RogerRZ
Whatta you lookin' at?
Reged: 01/09/06
Posts: 3082
Loc: West Collette, NB, Canada
|
|
It is permanently fixed. There are just three wheels supporting the dome, and at 600+ pounds (I have the purple thumb to prove it-I ran it between the wheel and the ring-Ouch!), there is no problem for the wheel to get traction...
If I pull the drive shaft out from the reduction gears, I can move the whole thing manually, so even if the battery runs out, I can still operate it.
--------------------
-Roger Pitre-
1 X 7 binocular
MN65, Nexstar 8SE, SV70ED, Lunt 60 PT
EQ6 Pro, Canon 50D, Modified XSi, SBIG ST-2000XM, 70-200 f/4L, BackyardEOS
"He's got shoulders on him like a smelt..."--Anonymous
http://www.facebook.com/album.php?aid=10723&id=509325956&l=79d06a1d10
http://ajpobservatory.is-great.org/
|
Keith Howlett
Pooh-Bah
Reged: 03/06/07
Posts: 1444
Loc: Northumberland, UK
|
|
Roger,
I can see you would have pretty good contact with 3 wheels and 200lbs resting on each of them! Wow. What is the dome rail made from and does it sag much in between the wheels?
Thanks again!
Cheers,
Keith
|
RogerRZ
Whatta you lookin' at?
Reged: 01/09/06
Posts: 3082
Loc: West Collette, NB, Canada
|
|
The ring is made out of 3/4" plywood, and screwed into the dome from the outside, using roughly 200 screws. Even at that, I've had to put in a bunch of braces made from one inch wide pieces of 2X2X 1/8" angle iron, as the ring wanted to tear out from the dome. One of them is just visible in the top right-hand corner of the second picture. Also visible is the big ugly piece of channel I needed to install where the two ring halves meet. I don't have any more sag whatsoever.
--------------------
-Roger Pitre-
1 X 7 binocular
MN65, Nexstar 8SE, SV70ED, Lunt 60 PT
EQ6 Pro, Canon 50D, Modified XSi, SBIG ST-2000XM, 70-200 f/4L, BackyardEOS
"He's got shoulders on him like a smelt..."--Anonymous
http://www.facebook.com/album.php?aid=10723&id=509325956&l=79d06a1d10
http://ajpobservatory.is-great.org/
|
Keith Howlett
Pooh-Bah
Reged: 03/06/07
Posts: 1444
Loc: Northumberland, UK
|
|
Roger,
That's very interesting. I'm looking to reduce the rolling resistance of my dome before before adding a drive.
My dome uses a fiberglass ring running on six equally spaced rollers. The rail sags slightly if it has stood still for a few days and this can make it hard to rotate the dome smoothly.
If I can achieve zero rail sag with a similar steel rail to yours then a system using three high quality rollers is very attractive. The vertical load will distribute evenly and leveling the dome will be very simple.
That's something to think about, thanks for the idea.
Cheers,
Keith
|
Keith Howlett
Pooh-Bah
Reged: 03/06/07
Posts: 1444
Loc: Northumberland, UK
|
|
All,
Getting back on topic...
The type of friction drive I'm interested in myself would need to be quiet. I have great neighbors and I'm not keen to wake them up in the middle of the night. I've heard that the small wall-mounted motors used on the TI Home / Pro and Sirius Domes are quite noisy.
I am considering using a large floor mounted variable speed motor and using a drive shaft up to the top of the dome wall. To save me re-inventing the wheel, has anyone here tried this successfully?
Thanks,
Keith
|
RogerRZ
Whatta you lookin' at?
Reged: 01/09/06
Posts: 3082
Loc: West Collette, NB, Canada
|
|
I tried this using a bunch of bicycle chains and sprockets, but decided to go the direct drive method. I don't have AC power going to my dome, though.
--------------------
-Roger Pitre-
1 X 7 binocular
MN65, Nexstar 8SE, SV70ED, Lunt 60 PT
EQ6 Pro, Canon 50D, Modified XSi, SBIG ST-2000XM, 70-200 f/4L, BackyardEOS
"He's got shoulders on him like a smelt..."--Anonymous
http://www.facebook.com/album.php?aid=10723&id=509325956&l=79d06a1d10
http://ajpobservatory.is-great.org/
|
Tom Clark
professor emeritus
Reged: 11/14/07
Posts: 622
Loc: North of Deming, NM
|
|
I used a solid rubber tire to rotate my home-made 24' dome. The 16" diameter tire is from a bush hog deck, and only costs $34. The motor is a reversable 3/4hp gear motor from Granger. The dome weighs about 3000 pounds and rotates quite nicely, but not as quiet as I would like. It rumbles a bit as the rotation speed is a little too fast. I set the dome to rotate at twice the speed of the slewing scope so I could move it quickly into place. The dome has been used for three years now, and works very well.
The bottom of the dome is a plywood ring, sitting on a piece of 3x3" angle iron I had rolled into a ring and welded in place. The rolled ring rides in the v-groves in the 6" diameter steel wheels. I recently ran a thread "Building the dome and the beast" in the ATM section, showing the dome's construction.
Here is a side show of the dome and scope construction:
http://tinyurl.com/2h9u5m
|
Wayne Parrish
sage
Reged: 02/23/04
Posts: 443
|
|
Tom, I thought i had something special with my rolloff/dome,BUT,WOW,what a project you undertook !! Do i see machinist background in some of the pieces ? It is a fantastic piece of work ! You have definitely raised the bar that we all must strive for now. Wayne Parrish
|
Previous
Index
Next
Threaded
[Re: 
Edit
Reply
Quote
