New mount under test

Hi folks,

Well the skies finally cleared and I am in the process of testing our new redesigned 600 mount. The first test will be periodic error. Already I am delighted by what I see with the first images. I can see almost no wiggle in the image of a star trail at 1.8 arc seconds per pixel in a 7 minute time exposure (azimuth axis offset to allow trailing). If everything goes well and the mount performs up to our expectations, then Marj will let me post an image of the mount so you can see what it looks like, along with a preliminary set of measurements and specs.

We have worked very hard these last 6 months on the design and in machining parts, making fixtures and tooling. I originally said it would be done in late fall, and we indeed did finish it with one day to spare on Dec 20, technically the last day of fall. However, it has been cloudy here ever since, and I had no chance to actually test it until tonight.

I will post more tomorrow when I have had a chance to examine the data that I am getting tonight. Until then .....

Uncle Rollo

Roland,
I am sure that it will be an attractive as well as finely crafted piece of equipment. It would surprise me if it did not work up to your standards. I look forward to seeing it.

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

Roland, it's considered good manners for manufacturers to send free samples of new products to the moderators of their forums. Just thought I'd mention that. This is so that we moderators can, um, make sure these new products aren't, er, vaporware. Or something.

Yeah.

Hi Roland

I'm glad to hear of your progress, and it sounds like a great product for folks who want a top quality mount that's easy to treat as a portable.

Do you have any indication of how long it will take to whittle down the waiting list for the 600 and 400 mounts?

Roland - I noticed the new mount is sitting on what appears to be the "old" 400/600 tripod. Do you plan on carrying forward with this? In other words, when my number comes up on the waiting list, will I be able to use the new mount on my old tripod?

Lane