Topics

Rotating pier adapter #Polar_Alignment


r1300rs
 

I'm thinking of placing an AP1600/1100 in my portable observatory trailer.  Since it moves around field to field; it can't be parked precisely so that the pier is facing North for Polar Alignment.  Does the RPA allow the base of the mount to be "swiveled" 360 degrees and then locked down?

I've had several in the past but can't remember if this is a feature of the RPA or if it just moves a short distance.

Rick
cardiofuse observatory


uncarollo2 <chris1011@aol.com>
 


Does the RPA allow the base of the mount to be "swiveled" 360 degrees and then locked down?
No 360 degree movement. I believe it has about 15 degree freedom of movement.

Rolando


-----Original Message-----
From: r1300rs via Groups.Io <cardiofuse@...>
To: main <main@ap-gto.groups.io>
Sent: Mon, Jan 20, 2020 11:20 am
Subject: [ap-gto] Rotating pier adapter #Polar_Alignment

I'm thinking of placing an AP1600/1100 in my portable observatory trailer.  Since it moves around field to field; it can't be parked precisely so that the pier is facing North for Polar Alignment.  Does the RPA allow the base of the mount to be "swiveled" 360 degrees and then locked down?

I've had several in the past but can't remember if this is a feature of the RPA or if it just moves a short distance.

Rick
cardiofuse observatory


fl.lusen
 

Rick,

 

Aside from astronomy I am also a hobby machinist.  Years ago I helped a fellow that built an observatory in a surplus ambulance.  He had the same problem.  What I suggested to him and he did implement was to get an 8” or 10” machinists Horizontal rotary table.   https://en.wikipedia.org/wiki/Rotary_table  They rotate 360 degrees and lock down solidly enough to overcome the forces produced by the cutting action of a milling machine cutter.  Extremely rigid.

 

That may be an option for you.  I would stay away from the Chinese made.  Go with Japanese, Taiwanese, or eastern Europe.

 

Fred

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of r1300rs via Groups.Io
Sent: Monday, January 20, 2020 11:20 AM
To: main@ap-gto.groups.io
Subject: [ap-gto] Rotating pier adapter #Polar_Alignment

 

I'm thinking of placing an AP1600/1100 in my portable observatory trailer.  Since it moves around field to field; it can't be parked precisely so that the pier is facing North for Polar Alignment.  Does the RPA allow the base of the mount to be "swiveled" 360 degrees and then locked down?

I've had several in the past but can't remember if this is a feature of the RPA or if it just moves a short distance.

Rick
cardiofuse observatory


Michael Hambrick <mike.hambrick@...>
 

You might try looking on eBay. I accumulated a pretty good collection of machine tooling from eBay over the years. This was back when they did real auctions and not the "buy it now" system that they have gone to.

In most cases, the old American made tooling is far far better than anything on the market today. Rotary tables have a crank wheel that turns a worm gear to rotate the table. The good ones have a 90:1 ratio (90 turns of the crank to achieve 360 degrees rotation) with a properly graduated crank wheel these rotary tables are accurate to within a few arc minutes.

Palmgren used to make some really nice rotary tables. They used to be made in the US, but like everyone else they moved their manufacturing to China. The quality has suffered because of it.
Another good brand is Troyke. They are considered the Cadillac of rotary tables. As far as I know they still make a 9-inch rotary table here in the US, but you will pay dearly for a new one. Every once in a while you can find a used one on eBay for a pretty decent price.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...


thefamily90 Phillips
 

They look pretty cool. But, how would you attach one to a pier and AP GOTO
900 or 1200 mount?

Jim


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Michael Hambrick via Groups.Io <mike.hambrick@...>
Sent: Tuesday, January 21, 2020 8:35:36 AM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Rotating pier adapter #Polar_Alignment
 
You might try looking on eBay. I accumulated a pretty good collection of machine tooling from eBay over the years. This was back when they did real auctions and not the "buy it now" system that they have gone to.

In most cases, the old American made tooling is far far better than anything on the market today. Rotary tables have a crank wheel that turns a worm gear to rotate the table. The good ones have a 90:1 ratio (90 turns of the crank to achieve 360 degrees rotation) with a properly graduated crank wheel these rotary tables are accurate to within a few arc minutes.

