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wirenut
scholastic sledgehammer


Reged: 09/21/06

Loc: m'dale Pa
Re: Equatorial tracking platforms for Dobsonians? new [Re: MikeRatcliff]
      #5716693 - 03/06/13 03:46 PM

I built my own EQ platform mostly cause of price/available but one other reasons was features. I wanted my feet to have 12" of adjustment since my yard isn't very level and to be able to move the whole set up with a hand truck/dolly. it's not as pretty as Atomic's or Ed's but it's a thing of beauty to me.

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Tim Gilliland
professor emeritus


Reged: 03/28/09

Loc: Sand Springs Okla.
Re: Equatorial tracking platforms for Dobsonians? new [Re: MikeRatcliff]
      #5716910 - 03/06/13 05:30 PM

Quote:

I'm happy with my Atomic Platform also. After a year the drive circuitry died, and he sent a replacement for $40. So far so good on the new one. The drive circuitry is from a Celestron product.

I would like to add wheelbarrow handles, but the platform/telescope setup is not really able to be picked up and moved all at once. There is too much danger in having the platform shift and have the telescope fall over. There would have to be more design put into it to make it easily moveable. Plus the base needs leveling and often need wooden spacers put under some corners, not easy when the weight of the telescope is on the platform. An idea for the Atomic II?

Mike




I have removable wheelbarrow handles on my Discovery 17.5 split tube. I drive it on my blandin platform drop in my center bolt and add a lock nut on bottom. Easy peasy. Encoders work fine by setting them with the platform at the start of travel. Just reset platform and switch off before trying to find targets.


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JLovell
scholastic sledgehammer


Reged: 01/12/10

Loc: Georgia
Re: Equatorial tracking platforms for Dobsonians? new [Re: Tim Gilliland]
      #5718138 - 03/07/13 10:53 AM

One thing about Ed Jones...

He stops taking orders on Halloween, and won't take new ones till March 1st, although I talked to him by email starting in early February, and gave him all the measurements on my scope, sent the deposit, etc. I made sure he knew I wasn't expecting him to start until March, and that whenever he considered my order "accepted" would be fine with me. He seemed glad to get all the numbers and such so he could do all the math, and order motors, etc, to get a head start. He's been very nice, and emailed me with updates such as getting my deposit check, order status on motors, etc.

Just keep in mind his "winter break" if you plan to wait on an Atomic for a while, then switch to him if you are not successful. If you wait too many months, you may have to wait a few more.


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JLovell
scholastic sledgehammer


Reged: 01/12/10

Loc: Georgia
Re: Equatorial tracking platforms for Dobsonians? new [Re: JLovell]
      #5718156 - 03/07/13 11:01 AM

I agree with the post that most people would be happy with most any one of these platforms mentioned in this thread. As long as the platform is designed for the center of rotation of the platform and center of gravity of the scope to be close to the same, or the CoG of the scope to be a bit below the CoR of the platform, there should be no problem with any of them. As long as they've been built to handle the weight of the scope (They all seem way over engineered in that respect for rigidity) and the CoG of the scope is managed so it won't tip over or have too much of the weight lifted off the drive mechanism, causing slippage, I'm sure they all work just fine. Just choose the power option that fits where you will be using the scope most, or the one that becomes available first.

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Jeff2011
Pooh-Bah
*****

Reged: 01/01/13

Loc: Sugar Land, TX
Re: Equatorial tracking platforms for Dobsonians? new [Re: JLovell]
      #5718342 - 03/07/13 12:32 PM

These platforms can be multi use as well. I have placed my DSLR on a tripod on my platform and was abe to get 2 minute exposures with round stars using my 35mm lens and that was with just an eyeball polar alignment of the platform.

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kfiscus
Carpal Tunnel
*****

Reged: 07/09/12

Loc: Albert Lea, MN, USA
Re: Equatorial tracking platforms for Dobsonians? new [Re: Jeff2011]
      #5718605 - 03/07/13 02:54 PM

Yep. I put my PST on a small tripod riding on the platform.

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Tim Gilliland
professor emeritus


Reged: 03/28/09

Loc: Sand Springs Okla.
Re: Equatorial tracking platforms for Dobsonians? new [Re: kfiscus]
      #5718719 - 03/07/13 03:58 PM

Quote:

Yep. I put my PST on a small tripod riding on the platform.




Now that is something I will have to try!


