Post by Kalvis on Feb 1, 2006 23:53:14 GMT -6
I was wondering if any of you amateur telescope makers (ATM-ers) have
1. Experience in building a dobsonian mount for a newtonian reflector
2. Found inexpensive or free PocketPC or phone software with alt/az coordinate functionality
3. Built or came upon a nice portable and easily stowable observing chair.
I’ll describe what I have to work with, what I’ve done so far, and where I could use some additional pointers.
Background
My optical tube assembly (OTA) is the Orion 6 inch f/8 newtonian (so called “LT” for long tube) reflector. It was graciously sold to me last December by Chicago Astronomer (CA) Bill whose CA forum name is atomant. With the rings that accompanied the tube I was able to successfully mount the reflector onto my SkyView equatorial (EQ) mount and take in some awesome views of Saturn. However, the relatively tall height of my EQ mount even with the legs fully retracted places the eyepiece (EP) high off the ground. Often it is necessary to stand and even lean over when observing. The deeper I get into this hobby the more I realize that to really observe an object, soak it in and see its finer points you need to look at it for a longer time and not just a quick 3 second glance. For this reason accessibility to the eyepiece and a comfortable seated observing position have crept to the top of my list.
Dob altitude bearings
I don’t really like the cave man version of basic John Dobson’s tube box members.aol.com/sfsidewalk/sectionc.htm It’s too bulky and doesn’t allow for the tube to be easily rotated (for EP accessibility) or moved axially to adjust balance as needed. This is why I also want to avoid attaching permanent altitude wheels a.k.a. side bearings to the OTA such as can be seen in this otherwise very nice design guide: www.skyvalleyscopes.com/wood.htm Instead I very much like the idea of attaching such wheels / side bearings to my OTA by utilizing the mounting rings. I’m talking about the same rings that came along with the OTA and were used for attachment to my EQ mount. An off-the-shelf large diameter bearing which I’ve seen used in some ATM designs is the ole toilet floor flange. I just bought a pair of PlumBest 4” PVC Plumb Fit Closet Flanges at Lowe’s for $3.76 apiece. It took only two pairs of screws and a few minutes to attach both of these to opposite sides of my rings. Hey, it’s already starting to look like a dob!
Dob rocker box
I’m not going to use any real fancy design for this, just something plain. Perhaps inclining the vertical walls inward at the top might make it a little more stable and add to the aesthetic appeal, but I haven’t yet decided. My only real questions here are:
1. Should I use the traditional approach of cutting a notch at the top of the side boards and affixing a couple of Teflon pads spaced 90 degrees apart (45 in front of and 45 behind vertical)? An alternative approach I’ve seen is to cut out a quarter of a circle and line it with a strip of outdoor carpeting. What are the pros and cons?
2. What thickness of plywood is adequate? To keep the weight down I know to steer clear of particle board, but what should I use: half inch? three quarters? full-inch?
Dob ground board base and azimuth bearing
I really like the approach used by Berislav Bracun: www.pondi.hr/~beri/cald.htm I think that I want the leveling feet feature, but am unsure of how to convert wood clamps to this type of application. Also, he uses a polished steel plate on top of 3 roller bearings with a center Teflon guide bearing sandwiched in the middle. I love it, but I don’t think I can do it. Any suggestions on doing it simpler but maintaining the functionality? Furniture glides and Ebony Star laminate apparently work well since they are so popular for ATM dobs, but this roller bearing and steel place combo claims to be better. Thoughts?
Dreaming about adding a poor man’s digital Push-N-Go
Some crazy dob owners who want the functionality of a computerized finder install incredibly expensive digital setting circles and a handheld controller with LED readouts. This will easily drain your wallet by $500+. You could also buy the less expensive version from Orion know as the Intelliscope which comes preinstalled on their higher end dobs. Nevertheless, it still adds $230 to the price of their basic $260 SkyQuest XT6 Classic. Both Chicago Astronomer Joe and I admire the McGuiver approach where doing things with pencil, paper, magnets and paper clips (with a little bit of freeware/shareware) can give you something almost as good, sometimes even better, but definitely more satisfying. That’s why I like how Berislav Bracun used the StarTrak position tracking and setting circle template freeware www.startrak.co.uk The SetCirc.exe program is simple and easy to use. I’ve already printed out the scales I plan on using. However, I don’t have a Psion hand held anymore (mine busted years ago) so I will have to find inexpensive software for my PDA (running PocketPC) or for my cell phone. I’m intrigued by the Pocket Star software: www.nomadelectronics.com/PocketPC/PocketStars/PocketStarsIntro.htm. Anyone out there tried it and liked it? As an even cheaper version I would like to try out the freeware Orionic v1.2 www.dasys.cz/kamzi/ but the website seems not to be functional. I’ll search around on the Web to see if I can find it elsewhere. In any case, this type of software would require me only to input my lat/long coordinates and have the correct time of day running. The output should be an amazingly accurate pair of alt/az coordinates for any deep space object (DSO) in the database. With a my envisioned dob set-up it could be as simple as point-and shoot -- that is after a quick initialization. What d’ya think?
Observing chair
Being sick of standing, crouching, kneeling and bending over I want to get myself a nice observing chair. Yes, I know that Apogee sells a nice one for $70 www.apogeeinc.com/product.asp?itemid=77, but once again, I’m cheap and looking for something better. I love this TeleVue pneumatic stool www.focuscamera.com/prods/835835114.asp , but it can’t be worth $220! My thoughts are to find a used adjustable height drum throne (that’s what rock-n-roll drummers call their swivel stools) for under $50. Another thought I had was to take a height adjustable lumber support stand and convert it into an adjustable stool. It would still fold up and store easily taking up very little space. These cost only $15 at HomeDepot. All I would need to do is replace the roller bearing on top with some semi-comfortable sitting platform. Anybody ever tried it? Is this a stupid approach?
If any of you have gotten to the bottom of this message and have some helpful hints or experience to offer I would much appreciate it.
Thanks,
Kalvis
1. Experience in building a dobsonian mount for a newtonian reflector
2. Found inexpensive or free PocketPC or phone software with alt/az coordinate functionality
3. Built or came upon a nice portable and easily stowable observing chair.
I’ll describe what I have to work with, what I’ve done so far, and where I could use some additional pointers.
Background
My optical tube assembly (OTA) is the Orion 6 inch f/8 newtonian (so called “LT” for long tube) reflector. It was graciously sold to me last December by Chicago Astronomer (CA) Bill whose CA forum name is atomant. With the rings that accompanied the tube I was able to successfully mount the reflector onto my SkyView equatorial (EQ) mount and take in some awesome views of Saturn. However, the relatively tall height of my EQ mount even with the legs fully retracted places the eyepiece (EP) high off the ground. Often it is necessary to stand and even lean over when observing. The deeper I get into this hobby the more I realize that to really observe an object, soak it in and see its finer points you need to look at it for a longer time and not just a quick 3 second glance. For this reason accessibility to the eyepiece and a comfortable seated observing position have crept to the top of my list.
Dob altitude bearings
I don’t really like the cave man version of basic John Dobson’s tube box members.aol.com/sfsidewalk/sectionc.htm It’s too bulky and doesn’t allow for the tube to be easily rotated (for EP accessibility) or moved axially to adjust balance as needed. This is why I also want to avoid attaching permanent altitude wheels a.k.a. side bearings to the OTA such as can be seen in this otherwise very nice design guide: www.skyvalleyscopes.com/wood.htm Instead I very much like the idea of attaching such wheels / side bearings to my OTA by utilizing the mounting rings. I’m talking about the same rings that came along with the OTA and were used for attachment to my EQ mount. An off-the-shelf large diameter bearing which I’ve seen used in some ATM designs is the ole toilet floor flange. I just bought a pair of PlumBest 4” PVC Plumb Fit Closet Flanges at Lowe’s for $3.76 apiece. It took only two pairs of screws and a few minutes to attach both of these to opposite sides of my rings. Hey, it’s already starting to look like a dob!
