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Equipment Discussions >> Mounts

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JoseBorrero
Post Laureate
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Reged: 09/04/09

Loc: Puerto Rico Island
Polishing a Worm!
      #5577916 - 12/18/12 09:02 PM

Any suggestion? Pro's? or Con's?

Thanks for your help


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CharlesW
Pooh-Bah


Reged: 11/02/12

Loc: Chula Vista & Indio, CA
Re: Polishing a Worm! new [Re: JoseBorrero]
      #5578102 - 12/18/12 11:08 PM

Pistol owners spend substantial amounts of effort polishing the surfaces inside the feed and slide systems to improve shooting accuracy. I can only imagine that polishing the gears inside a telescope drive couldn't do the same, as long as the material removed didn't increase slop.

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Hilmi
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Reged: 03/07/10

Loc: Muscat, Sultanate of Oman
Re: Polishing a Worm! new [Re: JoseBorrero]
      #5578103 - 12/18/12 11:08 PM

I've polished mine using a Dremel polishing pad and some mild chrome polish. I did that to get rid of some burs in the worm gear. I haven't had the chance to test the result at the scope because both my RA & Dec motors have burnt out and I am waiting for Scott Losmandy to send me replacements (which he agreed to do for free).

I did read on the internet about a guy who had similar tracking issues to what I had and when he polished his worm gear, all the issues went away! Here is the link to his write up http://www.helixgate.net/raworm.html

I hope this information helps

Edit: By feeling the worm by finger as I rotate, the sharpest of the bits that where sticking out have definitely been smoothed out. But I used the mildest polish I could get my hands on.

Edited by Hilmi (12/18/12 11:36 PM)


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MHamburg
scholastic sledgehammer
*****

Reged: 06/21/06

Loc: Brooklyn, NY/Berkshires, MA
Re: Polishing a Worm! new [Re: JoseBorrero]
      #5578600 - 12/19/12 09:14 AM

Talk with Ed Thomas at Deep Space Products.
Michael


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Polishing a Worm! new [Re: JoseBorrero]
      #5578616 - 12/19/12 09:20 AM

The problem with polishing a worm simply using a polishing wheel or something else is that polishing is actually removing metal from the surface of the worm. A worm is cut using using a tool that forms it to the specific tooth shape desired (essentially the negative of the cutting tool). By polishing you are essentially cutting the worm with a tool that is not the shape of the cutting tool. In a realatively low precision worm this is unlikely to make a lot of difference (positive or negative) if you do not go too far with it. However, on a high precision worm you risk increasing the periodic error of the worm by reshaping its surface.

In general, it is not something I would recommend playing with.

Lapping the worm to the wheel is less risky and can be done with polishing compound.


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Hilmi
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Reged: 03/07/10

Loc: Muscat, Sultanate of Oman
Re: Polishing a Worm! new [Re: EFT]
      #5578649 - 12/19/12 09:55 AM

Ed,

I agree with you on the risks, but the way I saw it, the worm gear wasn't performing anyway and a replacement is $65 only. What's the worst that can happen?


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mayidunk
Don't Ask...
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Reged: 02/17/10

Loc: Betwixt & Between...
Re: Polishing a Worm! new [Re: Hilmi]
      #5578675 - 12/19/12 10:17 AM

Perhaps inadvertently changing the pressure angles on the worm may induce uneven wear on the pinion gear over time, causing it to develop increasing periodic error? I would check with Hollywood Machine first, before doing this.

Hollywood General Machining, Inc.
1033 N. Sycamore Avenue
Los Angeles, California 90038
323-462-2855 FAX: 323-462-2682


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Polishing a Worm! new [Re: Hilmi]
      #5578708 - 12/19/12 10:41 AM

Quote:

Ed,

I agree with you on the risks, but the way I saw it, the worm gear wasn't performing anyway and a replacement is $65 only. What's the worst that can happen?




If there is a replacement available, then there is certainly less risk. For many mounts, no replacements are avialable so I wouldn't risk it. The only downside with experimenting is that anything you do to the worm will impact the worm wheel (which is usually softer metal), for which a replacement may not be available.

BTW, just smoothing the surface of the worm is not likely to cause trouble. Its when you get into the tooth face that you can cause problems.


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Hilmi
Post Laureate
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Reged: 03/07/10

Loc: Muscat, Sultanate of Oman
Re: Polishing a Worm! new [Re: EFT]
      #5579031 - 12/19/12 02:20 PM

I didn't have a polishing pad that tiny! No, I just smoothed out the rough edges on the surface. Didn't change the angle of the teeth. I doubt I could have even if I wanted to, this is because I don't have any polishing pad that tiny. The combination of polish and polish pad which I had couldn't remove that much material anyway. I used very very mild chrome polish and the standard dremel polishing pad. My Skil rotary tool was set to no. 1 or no. 2 on the speed dial and I made sure the worm could spin freely as I polished it, thus avoiding polishing any one place for too long.

