Date
1 - 20 of 22
Balancing the declination axis
|
Gavin Bray
Hello
I have a 14" LX200R mounted on a AP1200 with the 1200RP mounting plate and Parallax Instruments rings. There's not enough adjustment of the OTA in the rings to balance it in the declination axis. Does this mean I need to purchase a tube counterweight? If so, any recommendations? Is there some alternative?? Thanks Gavin |
|
|
|
Kent Kirkley
In a message dated 6/8/07 5:35:20 AM, gavbray@... writes:
HelloGavin: Depends on how unbalanced it is. The 1200 will tolerate some imbalance. More than likely yours is tail heavy, anyway you can add weight to the front should balance it. A lot of us adjustable saddles (like the Cassady Tip-In) for this very reason. Kent Kirkley ************************************** See what's free at http://www.aol.com. |
|
|
|
Roland Christen
In a message dated 6/8/2007 5:35:29 AM Central Daylight Time,
gavbray@... writes: There's not enough adjustment of the OTA in the rings to balance it inIf it is a lot out of balance you may need to add a counterweight to the tube. A small amount ~ 3 - 4 lb is not going to cause any problem for the mount. Roland Christen ************************************** See what's free at http://www.aol.com. |
|
|
|
Kent Kirkley
In a message dated 6/8/07 12:07:39 PM, marj@... writes:
Or the AP plate that is the original tip-in - the DOVELM16..........Right Marj.......sorry I left that one out. Kent Kirkley ************************************** See what's free at http://www.aol.com. |
|
|
|
Jeff Young <jey@...>
Gavin --
I've got a similar setup (16" LX200GPS OTA in Parallax rings on 1200GTO), but with a 4" refractor on top. The refractor is front-heavy enough that if I mount it reasonably far forward it balances things out. I use a short, flexible, felt-lined ABS dew shield. I imagine a full-length aluminium one would weigh considerably more, and help to balance things (as well as controlling dew and ambient light). Do you have a dew shield, or is your location dry enough not to need one? Barring that, then yes, you'd need to attach some sort of counterweight to the front. Losmandy has some weights on threaded rods that normally attach to dovetail blocks, but you could probably drill and tap the front of your 1200RP plate to attach it. I'm going to guess based on your name and your post regarding the southern hemisphere that you're in Australia. Do they use lead flashing on roofs down there? If so, you could poke a couple of holes in a strip of lead and use the larger screws around the front cell (the ones normally used to attach a dovetail) to attach it to the underside of the cell. -- Jeff. ________________________________ From: ap-gto@... [mailto:ap-gto@...] On Behalf Of Gavin Bray Sent: Friday, June 08, 2007 11:31 AM To: ap-gto@... Subject: [ap-gto] Balancing the declination axis Hello I have a 14" LX200R mounted on a AP1200 with the 1200RP mounting plate and Parallax Instruments rings. There's not enough adjustment of the OTA in the rings to balance it in the declination axis. Does this mean I need to purchase a tube counterweight? If so, any recommendations? Is there some alternative?? Thanks Gavin |
|
|
|
michael mcdermott <classicstone9474@...>
Hi Garvin, As Jeff has stated I have a aluminium dew shield that I hack-sawed down the length due to dome clearance problem (in a Sirius Home model). I have a 14" sct wth Orion 80 ed guide scope. The dew shield helps balance the scope on my AP1200GTO. I also customed design my own Declination weights from 2" hex bar stock. I tapped threaded the ends of the bar stock and bolted it thru the holes that are already in the AP ribbed Plate. I also drilled a hole thru the face of the hex stock, this is how I can add additional weights to the front of the scope if I need to attach my Dream Machine camera on the rear. - Mike
