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Post by GrahamP on Jun 15, 2020 8:26:50 GMT -5
So down to the business! Why D180?
Since rediscovering amatuer astronomy I have placed high value on a quick setup. When setting up at home I expect 5-10 minutes, 15 minutes tops. I like to keep an eye on the sky, and if it's clear then I will grab something for a quick look..... or more. I still work full time, and want something I can use during the week when time is precious. My largest commercial scope at present is a SkyWatcher 150 F/8 with an NEQ6-Pro mount. I find this is a about as big as I would like to go for a quick setup. I can carry the mount (minus counterweights) with relative ease, and the scope tube is easy enough for one person to carry at 7.7Kg. I figured I could go just a bit bigger with a D180, work on keeping the tube weight down, and still be able to use the NEQ6-Pro mount. I seriously doubt that an NEQ6-Pro would take a D204 refractor as the increase in weight and inertia is significant. Well, who knows, maybe one day. So I finally ordered my iStar objective at the end of April and it arrived on 5th May, oh yeah! cheers .... Graham.P
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Post by GrahamP on Jun 23, 2020 8:39:34 GMT -5
Hello again, my plan for keeping the weight right down is to build this tube from sheet metal. These days sheet metal parts can be as complicated as you like because a laser cutter will take care of the hard work. Here are some photos of a short prototype tube which I have made which has an outside diameter of 9" (228.6). Small tabs on the webs are partially cut through so that they bend by hand in the correct place. Webs are held in place using a jig, then the 0.6mm aluminium skin is wrapped around the frame and held with straps.
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Post by GrahamP on Jun 23, 2020 8:45:17 GMT -5
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Post by jamesling1000 on Jun 29, 2020 4:37:42 GMT -5
Hi Graham.
Please continue to share with us your DIY for this great D180 scope... Especially later on the first light observation with this scope...
Regards
James Ling
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Post by GrahamP on Jun 29, 2020 5:21:28 GMT -5
Hi Graham. Please continue to share with us your DIY for this great D180 scope... Especially later on the first light observation with this scope... Regards James Ling Hi James, yep, sure thing. I have it in mind to do a rough setup that will allow me to confirm the focal plane location before committing to the final tube design. That might involve a sort of preliminary first light. cheers ... Graham.P
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Post by jamesling1000 on Jul 1, 2020 21:28:57 GMT -5
Hi Graham.... I always admire people like you and many others who only purchase the lens cell and make the whole telescope , whereas I am importing the whole scope from oversea... The only thing I can do modification to my scope is to cut it into two, for easier transportation purpose , since I only have a saloon car ......And I am happy with what I have now, the 8" Istar , as I can bring it to anywhere I want for outreach activities..., just half an hour to assemble the two halves into one... Regards James Ling
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Post by GrahamP on Jul 4, 2020 8:12:12 GMT -5
Hi Graham.... I always admire people like you and many others who only purchase the lens cell and make the whole telescope , whereas I am importing the whole scope from oversea... The only thing I can do modification to my scope is to cut it into two, for easier transportation purpose , since I only have a saloon car ......And I am happy with what I have now, the 8" Istar , as I can bring it to anywhere I want for outreach activities..., just half an hour to assemble the two halves into one... Regards James Ling Thanks James, and thanks for sharing, that's still a handy bit of work. Takes some faith to cut an 8" refractor in half, but it has clearly worked for you. Regards .. Graham.P
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Post by GrahamP on Jul 4, 2020 8:20:52 GMT -5
OK, here I have attached an illustration of the complete tube. The design is taking shape, but it takes a long time to deal with all the small details. I am thinking now that I will use a main tube OD of 235mm. This will use off the shelf mounting rings and is also large enough to use again with an 8" objective. I am also considering a dew shield diameter of 288mm. Again, the shield design elements could be reused for a main tube for a 9" or 10" objective and would also use off the shelf mounting rings. I have sourced an aluminium section, 200x50x3 to use as a base for mounting the objective with a focuser to test focal length. More on this soon. regards... Graham.P Attachments:
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Post by GrahamP on Jul 26, 2020 8:35:08 GMT -5
Hi again all, I have finished making a test bench for checking focal length and measured that to be 1438mm from the mating face of the lens cell mounting flange (ie. the rear face). So for me, this confirms a nominal focal length of 1440mm (F8). Now I can finalize elements of the tube design with full confidence. I have attached some images of the rig. The whole thing has been improvised using aluminium sections which I purchased from one of the local scrap metal merchants at scrap rates (total about $30 of aluminium) plus two 50mm slotted steel angles ($24). The lens mounting plate is 300x300x5, mounting plate supports 50x50x3 angle and the main beam 200x50x3 hollow. Regards.... Graham.P
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Post by GrahamP on Jul 26, 2020 8:58:12 GMT -5
