sit there, completely relaxed, binoculars suspended in front of me.  I could nudge them with the bridge of my nose if I wanted to move them, or grab them and scan huge swathes of sky without moving my chair at all.  It's everything I'd hoped for!

I was using the 20x80 Celestrons I've just bought from @Pete Presland, (bargain!).  I spent some time looking at the moon of course, and kept on going back to it.  It was still worth looking at the rest of the sky though, and so I spent some time on M42, as well as the double cluster, and M36, M37, and M38 in Auriga.

I'm sure this is going to be my primary visual observation tool from now on.  I'll still be using my 10" newtonian for high power bino-viewing, but until I can lie back in a reclining chair, and have my newt just float above me, I think the parallelogram is going to be what I'm reaching for more often than not!

Cheers!

[MarkRadice]

Sounds like you’re on to a winner! As you say, it’s very comfortable to observe with isn’t it? And it looks like you have some lovely dark skies behind you. 

[RobinH]

that's a nice looking P mount.

I have made one my self  and  love how easy they are to use.

I like the double hinge idea, I have recently added a single hinge to mine and am now experimenting to decide how much it needs to be able to turn. Previously I used it standing and  found no hinge was needed. I need the hinge to suit using it sitting. I have a felt washer rubbing on a metal plate to give friction to the hinge.

I think you need a larger contact area and perhaps felt or plastic washers on the double hinge with adjustable tension on the joints to get smooth operation.

where did you get the bolts on the arms? I have used m6 bolts with nylock nuts but need tools to set the tension. I like the idea of hand adjustments.

[tombardier]

Hi @RobinH,

Thanks for sharing that.  I read a number of posts/build logs, and the hand tightening knobs sounded like a winner.  I bought some normal plain-shanked 110mm M8 bolts [https://www.ebay.co.uk/itm/254937460261], and then found the hand knobs separately.  These ones house the hex head of the bolt: [https://www.ebay.co.uk/itm/255243420182] and then I've used these in place of nuts [https://www.ebay.co.uk/itm/403304899314].  The shanked portion of the bolts was the perfect length to go through the 3 1" thick pieces of oak, with 4 teflon washers (two on the outside, two on the inside), which are 3mm from memory.

I probably could have done it all a lot more economically, using a local fasteners store, but I was impatient!   All of the rotating surfaces throughout are using teflon washers (with the exception of the azimuth bearing).  I haven't tried it all out since modifying the droop and the bits that were catching on the hinge mount, so I'm going to see how I get on with it, next time the flippin' clouds clear off again!  I want the binocular l-bracket to be adjustable up and down to ensure it can be balanced properly, with the binoculars centre of gravity rotating around the fulcrum.  They don't move by virtue of the tension on the teflon washers at the moment.

I'm not very happy with the thread insert the counterweigh bar is screwed into, so I'm going to come up with something more robust there.  I have some angle grinder handles to attach too. 

It's all very usable without doing any of this though.

Cheers!

[tombardier]

I have to add; I stole the tripod from my EQ6-R Pro.   I was in the right place at the right time the other day when a chap advertised a brand new, unused 2" stainless legged tripod from an EQ6-R Pro, for £65 on the astrobuysell website!  It arrived today.  What an absolute bargain!

[westmarch]

A lovely piece of work.  I wish you dark skies to enjoy it.

John

[RobinH]

thanks for the links for the hand bolts etc I may change mine to match. I have been using my mount for about a year now and it keeps changing as new refinements occur to me. It works well but it doesn't cost much to make it better,  just a bit of time.

I have just used large steel washers on the outside of the arm joints and wood to wood on the inside of the joints. I usually tighten the nut and bolt until the washer will just not turn using fingers. This makes the joints slightly stiffer so the bins stayput even if the balance is not perfect.

I made a similar mount a few years ago but was never happy with the tripod. The surveyors tripod that I use now is super.

[tombardier]

On 09/02/2022 at 19:53, westmarch said:

A lovely piece of work.  I wish you dark skies to enjoy it.

John

Thank you, John.  I've been enjoying it tonight, albeit not under dark skies.  Just casually gazing at the moon before tea.  It really is a pleasure!  After tea, I got my 10" newtonian out for some lunar binoviewing.  Also a pleasure!

[Merkhet]

I am in the process of making a wooden parallelogram myself.

When putting Teflon or PTFE washers in between the moving wooden faces,  should I use large washers about three inches in diameter or the commonly available ones around  one inch in diameter?

I have a small sheet of 1mm thick PTFE and was thinking of cutting three inch discs to use between the wood faces.

Any advice welcomed.

Thank you.

 

 

[RobinH]

 

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.