Possible to use smaller dove rings than tube?

[Lognic04]

Hi all,
I have a takahashi mt-160, and the clamshell that came with it has no way of mounting to any modern dovetail, so i need to get tube rings. the OD of the tube is 8 inches, thus requiring a 200mm ID tube ring (which dont exist.) so, i have found 180mm tube rings, is it possible to use those with a 200mm OD scope? :help::question::thanx:

[doppler]

Probably not, the curve of the rings would not match the tube and you would not be able to tighten it without denting it. Better to go larger and pad the inside of the rings to reduce the diameter to suit.

[Lognic04]

does anyone know if 200mm rings exist? and how would i pad a 235mm tube ring?

[LewisM]

The Tak clamshell CAN fit a modern dovetail - either Losmandy D section or Vixen V section. Many makers make a Losmandy D plate with specific Takahashi mounting spacing and rebated circular section, or you can simply use a Vixen dovetail with the bolt SLOTS like this one: http://myastroshop.com.au/products/details.asp?id=MAS-096I3

I have some customs made Tak clamshell allen head screws if you need some - they fit the Tak clamshell holes precisely, and then step down for standard 6mm slots.

You can also drill your own holes in a standard V plate or D plate to save some money.

Here's a Google link to images of the ready made plates: https://www.google.com.au/search?q=Takahashi+losmandy&rlz=1C1CHBF_en-GBAU723AU723&espv=2&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjgvfqK0fPSAhVO_mMKHYz_Ba gQ_AUIBigB&biw=1536&bih=759 - take your pick!

Here is the Farpoint: http://www.buytelescopes.com/farpoint-astro-takahashi-clamshell-to-losmandy-d-style-dovetail-plate-short

As to 200mm rings, Parallax in the USA make them - they are a couple hundred dollars.

[Lognic04]

My clam shell looks like this, it has the 4 screws but they arent diagonal: https://cdn.discordapp.com/attachments/247338197921693697/290390778675462145/df213772-f241-43f4-b4f7-8f4c167e03a6.jpg

[LewisM]

The 2 larger central ones are the original ones - someone modified those, as well as adding the other 4. Remove the 4 added screws, and use the 2 larger central ones.

[LewisM]

Here is what an original Tak hole spacing looks like (some had this central smaller hole, most dont)

[LewisM]

Some more help, using the system I already mentioned (a Vixen dovetail system):

https://www.google.com.au/imgres?imgurl=http%3A%2F%2Fwww.clou dynights.com%2Fuploads%2Fmonthly_07 _2016%2Fpost-44172-0-01889000-1467422571.jpg&imgrefurl=http%3A%2F%2Fwww.cloudyni ghts.com%2Ftopic%2F542192-mounting-plate-for-a-tak-100-dl%2F&docid=HOp0x0NbJ4sN_M&tbnid=NIFIyUfaYSlbuM%3A&vet=10ahUKEwjSh8_y2fPSAhVPHGMKHSk_A kYQMwgdKAIwAg..i&w=1113&h=849&itg=1&bih=759&biw=1536&q=Tak%20clamshell&ved=0ahUKEwjSh8_y2fPSAhVPHGMKHSk_Ak YQMwgdKAIwAg&iact=mrc&uact=8#h=849&imgrc=NIFIyUfaYSlbuM:&vet=10ahUKEwjSh8_y2fPSAhVPHGMKHSk_A kYQMwgdKAIwAg..i&w=1113

and

https://www.google.com.au/imgres?imgurl=http%3A%2F%2Fwww.clou dynights.com%2Fuploads%2Fmonthly_07 _2016%2Fpost-44172-0-02504300-1467422560.jpg&imgrefurl=http%3A%2F%2Fwww.cloudyni ghts.com%2Ftopic%2F542192-mounting-plate-for-a-tak-100-dl%2F&docid=HOp0x0NbJ4sN_M&tbnid=w5hUQnP1hSdgCM%3A&vet=10ahUKEwjSh8_y2fPSAhVPHGMKHSk_A kYQMwgcKAEwAQ..i&w=1050&h=972&itg=1&bih=759&biw=1536&q=Tak%20clamshell&ved=0ahUKEwjSh8_y2fPSAhVPHGMKHSk_Ak YQMwgcKAEwAQ&iact=mrc&uact=8#h=972&imgrc=w5hUQnP1hSdgCM:&vet=10ahUKEwjSh8_y2fPSAhVPHGMKHSk_A kYQMwgcKAEwAQ..i&w=1050

[Stardrifter_WA]

Try Saxon, may have what you want

http://www.saxon.com.au/accessories/accessories-tube-rings.html

[Lognic04]

Hey LewisM, where would i find a screw to go in those two holes?

[Lognic04]

and where would i get a dovetail for a tak clamshell in AU?

[LewisM]

You can use a standard Vixen dovetail - comes with 99% of scopes on the planet, and can be obtained from bintel.com.au, myastroshop.com.au and others. As can the Losmandy plates.

What mount is it going on?

As to SPECIFIC Tak designed plates, no, you'll have to import one from Farpoint or others.

I have specifically custom made screws as I mentioned before.

[Lognic04]

I will use the vixen dovetail, thanks. one thing i have noticed though, is the upper screw of the two has been modified a lot and is more pear shaped, bit it shouldnt matter with a big enough nut. it is going on an eq6 (when i find a cheap one on IIS :P)

[Lognic04]

Would this work: https://www.bintel.com.au/product/losmandy-vixen-universal-plate-4-inch/

[LewisM]

Yes, but I think you'd want a longer one like the astroshop one I linked to - easier in balancing.

As to the mount for the MT-160 - a Skywatchr HEQ5 is sufficient if using DSLR and is a BETTER mount in some ways (reports of better accuracy and tracking compared to the NEQ6 abound)

[Lognic04]

My only problem is, i cant upgrade to a bigger scope if i wanted to. Its sort of a dilemma, because i would want to upgrade to a c14 or 12, but an eq6 probably couldnt carry that load. an eq5 for imaging even?

[Windston]

For imaging on an NEQ6, a C14 would really be pushing it, so would a C11, you are better off sticking under 2000mm, and under f8. A RC10 would be the biggest I would put on a NEQ6 for imaging.

Also SCTs arnt the best choice for DSO astrophotography, unless you are doing planetary or visual, and RC or larger newtonian is a better idea. :D

[LewisM]

Dan is pretty spot on.

When you want to sell the MT160, drop me a line :)

[Lognic04]

you really want that scope lewis! lol will do.

[doppler]

You can get various sized strips of hi density rubber from clark rubber(bought by the meter). I used some 25mm x 10mm thick rubber to pad out the rings on my 10" skywatcher, then glued some felt on top of that so the tube would slide for easier balancing.

[Lognic04]

Hey LewisM, apparently my scope is 12 kgs, so i dont think i could use an eq5.

[Lognic04]

what does everyone think, eq6 for sure? for imaging and visual, at f5 to f8