Help required with my Binocular Parallelogram Mount

[MrZuiko]

Hi all,I've built a parallelogram mount for my celestron badged Vixen 20x80's which I must say are an excellent binocular! the problem I'm having is with the axis where the binocular pivots up and down.

I've used a 6mm bolt with large metal washers inbetween both pieces of oak to secure it to the bars with a spring washer and self locking nut.

I tighten it up so that the weight of the binoculars do not make it slip when tilting the handle assembly but when you move it up and down a few times it becomes loose,what do others use to combat this problem?

Do you have to leave the whole handle assembly to be able to move freely and then balance the binocular using the built in bar to address this problem?

any help and advive would be greatly appreciated! please see attached photographs.

 

Clear skies.

Ash.

[lenscap]

Hi Ash, I made a similar p-mount using mostly oak.

All my pivots were M6 bolts sitting in threaded holes tapped in the oak using a modified M6 bolt as the tap.

This gives a tighter fit than metal nuts. The tapped thread acts like a Nylock, so its easy to adjust the friction which then stays put without spring washers.

My L-bracket that holds the bino is metal & I used a CD as a "bearing" to stop the metal scoring the oak. Again the pivot bolt fits a tapped wooden hole.

[Trikeflyer]

I had a similar problem and could easily fix it. I decide to stop that axis moving  on the mount and to use the pan and tilt unit unit off my horizon 8115 tripod. Enclosed pic. You could use something like that which has rotatable joints that you can tighten and use a pan handle with or you could possibly use a ball head type mount if you can find one.

Others May different solutions.

[BinocularSky]

It seems from your photographs that the centre of mass of the binocular and bracket is not co-linear with the altitude fulcrum (bolt). That will automatically introduce an imbalance as soon as you rotate the binocular bracket assembly. Ideally, you need another degree of freedom, ie to raise and lower the binocular relative to the altitude fulcrum bolt, or a counterweight above the fulcrum so that the binocular is perfectly balanced in altitude when it is pointed at the zenith. Failing that, you'll be reliant on friction to prevent your binocular from slipping in altitude,

Quote

large metal washers inbetween both pieces of oak

I would be inclined to use a thin nylon (or similar) washer whose outer diameter is at least the width of the timber pieces. In the past, I have successfully made bearings like this from plastic document wallets.

Also, to lock the bolt, you might find that, in the long term, two nuts are better than a self-locking (nylock, I presume?) nut (but, if you get it properly balanced, that probably won't be an issue).

HTH

[BinocularSky]

FWIW, here's a slightly different counterweighted option. Scott has the binocular above the fulcrum with the counterweight below, so that the counterweight is on the opposite side of th efulcrum to your head ?
http://web.archive.org/web/20080720003005/http://members.aol.com/scottw8088/binoc.html

 

[BinocularSky]

Lastly, I'm not sure how practical it would be to implement this sort of adjustment in wood (I'm no woodworker: my careful use of a fretsaw can look like something a blind monkey has done with a chainsaw),but this is the binocular bracket vertical adjustment on my T-mount - co-linearity of altitude fulcrum and binocular centre of mass enables 6kg binoculars to be perfectly balanced in altitude; the result is that they feel like they're floating in space: lovely to use like that. (The downside to perfect balance and very low friction is that, in a stiff breeze, you can have a windsock, not an observing instrument).

[MrZuiko]

Hi all and thanks for all your help here,I have a ball and socket head but I've have ordered a pan and tilt head so what I'll probably do is fix the handle assembly and use the pan and tilt head to achive the required motion .

I was using this diagram I found online as regards to the postion of the binoculars to achive correct balance.

Kind regards and clear skies!

 

Ash.

[Trikeflyer]

Good choice, mine works a treat. Which pan and tilt head did you go for? 

Steve

[MrZuiko]

Hi Steve,

I found this on fleabay new for £10 and free p+p should do the job,didn't want anything too heavy might upset the balance.

 

Ash.

Edited May 2, 2019 by MrZuiko
correction

[BinocularSky]

16 hours ago, MrZuiko said:

I was using this diagram I found online as regards to the postion of the binoculars to achive correct balance.

 

Hmmm. That only works if the binocular's centre of mass is on its hinge axis. Some might be, but many aren't, and changing the IPD will alter it anyway.

[michael.h.f.wilkinson]

I have built a fairly similar P-mount, as shown below, but use M10 rather than M6 bolts for the axes. I also use Teflon disks to make the action smoother. I also made special knobs with embedded lock nuts to make all tension adjustments readily possible without any tools.

[MrZuiko]

Hi Michael nicely done great mount.

Thanks for taking the time to reply.

 

Clear skies.

Ash.

[ollypenrice]

Like Steve I thought the problem would be greatly exacerbated by the fact that the axis of the fulcrum doesn't seem to be passing through the centre of gravity of the binoculars. I come across this issue when trying to use non-TeleVue scopes on a TeleVue Gibraltar mount.

Olly

[MrZuiko]

Hi all,a quick update I've now installed a "pan and tilt" head and it works a treat,had first light the other night and the moon was too good to miss.

Amazing views mount steady had to wait a second or two for any vibration to die down,found the crater "Copernicus" and at even 20x I was able to make out the central mountain mass very pleased.

 

Clear skies all. Ash.