· Get a Cloudy Nights T-Shirt · Submit a Review / Article    Click here if you are having trouble logging into the forums Cloudy Nights - Official Forums of the 2009 International Year of Astronomy Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu.... uh, User   You are not logged in. [Login] Forum Archives · Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> ATM, Optics and DIY Forum Previous   Index   Next   Threaded   Pages: 1 | 2 | 3 | 4 | (show all) Glig sage Reged: 10/02/05 Posts: 370 Loc: Baltimore, MD Types of grinding/polishing machines       #3297243 - 08/27/09 08:14 AM Edit   Reply   Quote Quick Reply   Types of grinding/polishing machines I would like this thread to help educate me and other newbies about the types of grinding/polishing machines. The types: Porter. Hindle. Elgin. Draper. Let’s get more names, guys, and details about what makes one type different from the others. Characteristics: How large does this type of machine typically get? What size mirror can it take? What speed does the mirror turn? Can it figure? How many arms, how many eccentrics? What are the Advantages/Disadvantages? Personal preferences: Which type do YOU like and why? Lastly, how to build it. -------------------- Richard Caldwell Post Extras:       danmdak member Reged: 10/03/07 Posts: 37 Loc: NE Ohio Re: Types of grinding/polishing machines [Re: Glig]       #3299080 - 08/28/09 01:03 AM Edit   Reply   Quote Quick Reply   Good luck. I have wanted plans/advice on this for YEARS! Finally, years ago, Amateur telescope Making Journal (undated, issue #13)ran an article on one. Unfortunately, they took the easy way out: they referred you to a website that had all the plans and dimensions. okay, no problem. I turned on the computer, typed in the web address....and it was not to be found ! That is the one trouble with these computer webistes..here today, gone tomorrow. Meanwhile, had they actually printed the plans, I could have access to them always. -------------------- Main instrument: homemade 16" f/4.5 secondary instruments: Homemade 8" f/8 & Meade 2045 4" Garrett 15X70 binos In the works: Homemade 8" f/4 Post Extras:       Crayfordjon Inventor Reged: 06/17/09 Posts: 372 Loc: UK Re: Types of grinding/polishing machines [Re: danmdak]       #3299188 - 08/28/09 02:58 AM Edit   Reply   Quote Quick Reply   I made a Hindle type machine from scrap machinery with a 48 inch capacity, I made two 48", one 42", and a 32" mirror and a 30" inch objective lens. plus many smaller mirrors and doublets up to 8". I cast the massive concrete table in situ, the machine was sited in a tiny workshop only half as big again as the machine. The table rotated at about 2rpm, the driver at 28 rpm, but the offset spindle was static, and fixed to a cross slide so that the degree of offset was managed by accasionally shifting it manually.power source, a half horsepower squirrel cage motor from the first world war era. Post Extras:       Crayfordjon Inventor Reged: 06/17/09 Posts: 372 Loc: UK Re: Types of grinding/polishing machines [Re: Crayfordjon]       #3299288 - 08/28/09 05:47 AM Attachment (70 downloads) Edit   Reply   Quote Quick Reply   For every ones information, some illustrations culled from a paper to the BAA,by J,Wall and R,Nichol. Journal of the British Astronomical Association, 1992 August. vol 102, No4. Post Extras:       Crayfordjon Inventor Reged: 06/17/09 Posts: 372 Loc: UK Re: Types of grinding/polishing machines [Re: Crayfordjon]       #3299291 - 08/28/09 05:48 AM Attachment (53 downloads) Edit   Reply   Quote Quick Reply   And Post Extras:       Crayfordjon Inventor Reged: 06/17/09 Posts: 372 Loc: UK Re: Types of grinding/polishing machines [Re: Crayfordjon]       #3299292 - 08/28/09 05:48 AM Attachment (37 downloads) Edit   Reply   Quote Quick Reply   Also. Post Extras:       Crayfordjon Inventor Reged: 06/17/09 Posts: 372 Loc: UK Re: Types of grinding/polishing machines [Re: Crayfordjon]       #3299294 - 08/28/09 05:49 AM Attachment (31 downloads) Edit   Reply   Quote Quick Reply   And. Post Extras:       Crayfordjon Inventor Reged: 06/17/09 Posts: 372 Loc: UK Re: Types of grinding/polishing machines [Re: Crayfordjon]       #3299295 - 08/28/09 05:50 AM Attachment (50 downloads) Edit   Reply   Quote Quick Reply   And for my last trick. Post Extras:       Beri sage Reged: 06/29/05 Posts: 294 Loc: Croatia Re: Types of grinding/polishing machines [Re: Crayfordjon]       #3299320 - 08/28/09 06:28 AM Edit   Reply   Quote Quick Reply   Thanks! Any chance for a larger size of these images ? -------------------- 15x70 Binoculars 10" truss Dob http://www.scopemaking.net Post Extras:       Glig sage Reged: 10/02/05 Posts: 370 Loc: Baltimore, MD Re: Types of grinding/polishing machines [Re: Crayfordjon]       #3299399 - 08/28/09 07:53 AM Edit   Reply   Quote Quick Reply   Thanks for responding, guys. Crayfordjon, about that