Posts Made By: Guy Earle

I thought I'd take a second and post the pics of what I've done so far. This was my first attempt using a router, and enjoyed the satisfaction of making the four rings. I even cut the top one with an inner groove so it hides the edge of the sonotube.



I followed the great advice of Fiske Miles and how he made his rings, at http://www.fiskemiles.com/buildinga22inchdob/secondarycagerings.php





Here is the one on the front of the UTA



And what I have as of tonight...



You can see I have Moonlite truss poles and blocks. I plan on moving my spider and primary/cell, and even the adjustable altitude bearings. If I've figured it out right, I'll lose 7" off the height at zenith, which, when I've cut (or simply remake) the rocker box, it should be at perfect eye level (I'm 6'4").

All I did tonight was attach each ring at four points to the tube, which hasn't even been strengthened yet, and used simple drywall screws to attach the blocks. Just with that alone, I'm astonished how there is no flexing whatsoever. It's as rigid as can be, and I love how LIGHT it is!!!!

Please ignore the very messy garage. If my wife knew I was posting this.....lol. Oh, and the beast is in the background.

I'm currently looking, after many years, for a new finderscope. I did the small 30mm finders so long ago for starhopping, then eventually got digital setting circles and a telrad. After many years, I'm seeing the need to use one again on my 16". I'd like to see nice, wide field views that are crisp. My question is: is it worth it paying the extra $$ going up to a 60mm finder, or is it basically the same as the 50?

I think I might take this little finder on trips when not on the scope. Does it make a good mini scope to fool around with when you don't have the urge to lug out the dob?

Thanks!

Guy

I got home a few hours before the wife, and TS Fay had decided to do a hook around Tampa, so I took advantage of the cloudy weather to pull my tools out of the garage and get sawdusty..

Here is the new truss setup in the old rocker base. I put this shot in to compare with the next one, which is what I did today.





I had to go back and trim the bottom ring flat in a couple spots, b/c I ended up having a ring wider than the rocker box...lol



Up against the front board...



Lastly, I gave myself just under a 1/2" clearance (I'm to chicken to attempt less) between the ring and my encoder.



Wife is going away this weekend, so I can get some time to myself all day working on this. Next step is to add the reinforcing rings, trim the rocker box on the corners and router them, also cutting the front board down, and mount the primary. If all goes well, I might be able to star test Saturday night, or possibly Sunday at the latest. Once that is all done, I will disassemble it all and then paint and polyurethane it.

I know it's not Obsession quality like many of you can do, but I learn as I go and hope I don't make any major errors. It has been rewarding, and it has been seven years since I've done a major overhaul on a scope.

Clear Skies,

Guy

I only have the secondary to mount and then adjust the length of the poles. I hope to star test Monday night, then by next weekend have it finish sanded and painted. The secondary stuff like eyepiece tray, Sky Commander mount and stuff will be next.

On another note, I got all the wax paper off today from the sonotubes. When I tried this years ago on my old 12.5" the paper didn't want to come off, but this was a real breeze. So no worries now about applying the black paint!

I'm having trouble remembering, but can someone tell me, with a 35 Pan, is the focuser racked all the way in, or out? I'm getting ready to cut the poles on my 16" rebuild, and I'm about to star test, and I can't remember if I had my Pan all the way racked in or out. I know everyone is a bit different, but my 35 Pan was at one extreme of focus, while my binoviewer is at the other.

Thanks in advance for any help.

Cheers,

Guy

I've been looking around trying to find specifics about the virtual counterweight system. I don't have a S&T '99 issue to reference, and have been looking at peoples designs online.

Is there a website that tells specifically what type of spring and how to calculate where to put them? I see some that are simply tension that pull vertically down, which to me doesn't seem nearly as effective as some who have the spring attached to a pulley and then to an anchor spot on the altitude bearing.

All advice is most welcome.

Thanks,

Guy

I've got my two virtual counterweight springs working well, however I'm still a bit top heavy (all told, between my rings, the bino, and all the other stuff I'm about 25 lbs out of balance!). Where I end up loosing it is in the end ring, which is baltic birch and as heavy as can be. It's probably 2-3 pounds, meaning I've got nearly 15 lbs at the end to counter just that, let alone a binoviewer, telrad, and finder. I am trying to keep the scope looking clean, without weights stuck all over the place like I have in the past.

What I'm wondering is, If I add a third pulley/spring system inside the rocker box, on the opposite side of another, will it counteract it? If I get a different spring will that not mess up the other two? I'm thinking if I add a third, in a setup where it kicks in when I get below 40 degrees (or normal method) will that simply add to the lack of needed weights? I must say I'm tempted b/c I really don't want to stack to ugly 5 lb weights on the underside of the scope, and I must admit that the pulley system looks quite neat, and is totally silent.

Guy

As of tonight, Tuesday. The mirrors are not in yet, due to the fact that I have to clean them and do finishing touches on the scope tomorrow. I'm still waiting on parts for the laptop table, and the finderscope, and will probably not be all put together until next week sometime, but as of tomorrow it will all be together and 95% done.

Please excuse the messy garage...don't have a nice place to put it up for a photo yet...



Guy

Okay, my mind is spinning over the math here, and I'm hoping someone can help me out a bit. I have a 16" f/4.52 dob, with a Denk binoviwer. My problem is trying to figure out the magnifications of my eyepieces. I have the 2" OCS with the 1.2 Optical Cell. I have it all the way closed in the lowest position (in other words I did not unthread the OCS at all). I have a dual-arm power switch, yielding 1.2X, 1.8X, and 2.3X magnifications. My problem is that I also have a single-arm stacked in front of the dual, to give me an additional three magnifications per eyepiece. The single arm operates in 1.2X and 2.5X. So.....yeah, this is where I fuzz out. I've got three things going on: the Optical Cell of 1.2X (is this part of the equation anyway?); the dual-arm, and lastly the single arm.

I asked Russ for some help, and he said that the 1.2, 1.8, and 2.3 is what I get with the dual arm switch, but I don't know if he took into account the 1.2X OCS Optical Cell. And that leaves out the single arm in the equation.

I have a 24.5mm Meade SWA set, and if anyone can help me figure this out, I'd be very grateful. Essentially you'll have 6 magnification settings; 3 for the dual, 3 for the dual plus the single.

Thanks in advance,

Guy

Well, I had made a table to go on a single aluminum pole, however, it drawing did not match expected application, as it turned out to be wayyyy to heavy and had a tilt and high wobble.



I went back to the drawing board, and took a page from Roger Greenwood's table, and came up with this version.



It rotates to go out of the way, and in addition to being very light and highly portable (simply undo the one moonlight clamp on the rocker box), I now have a spot for a 2" eyepiece (only need 1 to swap bino for pan) and put a second one in below for my digital coffee mug (again, thanks to Roger on that one..hehehe). The table is sturdy, and looks really neat. I've got some polyacrylic to put on and finish up, but with the exception of the light shroud, I'm nearly there as this was the last big project for the scope.




See the Moonlight ball/socket under the table? Unlock this to swivel the table.



Best,

Guy