I've been wanting to do something about the stickiness of movement in the base of my dob and originally planned on going the lazy susan route (I even bought a bearing for it) but have decided I would give the ebony star/teflon route a go first as that seems to be the most agreed upon method here and other places around the web.
I've called several local kitchen specialists and cabinet makers and haven't had much luck finding the exact laminate. I've been led to believe that the true ebony star has been discontinued and finding another roughly textured replacement has proven difficult. Today however I managed to get onto another mob who had a piece of "river wash" laminate that they didn't need and said I could have it free of charge.
Basically, before I go ahead and bother using it I thought I would upload some pictures for people who have seen the proper ebony star and if you could let me know if this looks the goods, that would be good It looks quite rough in the pictures but that's because of the lighting. Rubbing your hand over it it doesn't feel rough at all but I don't have anything to compare it to. I tried getting a side on picture so you could see how textured it is but the picture quality isn't the best.
Hi James.
What bearing surface is on your Dob now?
The River Wash will probably work ok. Rub a piece of Teflon over it and see how it feels. See if you can make very small movements without any stiction.
I work in a Joinery company making benchtops so I still have a small amount of Ebony Star. Some time ago I did some tests with WilsonArt HD Aeon laminates (River Gemstone 1832-35 and Bella Noche 1820-35) and they compared very favourably with Ebony Star. I haven't actually used it on a scope yet but I will when I run out of E.S. If you don't like the feel of the River Wash try some HD Aeon. Btw, the colour isn't important, it's the 35 finish you want.
I should add...
The Ebony Star "colour" is still available but not in the "50" finish that works so well. Anyone looking for E.S. only use the off range 50 finish.
My dob is a store bought one. It's a 10" Sky-watcher full tube type with the standard base that comes with it. It has been a great scope, I just can't stand the amount of stiction in the base.
One of the kitchen places I went to did suggest a HD laminate but the samples I saw were a smooth finish and I assumed they would have been no good. "Ebony Star" as you said was still available but only in the 90 finish and not the 50 apparently.
I haven't had a chance to rub anything yet but I will have a look tomorrow. Thanks for the suggestions.
I'm not familiar with the Sky-Watcher base bearing but if it's Teflon onto the colour-board used for the rest of the mount then any textured laminate should be a reasonable improvement.
Spraying Armour-all on the surface that the Teflon contacts can reduce stiction as well.
Dave
Last edited by dave brock; 27-07-2015 at 08:12 PM.
I'm not familiar with the Sky-Watcher base bearing but if it's Teflon onto the colour-board used for the rest of the mount then any textured laminate should be a reasonable improvement.
Well I finally got around to cutting a ring for the base and I got some plastic from a plastic repair shop. It wasn't teflon but they assured me it would do the same job. I was and still am a little skeptical but hey it was free. Decided I would put it on the cheap second hand dob I recently bought in case it didn't turn out and well you were right, now it's the better of the two.
Massive improvement over the stock setup which makes you question why they don't come with something like that from the factory. It wouldn't cost that much extra for a lot better movement. I had put a thin coat of turtle wax on the laminate as well which would be helping but the difference in the two is like night and day.
Might still try and get a hold of some of the 90 grade ebonystar for the other one though. Interested to see if there is even more improvement to be had.
50 finish is what you want, not 90.
If you can get some Teflon I think it will be a significant improvement over plastic despite what they told you.
Dave
I've already tried to get some of the 50 finish but have been unable, that's why I ended up with the stuff in this thread to begin with. mental4astro has since mentioned (in this thread: http://www.iceinspace.com.au/forum/s...2&postcount=11) that the 90 finish which I can get ahold of is still good.
I agree on the teflon and it's still planned. It's easy enough to remove the plastic bits that are on there now, I just wanted to see if it would work.
Dave has given you excellent advice. Take note of it and don't waste your money on 90 finish ebony star. If it worked as well as 50 finish ebony star (discontinued by Wilsonart in about 2008) all of the larger professional custom telescope makers would be using it and to my knowledge none of them are. The 2 are not even close in their surface texture.
50 finish ebony star is shiny with "even" course dimples. The river wash you have has a course texture but the ridges are very "uneven" in size. I would try cutting "leads" on all of your plastic pads to help reduce "sticktion". In other words you should bevel the 4 top edges of each pad at 45 degrees. I have done this with a couple of scopes and it has helped a lot. I think it will help a lot with the uneven textured laminate you are using. I did this on a bench grinder and bevelled about 3mm at 45 degrees on each of the 4 sides of the pad face. I did this on 2 scopes that used the correct "50" series ebony star and it still improved movement smoothness.
I have been trying out a few laminates recently to see how they work with Teflon. At the moment I am leaning toward Polytec Basalt Pearl Texture. This laminate has a much finer pattern than Ebony star 50 but still is a nice slippery surface, another candidate is the Laminex 'Dimensions' texture.
Third option will be tested soon and reported thereafter.....
I have been trying out a few laminates recently to see how they work with Teflon. At the moment I am leaning toward Polytec Basalt Pearl Texture. This laminate has a much finer pattern than Ebony star 50 but still is a nice slippery surface, another candidate is the Laminex 'Dimensions' texture.
Third option will be tested soon and reported thereafter.....
Hi Matt,
I know someone who still has almost a full sheet of ebony star 50 in the roof of his workshop, but he isn't parting with it at any price, as in his opinion everything else only comes close to the real thing.
On a serious note, I am not familiar with the Polytech Basalt Pearl. I am familiar with the Laminex Dimensions and it does work pretty well, but I am not sure if its still in current production. It starts to struggle on really large scopes > 24" and usually requires additional support in the center of the ground board to get smooth motion. This extra support isn't usually required with ebony star #50. The extra support isn't that much of an inconvenience when building the scope. The bevelled edge Teflon pads definitely help in this regard.
Dave has given you excellent advice. Take note of it and don't waste your money on 90 finish ebony star. If it worked as well as 50 finish ebony star (discontinued by Wilsonart in about 2008) all of the larger professional custom telescope makers would be using it and to my knowledge none of them are. The 2 are not even close in their surface texture.
Hey John, thanks for your advice and knowledge on this subject. One question though if I may? Seeing as the 50 finish ebony star has been discontinued and as you said some people still have it but would not part with it any time soon, what exactly do the professional custom telescope makers use then? What happens when all of the spare stuff laying around runs out?
Quote:
I would try cutting "leads" on all of your plastic pads to help reduce "sticktion". In other words you should bevel the 4 top edges of each pad at 45 degrees.
I actually did do this to all three pads already after reading a similar thread either on here or cloudy nights. As you said though replacing them with teflon is the ultimate end goal but for now this has been a massive improvement over the stock setup.
As for the plastic, I didn't pay for it. It was an offcut they had spare.
Seeing as the 50 finish ebony star has been discontinued and as you said some people still have it but would not part with it any time soon, what exactly do the professional custom telescope makers use then? What happens when all of the spare stuff laying around runs out?
Hi James,
Dave Kriege at Obsession Telescopes found through experimentation
that textured laminates surprisingly provided less friction than smooth laminates. See page 72 of The Dobsonian Telescope for details.
Both Formica and Wilsonart offer a variety of textured laminates.
In his book, Dave mentions that Wilsonart call their textured surface "Touchstone" and Formica call theirs "Quarry Finish".
I think he picked on Ebony Star and Stardust because of what he called
the "pleasing coincidence" that their names contained the word star.
Others he recommends in "The Dobsonian Telescope" include -
Wilsonart Inc Touchstone range -
#4406 Diamonhead
#4408 Surfside
But a similar textured laminate from any manufacturer will do.
Though there is a representative for Wilsonart in Australia, Formica would
be the leading brand of the two here in Australia.
See http://formica.com.au/
There is certainly no magical "pixie dust" in Ebony Star that makes it the only choice.
In a presentation I attended entitled "Care and Feeding of Large-Aperture
Dobsonians" which Dave Kriege gave in Texas in March of this year,
he has been experimenting with other combinations
of bearing surface materials which no doubt will make their way into
future scope designs.
I have been following this thread with some considerable interest. I feel it is now appropriate and necessary for me to contribute to the discussion.
I see many references made to the good book by Dave Kriege. I also see some people saying you need to use "this" and not "that" model of Ebony Star.
What I do not see is anyone with any actual practical experience with repeated mount construction who in turn has used all manner of different laminate varieties. I also do not see any mention that the majority, actually nearly ALL, the laminate varieties recommended in the good book are now no longer available. Some for close to 10 years. The good book was published in 1997, so the information of the laminates recommendations is very much out of date as laminate manufacturers have moved away from the fashion of the late 1990's. This means we as scope builders need to look for alternative materials.
As has been mentioned earlier by John, Ebony Star 4552-50 was discontinued some 10 years ago. The textured laminates made by Laminex and Fomica also are close to 10 years past discontinuation. Even when Laminex and Formica were producing textured laminates, NONE were as textured as Ebony Star 4552-50, and NONE were as textured as Ebony Star 4552-90, which of all the currently produced textured laminates is the most textured.
I have used many types of textured laminates, from Ebony Star 4552-50 through to the Dimensions range by Formica and many others. Today, the only textured laminate I use is Ebony Star 4552-90 as it is the only material still in production that comes close to 4552-50. To dismiss 4552-90 as essentially 'rubbish' demonstrates a lack of experience with the material, and experience with other laminate types. It also demonstrates a lack of wanting to progress to new materials and techniques. As a manufacturer, I need to continually look at new materials for product development - that is my responsibility, to be constantly open and accessing new materials that are being produced, not to be closed minded to insist on only OLD and now discontinued technology. Or are we still insisting on using the Apple 2E??? Making my point? And eventually, there will come a day when textured laminates will stop being produced altogether. So what do we do then? Stop building scopes, or source new materials. I know which i'll be choosing.
