Keiths next scope modding plans

PhilipLardner wrote:


PS - forgot to ask - how much wood do you need. I may have an off-cut that will do you. I have 1/4", 1/2" & 3/4" in my wood-pile.[/quote]

Thanks for the info folks. Thanks for the heads up on the wood Phil. I wont be taking you up on your offer just yet. Have been planning to build a 16" scope for a while but its still in the inception phase ( i.e a little idea cloud in my head!).

rather than design something was considering recently completely ripping off a design such as the telescopic skywatchers. really like them but there are just a few things that i dont like, but could be rectified in my own refined version of them.

Phil, can you recommend a decent book that outlines the basic required knowledge for dob building?

fguihen wrote:

rather than design something was considering recently completely ripping off a design such as the telescopic skywatchers. really like them but there are just a few things that i dont like, but could be rectified in my own refined version of them.

Phil, can you recommend a decent book that outlines the basic required knowledge for dob building?

There are bags of ATM (amateur telescope making) sites giving loads of ideas and designs and concepts - Google ATM or Telescope Making. One useful site, mostly aimed at glass pushers, is Stellafane stellafane.org/misc/links.html , but there's plenty of links to telescopes that people have built in general.

"The Dobsonian Telescope" by Dave Kerige and Richard Berry (pub: Willmann-Bell) is a good place to start, but to be honest, you'll pick up more ideas off the web. There's also the ATM mailing list and archives - www.atmlist.net/ and the ATM Site - www.atmsite.org/keyword.html

Phil.

Fintan. The negative aspect of the Chinese scopes being made from chipboard is not so much worries about dew and damp but in the fact that it isn't as stiff as is really necessary for minimal flexure. There is a springiness to it which results in you thinking you have moved the scope but merely flexed the base and when you let go of the scope it springs back to its original position. You end up having to lead your target in the eyepeice and talking into account this spring back when trying to center a target in the eyepiece. This would be solved by increasing the width of the base pieces but the weight of chipboard increases exponentially. Better off with lighter but also stiffer plywood.

WRT dew and damp. The plastic coating the the chinese apply to the chipboard seems to do a good job sealing the chipboard from damp. Eamonns point to me was that when one starts drilling holes in a chinese plastic coated chipboard base, one risks compromising the damp protection.

As for me, I might go the route of taking up Philip on his offer of some 1/4 ply to re-inforce a Lightbridge base to reduce the flexure. If it doesn't work out, I can then go the whole hog and rebuild the base in 3/4 ply. But why go to that trouble if I don't have to. I lose nothing by trying.

BTW Fintan. If you ever get around to building your dob I can do you a great deal on an Orion Intelliscope SVP DSC kit that we can mod to work on your dob. I got mine just before they cleared the last of their stock. Cost me about 80 euro's including postage from a friend in the states. That is shockingly cheap for a DSC. Turns out I probably wont be using it on my future Lightbridge project as Dave has convinced me on the benefits of the Servocat and argo navis combo. Let me know in the future if you want it.

Hi Keith,
Its interesting to see you're going with the argo/servo combo.
The way I see it, even though it's expensive, it does what it says on the tin, thats what swung it for me, do it once and do it right.
I look forward to someday seeing it on whatever scope you end up getting.

Dave_Lillis wrote:

Hi Keith,
Its interesting to see you're going with the argo/servo combo.
The way I see it, even though it's expensive, it does what it says on the tin, thats what swung it for me, do it once and do it right.
I look forward to someday seeing it on whatever scope you end up getting.

Pretty sure now its going to be the Lightbridge 16 inch Dave. It is funny that I was focussing on the GSO for so long thinking that that one was the scope with the most features I wanted and most easily modded with the best features of others.

Can't remember what it was in this thread that flipped the switch but I now realise the Lightbridge suited my needs so much better and always did. I guess it was that I had invested so much thought in how to do this or that with the GSO that I just didn't give due consideration to the other chinese 16" scopes once I had thought I had made my mind up.

I think why I had discounted the servocat/argo combo was that I had remembered seeing the price of these fitted to a new Obsession on the Obsession site. Approx $3000 which after adding custmoms and tax turned into near enough €3000. Of course I now realise this was the full size system rather than the servocat junior. So I was comparing €3000 with the €1000 Dob Driver II and my €80 Intelliscope DSC. After discovering that there was an actual Servocat/argo Lightbridge 16 kit based on the SC Jnr for €1650(Inc Customs&Tax) well that changes the picture entirely. The €500 odd extra is worth paying, for all the extra features the SC/Argo provide, whereas when I thought the price differential was nearly €2000, I certainly didn't think the extra features were worth paying for.

That said, €1650 is still an amount not to be sniffed at but like you said it is an investment. I am confident like I said in some earlier posts, that The Buck stops here :laugh: with regard to apeture fever. Sure I'll still experience it, but I can't help but baulk at the price of a 20 or 25" premium scope with premium optics. Not gonna happen unless I win the lottery :laugh: So I am sure the servocat/argo will pay me back that €1650 10 fold in enjoyment over the next decade that I'll have it and this Lightbridge scope.

Getting back to the transport and weight issues, I'm not really worried tbh. I know Eamonn is just trying to make me aware of the possible weight/transport difficulties that I may encounter so I don't enter into this upgrade with my eyes closed. I have a feeling our different views on what might be easy or a chore are relative and shaped by past experience. First off I think I have it easier from the get go in that although my car is a smallish sports coupe, it is a hatchback with a wide and long apeture whereas Eamonns car is a Saloon style.

We are both coming from different directions. Eamonn had a Lightbridge 12" before his 16" if I remember correctly. He went from a scope that broke down into pieces easily fitted into his car without too much manhandling to a heavier scope with larger and more awquard pieces that he had to tilt this way and that, drag this way and that, to manhandle them into his car. The 16" no doubt presented him with much greater difficulty relatively speaking and he looks back at how easy he had things with the 12" Lightbridge.

However in my case, although I also have a 12", it is a heavy solid tube dob, with a base 26" in diametre but 30" tall. No breaking down into constituent parts for efficient packing with my scope!! My OTA took up half the car and although my Orion OTA carry bag makes it a lot easier to carry, its still an object the same weight as a 16" Mirror tub but nearly 3 times the lenght and thus more unwieldy. As for the base. Because my roofline goes as low as 24" from the folded down rear seats, my 30" tall base had to be manhandled in and then rotated and tilted over to get the baseboard under the 24" roof lip and then laid on its side.

So for me relatively speaking, I won't know myself with how easy I'll have it with a LB16 base that although a bit heavier than my current base can literally be placed in the boot through the wide low long bootlid apeture and slid up the car and wont have to worry about the 24.5" high forks of the LB16 base catching on the roof. (Like a said there is a lip of 24" but 99% of the roofline is heigher than 27in) I think the added weight of the base will probably compress the folded down seat cushions enough so that the available clearance will actually be about 25" rather than 24".

I have measured up the car with the measurements Eamonn gave me and I know now it can be done. Snug as a bug. Base up behind the front seats on the folded down back seats. The EP case and other accessories alongside, the UTA within the base and the Mirror tub will fit snugly between the base and the bootlid so no rolling around, with space beside that for more bits and bobs.

Relatively speaking it will be an absolute breeze loading the car with a LB16 compared to my Orion XT12i. Maybe no harder nor easier than the actual hassles Eamonn has in getting one in his car but our perception of the issue is different because this level of hassle is more than Eamonn was used to but in my case its less hassle than I was used to, so he is frustrated by it and I will be thrilled by it.

Want to finish of the transport issue discussion by clarifying again though that its not that the Orion XT12i is particularily difficult to load into cars. Its just difficult to load into My particular car. Average 3 or 5 door hatchback for instance. Not a problem.