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kfiscus
Carpal Tunnel
*****

Reged: 07/09/12

Loc: Albert Lea, MN, USA
Re: Equatorial tracking platforms for Dobsonians? new [Re: Tim Gilliland]
      #5719028 - 03/07/13 06:39 PM

I have the PST on the Orion EZ-Trac (I think that's its name). This gives me very fine pan/tilt motions while the EQ platform does the main tracking.

I made a safety disk of 1/4" plywood that rides the surface of the platform and has 3 rings that capture the small tripod's feet. Nothing can slide off.


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Metalmanstan
super member


Reged: 07/02/12

Loc: Oneonta, NY
Re: Equatorial tracking platforms for Dobsonians? new [Re: kfiscus]
      #5719170 - 03/07/13 07:37 PM

That stinks that he only sells like 2 per month. I understand why(labor, time consuming and all) I'm really anxious on getting one of these or trying to make my own. It's just very confusing on how to make and assemble everything. I've looked on every Page that has information on the platforms and I just don't understand alot(plus I don't want to mess it up so it doesn't work right!!)

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wcstarguy
member
*****

Reged: 12/04/08

Re: Equatorial tracking platforms for Dobsonians? new [Re: kfiscus]
      #5719199 - 03/07/13 07:56 PM

I have one of the previous generation Atomic Platforms. It works well and I just made a three armed attachment for it so I can mount my AT Voyager tripod and another tripod (double scope pipe mount I made) to it. It bolts to the platform base (top part that rotates) and I use an eyebolt through each tripod leg to an eyebolt on the attachment with a small turnbuckle between the eyebolts. Throw a couple of weights in the middle, works great and the tripods are very secure...actually part of the eq platform. I don't have a pic tonight but will put one up if anyone wants to see it. WC

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JLovell
scholastic sledgehammer


Reged: 01/12/10

Loc: Georgia
Re: Equatorial tracking platforms for Dobsonians? new [Re: Jeff2011]
      #5720330 - 03/08/13 11:31 AM

Quote:

These platforms can be multi use as well. I have placed my DSLR on a tripod on my platform and was abe to get 2 minute exposures with round stars using my 35mm lens and that was with just an eyeball polar alignment of the platform.




I plan on doing exactly this myself.


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tag1260
scholastic sledgehammer
*****

Reged: 10/07/12

Loc: Ohio, USA
Re: Equatorial tracking platforms for Dobsonians? new [Re: JLovell]
      #5720725 - 03/08/13 03:13 PM

I would love to make my own but have yet to find any plans anywhere that give detailed dimensions for N40 lat. I'm not much on math so having to make all the figuring is out of the question.

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Jeff2011
Pooh-Bah
*****

Reged: 01/01/13

Loc: Sugar Land, TX
Re: Equatorial tracking platforms for Dobsonians? new [Re: tag1260]
      #5720842 - 03/08/13 05:00 PM

The following website has a link to a spreadsheet that does the heavy math for you. I used it for my platform.

http://members.ziggo.nl/jhm.vangastel/Astronomy/Poncet/e_index.htm


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VectorRoll
super member


Reged: 11/27/12

Re: Equatorial tracking platforms for Dobsonians? new [Re: Jeff2011]
      #5790495 - 04/10/13 02:46 PM

Quote:

I built my own platform because I thought it would be a fun project and it was. However, I have put into it about what Atomic sells theirs for. Ed has really good platforms too and he is a master at building them. Platforms are built for a specific latitude and can generally be used within 5 degrees of that, so if you buy one used, take that into consideration.

Here is the link to my platform pictures:
http://www.flickr.com/photos/jeff-guck-in-die-luft/8257785049/in/set-72157632...



I was looking at your design and was wondering. Is it made to be adjustable to the Latitude? I ask because it looks like the north and south bearing arcs and guides can have there angle adjustable with those threaded eye-hooks and turnbuckles.


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buddyjesus
Carpal Tunnel
*****

Reged: 07/07/10

Loc: Davison, Michigan
Re: Equatorial tracking platforms for Dobsonians? new [Re: VectorRoll]
      #5791173 - 04/10/13 08:01 PM

don't believe they are adjustable for different latitudes, but will still work for visual use if reasonably close to the latitude it was built for.

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kfiscus
Carpal Tunnel
*****

Reged: 07/09/12

Loc: Albert Lea, MN, USA
Re: Equatorial tracking platforms for Dobsonians? new [Re: buddyjesus]
      #5791218 - 04/10/13 08:17 PM

Most are adjustable about 5 degrees +/- their designed latitude. For instance, I bought a used Atomic EQ platform that was built for 45. I live at 43.6. I bought 2 steel collars and shortened them to the calculated length before adding them to the two south feet. I'll probably make a large "shim plate" for my planned trip a little farther south for this summer's Nebraska Star Party.

