I can't remember exactly but just measure the outside circumference. Check some of the astro sites that list rings and they'll have a few standard sizes.
The GSO newts and the skywatcher newts may be separate sizes, so make sure you get it right
I have a 8" Skywatcher dob tube as well, and just got some 230mm rings. They seem a little tight, and Im concerned if I do them up the are going to buckle the tube.
Does anyone else here have a Skywatcher dob tube and are using 230mm rings ??
Its only a 5mm difference though, I wonder how tight the 235mm are..
Thanks
If the rings you have are too tight then they are too tight. You should be able to close the rings easily and just have to nip down the last few millimetres. If you have to force your rings shut then they are too small, and you are right, you will damage your tube if you force them closed over your tube.
I just dug my 8" SW600 OTA out of the cupboard and checked the factory ring size. They are 235mm, and don't clamp completely shut. There is a gap of about 8mm between the clamp faces when tightened.
Interesting. Tonight after work, I'll investigate further. I only had a change to check the rings on the tube last night briefly.
They do feel like a tight fit; but Id rather it be a tight fit then having freeplay where the tube might slip, just as long as it doesnt buckle the tube in the process.
Anyone in Perth with 235mm rings that are no longer needed?
Might have to make an order from AstroShop with the piggyback mounting on the rings. Rings I got are from bintel which dont have this.
Thats quite interesting.
I wonder how different the diamater of the SW600 OTA tube is compared to the 8" Dob tube
Quote:
Originally Posted by Omaroo
I just dug my 8" SW600 OTA out of the cupboard and checked the factory ring size. They are 235mm, and don't clamp completely shut. There is a gap of about 8mm between the clamp faces when tightened.
Myastro has Skywatcher 235 rings for $69. Better a bit loose than to tight. $1.60 3mm thick cork placemats from Woolies cut up and glued inside will take up any slack.
The 230mm rings are just way to tight on the 8' Dob tube; I couldnt even secure and connect them round the tube without really squeezing, and the threaded holes are not centered on the ring block. That I didnt understand.
I thought the rings would also snug fight on the bar; and be screwed in, but the ring mount block just sits on the angled edge of the bar. Am i missing a spacer to put both together.
I know this sounds dumb; but could someone take a pic of the assembly.
I think I will buy the 235mm rings from MyAstro; and put these up for sale.
Here's a pic of the 235mm rings on mine. That's a 300mm dovetail and I took the dobson side mounts off to save weight. There's one of the bolts and the other pic is the counterweight extension bar I had to get made to balance the sucker
Thanx Tandum
Where did you get your bolts for the dovetail and rings.
Are those the skywatcher rings from Myastro? I gather the rings have three threaded holes?
I bought a Losamandy 17" (432mm) dovetail bar; and also have the supplied Eq6 dovetail which appears to be 335mm.
For anyone contemplating buying a dob to mount on an EQ5/6, Andrews have Skywatcher 8 inch newt OTA's for $399 including rings, dovetail and finderscope. It's probably a better option that getting the dob and having to buy the rings and dovetail.
Last edited by acropolite; 08-06-2008 at 09:06 AM.
I know this is slightly off topic, but I hope someone knows. I'm thinking of getting a GSO 10" Dob and an EQ6 Pro and mounting the 10" OTA on the EQ6. Do Andrews have the rings which allow another scope (eg an ED80) to be mounted opposite the dovetail? Ideally I'd like to minimise the stuff I need to buy, so rings which allow that straight up would be great. I'd also like to mount a DSLR for piggyback sometimes, maybe even on the other side of the ED80. Would that work, or do I need other stuff for that?
For anyone contemplating buying a dob to mount on an EQ5/6, Andrews have Skywatcher 8 inch newt OTA's for $399 including rings, dovetail and finderscope. It's probably a better option that getting the dob and having to buy the rings and dovetail.:sonfuse3:
Im wondering what the difference also is with counterbalancing; compared to piggybacking them.
Quote:
Originally Posted by bindibadgi
I know this is slightly off topic, but I hope someone knows. I'm thinking of getting a GSO 10" Dob and an EQ6 Pro and mounting the 10" OTA on the EQ6. Do Andrews have the rings which allow another scope (eg an ED80) to be mounted opposite the dovetail? Ideally I'd like to minimise the stuff I need to buy, so rings which allow that straight up would be great. I'd also like to mount a DSLR for piggyback sometimes, maybe even on the other side of the ED80. Would that work, or do I need other stuff for that?
Thanx Tandum
Where did you get your bolts for the dovetail and rings.
Are those the skywatcher rings from Myastro? I gather the rings have three threaded holes?
I bought a Losamandy 17" (432mm) dovetail bar; and also have the supplied Eq6 dovetail which appears to be 335mm.
The bolts came with the rings. I haven't bought any rings that didn't have bolts with them. You should be able to get bolts at any shop that sells machine screws and bolts (Not Bunnings, maybe Repco). The allen screws came with the bar. They don't screw into the rings, they push on the rings. Can't remember what they are supposed to do but there is a reason for that adjustment. I got them locally, Sirius Optics. I got them to put them on an 8" skywatcher before I walked out with them
