Jonscheuler Counter cell

[jonscheuler]

I'll start by posting this countercell I machined. I left .010" clearance around the cell to have an adjustable area. the material is 6061. Started it by truing the faces, then plunge cutting a plug from the center approx 6.5" diameter, from either side. then finishe boring to be a snug fit (approx .004") clearance to the tube - a nice tap fit, secured with 3 machine screws. The holes in the cell provided a method of marking for the tapped holes on the face using transfer punches, drilled and tapped to 5 X .8 mm. I've installed 5 X .8 X 12mm set screws for adj into the cell's tapped holes (measured with threaded plug gage to verify size & Pitch). The use of it viewing it last night showed where I need to adjust it for collimation of the cell and the eyepiece. It will be raining the next few days - plemty of time for adjustments.

[jonscheuler]

Here's 1 picture of the machined cell.

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[jonscheuler]

Here is a side view, nothing terribly fancy, just well fitting and centers are cut accuratly. and it's fairly light.

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[jonscheuler]

Here is the original cell with the 2 lenses in place in the cell. It slid over the tube.

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[jonscheuler]

The 1st mounting of the new istar in the machined cell - had to cut 1.2" from the tube length to let the focuser work. All of my eyepieces down to 4mm worked when viewing the moon, I definatly found that the colimation is off, centered to the top of the eyepiece when adjusting the image for sharpness and position. I'll use a laser colimator to adjust the centering of the eyepiece, then check the front cell's centering in the colimated focuser.

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[Watcher3]

Nice work Jon. What I wouldn't give to have a lathe and the ability to use it!

[borispider]

Yes great work.
The pic just above Watcher's post makes the tube
look so much smaller than the lens cell.

[jonscheuler]

Yes it does, the tricks light can play is something, huh? the tubes ID is the same as the id of the lense cell, I left an extra 3/8" or so untill I decide on a setup for a sliding shade. I've got a black nylon ring that can be bored for an easy sliding fit under the cell on the tube, and would then turn the outside of the counter cell to a smaller diameter. But the tube's diameter is the tubes diameter, can't easily make it larger, but there is no vingetting of the image from the lense. I was anxious to get in some viewing before the stormy seasons started again - got 2 evenings, the 2nd betterr than the 1st. I can turn the counter cell down anytime I feel like it. That's also why the counter cell fits over the outside of the tube, and likely why whoever originally built the telescope mounted the rear cover over the outside of the tube. The tubes original paint is "Meade-blue-metal flake", painted over in egshell white/light cream. But the paint is smooth, and the views are great, and I've got a 6" scope for less than the cost of a used car. That's good to me.

[jonscheuler]

To Watcher: is there a local vocational technical school near you? Night classes are usually available at them. I went to one a few years ago to machine a table for my horizontal mill, the table was bigger than anything I had to make it on at the time. I cut the t-slots in the table later when I picket up a mil-drill - one of the heaviest made, but with the features I wanted for my uses. (I've yet to put the horizontal mill back together). I started on some other projects, then got back into astronomy. It's really enjoyable to make parts for the scopes and mounts. Machining isn't really hard - but the tools can be expensive, more than telescopes, and a shop is needed to set the big tools up in, You don't want them shifting around. I can re-mount to countercell I made to within 0.0001" if I need to, Machining is primarily about carefull setup, and practice. There are places - like the vo-tech school that will teach tecniques, just like we learn from friends about astronomy and telescopes.

[Watcher3]

Thanks for the tips Jon. Just moved to a new state, but once I'm settled,(and employed) I'll have to look into this further.

[borispider]

That's great info Jon. tnx

[jonscheuler]

I decided to get my act together and get this scope colimated this afternoon, I finally hit on the right combination of setup to get something usable to align with. Since the laser diode puts out a "line of dots" and the hole in the colimatoing disc's hole is spliting the line, I'd say this scope is ready to go at this time. Of course, we had 3 seasons of weather around here today, we'll see what the clear sky charts say.....

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[Watcher3]

Don't know where in the country you are, Jon, but if you have the same sky conditions as me, I almost hope you don't first light it tonight. Skies here are nice and clear, but there's a whole lot of twinkling going on!

From St. Louis
Joe

[jonscheuler]

I'm a little west of you in KCKS. and I'm setting up on a CG5 on a wood deck with High trees all around. But, is also a bit cold so the sparce view and incoming clouds from the west are ok. I was able to get between some lims to catch some clusters - didn't take the timeto put batteries in the tracking motors or to go get the star charts - couldn't see Polaris anyway. If the waether gods are satisfied with the sacrifice of my back (I really should pull the counter weights off of the mounts befor I move them - hurrying tho', I'll go out to a valley south east of Lawrence were my daughter lives and setup the LXD75 mount and be able to identify were I'm looking. That should all work since it talks to each other fine in the house(I'll be using a laptop to run the Auto star suitefor steering and guiding). I'm anxious to use the camera setup too - have got a couple of DSI's to phot and guide with that I haven't used yet, but the computer can communicate with everything so.... we'll see. Since you are in St louis - yoube finding out how quick things change when living next to a major river valley.