Gavin Bray <gavbray@...> wrote: Hello I have a 14" LX200R mounted on a AP1200 with the 1200RP mounting plate and Parallax Instruments rings. There's not enough adjustment of the OTA in the rings to balance it in the declination axis. Does this mean I need to purchase a tube counterweight? If so, any recommendations? Is there some alternative?? Thanks Gavin |
|
|
|
Joe Zeglinski
Hi Gavin,
toggle quoted message
Show quoted text
Just another OTA balancing approach. In case you go for an OTA counterweight - I have a Questar-7 which came with a "cumber bun" looking OTA counterweight. It is just one of those soft lead sheets covered on both surfaces in thick Mylar, with Velcro end flaps to secure it when it is wrapped around the 9 inch OTA. It is a standard Questar product for the Q7. The nice thing is that it doesn't need screws for attachment, and can be positioned around the OTA, at any point of it's length, for counter balancing. In the old days of drafting tables, they used to sell large drafting table weighted "cover sheets" made of similar material - to keep the thin drafting sheets from sliding to the floor overnight. If you could find an architectural supply store, perhaps they still have them - then cut up a strip to suit your OTA and weight needed. Otherwise, you could purchase or two of these belts from Questar and join the Velcro tabs end to end to fit your OTA diameter. At 3 lbs, maybe one might suffice, and you could make up the missing length with a span of Velcro - sewing supply stores would have them in very wide widths. The Questar-7 lead OTA weight "cumber bun" measures 26"L x 6"W x 1/8" thick, and weighs 3 lbs. Joe ----- Original Message -----
From: "Gavin Bray" <gavbray@...> To: <ap-gto@...> Sent: Friday, June 08, 2007 6:30 AM Subject: [ap-gto] Balancing the declination axis Hello |
|
|
|
Another similar option is to join a few ankle weights that wrap around the ankle and attach with velcro (great stuff). You can probably find them in sporting goods departments.
toggle quoted message
Show quoted text
Marj Christen Astro-Physics, Inc 11250 Forest Hills Road Machesney Park, IL 61115 Phone: 815-282-1513 Fax: 815-282-9847 www.astro-physics.com Please include this e-mail with your response. -----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]On Behalf Of Joseph Zeglinski Sent: Friday, June 08, 2007 10:11 AM To: ap-gto@... Subject: Re: [ap-gto] Balancing the declination axis Hi Gavin, Just another OTA balancing approach. In case you go for an OTA counterweight - I have a Questar-7 which came with a "cumber bun" looking OTA counterweight. It is just one of those soft lead sheets covered on both surfaces in thick Mylar, with Velcro end flaps to secure it when it is wrapped around the 9 inch OTA. It is a standard Questar product for the Q7. The nice thing is that it doesn't need screws for attachment, and can be positioned around the OTA, at any point of it's length, for counter balancing. In the old days of drafting tables, they used to sell large drafting table weighted "cover sheets" made of similar material - to keep the thin drafting sheets from sliding to the floor overnight. If you could find an architectural supply store, perhaps they still have them - then cut up a strip to suit your OTA and weight needed. Otherwise, you could purchase or two of these belts from Questar and join the Velcro tabs end to end to fit your OTA diameter. At 3 lbs, maybe one might suffice, and you could make up the missing length with a span of Velcro - sewing supply stores would have them in very wide widths. The Questar-7 lead OTA weight "cumber bun" measures 26"L x 6"W x 1/8" thick, and weighs 3 lbs. Joe ----- Original Message ----- From: "Gavin Bray" < gavbray@gmail. <mailto:gavbray%40gmail.com> com> To: < ap-gto@yahoogroups. <mailto:ap-gto%40yahoogroups.com> com> Sent: Friday, June 08, 2007 6:30 AM Subject: [ap-gto] Balancing the declination axis Hello |
|
|
|
Or the AP plate that is the original tip-in - the DOVELM16..........