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JLovell
scholastic sledgehammer


Reged: 01/12/10

Loc: Georgia
Re: Equatorial tracking platforms for Dobsonians? new [Re: buddyjesus]
      #5791255 - 04/10/13 08:30 PM

Well, from what I've learned about the platforms, yes, they can be adjusted SOME for different latitudes. The bearing arcs, geometrically, are simply slices of a cone that when aligned with Polaris, the center line, or axis of rotation, passes through the center of gravity of the scope, and through Polaris. The width of the cone, or the angle of the vertex, is determined by your latitude.

Essentially, you look at your latitude, and draw a tangent line at the Earth's surface at that latitude, then draw a line to Polaris, and measure the angle between them, and that is the width of your cone. It works out through geometry that it is also your latitude.

If you are lowering or raising either of the North or South ends of the platform, you are essentially changing the angle of the tangent to the Earth's surface to the center line of the cone, which is also changing the latitude at which it is set.

The main problem with adjusting the latitude with that method is with the CoG of the scope. When you tilt the scope/platform assembly relative to the ground, yes, you do adjust the axis of rotation of the cone. However, you do NOT adjust where the CoG of the scope is. Many (most?) platforms will have problems if adjusted too far from where they are designed to operate, and the scope may become unstable and even fall off, or the platform will slip off of its bearings. Also, the CoG shift may remove enough weight from the drive shaft that there is no longer enough friction at that point to drive the platform.

Edited by JLovell (04/10/13 08:34 PM)


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kfiscus
Carpal Tunnel
*****

Reged: 07/09/12

Loc: Albert Lea, MN, USA
Re: Equatorial tracking platforms for Dobsonians? new [Re: JLovell]
      #5791431 - 04/10/13 10:14 PM

You are correct about gravity being a concern. My Z12's rockerboard rides directly on the platform. I didn't even make a ground board for it when making my redo. I have 3 teflon pads on the platform's table that contact the EbonyStar laminate.

Also, when adding small amounts of height to one end or the other, the real tipping concerns are still perpendicular (Right Ascension) in nature. I haven't had ANY problems yet.


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Jeff2011
Pooh-Bah
*****

Reged: 01/01/13

Loc: Sugar Land, TX
Re: Equatorial tracking platforms for Dobsonians? new [Re: VectorRoll]
      #5791723 - 04/11/13 02:05 AM

Quote:

I was looking at your design and was wondering. Is it made to be adjustable to the Latitude? I ask because it looks like the north and south bearing arcs and guides can have there angle adjustable with those threaded eye-hooks and turnbuckles.




Yes, the turnbuckles allow for some adjustment in latitude. They are very stable as well. I have not tried it out at a different latitude yet. I believe the comments about COG are true even with the turnbuckles, but the XT8 is not as heavy as bigger dobs so I am not as concerned about that. With other platforms you have to raise or lower one end to adjust for lat. With the turn buckles, you can keep the platform level and still change the lat. The other benefit of the turnbuckle is that you don't need to worry about getting the angles cut exactly for the sector supports.

Edited by Jeff2011 (04/11/13 02:12 AM)


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VectorRoll
super member


Reged: 11/27/12

Re: Equatorial tracking platforms for Dobsonians? new [Re: Jeff2011]
      #5792134 - 04/11/13 11:09 AM

Quote:

Quote:

I was looking at your design and was wondering. Is it made to be adjustable to the Latitude? I ask because it looks like the north and south bearing arcs and guides can have there angle adjustable with those threaded eye-hooks and turnbuckles.




Yes, the turnbuckles allow for some adjustment in latitude. They are very stable as well. I have not tried it out at a different latitude yet. I believe the comments about COG are true even with the turnbuckles, but the XT8 is not as heavy as bigger dobs so I am not as concerned about that. With other platforms you have to raise or lower one end to adjust for lat. With the turn buckles, you can keep the platform level and still change the lat. The other benefit of the turnbuckle is that you don't need to worry about getting the angles cut exactly for the sector supports.



Very Interesting. Not having to worry about that angle cut could benefit many. I can see many not having the tools or maybe just the skill to get the cut right. Having to not worry about that would help such people.

One thing I was wondering about these platforms is if anyone has decided to forgo making it a separate piece and just make it part of the base itself. Basically having the top EQ Platform as the bottom of the Rocker Base. It would be another way to get a little lower profile to the scope.


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