First parallelogram binocular mount

[furrysocks2]

Since I pulled the scope from storage last weekend, I wanted something for the kids to get excited about and figured the binoculars on a parallelogram mount would be a good start. My 15x70s were WAY out of alignment - I had a fiddle last week and made them worse. Nearly replaced them a couple of nights ago but opened them up, reseated the prisms, lined them up again and they're ok.

I used to mount them on the end of a pole clamped into a bicycle work stand, giving me tilt and swivel and a manual height adjustment, but I had to stand pretty close to the legs. I'm still using the bottom half of that stand, having removed the top tube and bike clamp bit and replaced with a steel pole to carry all the gubbins. It's a four legged stand, but should easy enough to pack a foot of two until I get bored of doing that.

I started with the head...

I made it up as a I went along from stuff I had lying around - three metal brackets, a couple of plywood discs, dowel, various nuts, bolts and washers, a lobe knob, a plastic washer and a skateboard bearing. I tapped holes in a length of an old aluminium bar clamp to carry it all. For the horizontal swivel, I screwed two M6 bolts in to 5mm holes in the top and bottom of one of the plywood discs. For the vertical swivel, I used a plastic washer between the plywood discs, and the skateboard bearing under the lobe knob with a clearance hole to ensure it didn't loosen through use. It all runs smoothly and seems pretty sound with the exception of the bolt into the binos themselves, but I only had one with the correct thread.

I used two extendable washing line props for the arms, the top one I kept both sections inside each other for stiffness. That was probably the most fun bit to be honest (though probably the first bits I'll replace). I used the cross vice on the drill press with a v-block clamp and a center finder to try to drill the holes perpendicularly through the props exactly where I wanted them.

The swivel's probably one of a kind...

I used a length of 16mm threaded rod with two flange nuts either end of the steel pipe that mounts in the stand, leaving 8 inches or so exposed above. A length of washing line prop slides over that with 4 zip ties taped together inside to pack the gap. To the pipe, I zip tied another length of the old bar clamp. A nut on top tensions it so that the horizontal swivel on the head moves before it swivels at the mount.

Having put all that together, I hung a bottle from the end forgetting it would swing about. I didn't know what I was going to use for a counterweight - was contemplating a coffee can filled with gravel, or casting some concrete. Then I remembered an old 4-jaw chuck I had for the wood lathe - perfect weight. I took six inches off the length of the poles (travel went higher than I needed even for zenith and lower than my kids) then roughly positioned the chuck. I took the top arm off again to drill a hole near the end for a safety bolt to prevent the chuck from coming off the end.

It's blowing a gale outside and the binos fogged up immediately, but I got a quick look at the moon, the Pleiades and Hyades. I know from being inside that it doesn't dampen particularly quickly - I think flat wooden arms with better contact area at the pivots is probably the way to go. From top to bottom, the moon shifted by about a third of the FOV - poor engineering.

It was a great thing to be able to use something like this for the first time - it does enough of what it should that I'm content for now. See what the kids think...

 

[Peter Drew]

Tall kids?    The 4 jaw was a nice touch.

[D4N]

That looks nice, a shame it doesn't settle well but maybe you could improve that by filling the tubes with sand?  Maybe a squirt of silicone or expanding foam by the joints to stop the sand coming out would be needed though.

[furrysocks2]

1 hour ago, D4N said:

That looks nice, a shame it doesn't settle well but maybe you could improve that by filling the tubes with sand?  Maybe a squirt of silicone or expanding foam by the joints to stop the sand coming out would be needed though.

I thought about the very same, however after removing a couple of felt pads and watching it closely there might be a little give or elasticity in the zip ties on the swivel. I've got some stainless hose clips I'll try to tension round it - failing that, perhaps epoxy.

No doubt a combination of factors. I kinda like the poles, so be nice to keep them.

[furrysocks2]

Slumped out tonight on the observing chair with the eye cups shoved deep into my eye sockets. It was a first for spending a decent length of time observing the same spots (the Pleiades and around Cassiopeia and Perseus), so definitely a worthwhile build.

I may revisit its foibles at some point, but it's good enough (and the poles match my new scope!) 

[michael.h.f.wilkinson]

Nice work. I built a wooden P-mount for my 15x70s (don't really use it enough, however). Borrowing ideas from John Dobson I use Teflon pads with ebonite disks I cut from sheets I got from Teleskop Service to make the (wood) surfaces glide smoothly without play. Works well. Details here: