f4.9/13.5" Dobsonian

Journal:

01 June 2005     -    Collected the 14.5" porthole glass, it is extremely pitted and rough around the edges so unfortunately this will require water-jetting to make it more hand friendly.

10 June 2005    -    Collected the glass from Waterjet Technologies in Stikland, it looks awesome and clean for a change (waterjet glass here).

11 June 2005    -    Bought some sanding belts and rigged up my drum/table setup which is required for the rough grinding done on 60 grit

12 June 2005    -    (65min) Put a bevel on both sides using belt sander, leveled out the back with 200 grit and started grinding (1mm deep) I require +-4.2mm

13 June 2005    -    (40min) Turned the mirror on top and tool on the bottom (MOT) and rough ground down to 1.6mm sagitta

14 June 2005    -    (40min) Rough ground 60grit MOT to 2.0mm (picture of saggitta here)

19 June 2005    -    (40min) Rough ground 60grit MOT to 2.5mm sagitta (edge 25mm)

20 June 2005    -    (40min) Rough ground 60grit MOT to 3.0mm sagitta (edge 20mm)

22 June 2005    -    (25min) Rough ground 60grit MOT to 3.5mm sagitta (edge 17mm)

23 June 2005    -    (60min) Rough ground 60grit TOT to 4.0mm sagitta (edge 0mm) Now ready for 120grit!

24 June 2005    -    (30min) Tiding garage and cleaning up after 60grit

25 June 2005    -    (80min) 120grit combination of TOT and MOT (1 or 2 shallow pits going to do 220 grit and see how they disappear)

27 June 2005    -    (40min) 220grit MOT and TOT (quite a few pits)

05 July 2005    -    (30min) Mounted 'turn-table' 220grit TOT - very shallow pitting (4.3mm sagitta)

06 July 2005    -    (25min) 220grit TOT - (20min) 600grit TOT - some deep pitting but SMOOTH!

07 July 2005    -    (45min) 600grit TOT - saggitta reducing and still many pits, may have to switch to 400grit and attempt MOT

09 July 2005    -    (120min) scratched mirror with 600grit TOT and had to switch to 320grit to try remove :-( 30 minutes left to remove

11 July 2005    -    (25min) 320 grit scratch 95% gone, will hope it disappears on 600/1000grit. Concerned about decreasing sagitta!

12 July 2005    -    (70min) 50min on 600grit - 5-7 deep 60grit sized pits restart at 150grit for 20min

13 July 2005    -   (30min) 150grit after cleaning the edges of the grinding tool

18 July 2005    -    (45min) 220grit and 320grit

20 July 2005    -    (60min) 320grit some new pits appear to be constantly appearing, I suspect I need to remake main grinding tool (cast plaster mold in anticipation)

21 July 2005    -    (60min) added a tile matt over the grinding tool with lots of fibre resin. Lets hope this works!

23 July 2005    -    (60min) 220grit regrind to refit tool

    Total Time Spent:   950min

29 July 2005     -    Discontinued updates until the grinding tool is working properly/finished setting :-(

03 August 2005    -    General Update - Shaped the new grinding tool, accidentally went to 4.8mm sagitta so working my way back, 60min on 150grit, 30min on 220grit,

                                 busy with the plans for the resized aluminum design in Solid Works 2005 (its easy enough but Its hardly in my field of expertise!)

03 August 2005    -    Had some issues with the fibre resin taking 4 days to dry, turned out to be an expired batch, bought some new stuff and it dried in 4 hours

04 August 2005    -    Almost completed design of the telescope cradle and flexrocker

05 August 2005    -    Cut the concentric rings for the telescope base and spent 20min on 320grit

06 August 2005    -    Joined concentric rings together to form base and spent 20min on 320grit

07 August 2005    -    Varnished base and attached formica to telescope base and spent (40min) on 320 grit

08 August 2005    -    (20min) 320 grit, no new pits appearing, finally some progress!

09 August 2005    -    Started bending the upper ring, completed bended ring here

13 August 2005    -    Finished on 600grit busy making polishing tools *wibble*

18 August 2005    -    Submitted the final plans from solid works to Waterjet Technologies (4 days)

22 August 2005    -    Collected waterject parts, they looks really neat!

23 August 2005    -    Find grinding done for 60 minuntes - finished

27 August 2005    -    Made primary polishing tool, pressed and fitted it to mirror surface - 120minutes

                           -    Made mirror cell components

                            -    Drilled and tapped trunian mirror cell support components

28 August 2005    -    Polished for 30 minutes, focal length appears to be 165cms, slight 'circles' around the mirror, may be due to grinding machine.

7 September 2005    -    Scratched mirror surface due to chips of plaster falling off the tool, spent 240 minutes regrinding to get back to being ready to polish

8 September 2005    -    Prepared telescope frame for welding, performed machine work etc.

10 September 2005    -    Had telescope frame welded up. Cradle here, Secondary holder here!

15 September 2005    -    Brent Russel and his milling machine to the rescue for my telfon bearings!

18 September 2005    -    (60min) polishing with 10" tool

20 September 2005    -    (60min) polishing with 8" tool, focal length is +-165cms (f4.8)

22 September 2005    -    (30min) polishing with 10" tool

23 September 2005    -    (30min) polishing with 10" tool

28 September 2005    -    (30min) polishing with 8" tool

30 September 2005    -    (30min)polishing with 10" tool

4 October 2005    -    (120min) built focuser shelf

6 October 2005    -    (60min) Concerned about high profile of focuser, reduced height by 2cms, picture here

10 October 2005    -    (45min polishing with 10" tool almost ready for figuring, another 60mins polishing with 8"

31 October 2005    -    Latest picture of scope here!

12 June 2006    -    Turned some brass knobs for the focuser!

13 June 2006    -    Spent some time with the mirror under foucault, it looks very good except for a 'ridge' at the 70-50% zone

15 June 2006    -    Had the scope anodized black (looks amazingly sweet!)

17 June 2006    -    Worked 50-70% zone for 3minutes MOT, foucalt and startest look brilliant except for a slightly TUE

4 July 2006    -    Worked MOT for 2 minutes and TOT for 3 minutes hoping to reduce TUE and finalize 50-70% ridge. (bad weather means no star test to confirm so I wait nervously for confirmation, is the mirror finally done??)

5 July 2006    -    Latest picture of scope, now with anodizing here!

Costs:

Saggitta: