Building a fixed post mirror grinding machine
- Kanadalainen
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Re: Building a fixed post mirror grinding machine
Things I need to probably change or fix: My gearing of the DC motor. I will need a slow speed for polishing (5 rpm), and faster speeds for hogging out and fine grinding (15- 30 rpm), so likely need to think about adding a gear reduction.
Fixing the aluminum turntable to the wooden turntable base.
Building wedges to locate the mirror on the turntable.
Fracs: Stellarvue 70T f6; SW 120mm Esprit f7; "Mark Mk. II" - 60 mm Tasco f6; C80 frac f 11.4
SCT: C8 Edge f10 or f7 with reducer
Dob: 14.5" homebuilt strut dob (f4.5 ZOC mirror), Nexus II, Moonlite focuser
Mounts - Ioptron Skyguider pro, Astro Physics GTO900
Cameras and lenses - ZWO 2600 mc, 290 mm mini, Canon 60D modded with Rokinon 10mm 2.8; Rokinon 135mm f2
Skysafari 6 Pro, Astro Pixel Processor, Pixinsight - using Mac tablet and ASIair pro to run the AP rig.
"Mothers! It is there!" - Rafael Gonzales-Acuna, 2018.
- Kanadalainen
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Re: Building a fixed post mirror grinding machine
In the bottom image, you can see the intersection of drawn lines marking centre. Not too exciting I guess, but hey.... progress!
Fracs: Stellarvue 70T f6; SW 120mm Esprit f7; "Mark Mk. II" - 60 mm Tasco f6; C80 frac f 11.4
SCT: C8 Edge f10 or f7 with reducer
Dob: 14.5" homebuilt strut dob (f4.5 ZOC mirror), Nexus II, Moonlite focuser
Mounts - Ioptron Skyguider pro, Astro Physics GTO900
Cameras and lenses - ZWO 2600 mc, 290 mm mini, Canon 60D modded with Rokinon 10mm 2.8; Rokinon 135mm f2
Skysafari 6 Pro, Astro Pixel Processor, Pixinsight - using Mac tablet and ASIair pro to run the AP rig.
"Mothers! It is there!" - Rafael Gonzales-Acuna, 2018.
- Kanadalainen
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Re: Building a fixed post mirror grinding machine
On the bottom is a 6 inch pulley bolted to a 5/8" shaft, held by two pillow blocks. The keyed shaft was kind of pricey... 25 bucks, and needed a lot of polishing with coarse sandpaper to get to fit the pillow blocks. This took me a couple of hours to get everything square and turning properly.
Edit: I can't get this photo to load, so I will show an image of the final product, when I put it together this evening!
Fracs: Stellarvue 70T f6; SW 120mm Esprit f7; "Mark Mk. II" - 60 mm Tasco f6; C80 frac f 11.4
SCT: C8 Edge f10 or f7 with reducer
Dob: 14.5" homebuilt strut dob (f4.5 ZOC mirror), Nexus II, Moonlite focuser
Mounts - Ioptron Skyguider pro, Astro Physics GTO900
Cameras and lenses - ZWO 2600 mc, 290 mm mini, Canon 60D modded with Rokinon 10mm 2.8; Rokinon 135mm f2
Skysafari 6 Pro, Astro Pixel Processor, Pixinsight - using Mac tablet and ASIair pro to run the AP rig.
"Mothers! It is there!" - Rafael Gonzales-Acuna, 2018.
- Kanadalainen
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Re: Building a fixed post mirror grinding machine
This evening I wrestled with the gear reduction drive. The idea is to get to a final reduction of somewhere near 8:1 - which would be best suited to the small DC motor that I'm running.
I built this, and took it apart in different iterations about 6 times before finally getting it to work properly.
Its not terribly attractive, but that's OK.
The idea is to use two small 5/8" pillow blocks holding a common drive shaft with differential pulleys on either end. I wanted the final drive to be adjustable, so I stacked a couple of pulleys, including a 1 and 1/2" as well as a 3' pulley. Seems simple, but to make everything work together (including the placement of the motor to achieve decent belt tension was not trivial.
Anyway - here's what it looks like.
Fracs: Stellarvue 70T f6; SW 120mm Esprit f7; "Mark Mk. II" - 60 mm Tasco f6; C80 frac f 11.4
SCT: C8 Edge f10 or f7 with reducer
Dob: 14.5" homebuilt strut dob (f4.5 ZOC mirror), Nexus II, Moonlite focuser
Mounts - Ioptron Skyguider pro, Astro Physics GTO900
Cameras and lenses - ZWO 2600 mc, 290 mm mini, Canon 60D modded with Rokinon 10mm 2.8; Rokinon 135mm f2
Skysafari 6 Pro, Astro Pixel Processor, Pixinsight - using Mac tablet and ASIair pro to run the AP rig.
"Mothers! It is there!" - Rafael Gonzales-Acuna, 2018.
- Kanadalainen
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Re: Building a fixed post mirror grinding machine
Almost ready to use this thing. I put it all together and adjusted belt tension so nothing was under too much lateral stress when I tightened down all the bolts.
The best part is I think its going to actually work!!!
I'm going to order a 10" blank and some grinding grit plus tool-making materials from "got grit" in Florida.