Palmgren used to make some really nice rotary tables. They used to be made in the US, but like everyone else they moved their manufacturing to China. The quality has suffered because of it.
Another good brand is Troyke. They are considered the Cadillac of rotary tables. As far as I know they still make a 9-inch rotary table here in the US, but you will pay dearly for a new one. Every once in a while you can find a used one on eBay for a pretty decent price.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...


Michael Hambrick <mike.hambrick@...>
 

Hi Jom
You would probably need a combination of flat surface adapters and / or flat pier plates. The rotary tables are slotted, so it should be pretty straightforward to attach the mount base to the rotary table. The base of the rotary tables typically have two to four slotted lugs for bolting them to the machine table. You would probably have to modify (drill & tap) one of the flat surface adapters that fits your pier.

There are probably cheaper ways to do this.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...


Steven Panish
 

I may have missed what you have for a pier, but I have the RPA installed on a 10" schedule 20 pipe.   The RPA and other 10" adapters are held to a pier with 6 screws, which go through the pier pipe.  (Mine is a bit more complex but that's how the RPA is meant to be attached).  There are mechanical drawings on the AP website.  If you look at the 10" portable piers you can see how the holes are done.  This would allow you to rotate the RPA in 60 deg increments, not quite enough to get the 14 degree fine adjustment in the correct range.  

You could also buy one of the 10" portable piers which would likely work well if the trailer is big enough.   Very nice product and you can rotate as desired.  (I have an extra if you are interested).  

Steve


Mark
 

I may have a pier adapter for an AP 900GTO that rotates 360. Finding it is the problem…

It is machined for an ATS pier.

Mark


Robert Berta
 

Seems you could just drill extra holes in the pier tube to allow more position options. You could also machine slots in place of the holes on the tube and use washers and bolts to clamp once rotated. that would give you perhaps another total of 10 additional degrees adjustment besides the existing azimuth adjustment in the mount. A machinist could easily build an adapter for what you want.

I am a hobbiest in machining and have a metal lathe and milling machine. When I leave my home observatory and go in field I designed and machined a cap that fits on a modified Meade Giant Field Tripod that takes the flat plate adapter and allows me to rotate the entire assembly if needed to reach the range covered by the mounts azimuth control. The Meade tripod has the advantage it can be adjusted for uneven ground easier than a traditional pier and that was why I went that way instead of a pier. 


George
 

Be careful how far you rotate the mount in azimuth!   The “north” leg should always be under the counterweight shaft or your mount/scope setup will become very unstable.  

 

Regards,

 

George

 

George Whitney

Astro-Physics, Inc.

Phone:  815-282-1513

Email:  george@...

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Robert Berta
Sent: Wednesday, January 22, 2020 10:48 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Rotating pier adapter #Polar_Alignment

 

Seems you could just drill extra holes in the pier tube to allow more position options. You could also machine slots in place of the holes on the tube and use washers and bolts to clamp once rotated. that would give you perhaps another total of 10 additional degrees adjustment besides the existing azimuth adjustment in the mount. A machinist could easily build an adapter for what you want.

I am a hobbiest in machining and have a metal lathe and milling machine. When I leave my home observatory and go in field I designed and machined a cap that fits on a modified Meade Giant Field Tripod that takes the flat plate adapter and allows me to rotate the entire assembly if needed to reach the range covered by the mounts azimuth control. The Meade tripod has the advantage it can be adjusted for uneven ground easier than a traditional pier and that was why I went that way instead of a pier. 


Michael Hambrick <mike.hambrick@...>
 

Be careful if you modify the pier so as not to create a sloppy attachment of the mount base into the pier. In mounts where the bolts are on the side of the mount base (like on the 1100 GTO), oversize mounting holes (or slots) can result in a situation where the mount could shift under the load throw off your polar alignment.