Some of the talk here is bordering on slander. I openly offer Ebony Star 4552-90, and to suggest that it is not 'the real McCoy' is running a very fine line. I really suggest that if you have any doubts about the suitability of Ebony Star 4552-90, you are more than welcome to handle the telescopes I build with it. If the action of the instruments is as 'rubbish' as the implied quality of 4552-90 is, then I really am a fraud. Nor have I ever received a complaint from any of my customers, or anyone who has handled one of my instruments or mounts about the quality of the action.
The good book by Dave Kriege is an excellent publication. The very principles it talks about are as relevant today as when the book was published. But the book was published nearly 20 years ago and the availability of the recommended materials have moved on a long, long way from those recommendations. It is now up to us to find new materials that will be suitable for our requirements. To insist on ONLY recommending materials that have been out of production for so many years is just not up to date.
If there are a few scope builders that have Ebony Star 4552-50, then that is good for them. For the rest of us that need laminate, we need to utilize those materials that ARE available, and adapt the mechanics of the telescopes we build to suit these new materials.
Sincerely,
Alexander Massey.
Last edited by mental4astro; 18-08-2015 at 05:30 PM.
In the absence of the 'real McCoy' I am going to go down a different path altogether and will report my findings once I have had a chance to test it.
I don't think that slander applies here Alex, after all, these are just people expressing opinions based on personal experiences as you are. I would personally think that looking at the texture of the 90, it would probably be fine for the lightweight scopes you build. I would have some concerns about using it in larger scopes. My mirror box with cell and primary is over 40 kg without poles and UTA etc.
What will we do in the absence of any of the 'recommended' materials? There is no discussion here about moving onto new materials, or using the less favoured types. Just sit around and wait for the 'authority' to tell us? Nor is there any talk about changing scope designs to suit the materials that ARE available and new to the market. Why do we insist on only talking about what has been put to us by 'authorities' and not look outside the box. If it is not put in front of us by someone else then everything else is rubbish. No one even questions WHY this material and not the other, but just take it as gospel. I for one am not sitting idle twiddling my thumbs because 4552-50 is no longer available. I am adapting to new materials and different designs. The recommendations in the good book are disappearing folks. That train has long passed, and we are not looking at the trains that are now at the station in front of us.
The reference to 'the real McCoy' is to an ad that quoted this in their product description.
Matt, I commend you on exploring new alternatives. That is what we need more of!
WE (Australia that is) once upon a time used to create our own authority. Today we have deferred this to outside our shores. Worse still, we shout down anyone who dares offer an alternative. I for one insist on using as much Australian know-how and products as possible in what I create and offer.
Last edited by mental4astro; 19-08-2015 at 04:00 PM.
Reason: tempering language
I can jump in here and offer a perspective. Please note this is only my limited experience.
When I built my 8" travel dob I was lucky to be able to purchase some 4552-50 laminate for both alt and az axes. It worked perfectly fine. When I decided to redesign the alt mechanism to better accommodate DSCs, I decided to get some laminate from Alex, which as it turned out was the 4552-90. A comparison showed that it was a very different texture but I thought that's fine I will give it a go. The good news is it works fine and maybe gives a slightly smoother feel to that movement, but that may also be due to a better built alt system.
So, IMHO, the 4552-90 seems to be perfectly OK for smaller scopes. Obviously I haven't used it on a larger beast, so cannot offer an opinion on that, but for what it is worth, that is what I have found.
In the absence of the 'real McCoy' I am going to go down a different path altogether and will report my findings once I have had a chance to test it.
I don't think that slander applies here Alex, after all, these are just people expressing opinions based on personal experiences as you are. I would personally think that looking at the texture of the 90, it would probably be fine for the lightweight scopes you build. I would have some concerns about using it in larger scopes. My mirror box with cell and primary is over 40 kg without poles and UTA etc.
Matt is 100% correct. With the small to medium aperture light weight scopes Alex is building the ebony star 90 pattern will work ok. I used 4552-90 on a 10" scope about 14 years ago and it worked ok. I re did the base to that scope a couple of years later with 4552-50 and it was an improvement. I didn't re do the base just to change the laminate, its motions were ok, I rebuilt it to change other things with the base like internal battery pack etc.
Where 4552-90 fails is with medium to large aperture scopes over 16" built along the traditional obsession type design. Scopes of this design are quite a bit heavier than the ligtweight compact designs of the same aperture. The material fails on the azimuth bearing, it will usually still work ok on the altitude bearing.
That however is all pretty academic as I have suspicions that 4552-90 has also been recently discontinued and is no longer in production. The existing stocks however should last a while. As Dave Brock mentioned the Wilsonart #35 pattern is a heavily textured pattern and it should work well. I believe that overall it will be a better choice than 4552-90. It is also still in current production.
The process Matt is proposing will work well. I know what he is using and I am privy to some previous testing with it and I know it works well. The downside is that it is more difficult to fix to the base of the rocker box. However looking at the quality of Matt's workmanship thus far, I am sure he will be fine.
FWIW most of the professional large aperture scope builders in the US use "glassboard" on the bottom of the rocker box but it is very difficult to source in Australia.