Re: [ap-ug] [ap-gto] Re: New mount tests tonight


Jan 9, 2006

 


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#30487 Jan 9, 2006

Hi all,



I'm still at it, testing the PE of the mount. It looks like I'm getting about

2 pixels of PE at 1.8 arc sec/pixel in a 7 minute exposure (approximately 1

complete worm rotation). It looks quite smooth and something that PEMPro could

easily reduce. This is a raw worm wheel which has not been run in yet, so I e

xpect that it will improve either with use or if I lap it in. We normally do

that in production. In any case, I am quite delighted with the performance of

this new mounting.



Some prelim specs:



Size wise it is just a hair taller than the 600 mount. It has 5.85" diameter

- 225tooth worm wheels on both axes. Both axes have 60mm shafts held in place

with high quality machine tool bearings preloaded to approx. 300 lb.



There is a 2" diameter hole that goes all the way through the mount on both

axes. This allows the user to bring wires from the bottom of the RA up through

the top of the Dec axis. There is no restriction on rotation with these wires

in place. You can go 360 degrees and more in both axes without snagging

anything. The mount itself weighs around 24 lb without the piertop attached and

about 26 with the piertop (normally the piertop is left on the pier). This is

without any mounting plates or dovetail plates attached.



The mount has clutches, and they are designed without using any plastic

parts, so no more splaying of clutch plugs. The clutch can be tightened to the

point where it locks down fully.



The motors are the same as what we use for the 900/1200 mounts. The motor

gearbox is totally new, as is the worm itself. We went to a much bigger bearing

system on the worm so we can put a lot more preload to hold it tightly in place

without stressing the bearings or bending the worm itself. The internal

reduction gears were redesigned to provide much lower backlash time for quick

reversal of the Dec axis, and to reduce the moment to moment error of the

individual teeth. In the tests that I have run so far, I cannot detect any tooth ripple

on the periodic error. On lesser mounts this can be as much as 5 to 10 arc

seconds and is very problematic to guide out because it occurs rapidly over a

period of seconds. We designed this gearbox with high quality fine pitch gears

of fairly large diameters to get this well under 1 arc second. Because of the

size of these gears and the size of the worm and worm bearings, the gearboxes

look a bit oversized for this mount, but trust me, it is all for the good.



The altitude adjustment allows the mount to be used from zero to about 70

degrees latitude. There is a scale on the side for approximate adjustment in the

field and the mount will have a bubble level in the base. The azimuth

adjustment is approximately +- 15 degrees.



At this point I have no idea what the payload rating will be for this mount,

but realistically it can easily handle the 160F7.5 EDF refractor and certainly

a 9.25" Celestron SCT. I have not seen a 10" Meade tube assembly, so I cannot

say for certain.



The mount was designed to fit into an airline carry-on case. We are looking

at a couple of different ones, but the favorite for me thus far is the Pelican

roll-on case, #1510. We'll be making some foam inserts for this case, and

hopefully I will get to do some traveling with it.



We have also designed a new pier with adjustable height and level

adjustments, but this has not yet been machined. It will fold up into one piece for easy

transport.



More on this mount later tomorrow.



Roland Christen





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#30488 Jan 10, 2006

Your report sounds encouraging, cant wait to see some pictures.



> We have also designed a new pier with adjustable height and level

> adjustments, but this has not yet been machined. It will fold up into one

> piece for easy

> transport.



Will this be available in the 900 size?





Thanks

Mike



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#30490 Jan 10, 2006

--- In ap-ug@yahoogroups.com, chris1011@a... wrote:

> Size wise it is just a hair taller than the 600 mount. It has 5.85"

diameter > - 225tooth worm wheels on both axes. Both axes have 60mm shafts held

in place > with high quality machine tool bearings preloaded to approx. 300 lb.

>

> There is a 2" diameter hole that goes all the way through the mount

on both





Is there going to be provision for the use of the polar alignment

scope and if so, I am assuming that a different method of attachment

will be required - possibly just an adapter on the PAS to slip inside

the 2" hole?



That pier sounds like a wonderful addition as well. Is there any

possibility of upsizing for the AP900 mount sometime in the future or

will it be beefy enough as is with the proper adapter plate?



Rick.



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#30512 Jan 11, 2006

--- In ap-ug@yahoogroups.com, chris1011@a... wrote:

It all sounds exciting, but I keyed on your pier idea-- for my 900--for

using vastly different scopes, without having to buy additional pier

lengths. Is that a likely spin off?

BC



> Hi all,

------

> We have also designed a new pier with adjustable height and level

> adjustments, but this has not yet been machined. It will fold up into

one piece for easy transport.

More on this mount later tomorrow.

Roland Christen







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#30514 Jan 11, 2006

In a message dated 1/11/2006 3:14:31 PM Central Standard Time, bobc22@...

writes:



> It all sounds exciting, but I keyed on your pier idea-- for my 900--for

> using vastly different scopes, without having to buy additional pier

> lengths. Is that a likely spin off?

>



Perhaps, if it works out on this mount.



RC





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