first picture. It shows 2 types of machines. The top one is labeled a Hindle machine, the bottom one is labeled a modified Hindle machine. Am I right in saying that the bottom one is also called a Draper? I would very much like to know the relative merits of these designs. -------------------- Richard Caldwell Post Extras:       Glig sage Reged: 10/02/05 Posts: 370 Loc: Baltimore, MD Re: Types of grinding/polishing machines [Re: Glig]       #3299448 - 08/28/09 08:44 AM Attachment (47 downloads) Edit   Reply   Quote Quick Reply   Here is a better pic of the first one. -------------------- Richard Caldwell Edited by Glig (08/28/09 08:55 AM) Post Extras:       Glig sage Reged: 10/02/05 Posts: 370 Loc: Baltimore, MD Re: Types of grinding/polishing machines [Re: Glig]       #3299463 - 08/28/09 08:52 AM Attachment (28 downloads) Edit   Reply   Quote Quick Reply   2nd one. -------------------- Richard Caldwell Post Extras:       Stefan Rostyne Pooh-Bah Reged: 10/19/04 Posts: 1009 Loc: Assenede, Belgium Re: Types of grinding/polishing machines [Re: Glig]       #3299505 - 08/28/09 09:21 AM Edit   Reply   Quote Quick Reply   http://www.astrosurf.com/gap47/T400/Machine/3-machines-type-eng.htm -------------------- Stefan Van de Rostijne 4.5" F4.5 newt 5°widefield/finderscope 8" f/5.6 travel dob old 12.5" F5 dob (used to look better...) 30 cm f/30 Classic Cassegrain (polishing primary) 23" f/4 dob project Post Extras:       Stefan Rostyne Pooh-Bah Reged: 10/19/04 Posts: 1009 Loc: Assenede, Belgium Re: Types of grinding/polishing machines [Re: Stefan Rostyne]       #3299512 - 08/28/09 09:26 AM Edit   Reply   Quote Quick Reply   Here are some vids of our own draper style machine. Recently we finished polishing a 18" f/4 mirror. http://www.youtube.com/watch?v=3VGmGk2eIEw Currently we are figuring out how to parabolise. There is very little information on the internet about figuring with a machine. I also would like to know more about that. Edited by Stefan Rostyne (08/28/09 10:58 AM) Post Extras:       Glig sage Reged: 10/02/05 Posts: 370 Loc: Baltimore, MD Re: Types of grinding/polishing machines [Re: Stefan Rostyne]       #3299605 - 08/28/09 10:16 AM Edit   Reply   Quote Quick Reply   That's a great link, Stefan. Couldn't find the link for the videos, though. -------------------- Richard Caldwell Post Extras:       Crayfordjon Inventor Reged: 06/17/09 Posts: 372 Loc: UK Re: Types of grinding/polishing machines *DELETED* [Re: Glig]       #3299649 - 08/28/09 10:40 AM Edit   Reply   Quote Quick Reply   Post deleted by Crayfordjon Post Extras:       Crayfordjon Inventor Reged: 06/17/09 Posts: 372 Loc: UK Re: Types of grinding/polishing machines [Re: Crayfordjon]       #3299677 - 08/28/09 10:54 AM Edit   Reply   Quote Quick Reply   Hi glig. both are Hindle type machines, the top one is the standard as laid down in scriptures; ATM book 1. pg 235. The bottom one is a modified version by yours truly, I have replaced the alligatior by a double beam, and the offset spindle is not driven but static and mounted on a cross slide, so that the spindle can be moved occasionally, this makes for a simpler design machinery wise. I cannot send any picture that is larger due to the 10kb restriction on the web site. Post Extras:       Stefan Rostyne Pooh-Bah Reged: 10/19/04 Posts: 1009 Loc: Assenede, Belgium Re: Types of grinding/polishing machines [Re: Crayfordjon]       #3299685 - 08/28/09 11:01 AM Edit   Reply   Quote Quick Reply   Sorry Richard, I forgot. I added the link, now. EDIT I'm the one that steps into view in vid #7 -------------------- Stefan Van de Rostijne 4.5" F4.5 newt 5°widefield/finderscope 8" f/5.6 travel dob old 12.5" F5 dob (used to look better...) 30 cm f/30 Classic Cassegrain (polishing primary) 23" f/4 dob project Edited by Stefan Rostyne (08/28/09 11:19 AM) Post Extras:       Crayfordjon Inventor Reged: 06/17/09 Posts: 372 Loc: UK Re: Types of grinding/polishing machines [Re: Crayfordjon]       #3299687 - 08/28/09 11:02 AM Edit   Reply   Quote Quick Reply   Beri, try printing out the pics, the definition is much better Post Extras:       Stefan Rostyne Pooh-Bah Reged: 10/19/04 Posts: 1009 Loc: Assenede, Belgium Re: Types of grinding/polishing machines [Re: Crayfordjon]       #3299702 - 08/28/09 11:09 AM Edit   Reply   Quote Quick Reply   http://articles.adsabs.harvard.edu/full/1992JBAA..102..198N/0000198.000.html This is the same as in Crayfordjon's posts, but in better resolution. -------------------- Stefan Van de Rostijne 4.5" F4.5 newt 5°widefield/finderscope 8" f/5.6 travel dob old 12.5" F5 dob (used to look better...) 30 cm f/30 Classic Cassegrain (polishing primary) 23" f/4 dob project Post Extras:       Pages: 1 | 2 | 3 | 4 | (show all) Previous   Index   Next   Threaded   Extra information 4 registered and 8 anonymous users are browsing this forum. 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