toggle quoted message
Show quoted text
http://www.astro-physics.com/products/accessories/mounting_plates/mounting_plates.htm Marj Christen Astro-Physics, Inc 11250 Forest Hills Road Machesney Park, IL 61115 Phone: 815-282-1513 Fax: 815-282-9847 www.astro-physics.com Please include this e-mail with your response. -----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]On Behalf Of kgkirkley@... Sent: Friday, June 08, 2007 11:56 AM To: ap-gto@... Subject: Re: [ap-gto] Balancing the declination axis In a message dated 6/8/07 5:35:20 AM, gavbray@gmail. <mailto:gavbray%40gmail.com> com writes: HelloGavin: Depends on how unbalanced it is. The 1200 will tolerate some imbalance. More than likely yours is tail heavy, anyway you can add weight to the front should balance it. A lot of us adjustable saddles (like the Cassady Tip-In) for this very reason. Kent Kirkley ************************************** See what's free at http://www.aol. <http://www.aol.com.> com. |
|
|
|
ayiomamitis
Gavin,
toggle quoted message
Show quoted text
I have a similar problem with my AP160 with CCD camera attached. Since I have a Losmandy plate on top of the rings for a piggyback scope, I have used two pairs of Losmandy rings as pseudo-weights to balance everything. Not the most elegant solution but it works nicely. Prior to selling my Pronto, I always had it piggyback and used that for properly balancing everything. Anthony. --- In ap-gto@..., "Gavin Bray" <gavbray@...> wrote:
|
|
|
|
Jeff Young <jey@...>
Which reminds me... I still have the two radius blocks mounted to the
front of my OTA from when I had upper and lower dovetail plates attached (before moving to rings). They add a bit of weight to the front, and give a nice surface to seat the dewshield against. Had forgotten about that until Anthony's comment about the extra rings.... -- Jeff. ________________________________ From: ap-gto@... [mailto:ap-gto@...] On Behalf Of ayiomamitis Sent: Friday, June 08, 2007 8:33 PM To: ap-gto@... Subject: [ap-gto] Re: Balancing the declination axis Gavin, I have a similar problem with my AP160 with CCD camera attached. Since I have a Losmandy plate on top of the rings for a piggyback scope, I have used two pairs of Losmandy rings as pseudo-weights to balance everything. Not the most elegant solution but it works nicely. Prior to selling my Pronto, I always had it piggyback and used that for properly balancing everything. Anthony. --- In ap-gto@... <mailto:ap-gto%40yahoogroups.com> , "Gavin Bray" <gavbray@...> wrote: > > Hello > > I have a 14" LX200R mounted on a AP1200 with the 1200RP mounting plate > and Parallax Instruments rings. > > There's not enough adjustment of the OTA in the rings to balance it in > the declination axis. > > Does this mean I need to purchase a tube counterweight? > > If so, any recommendations? > > Is there some alternative?? > > Thanks > Gavin > |
|
|
|
Jeff <jlc@...>
Lots of good ideas so far.
I have the same problem w/ a 12" LX200 OTA on an AP1200. I use the cassady saddle, but I cant push the OTA far enough forward to balance. I have run it in "out of balance" mode for a little while now, but the dec motor seems to labor occasionally which was a cause for concern. (And, btw, it does not seem to be that much out of balance. I suspect the motor was laboring either due to cold, low battery power, or a dirty battery plug connection.) Recently I put a Losmandy three-axis camera dovetail mount on the bottom OTA dovetail plate near the front of the OTA, and put my Pentax 67 on the camera mount. That balanced it very well. So I'm going to get a couple Losmandy DA (dovetail adapter blocks) and mount some lead weights on them. I did this with my dob a long time ago -- I used a plastic electronics box from radio shack to hold the weights - it looks rather stylish. B^) (Losmandy sells a counterweight system, but it is $80 for 5 lbs.) _____ From: ap-gto@... [mailto:ap-gto@...] On Behalf Of Gavin Bray Sent: Friday, June 08, 2007 3:31 AM To: ap-gto@... Subject: [ap-gto] Balancing the declination axis Hello I have a 14" LX200R mounted on a AP1200 with the 1200RP mounting plate and Parallax Instruments rings. There's not enough adjustment of the OTA in the rings to balance it in the declination axis. Does this mean I need to purchase a tube counterweight? If so, any recommendations? Is there some alternative?? Thanks Gavin |
|
|
|
Gavin Bray
Thanks for all the suggestions.
I think I might have something fabricated, possibly in stainless steel, so as not to distract from the mount's good looks. :-) Regards Gavin |
|
|
|
Gavin Bray
Hello
Just to recap, I have a 14" LX200R and AP1200 connected using the AP 24" ribbed mounting plate and Parallax Instruments rings. The problem with this setup is that it's very back heavy, there's no way to move the OTA forward, and I've had to add about 30 lbs to the front of the mounting plate in order to balance the tube. BTW, there's nothing heavy hanging off the tube. This isn't a very satisfactory setup and I'm looking for something better and that will serve me for when I get into imaging. Specifically, I want to avoid or minimize the need for counterweights at the front of the tube and I like the idea of rings to avoid tube flexure. I assume the best approach is to somehow move the tube forward so it balances without the need for tube counterweights. Does anyone have any suggestions as to how to achieve this? Is something like the AP 16" dovetail the best approach? If so, would I be able to mount the rings to the sliding bar? Is there a better approach? I don't necessarily need to use the existing mounting plate or rings. Thanks Gavin |
|
|
|
Joe Zeglinski
Hi Gavin,
toggle quoted message
Show quoted text
I can't picture how the ribbed plate looks like underneath - is there room to drill an extra set of holes in the plate further towards the back of the OTA? That would be the same as sliding the OTA forward. If it were a flat plate, then you could drill the extra DEC attachment holes anywhere, but the ribs you mention, may interfere in this case, unless the new bolt holes can be drilled between the plate support ribs. Anyway, worth considering a shifted plate attachment pattern, if at all possible. Is there any room left on the plate to move both rings forward? If not, then perhaps, just the back ring could be moved closer to the front one, by drilling extra holes in the plate. Then slide the OTA forward in the "narrower spaced" rings. Moving the centre point of the ring support, might give you the extra bit of forward OTA overhang to equal the moment produced by that extra weight you have tried to add to the OTA. Joe ----- Original Message -----
From: "Gavin Bray" <gavbray@...> To: <ap-gto@...> Sent: Monday, July 02, 2007 7:40 PM Subject: [ap-gto] Re: Balancing the declination axis Hello |
|
|
|
Gavin Bray
Hi Joe
Yes, I've drilled new holes and have the rings and tube as far forward as possible without the tube overhanging the mounting plate too much. I think I need something where the backend of the tube is a lot closer to the dec axis. Regards Gavin --- In ap-gto@..., "Joseph Zeglinski" <J.Zeglinski@...> wrote: is there room to drill an extra set of holes in the plate further towards theback of the OTA? That would be the same as sliding the OTA forward. If it werea flat plate, then you could drill the extra DEC attachment holesanywhere, but the ribs you mention, may interfere in this case, unless the new boltholes can be drilled between the plate support ribs. Anyway, worth consideringa shifted plate attachment pattern, if at all possible.forward? If not, then perhaps, just the back ring could be moved closer to thefront one, by drilling extra holes in the plate. Then slide the OTA forward inthe "narrower spaced" rings. Moving the centre point of the ring support, mightgive you the extra bit of forward OTA overhang to equal the moment produced bythat extra weight you have tried to add to the OTA.the AP there's no24" ribbed mounting plate and Parallax Instruments rings. theway to move the OTA forward, and I've had to add about 30 lbs to there'sfront of the mounting plate in order to balance the tube. BTW, somethingnothing heavy hanging off the tube. counterweightsbetter and that will serve me for when I get into imaging. tubeat the front of the tube and I like the idea of rings to avoid so itflexure. balances without the need for tube counterweights. |
|
|
|
Mal Speer <mal@...>
I have a C-14 on a 1200 mount. I use a Losmandy plate and the 16" AP
saddle. The balance point is at the saddle plate and saddle flush in the rear with a Kendrick dew shield attached. I purchased one of those Losmandy weight sets, but I was not able to use it because I only have a saddle plate on the bottom. When I put the weight on the setup was not dynamically balanced. You probably need two of those weight sets one on the top and one on the bottom. Mal --- In ap-gto@..., "Gavin Bray" <gavbray@...> wrote: were a flattoplate, then you could drill the extra DEC attachment holesanywhere, but theribs you mention, may interfere in this case, unless the new boltholes can bedrilled between the plate support ribs. Anyway, worth consideringa shiftedplate attachment pattern, if at all possible.forward? If not, thethere'sfront of the mounting plate in order to balance the tube. BTW,somethingnothing heavy hanging off the tube. |