Put the mount into Park 3 and you will see what I am talking about. With the counterweights and scope attached, the weight is centered out beyond the north side of the pier. This cantilevered mass wants to tilt the whole mount downwards, and if it is not securely bolted to the pier it will shift.even if you think the bolts are tight. In my old 8-inch pier, the bolt holes are oversized enough that it allows the mount base to tilt about 1/16-inch. This is a shift of about 1/2 degree ! I have reduced the chances of the mount shifting by using high performance NORD LOCK wedge lock washers on the bolts that attach the mount to the pier, but a better solution would be to use a flat surface adapter so that the mount attaches to the top of the pier rather than from the side. Another option might be to replace three of the six side bolts with tapered dowel pins. Doing this would absolutely fix the mount base to the pier and not allow it to tilt under load.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...




From:        "Robert Berta" <biker123@...>
To:        main@ap-gto.groups.io
Date:        01/22/2020 10:48 AM
Subject:        Re: [ap-gto] Rotating pier adapter #Polar_Alignment
Sent by:        main@ap-gto.groups.io




Seems you could just drill extra holes in the pier tube to allow more position options. You could also machine slots in place of the holes on the tube and use washers and bolts to clamp once rotated. that would give you perhaps another total of 10 additional degrees adjustment besides the existing azimuth adjustment in the mount. A machinist could easily build an adapter for what you want.

I am a hobbiest in machining and have a metal lathe and milling machine. When I leave my home observatory and go in field I designed and machined a cap that fits on a modified Meade Giant Field Tripod that takes the flat plate adapter and allows me to rotate the entire assembly if needed to reach the range covered by the mounts azimuth control. The Meade tripod has the advantage it can be adjusted for uneven ground easier than a traditional pier and that was why I went that way instead of a pier.  



fernandorivera3
 

Those who are looking for a 360 degree rotating pier adapter should consider those made by Mal Speer of Malco Precision. These were available years ago for 900 & 1200 GTO mounts. I believe that the company is still around, but Mal has retired- don't know if the business stopped making their 360 degree RPA. Most likely the only way to get one now is by placing a wanted ad on CN or AM [used/secondhand]. I own one of these and it works smoothly on my 48" ATS pier as well as my Rob Miller Tri36M tripod. 

Fernando 


Leon
 


I designed and manufactured a rotate base for plus or minus 15 degrees, works great! Is that what you are looking for?

On Jan 22, 2020, at 3:59 PM, fernandorivera3 via Groups.Io <fernandorivera3@...> wrote:


Those who are looking for a 360 degree rotating pier adapter should consider those made by Mal Speer of Malco Precision. These were available years ago for 900 & 1200 GTO mounts. I believe that the company is still around, but Mal has retired- don't know if the business stopped making their 360 degree RPA. Most likely the only way to get one now is by placing a wanted ad on CN or AM [used/secondhand]. I own one of these and it works smoothly on my 48" ATS pier as well as my Rob Miller Tri36M tripod. 

Fernando 


r1300rs
 

That looks great.  Due to my setup, I’m looking for something that can actually turn 360 degrees and lock with set screws in the bottom.  A simple flat play “cap” design sitting on the pier and ready for a top mount plate.  Should be easy.


George
 

I recommend the acquisition of a compass!   <G>

 

Regards,

 

George

 

George Whitney

Astro-Physics, Inc.

Phone:  815-282-1513

Email:  george@...

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of r1300rs via Groups.Io
Sent: Thursday, January 23, 2020 10:01 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Rotating pier adapter

 

That looks great.  Due to my setup, I’m looking for something that can actually turn 360 degrees and lock with set screws in the bottom.  A simple flat play “cap” design sitting on the pier and ready for a top mount plate.  Should be easy.


r1300rs
 

Well, I have plenty of those (and often the mag difference or other metallic structures, can easily throw them off in the observatory); just walk around with one.  

For this application, aside from owning a compass, is a mobile PierTech trailer observatory.  Often, one cannot easily "park" this 9x9 device so that its internal pier is within 5 degrees of the NSP and many times you don't have a choice as to where to back it in a field and park in an assigned star party slot.  

Therefore, I need to rotate the mount as much as 270 degrees on occasion before I do my temporary pier modeling.  

I agree North is easy to find.....


r1300rs
 

I agree, if I had a lathe, this would be a piece of cake to make.  A simple cap and flat plate that sits on top of the pier tube.  Nothing to it.  


r1300rs
 

Thank you Michael, very useful information.