6737 replies to this topic

[brave_ulysses]

hi roscoe - what you wrote is more or less my plan! i need to to some machining/fitting on the top; probably be a couple of days to get to setting the pier

 

thanks

[jtsenghas]

perhaps I'm confused, but seems to me that if the bubble is a tick to the right, and you reverse the level, and it is still showing the bubble a tick to the right, the right side is high.

What I meant was THE SAME READING WITH RESPECT TO THE LEVEL, NOT THE OBJECT. 

 

For example, if the bubble is about half a millimeter off-centered to the lines, but when the level is reversed shows the same distances to the same lines  (although in the opposite direction to the object measured), then things are leveled within the precision of the level and within the accuracy of your ability to discern any differences. 

 

One of my four foot  levels, for example, has a very slightly curved tubes and shifts the bubble noticeably when one end is raised marginally - less than 1/32", however I know it is a little off and I have to target the bubble being about a millimeter towards the scratched end of the instrument when placed in either direction. 

 

I like your suggestion about the thinset film, by the way.  I did something like that for the tiny bubble level on my scope.  I tightened three #2 screws around the base of the level while the level was sitting atop a film of epoxy adhesive and the surface of the rocker box was on a precision - leveled surface plate at work. 

[jtsenghas]

 On a related note, the best digital levels and some phone apps for digital levels have a calibration procedure for taking two readings 180 degrees apart on the same surface, which the instrument averages. 

[roscoe]

 

perhaps I'm confused, but seems to me that if the bubble is a tick to the right, and you reverse the level, and it is still showing the bubble a tick to the right, the right side is high.

What I meant was THE SAME READING WITH RESPECT TO THE LEVEL, NOT THE OBJECT. 

 

Ahhh... an important distinction there!  The nice thing about adjustable levels like the Starrett pictured above, is that once you establish a truly level subsurface, you can tweak the level so the bubble is centered, which makes it a lot easier to use next time.

[Rusted]

More gravel!  Oh, and a massive, 1m x 70cm x 6cm [40" X 28" x 2.5"] buried concrete pipe for the pier base. 

 

 

Q: What has two wheelbarrows, one shovel and 20 tons of gravel to move over 40 yards in five days?

 

A: A 70-year-old couple with very long arms.

 

The ground for the intended, raised observatory site was 2' lower than the rest of the back yard. Now it's not.

[TonyStar]

Finished a low profile mounting plate for my moonlite focuser. Brazed 1/8" aluminum, powder-coated black.

 

[Ed Jones]

I finished up an experimental equatorial platform for 2 different latitudes version 2 for my medial refractor.  It has 2 sets of bearings for 39.2 degrees (Cincinnati) and 29.1 degrees (somewhere south).   You simply pick up the top platform and move it over 1.5 inches.  Since you can tilt it 5 degrees from either latitude it could be used over a good part of the US.  It would have been easier to have made 2 different platform however.  I had to recut one of the north bearings so that both matched the drive shafts angle.  

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[Michael Miles]

...It would have been easier to have made 2 different platform however.  I had to recut one of the north bearings so that both matched the drive shafts angle.  

Geez Ed - love your stuff.  It would have been easier for you to build 2 platforms, but it wouldn't have been as inspiring for us...

[Pinbout]

 

...It would have been easier to have made 2 different platform however.  I had to recut one of the north bearings so that both matched the drive shafts angle.  

Geez Ed - love your stuff.  It would have been easier for you to build 2 platforms, but it wouldn't have been as inspiring for us...

 

Its a double neck guitar.... Jimmy Page... Stairway. To heaven

[Ed Jones]

I think it will come in handy for the eclipse too.  I'll run it off 8 C batteries.  Not much discussion on the eclipse yet.

[jtsenghas]

I think it will come in handy for the eclipse too.  I'll run it off 8 C batteries.....

I thought that's what the "somewhere south" was about! 

 

I live nearly two degrees north of you, but will be within a mile of the line of maximum totality at a neighbor's aunt's house in Tennessee on 8/21.  I'm trying to decide what to bring for observing best myself. I've purchased some Baader film but not made any sun filters yet. I'm thinking about a three inch off-axis filter mask for my dob rather than smaller instruments since I hope to observe the night before more to the south then I have yet in summer time. 

Edited by jtsenghas, 28 April 2017 - 06:55 PM.