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Geo.
Carpal Tunnel
*****

Reged: 10/01/08

Loc: Upstate NY
Re: Polishing a Worm! new [Re: Hilmi]
      #5579118 - 12/19/12 03:11 PM

Even lapping helically cut worm wheels such as are found on Meade mounts made in the last 20 years won't improve things.

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gdd
Pooh-Bah


Reged: 11/23/05

Loc: N Seattle suburb, WA
Re: Polishing a Worm! new [Re: EFT]
      #5579342 - 12/19/12 05:44 PM

Quote:

Lapping the worm to the wheel is less risky and can be done with polishing compound.




Will lapping the worm to the wheel reduce PE, or will it only make the worm smoother and get rid of some of the high frequency noise?

Gale


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: Polishing a Worm! new [Re: gdd]
      #5579394 - 12/19/12 06:24 PM

well i don't know but i tried lapping the Aeroquest worm on my CGEM... (by putting toothpaste on it, putting it back on the mount, then turning the worm slowly with a drill for half an hour).

it didn't do one *&^& thing.

The stock worm was about 30" fundamental (peak-to-peak) and the Aeroquest is 16", but lapping made no difference. maybe i should have used metal polish instead of toothpaste.


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blueman
Photon Catcher
*****

Reged: 07/20/07

Loc: California
Re: Polishing a Worm! new [Re: orlyandico]
      #5579454 - 12/19/12 07:18 PM

Polishing is only doing one part, the worm. Lapping is matching the two parts together, Worm and Wheel.

Now, if the worm is bad or the wheel is bad, lapping will not fix anything. But if they are both good, the it can reduce PE and making things smoother.

Cerium is used by AstroPhysics I believe, this is what is used to polish a mirror for optics. So you want the polish to make a very smooth surface, but not cut the metal that much.
Blueman


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JoseBorrero
Post Laureate
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Reged: 09/04/09

Loc: Puerto Rico Island
Re: Polishing a Worm! new [Re: Hilmi]
      #5579528 - 12/19/12 08:04 PM

Thanks Hilmi my question came out from this website Also I just installed the OPW-G11 without the worm wasn't in stock. I reinstalled without any polish if don't like the the improvement then will go with a new worm.
Quote:

I've polished mine using a Dremel polishing pad and some mild chrome polish. I did that to get rid of some burs in the worm gear. I haven't had the chance to test the result at the scope because both my RA & Dec motors have burnt out and I am waiting for Scott Losmandy to send me replacements (which he agreed to do for free).

I did read on the internet about a guy who had similar tracking issues to what I had and when he polished his worm gear, all the issues went away! Here is the link to his write up http://www.helixgate.net/raworm.html

I hope this information helps

Edit: By feeling the worm by finger as I rotate, the sharpest of the bits that where sticking out have definitely been smoothed out. But I used the mildest polish I could get my hands on.




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JoseBorrero
Post Laureate
*****

Reged: 09/04/09

Loc: Puerto Rico Island
Re: Polishing a Worm! new [Re: JoseBorrero]
      #5579533 - 12/19/12 08:10 PM

I'll appreciate everyone input, I just need a test

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John Miele
Carpal Tunnel
*****

Reged: 05/29/05

Loc: North Alabama
Re: Polishing a Worm! new [Re: JoseBorrero]
      #5579618 - 12/19/12 09:00 PM

Man...you guys are sure serious! I was thinking of so many funny ways to answer this question...but now I'm afraid I'd thrown out of here iffin I did... ...John

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Hilmi
Post Laureate
*****

Reged: 03/07/10

Loc: Muscat, Sultanate of Oman
Re: Polishing a Worm! new [Re: John Miele]
      #5579833 - 12/19/12 11:31 PM

Quote:

Also I just installed the OPW-G11 without the worm wasn't in stock.



If I recall correctly, OPT had them in stock last time I checked.


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neilson
professor emeritus


Reged: 08/22/10

Re: Polishing a Worm! new [Re: Hilmi]
      #5579938 - 12/20/12 12:55 AM

Hi,
What kind of PE should be expected from a brand new G11 with Gemini 2 out of the box. From what I have read in several places about 5 arcseconds peak to peak. Can anyone verify this.
I know how to lap valves on a car when doing a valve job, but how do you lap a worm.

neilson


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Raginar
Postmaster
*****

Reged: 10/19/10

Loc: Rapid CIty, SD
Re: Polishing a Worm! new [Re: neilson]
      #5580079 - 12/20/12 04:57 AM

I think +/-5 arcseconds is probably not realistic +/-15 is probably realistic. But you can use things like PEC and guiding to reduce it to a manageable level.

http://goo.gl/yrRXj

Here is a link to a thread from a few years ago on the subject. Looks like most people were experiencing stock PE of < +/-10. Again, really good compared to the CGEMs and iEQ45s.


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gdd
Pooh-Bah


Reged: 11/23/05

Loc: N Seattle suburb, WA
Re: Polishing a Worm! new [Re: Raginar]
      #5580382 - 12/20/12 10:32 AM

Are the Aeroquest worms as precise as Losmandy's High Precision worms? Does anyone make a higher precision worm that will fit in the OPWB?

Gale


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