| Date |
Hours |
Description |
| ALL |
105.5 |
Total Working Time |
| |
|
|
| 4/19/06 |
2.5 |
Success! If I've done my measurements correctly, I
think so. I worked on a little 1/3 center over center to try to
settle the mirror down a little bit due to the high area in zones 4 &
5. Only worked on it for about 10 minutes, then went back to
the tester. Took me about 10 minutes to get set up, and found that
the numbers were way off from what I expected. .074 from bottom to
top, which was more than the needed .067. My hopes were crushed, but
I decided to take 3 sets of measurements and then average them together to
see what I got. Similar results each time, and not looking
good. I decided to scratch it up to practice, and went back to
FigureXP to plug in the numbers and see what I had. Surprisingly
enough, the figures showed that I had a fairly respectable mirror, but a
little low in the center. This isn't so bad, though, as
Overall, a 1/12.72 wavelength (.985 Strehl ratio). I couldn't
believe my eyes, so I plugged all the numbers into Foucault Test Analysis
2.0B, and it showed approximately the same value (1/11.6 and .9766 Strehl).
By then it was about 10:20pm, so I decided to see what I could do outdoors
with it. After about 45 minutes, I finally figured out what I was
doing, and came up with a view of some stars, that actually focused to a
point. I then tried it on Jupiter, and although it was still
extremely small, I could definitely see that it was round, and not a
point. I was utterly amazed. I still don't think that I really
believe that it could be true.
The trick now, is to have Dave Kelley test it with the Stellafane tester
with the flat mirror (Double Null Tester?) and see what he thinks.
I'm going to keep my fingers crossed. |
| 4/16/06 |
1.5 |
3 turns of W's, tested, 3 more turns of W's, tested.
Unfortunately, my lap got a little dry on the last polish, and being a
little overanxious at the progress, I tried working it a little bit.
Bad idea. Wound up digging a good hole at about Zone 3. Wasn't
really sure what I was seeing, so I started sketching the measurements out
on a sheet of paper, and then applied my measurements to the same
sketch. It shows I'm still high in Zones 5 & 4, but very low in
Zone 3, and a little low in Zone 2, giving the effect that it's flat in
the middle zones, then high walls to the upper level, or at least that's
my best guess at this point. Will have to ponder it some more, but I
think I'm picturing it correctly here. |
| 4/15/06 |
.5 |
A couple minutes of W strokes, about 7 times around the
mirror. Then tested. Getting closer. I'm about 1/2 way
to a parabola. Going well. |
| 4/12/06 |
1.0 |
Started my W strokes tonight. Spent about 5 minutes on
the W's, going around the mirror about 5 times, then went down to the
tester. It's already starting to show a slight figure. It
looks like I'm about 25% of the way toward being a parabola. Will
need to go slow and easy on this. |
| 4/9/06 |
2.0 |
About 1/2 hour more of slight W 1/3 Center over Center
stroke, then spent some time setting up the tester. Found it was
time consuming to set it up each time, so I picked up a
1"x12"x10' so that I could build a stand for it with my
sawhorses, in the basement. It works well. Couldn't find any
figure in my mirror, so I've decided to try to figure it myself. If
it doesn't work, I've got time to go back to almost spherical before I go
back to class #7. |
| 3/30/06 |
1.5 |
Polished for a while using an almost 1/3 Center over center
stroke (slight W 1/2" on each side of center.) Heading back to
almost a sphere, but don't need to quite go that far. |
| 3/18/06 |
6.5 |
Mirror Class #6 - Telescope Building Lecture - Continued
Figuring, and finished my mirror, just before I killed it. I wound
up bringing the mirror center down a little too low, with about 2 extra
minutes of trying to make it a little bit better. I have a little
homework to do, and then 2-3 hours worth of work at the next class to
finish it up. Should be fine, and I should have a finished mirror to
use this summer. |
| 2/18/06 |
6.5 |
Mirror Class #5 - Foucault Testing Lecture (How to test for
a parabola) - I had Dave Kelly test my mirror, and he found that it was a
nice spherical shape all the way to the edge, with the exception of a
slight high spot in the middle of the mirror. He wasn't worried
about this though, as the middle gets ground down slightly to make the
parabola. He started me in on the 'Classic W' stroke, which I must
have done incorrectly as within about 5 minutes, I'd dug a hole in the
middle of the mirror. Remember that at this stage, a hole is a few
'millionths' of an inch deep. So I went back to making it a sphere
again. It took about a half hour, and then I had a decent
sphere again. I went back to work a little slower this time, and by
the end of class, we'd started pushing it a little bit toward parabolic,
but still with a long way to go, but still within the 'few millionths of