[dave brock]

Eased the tightly mounted secondary mirror on this 8" Cassegrain that I recently picked up cheaply on TradeMe (NZ equivalent of Ebay / Craigs List).  Eased the primary and collimated (including the star diagonal which was way out) on Thursday which improved the images but looks like it'll need refiguring as it's undercorrected.

 

 

 

As you can see it has provision to change to a Newtonian but I'll wait until I've checked the correction on the primary to decide if I'll use that. The undercorrection might be from the secondary or primary or both. An elliptical secondary was included but not a mounting for it.

 Also came with a set of Meade series 4000 plossls, barlow and filters.

 

Dave

[roscoe]

Nice!! All sorts of good ideas on that scope!   The compass is a great idea.

[member010719]

Dave

 

That's a very nice telescope.

I have a suggestion for you.

The Cassegrainian focus is not well accessible at high altitudes.

I would use the flat secondary to move the Cass focus to the side of the tube ,above the primary mirror.

The flat  secondary would stay on a stalk through the hole of the primary ,to minimize the diffraction by eliminating the need for a spider.

(But maybe the secondary  is too big?)

You have also and already the focuser for it.

 

I see you have  plenty of Newtonian aperture.

I would make this a dedicated Cassegrainian reflector.

 

I wish you good luck whatever you decide to do!

 

Ziridava

[Heli Bass]

 

(Come to think of it, I could bore a through hole in it, mount my kaleidoscope, and make a gag lunar eyepiece for outreach events! )

What a great idea! Could also be used as a give away at a function or as a gift.

I'm going to steal this idea and make a couple.

[Andy Tucker]

I designed an adapter to mount my C90 with a Vixen-style dovetail onto an Orion EQ-1 mount.  It looks a little chunky but it won't be very visible so I'll probably print it as is, in black PLA plastic. The angular surfaces you can see in the mounting holes are press-fit slots for M6 nuts for the M6 screws that come with the EQ1 mount.  There's another nut trap you can't see in the dovetail clamp. Unfortunately I have to replace one or  more bearings on my 3D printer before I can do a test print!

andy

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[pferendzo]

Worked on a 105mm f15... assembled everything to make sure it would work - another Vixen spec lens I bought more than a decade ago. A larger version of the 80mm f11 I finished earlier this month.

Edited by pferendzo, 30 April 2017 - 11:55 AM.

[DonP]

Hi All

 

I took the mirror cell out of my Meade 114mm x 910mm  Newtonian and removed the three hold down clamps and removed the mirror.

Placed the mirror face down on a stack of new white printer paper to make a pattern to put a center dot on the mirror.

 

Also cleaned the mirror then glued it in the mirror cell with three big dabs of clear rtv silicone.

 

I am not going to use the rubber clamps to hold the mirror in, at 144mm not very heavy mirror.

 

I set the mirror and mirror holder with mirror down on new white printer paper to let them set up for 24 hours.

 

 

Raining for the past 24 hours, i can't use my telescope so i will do some maintenance on it.

 

Don

[michaeldurban]

I should have worked on my abs...

 

instead I worked on my beer grabbing skills...

 

priorities I guess..

[michaeldurban]

sorry, just delete my previous post moderator...

and this one too i guess..

 

otherwise it doesn't make sense

Edited by michaeldurban, 03 May 2017 - 01:13 PM.

[Rusted]

Sick of the sight of gravel? Not as much as I am!

Loads more boulders dug up to get my raised observatory's octagon of footings in next to the shed.

Each had to be levered to the surface as I stacked split logs beneath each lift with my third hand.

The largest were too heavy to move across the site without a crowbar.

What's this rumour about universal robots being just around the corner?

I keep looking, but no sign yet.

 

[Rusted]

And yet another view of gravel which makes weeks of backbreaking work look like nothing at all.

Running cord lines across the center between the octagon footings was the best way to confirm their placement.

Trying to do it with measuring rods, or a tape measure, was an exercise in frustration!

Still needs several more car trailers full of self-compacting sand/gravel.

 

[Benach]

Yesterday, but still: working on the project "Who's c?" with a friend. Making three 16" autocollimation flats. After about 8 hours of grinding, about 80% of all the work with SiC 80 has been done. Sigh. Finally...

[sickfish]

My solar shield for my st80

Edited by sickfish, 06 May 2017 - 02:05 PM.

[Pinbout]

I have a 8inf6 laying around somewhere that needs a home, had some scrap plywood around so I cut up about 1/2 sheet of ply to make a trad truss dob.