Ebony Star modification to GSO Dobsonian

Tannehill · #1 10-04-2007, 08:36 PM

Sounds like there are at least a few folks interested in upgrading their GSO or other dob stock base to ebony star....at least a few so far from the Melbourne area...

I'd also probably consider upgrading the teflon pads to the right surface area relative to weight, and glue on new pads rather than the GSO stapled-on...that staple could conceivably work up and scratch the laminate...hence Bintel's advice to drive it solidly deeper with a punch and hammer. That's on both the AZ and ALT bearings.

If we all get our ebony star, all we need is 1) someone with a router to trim it right and something to roughen up the stock laminate surface so it adheres well (a sander of sorts?), 2) a source of virgin teflon (I've a couple leads on that here), 3) some glue, 4) a place to meet to accomplish aforementioned mods on some weekend day, and 5) refreshments.

Scott

erick (Eric) · #2 11-04-2007, 12:47 AM

Scott, I'm interested.

I have 1) a cheap router that should do the job, but I need someone a bit more experienced than me to operate it, and a suitable sander, 3) "liquid nails" should do the job, 4) my garage (but it's stuffed full, so if weather is fine, my driveway), 5) I can do coffee and tea?

The weekend day is a bit of a challenge over the next weeks - I'm away a few of them.

Still, we can try. I was going to check the Ringwood place for the laminate - anyone done that? I understand that one sheet should do three bases?

Eric

ausastronomer (John Bambury) · #3 12-04-2007, 11:00 AM

Hi Scott and Eric,

To Glue the Ebony star laminate you need to use contact adhesive. It does a better job of this than any other adhesive.

If you wish to also use ebony star on your altitude bearings you can buy special "thin" ebony star from a guy in the USA.

www.inspirationtoolworks.com

Follow the link and go down the left hand side to "Ebony Star Flexi Strips"

These work really well and because they are thinner and less prone to flex back, glue really well to the smaller diameter altitude bearings. Use contact cement, cut the length so they just fail to touch and don't overlap and then use 2 cable ties around the bearing as clamps.

I prefer to "glue" the virgin teflon pads. You don't need to use "etched" virgin teflon to do this. You need to get Loctite 770 primer and Loctite 406 Adhesive. Get this from an industrial supplier. It will cost about $25 for both and is an extremely handy glue to have around. Loctite 406 is like a super duper, super strength super glue.

I have done my 10" dob with virgin teflon and ebony star on both the altitude and azimuth bearings and it moves beautifully. Another tip is to "grind" a "lead" onto all the virgin teflon pads before you glue them in place. This involves using a bench grinder to bevel the 4 edges on the bearing surface of each pad at a 45 degree angle for about 2mm. This reduces any possible resistance as the pads start to move.

CS-John B

Tannehill · #4 13-04-2007, 07:36 PM

Sounds good to me. I have no experience with routers. I've secured a chunk of ebony star already, but haven't any confirmed way to cut, trim it. Recent poster provided some help on how to glue...this and other advice I've gotten off-group should have us set up okay.

I can get us a few pieces of teflon.

I'll PM you

scott

Quote:

Originally Posted by erick

Scott, I'm interested.

I have 1) a cheap router that should do the job, but I need someone a bit more experienced than me to operate it, and a suitable sander, 3) "liquid nails" should do the job, 4) my garage (but it's stuffed full, so if weather is fine, my driveway), 5) I can do coffee and tea?

The weekend day is a bit of a challenge over the next weeks - I'm away a few of them.

Still, we can try. I was going to check the Ringwood place for the laminate - anyone done that? I understand that one sheet should do three bases?

Eric

wasyoungonce (Brendan) · #5 13-04-2007, 07:37 PM

Was tooling around the Internet and saw this place selling Ebony Star strips:

http://www.scopestuff.com/ss_lexx.htm

Don't know if this is a good buy or not but thought I'd mention it.

taminga16 (Greg) · #6 13-04-2007, 09:47 PM

Watching this thread evolve from a question on the whereabouts of suppliers to a potential woking bee is a beaut thing and shows a great spirit in like minds.
I am not quite ready for the ebony star mod, but before I do it I am going to fit some gussets to the forks in an effort to reduce sideways movement. Greg.

erick (Eric) · #7 13-04-2007, 10:08 PM

Quote:

Originally Posted by wasyoungonce

Was tooling around the Internet and saw this place selling Ebony Star strips:

http://www.scopestuff.com/ss_lexx.htm

Don't know if this is a good buy or not but thought I'd mention it.

I also saw a lead to this supplier:-

http://www.inspirationtoolworks.com/astronomy/1001/

He says:-

"These are pre-cut strips of Ebony Star Formica, but they have been thinned to to be more flexible. Normally, formica is .045"-.050" thick. I reduce that to .020"-.025". This allows them to be cemented to a bearing as small as 3" in diameter."

And I think the Bintel dob bearing must be not much more than 4" in diameter. He's out of stock and not answering email just at the moment, but says he'll be back in touch soon. Scopestuff's formica is said to be 0.045" thick - more for the larger diameter of a rocker box bearing, I would think.