Meade superwedge to Milburn: worth it?

rogerg (Roger) · #1 24-11-2009, 01:55 PM

G'day all,

I've known of Milburn wedges since not long after I bought my 12" LX200 way back in 2000. But until now I haven't had significant cause to consider upgrading to a Milburn.

The way I use my telescope has changed in the last year. It's 100% automated and I have only been using it about once every month (on average). My change in use has meant flexure and polar alignment drift are causing me considerably more pain than they once did.

I'm finding that after a month of no use I have quite poor pointing accuracy. It feels much worse than it used to be 2-3 years ago because I am using it so much less. And slewing across the sky gives poor pointing accuracy, I think due to flexure as well as the polar alignment.

I'm wondering if upgrading to a Milburn wedge would have a significant real tangible affect on the accuracy of my setup - that is, how long the polar alignment sticks and the flexure.

I don't know if the flexure is in the wedge or the fork.

My upgrade path is a PME so I'm not wanting people to tell me to buy a new telescope mount - I'm not interested, this is a stop gap measure while I continue saving for the PME. Similarly I'm hesitant to spend the money on the Milburn, hence my desire to know if it would provide a significant real tangible improvement. If not, I will happily continue with my capable 'old LX200.

I'd love to hear from anyone who has gone from meade superwedge to milburn and can offer experience on the difference made.

Thanks,
Roger.

Barrykgerdes · #2 24-11-2009, 03:05 PM

Hi Roger
The description of your problems leads me to believe that the poor alignment and Goto accuracy is not due to your wedge. I have not used a Meade super wedge but I did make my own from steel using the basic idea of the Meade Super Wedge and I used it to support my LX200GPS 12" for six years in the observatory.

I was able to get a very good polar alignment, 1 arcminute or better and this was maintained for this period without the need to re-align. Slewing from east to west was always better than 4 arc minutes and short slews no measureable errors. This was was achieved by very careful orthogonal alignment of the forks and OTA such that the orthogonality was better than 10 arc seconds.

LX200's were notorious for poor orthogonoality in the forks. I saw one out of the box that had one fork 3 mm higher than the other. Gotos were nonexistant.

I was able to lift the telescope off the wedge for maintenance (I have a crane to do this) and replace it without any need to do any more than goto a star from the park position and centre and sync.

There was some flexure of the forks and base but none in the wedge.

The Milburne wedge is very strong and firm but it won't correct problems of orthogonality and flexure of the fork arm and it is a lot of money.

Barry

rogerg (Roger) · #3 24-11-2009, 03:57 PM

Thanks Barry.

I have to admit the word "orthogonality" has always sent shivers down my spine. I fear that there's a 50% chance I would make it better and a 50% chance I'd make it worse. I've never tried adjusting my LX200 in the 10 years I've had it.

I have found this on how to do it:
http://www.mapug-astronomy.net/Astro...ent/OTA-1.html

Could you recommend any other instructions on doing it? tips? know anyone in WA who's done it so can help?

Thanks,
Roger.

coldspace · #4 24-11-2009, 05:19 PM

I just ordered a new Milburn "delux" model wedge for my 12 inch.
The delux version is 1 inch thick compared to 3/4 for the standard Milburn and very solid apparantly. It should be here to me in a week or so.

The Meade ultra wedge is apparantly far superior to the Meade super wedge as they were brought out for the RCX line of scopes.

The Milburn and Mitty wedges are supposed to be alot better again compared to the Meade ultra.

I went with Milburn, based on many excellent reviews and it worked out for the delux 1 inch thick version which is black anodised as well $50 less shipped to me in Brisbane than than the Meade ultra wedge, so not a real difficult decision for me. The delux version was brought out for the larger 12 and 14 inch scopes but the standard milburn is supposed to be very good so the delux can only be better.
This is my first wedge so I can't comment on user experience only from what I have found out on various astro forums.
Also service and response from Ken Milburn has been very proffesional, got to love the high Aussie dollar ATM

.

Regards Matt.

Barrykgerdes · #5 24-11-2009, 07:34 PM

Quote:

Originally Posted by rogerg

Thanks Barry.

I have to admit the word "orthogonality" has always sent shivers down my spine. I fear that there's a 50% chance I would make it better and a 50% chance I'd make it worse. I've never tried adjusting my LX200 in the 10 years I've had it.

I have found this on how to do it:
http://www.mapug-astronomy.net/Astro...ent/OTA-1.html

Could you recommend any other instructions on doing it? tips? know anyone in WA who's done it so can help?

Thanks,
Roger.

The orthogonality problems frighten most. It is a tedious job to do but if performed to correct the operation of the telescope it will make a "dog" into a precision instrument. You are too far away for me to fix it but I have done many telescopes and seen some very poor examples from Meade and also some near perfect.

I have a method I use that works but many people have their own methods and as long as orthogonality is achieved it does not matter how you do it.

I used to have a document on my web page on how I do this work but since geocities closed I do not have a web page. The document is 277 kb long so I do not know if it will attach but I will try. No it is too big I will zip it up into a zip file

The Milburn wedge to my knowledge is far superior to the Meade but it will not cure problems of fork flexure, azimuth bearing loading and orthtogonality as well as other problems assciated with polar mounting a fork type telelscope, particularly balance.

Barry

marki · #6 24-11-2009, 08:33 PM

I must have been lucky as my scope always puts the target in the centre of the EP. I have never checked alignment, might do it for a bit of fun

. The ultrawedge is OK but must be well supported along its entire length or vibrations will kill any attempts to take pics. I do not believe it to be ridgid enough when mounted on the meade tripod as it is not well supported. I have seen folks mount bracing and all sorts of crap to fix this. Barry is dead right about the forks (wobble wobble Arrrrrrggggghhhhh

). Balance is also fun as one fork is much heavier than the other. Currently I fill one side (battery box) with lead sinkers to balance it along with a ADM 3D weight system.

Mark

rogerg (Roger) · #7 25-11-2009, 10:29 AM

Quote:

Originally Posted by marki

I must have been lucky as my scope always puts the target in the centre of the EP....

Mine used to, from what I can remember. The first 5 or so years it was great, or at least much better than it is now

Quote:

Originally Posted by Barrykgerdes

The orthogonality problems frighten most. ....

Thanks for the info Barry. I've downloaded the document and hope to find time in the next few weekends to give it a shot.

Quote:

Originally Posted by coldspace

I just ordered a new Milburn "delux" model wedge for my 12 inch...

Thanks Matt, it was actually your post which got me thinking about it again and if it could improve my situation. Still unsure if I'll buy one at this stage.

Roger.