Here are some pics of the penultimate version. (I still have to screw down the aluminum top to the wooden base, and determine whether I need to add casters for stability under the turntable. Also I will need to fabricate some wedges to hold the mirror blank in place).
- Attachments
Fracs: Stellarvue 70T f6; SW 120mm Esprit f7; "Mark Mk. II" - 60 mm Tasco f6; C80 frac f 11.4
SCT: C8 Edge f10 or f7 with reducer
Dob: 14.5" homebuilt strut dob (f4.5 ZOC mirror), Nexus II, Moonlite focuser
Mounts - Ioptron Skyguider pro, Astro Physics GTO900
Cameras and lenses - ZWO 2600 mc, 290 mm mini, Canon 60D modded with Rokinon 10mm 2.8; Rokinon 135mm f2
Skysafari 6 Pro, Astro Pixel Processor, Pixinsight - using Mac tablet and ASIair pro to run the AP rig.
"Mothers! It is there!" - Rafael Gonzales-Acuna, 2018.
- Kanadalainen
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Re: Building a fixed post mirror grinding machine
<<crickets chirping, a sparrow yawns>>
The penultimate product, a nearly functional mirror grinding machine.
Here is a youtube link:
Enjoy!
Fracs: Stellarvue 70T f6; SW 120mm Esprit f7; "Mark Mk. II" - 60 mm Tasco f6; C80 frac f 11.4
SCT: C8 Edge f10 or f7 with reducer
Dob: 14.5" homebuilt strut dob (f4.5 ZOC mirror), Nexus II, Moonlite focuser
Mounts - Ioptron Skyguider pro, Astro Physics GTO900
Cameras and lenses - ZWO 2600 mc, 290 mm mini, Canon 60D modded with Rokinon 10mm 2.8; Rokinon 135mm f2
Skysafari 6 Pro, Astro Pixel Processor, Pixinsight - using Mac tablet and ASIair pro to run the AP rig.
"Mothers! It is there!" - Rafael Gonzales-Acuna, 2018.
- Kanadalainen
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Re: Building a fixed post mirror grinding machine
I still need to finish the turntable, and get serious about my Foucault test rig.
Thanks for reading to the bottom.
Ian
Fracs: Stellarvue 70T f6; SW 120mm Esprit f7; "Mark Mk. II" - 60 mm Tasco f6; C80 frac f 11.4
SCT: C8 Edge f10 or f7 with reducer
Dob: 14.5" homebuilt strut dob (f4.5 ZOC mirror), Nexus II, Moonlite focuser
Mounts - Ioptron Skyguider pro, Astro Physics GTO900
Cameras and lenses - ZWO 2600 mc, 290 mm mini, Canon 60D modded with Rokinon 10mm 2.8; Rokinon 135mm f2
Skysafari 6 Pro, Astro Pixel Processor, Pixinsight - using Mac tablet and ASIair pro to run the AP rig.
"Mothers! It is there!" - Rafael Gonzales-Acuna, 2018.
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Re: Building a fixed post mirror grinding machine
- yobbo89
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Re: Building a fixed post mirror grinding machine
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .
- Kanadalainen
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Re: Building a fixed post mirror grinding machine
I am.
I will "skill up" by first grinding one or two 8 " mirrors. These will likely be in the range of f5 or f6, and in so doing will learn how to hog out the glass, then rough grind and figure it with Foucault tests and bath interferometer data.
Thanks for asking.
Ian
Fracs: Stellarvue 70T f6; SW 120mm Esprit f7; "Mark Mk. II" - 60 mm Tasco f6; C80 frac f 11.4
SCT: C8 Edge f10 or f7 with reducer
Dob: 14.5" homebuilt strut dob (f4.5 ZOC mirror), Nexus II, Moonlite focuser
Mounts - Ioptron Skyguider pro, Astro Physics GTO900
Cameras and lenses - ZWO 2600 mc, 290 mm mini, Canon 60D modded with Rokinon 10mm 2.8; Rokinon 135mm f2
Skysafari 6 Pro, Astro Pixel Processor, Pixinsight - using Mac tablet and ASIair pro to run the AP rig.
"Mothers! It is there!" - Rafael Gonzales-Acuna, 2018.
- Kanadalainen
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Re: Building a fixed post mirror grinding machine
The goal is to make a 20" mirror. Ambitious, but possible I think. I would hog it to roughly f3.5 or f4, and figuring it from a sphere to an accurate parabola will be the difficult part.
The eyepieces currently made now allow for the use of very fast mirrors. Such a large, fast mirror would limit
Fracs: Stellarvue 70T f6; SW 120mm Esprit f7; "Mark Mk. II" - 60 mm Tasco f6; C80 frac f 11.4
SCT: C8 Edge f10 or f7 with reducer
Dob: 14.5" homebuilt strut dob (f4.5 ZOC mirror), Nexus II, Moonlite focuser
Mounts - Ioptron Skyguider pro, Astro Physics GTO900
Cameras and lenses - ZWO 2600 mc, 290 mm mini, Canon 60D modded with Rokinon 10mm 2.8; Rokinon 135mm f2
Skysafari 6 Pro, Astro Pixel Processor, Pixinsight - using Mac tablet and ASIair pro to run the AP rig.
"Mothers! It is there!" - Rafael Gonzales-Acuna, 2018.
- PatWilc
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Re: Building a fixed post mirror grinding machine
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