Hey de ho, here are a couple of images showing the rig in use. I have a small length of aluminium tube with angles riveted to it to create a tiny projection screen. With the setup aimed at the moon I can carefully focus the image and then measure the location of the little screen. I tried photographing the projected image of the moon, which you can just about see in the second photo. Of course I could not resist looking at a couple of objects, although I did not want to invite an act of providence. I'm sure if I spent too much time using this the objective would end up coming to grief. Seeing was not great (maybe a 5), with obvious thermal activity, but the lens worked well enough to give me a glimpse of what to expect, and I'm excited! Good contrast and detail visible on the moon, even through the thermals. Tried Televues 25 PL, 13N6 & 7N1. Same on Jupiter but thermal activity also didn't help, still obvious detail waiting for the picking on a good night. Finally, before it clouded over at 10:00pm I got onto Omega Centauri. Wow, very impressed. Stars were lovely little points of light and many were discernible with some structures which I haven't noticed before on my other scopes. I could easily use 7N1 (206x), but most pleasing view with 13N6 (111x). Without attempting to align the objective in the rig, it seems to have turned out pretty good. cheers .... Graham.P
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Post by GrahamP on Aug 14, 2020 8:45:28 GMT -5
Hello all, well, we have gone into stage 4 lock-down here in Victoria, so progress may be difficult. Fortunately, prior to lock-down I purchased the aluminium billets for the machined parts. Photo attached. The square plate is for the lens cap. Illustrations of the mounting ring and back plate also uploaded. The mount ring should be 1.02Kg and the back plate 0.69Kg, give or take. I have settled on a main tube diameter of 232mm (same as Takahashi E-180, Vixen Visac 200 and AT 8RC), and dew shield diameter 285mm. Billets have been delivered to the machinist, so fingers crossed! cheers ... Graham.P
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Post by boomboom on Sept 12, 2020 16:21:28 GMT -5
Hi Graham, Beautiful workmanship going on there. James Lings YouTube Video from years ago on setting up his 8” Istar is what led me to Istar and doing my whole ATM thing....thanks James! My scope and mount build thread from IIS if your interested. www.iceinspace.com.au/forum/showthread.php?t=139694Happy building in the meantime. Matt
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Post by GrahamP on Oct 17, 2020 7:24:41 GMT -5
Hi Graham, Beautiful workmanship going on there. James Lings YouTube Video from years ago on setting up his 8” Istar is what led me to Istar and doing my whole ATM thing....thanks James! My scope and mount build thread from IIS if your interested. www.iceinspace.com.au/forum/showthread.php?t=139694Happy building in the meantime. Matt Hi Matt, don't know how I overlooked your post. Thanks for your kind comments. I took a look at your mount project and say Wow! That's a solid bit of kit. Looks like it would take the 40kg easily and would be a wonderful permanent setup. Envy. cheers .. Graham.P
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Post by GrahamP on Oct 17, 2020 7:54:51 GMT -5
And hello all, a minor update:- Took delivery of a large format MoonLite CFL focuser on 9th October. Beautifully made to be sure. I have purchased two of MoonLite's 2-1/2" base extensions with the following plan:- - The telescope tube length will be chosen to work within the normal range of focuser movement with one of the 2-1/2" extensions in place. (ie. visual with a 2" diagonal and typical 2" or 1-1/4" eyepiece.
- The extension can be removed to allow use of a bino-viewer with 2" diagonal (native, no barlows).
- A second extension can be added to allow straight through visual with minimum number of optical elements in optical path (ie. no diagonal).
In using a base extension instead of a focuser tube extension I believe it will be easier to avoid vignetting (the inside diameter of the iStar flange adapter is 83.6mm). I will upload my tracing diagrams when done. The cold reality of living in Australia is reflected in the total cost of this purchase (exacerbated by Covid19 shipping issues) Goods & Shipping 2.5" CFL (4-1/2" Travel) focuser with shaft lock $470 2 x Base extensions (2-1/2") $158 spare iStar base adapter (M100x1.5) $95 Shipping/DHL $181 Total $904 USD ($1316.36 AUD) Charges Australian Government charges (including 5% import duty) = $88 Goods & Services Tax = $126.21 Disbursment = $20 Total $234.21 AUD Grand total = $1550.57 AUD, not for the feint hearted! Upsides, the MoonLite focuser is a dream and the DHL shipping was excellent and quick (cost inflated though above normal due to Covid19 disruption to airfreight). Note that the M100x1.5 iStar flange adapter is clearly visible in the last photo. cheers all, and good viewing.... Graham.P
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Post by GrahamP on Jan 29, 2021 7:46:30 GMT -5
Hi everyone, been a long time updating my progress as I have been in hospital a couple of times over the Christmas period, and Covid-19 has also done it's best to disrupt everything. Good news though as I now have the three large machined parts completed thanks to my skilled friend Ramesh Kumar. The lens cap and front lens ring were finished in October last year, and the back plate was completed this week. Hooray! I have also been spending some time refining the sheet metal tube design, and tooling. Photos of the machinings attached... regards all..... Graham.P
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