|
|
|
Joe Zeglinski
Hi Gavin,
toggle quoted message
Show quoted text
I'm not sure if you got what I meant by "moving the OTA rings closer together". (1) The idea is that by reducing the spacing "between" the rings, you might be able to slide the OTA more forward (since the back end ring is then closer to the front one). That could give you a few more inches of leverage, as the OTA now overhangs the front of the plate more. (2) The other approach - can you drill plate attachment holes in it, "shifted off centre of the plate", closer to the rear of the plate? In essence, you are now moving the entire OTA and rings forward as well. This was AP's approach in their recent DOVELM2 dovetail attachment to the AP900 DEC axle head. Actually, they shifted their pattern "forward of centre", since they wanted to accommodate refractors with heavy lenses, so the entire dovetail block ended up being shifted downward. You want the reverse of this, I believe. Actually, I found it necessary to drill my own DOVELM2 pattern as a mirror of the AP pattern position, since my Questar-7 balance and attachment procedure required it. If it had been a Losmandy G11 saddle, I would not have to do that, but the AP saddle is grooved on just one side, so rotating my DOVELM2 to shift the hole pattern in the opposite direction, would not have worked properly. Perhaps a combination of (1) and (2) above might be necessary, if the imbalance is really bad - hopefully not. Joe ----- Original Message -----
From: "Gavin Bray" <gavbray@...> To: <ap-gto@...> Sent: Tuesday, July 03, 2007 3:24 AM Subject: [ap-gto] Re: Balancing the declination axis Hi Joe |
|
|
|
Gavin Bray
Joe
Actually you're right - I misread what you said. Sorry about that and thanks for persisting. What I will do is drill some more holes for the back ring as close to the plate's attachments holes as possible. This will allow me to overhang the front of the OTA and hopefully go a long way to solving the balancing issue. I'll do this this weekend and will let the group know. I'm afraid your second suggestion about drilling new plate attachment holes isn't feasible due to the plate's ribbing. Also, someone suggested using the AP 15" ribbed mounting plate rather than the 24" as the 15"'s attachment holes are apparently off center. I'll look into this too. What would be really nice is if AP made a 24" plate that's off center. :-} Thanks Gavin --- In ap-gto@..., "Joseph Zeglinski" <J.Zeglinski@...> wrote: closer together".might be able to slide the OTA more forward (since the back end ring isthen closer to the front one). That could give you a few more inches of leverage,as the OTA now overhangs the front of the plate more.it, "shifted off centre of the plate", closer to the rear of the plate? Inessence, you are now moving the entire OTA and rings forward as well.to the AP900 DEC axle head. Actually, they shifted their pattern "forwardof centre", since they wanted to accommodate refractors with heavy lenses, sothe entire dovetail block ended up being shifted downward. You want thereverse of this, I believe.as a mirror of the AP pattern position, since my Questar-7 balance andattachment procedure required it. If it had been a Losmandy G11 saddle, Iwould not have to do that, but the AP saddle is grooved on just one side, sorotating my DOVELM2 to shift the hole pattern in the opposite direction, wouldnot have worked properly.the imbalance is really bad - hopefully not.plate too much. |
|
|
|
Joe Zeglinski
Gavin,
toggle quoted message
Show quoted text
An after thought. Rather than drilling the two rearward holes for the back ring, right away, can you get one or two Vice Grips or C-Clamps to fix the rear OTA ring to the plate temporarily, and see if it helps the balancing act. That way you aren't committed to more holes and making Swiss cheese out of the plate. The front ring will still provide solid support as you test the "optimum position" of the temporarily sliding rear OTA ring position. Too bad you can't find a nice clearing "between the ribs" of the plate, for all the screws, of an alternate displaced DEC axle hole pattern. Best of luck, Joe ----- Original Message -----
From: "Gavin Bray" <gavbray@...> To: <ap-gto@...> Sent: Tuesday, July 03, 2007 6:06 PM Subject: [ap-gto] Re: Balancing the declination axis Joe |
|
|