Re: [ATM] 16_Bino Progress

["Don D'Egidio" <djd521@comcast.net>]

James,

If you used an Acme thread tap instead a standard machine thread tap you would come very close to a standard worm gear thread form. Looking at the photos of your brass gear, I don't think you needed to cut the threads to such an extreme depth. There are formulas to calculate the depth of cut for a worm gear, but basically you need a depth of about 25 - 30% of the diameter of the worm to be used.

The rest of the pictures of the scope look great. That Tri-Dob sure is a nice compact low design.

Don

----- Original Message ----- 
From: "James Lerch" <jlerch1@tampabay.rr.com>
To: <binewt@yahoogroups.com>; <atm_free@yahoogroups.com>; "ATM" <atm@atmlist.net>
Sent: Sunday, November 07, 2004 2:42
Subject: [ATM] 16_Bino Progress


> Greetings All,
> 
> Looks like I'm going to be a day late to Chiefland,  but if all goes well the 
> new binos will get first light (with a pointing system) on Tuesday.
> 
> Had a set back at the beginning of the week fighting with the upper rotating 
> ring assemblies.  My first idea on guides for the rotating rings failed due to a 
> "My idea just didn't fit in the given amount of space" problem.  Solved guide 
> problem by converting a lot of Delrin in to tiny pieces, most of which found 
> their way to the trash heap.
> 
> Once the rotating ring guide problem was solved, I ran into a stiction problem 
> in the rotating rings.  The stiction problem was solved by selecting 'Really' 
> thin plastic laminates and just a touch of Lithium grease.
> 
> Experienced "wanna be first light" Wednesday.  I say wanna be as I didn't yet 
> have an alt / az system.  To build the Tri-Dob styled Alt/Az system, I had to 
> load all the optics into the OTA to find the center of gravity (as I'm not smart 
> enough to calculate it mathematically).  Since the optics were already in, I 
> just left it near zenith and took a quick peek to make sure everything 
> collimated / focused properly, which they did :)
> 
> The last few days have been dedicated to building the Tri-Dob Alt - Az system 
> and drive assemblies.  So far so good, today I dry fitted and manually tested 
> the Alt / Az system, so worse case I know it will work in manual mode for 
> Chiefland.
> 
> Late this evening I had a new 'first',  I hobbed out two 1" OD 16 thread per 
> inch brass worm gears.  Surprisingly, my jury rigged system worked on the first 
> try each time!  I'm fairly stunned at how simple making worm gears is  (well, I 
> guess these are not "true" worm gears, as I'm using machine threads....)
> 
> Anyway, pictures of all the above adventures can be seen here:
> http://lerch.no-ip.com/atm/Projects/DF_Optics_16_Bino_Stuff_Low/page_01.htm
> 
> Tomorrow I have to figure out how to attach the stepper motors, figure out the 
> final gear ratios, finish painting, add some light shields, and I think its 
> ready to go :)
> 
> Take Care,
> James Lerch
> http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)
> 
> "Anything that can happen, will happen" -Stephen Pollock from:
> "Particle Physics for Non-Physicists: A Tour of the Microcosmos"
> 
> " Press on: nothing in the world can take the place of perseverance.
> Talent will not; nothing is more common than unsuccessful men with talent.
> Genius will not; unrewarded genius is almost a proverb.
> Education will not; the world is full of educated derelicts.
> Persistence and determination alone are omnipotent. "
>                                                            Calvin Coolidge 
> 
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> 

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