Dob rocker box
I’m not going to use any real fancy design for this, just something plain. Perhaps inclining the vertical walls inward at the top might make it a little more stable and add to the aesthetic appeal, but I haven’t yet decided. My only real questions here are:
1. Should I use the traditional approach of cutting a notch at the top of the side boards and affixing a couple of Teflon pads spaced 90 degrees apart (45 in front of and 45 behind vertical)? An alternative approach I’ve seen is to cut out a quarter of a circle and line it with a strip of outdoor carpeting. What are the pros and cons?
2. What thickness of plywood is adequate? To keep the weight down I know to steer clear of particle board, but what should I use: half inch? three quarters? full-inch?
Dob ground board base and azimuth bearing
I really like the approach used by Berislav Bracun: www.pondi.hr/~beri/cald.htm I think that I want the leveling feet feature, but am unsure of how to convert wood clamps to this type of application. Also, he uses a polished steel plate on top of 3 roller bearings with a center Teflon guide bearing sandwiched in the middle. I love it, but I don’t think I can do it. Any suggestions on doing it simpler but maintaining the functionality? Furniture glides and Ebony Star laminate apparently work well since they are so popular for ATM dobs, but this roller bearing and steel place combo claims to be better. Thoughts?
Dreaming about adding a poor man’s digital Push-N-Go
Some crazy dob owners who want the functionality of a computerized finder install incredibly expensive digital setting circles and a handheld controller with LED readouts. This will easily drain your wallet by $500+. You could also buy the less expensive version from Orion know as the Intelliscope which comes preinstalled on their higher end dobs. Nevertheless, it still adds $230 to the price of their basic $260 SkyQuest XT6 Classic. Both Chicago Astronomer Joe and I admire the McGuiver approach where doing things with pencil, paper, magnets and paper clips (with a little bit of freeware/shareware) can give you something almost as good, sometimes even better, but definitely more satisfying. That’s why I like how Berislav Bracun used the StarTrak position tracking and setting circle template freeware www.startrak.co.uk The SetCirc.exe program is simple and easy to use. I’ve already printed out the scales I plan on using. However, I don’t have a Psion hand held anymore (mine busted years ago) so I will have to find inexpensive software for my PDA (running PocketPC) or for my cell phone. I’m intrigued by the Pocket Star software: www.nomadelectronics.com/PocketPC/PocketStars/PocketStarsIntro.htm. Anyone out there tried it and liked it? As an even cheaper version I would like to try out the freeware Orionic v1.2 www.dasys.cz/kamzi/ but the website seems not to be functional. I’ll search around on the Web to see if I can find it elsewhere. In any case, this type of software would require me only to input my lat/long coordinates and have the correct time of day running. The output should be an amazingly accurate pair of alt/az coordinates for any deep space object (DSO) in the database. With a my envisioned dob set-up it could be as simple as point-and shoot -- that is after a quick initialization. What d’ya think?
Observing chair
Being sick of standing, crouching, kneeling and bending over I want to get myself a nice observing chair. Yes, I know that Apogee sells a nice one for $70 www.apogeeinc.com/product.asp?itemid=77, but once again, I’m cheap and looking for something better. I love this TeleVue pneumatic stool www.focuscamera.com/prods/835835114.asp , but it can’t be worth $220! My thoughts are to find a used adjustable height drum throne (that’s what rock-n-roll drummers call their swivel stools) for under $50. Another thought I had was to take a height adjustable lumber support stand and convert it into an adjustable stool. It would still fold up and store easily taking up very little space. These cost only $15 at HomeDepot. All I would need to do is replace the roller bearing on top with some semi-comfortable sitting platform. Anybody ever tried it? Is this a stupid approach?
If any of you have gotten to the bottom of this message and have some helpful hints or experience to offer I would much appreciate it.
Thanks,
Kalvis