an inch' range. |
| 2/17/05 |
3.5 |
Decided to try pressing my pitch lap without warming it at
all. I had to press it for a little longer, but it worked very
well. I polished for well over 2 hours and then only needed a very
slight retrim of the pitch facets, instead having to dig out new facets
from pitch that had closed in, within about 45 minutes, like had been
happening. Now that I've seen how well it can work, it's easy to
tell how to keep it that way. Just a matter of being a beginner, and
not knowing the difference. It was a long lesson to learn, but one
I'll never forget. I was able to finish up tonight by doing another
Ronchi test, which showed very straight lines, indicating that I'd finally
reached a sphere, with no turned down edge. I'll have to have it
checked first thing tomorrow at class, though, in case I haven't checked
it properly. |
| 2/16/06 |
2.0 |
Trimmed my lap again tonight, then did some online
research. I think I've finally decided on the reason for my turned
down edge. My pitch lap is too soft. This causes the
pitch lap to polish the edges too much, while not polishing the center,
since the pitch is just squishing out of the way in the middle. Will
try again some more tomorrow while trying a couple tricks to keep the
pitch firmer, like not warming it as much before pressing, then letting it
sit for a bit, and cold pressing it before I polish. |
| 2/15/06 |
2.0 |
Polishing (Turned Down Edge Removal)
After polishing, checked the figure using the Ronchi test. This made
me a little frustrated, as I didn't really see any difference from the
Ronchi test that I did just before the last class. Guess there's
more work to do! |
| 2/14/06 |
2.5 |
Polishing (Turned Down Edge Removal)
If I'm seeing things correctly, it looks like the 'edge' is now only about 1/16"
to 1/8". Will have to work on it
some more this week, as it needs to be spherical with no turned down edge
by this weekend's class. |
| 2/8/06 |
1.0 |
Polishing (Turned Down Edge Removal) |
| 1/29/06 |
5.5 |
Mirror Class #4 - Figuring Basics Lecture - Re-Pitch
my pitch lap - Turned Down Edge removal instruction - Polishing out the
turned down edge
Turned down edge is about 3/8" to 1/2" wide. Dave and Ken
are confident that it won't take too long to polish it back out, but both
warn that it's going to take some work. |
| 1/28/06 |
1.5 |
Polishing out & Re-trimming grooves in pitch |
| 1/23/06 |
2.0 |
Polishing out & Re-t rimming grooves in pitch |
| 1/20/06 |
1.5 |
Polishing out & Re-t rimming grooves in pitch
Still having some trouble with the edge. It doesn't want to polish
out. Seems to be creeping closer, but going so slow. I'll keep
working it. Can't take forever. |
| 1/18/06 |
1.0 |
Polishing out |
| 1/14/06 |
1.5 |
Polishing out & Re-t rimming grooves in pitch |
| 1/9/06 |
2.0 |
Polishing out & Re-t rimming grooves in pitch |
| 1/7/06 |
1.0 |
Polishing out |
| 12/27/05 |
1.5 |
Trying out Foucault Testing
Overall looking good, but seems to have about a 3/4" turned down
edge. Did some research online, and the outlook doesn't look too
promising. It could take a while. Some websites even recommend
just masking out the edge, calling it a 6-1/2" mirror, and calling it
polished out. I don't want to do that, as I want an 8" mirror
when I'm done. I guess I'll just keep forging on and see if it goes
away. |
| 12/14/05 |
1.5 |
Polishing out & Re-t rimming grooves in pitch |
| 12/11/05 |
2.0 |
Polishing out & Re-t rimming grooves in pitch |
| 12/7/05 |
1.0 |
Polishing out |
| 12/3/05 |
6.5 |
Mirror Class #3 - Polishing Lecture - Pouring Pitch Laps -
Beginning Polishing |
| 12/2/05 |
1.0 |
Fine Grinding - 5 micron |
| 11/30/05 |
1.5 |
Fine Grinding - 12 micron AND re-polyurethaning my pitch lap
base |
| 11/27/05 |
1.0 |
Fine Grinding - 25 micron AND re-polyurethaning my pitch lap
base |
| 11/23/05 |
1.0 |
Fine Grinding - 25 micron AND initially polyurethaning
my pitch lap base |
| 11/18/05 |
1.0 |
Fine Grinding - 40 micron |
| 11/12/05 |
1.5 |
Fine Grinding - 40 micron |
| 11/9/05 |
1.0 |
Grinding - 220 grit |
| 11/5/05 |
7.5 |
Mirror Class #2 - Fine Grinding Lecture - Bad 120 Grit Show
& Tell - Grinding - 220 grit |
| 11/4/05 |
1.0 |
Grinding - 220 grit |
| 11/2/05 |
1.0 |
Grinding - 220 grit |
| 10/30/05 |
1.5 |
Grinding - 220 grit |
| 10/29/05 |
0.5 |
Making Bad 120 Grit Samples |
| 10/28/05 |
1.5 |
Grinding - 120 grit |
| 10/26/05 |
0.5 |
Grinding - 120 grit |
| 10/23/05 |
1.0 |
Grinding - 120 grit |
| 10/22/05 |
1.5 |
Grinding - 120 grit |
| 10/19/05 |
1.5 |
Grinding - 120 grit |
| 10/16/05 |
1.0 |
Grinding - 120 grit |
| 10/15/05 |
2.0 |
Grinding - 120 grit |
| 10/12/05 |
2.0 |
Grinding - 120 grit |
| 10/9/05 |
1.0 |
Grinding - 120 grit |
| 10/8/05 |
1.0 |
Grinding - 120 grit |
| 10/5/05 |
1.5 |
Grinding - 80 grit |
| 10/2/05 |
1.5 |
Grinding - 80 grit |
| 10/1/05 |
7.5 |
Mirror Class #1 - Grinding Lecture - Edge Beveling -
Grinding - 60 grit |
