DIY Dob Mount for Skywatcher 200p... can I?

[perkil8r]

Been the proud owner of a second had Skywatcher 200p with eq5 mount since last weekend. I am Okay with it all so far, made a few tweeks here and there after some studying on the net to improve the focuser and mount a bit. I like it, but..... (there's always a but )

I'm a bit concerned that for a quick session it seems like a lot of hassle to set up the EQ5 although I have now set block pavers and marked out to make setting up easier. I'm thinking since it's not very good for viewing due to cloud cover, maybe I should attemp to make a dob mount? The thinking is that it will be quicker to set up for a quick session, and also means I can go to any old site and set up in a few mins and get searching for the jewels in the sky.

I see with most 200's etc on dobs they have what appear to be handles on the side of the OTA, mine obviously has the mounting rings and dove tail bar thing on it. Should I try and make something to attatch to the dove tail which then comes around the sides to make something similar to the "handles" or is there more to it than that? Has anybody done this before? Is it a good idea? Are there any usefull plans or pages somewhere where I might get all the information I need?

I'm quite willing to make stuff, I am afterall an ex-mechanical engineer, so I can make things with metal or wood. I can weld if needs be, I just don't know enough about scopes in the first place, let alone building a new mount for one lol. Any pointers, drawings, advice or pictures very much appreciated

[ismangil]

This might give some ideas:

http://stellafane.org/tm/dob/index.html

[Carbon Brush]

Don't give up on the EQ5.

Do the minimum of dismantling when you put it away. You might even forget the eyepiece tray which improves rigidity.

For visual use, you can throw it on the ground sort of levelish and sort of northish without any real care. It will perform well enough.

Balancing only takes a minute.

But making a dob mount is easy enough if you a practical. I would suggest buying another pair of tube rings and making a link plate. This fastens to the "handles" you have seen on the dob base.

The benefits here are:

1/ You can easily swap the tube between dob & EQ mount.

2/ You can move the tube up/down in the dob holder to get best balance for the (maybe heavy) eyepiece in use.

[perkil8r]

I've not given up on the EQ5 at all, just thinking it might be nice to be able to use it on a dob from time to time, or for instance take it to my parents to show the old man or pop over into the peaks. The EQ5 is a bit of a hassle what with all the weights and so on. Just thinking about speed and ease in such circumstances.

[Gina]

Sounds good to me If your father is at all interested in the night skies I think that would be a lovely thing to do

[Coco]

For an ex mechanical engineer building a scope buggy should be simple.. I knocked one up in 2 hours.. Buggy wheels from eBay £20 (4 wheels! ) tube sizes drawn then cut to size at the sheet metal suppliers £30 if I needed it welded by them it would have cost an extra £45 , I have a mig welder so it cost less than £60 including large hammerite radiator enamel spray paint..

http://stargazerslounge.com/diy-astronomer/138969-scope-buggy-power-supply.html

When the clouds break simply wheel it out from under cover ... Alternatively make a scope coat and leave it out after work ready... Put it away last thing.. You can put one of those cheap alarms on it for security if your garden or area isn't secure..

[swamp thing]

For an ex mechanical engineer building a scope buggy should be simple.. I knocked one up in 2 hours.. Buggy wheels from eBay £20 (4 wheels! ) tube sizes drawn then cut to size at the sheet metal suppliers £30 if I needed it welded by them it would have cost an extra £45 , I have a mig welder so it cost less than £60 including large hammerite radiator enamel spray paint..

http://stargazerslounge.com/diy-astronomer/138969-scope-buggy-power-supply.html

When the clouds break simply wheel it out from under cover ... Alternatively make a scope coat and leave it out after work ready... Put it away last thing.. You can put one of those cheap alarms on it for security if your garden or area isn't secure..

Very nice, ideal for the garden, but I cannot see him towing that to his fathers house or over to the Peaks.

For portability a Dob is much easier.

Regards Steve

[JamesF]

i'm very tempted to make a dob base for my 200P so I can use it if the EQ6 is, say, being used for imaging using another scope. I've not come up with a neat solution for mounting it both in the EQ6 saddle and in a cradle for the dob yet though. Just as well I'm not in a desperate hurry.

Lovely scope buggy though, Guy. Very impressive. All it needs is a tow hitch and it would make a great "grab'n'go"

James

[Rusty Strings]

I built a dob mount for my 200p for exactly the same grab n go reasons. I mount the alt bearings on each side of the tube rings were the dovetail bolts on.

[perkil8r]

I built a dob mount for my 200p for exactly the same grab n go reasons. I mount the alt bearings on each side of the tube rings were the dovetail bolts on.

Wow, that looks good! Don't s'pose you'd have a few more pictures so I can see how it's all done? What bearings/bearing materials did you use?

[Coco]

I built a dob mount for my 200p for exactly the same grab n go reasons. I mount the alt bearings on each side of the tube rings were the dovetail bolts on.

John that looks brilliant

I'd like some more images..

[JamesF]

Yes, please, more images. That looks lovely.

James

[SplintUK]

I want one. Why isn't somebody manufacturing these?

[Moonshane]

here's my threads which show detail of a 6" dob and a 16" dob base that I made - I go on a bit. I have basic/average DIY skills and bought a router and a jigsaw (never really used either before this) which have come in handy for other things since. if you can borrow these even better.

http://stargazerslounge.com/diy-astronomer/140533-16-f4-orion-optics-uk-dobsonian-project.html

http://stargazerslounge.com/diy-astronomer/144997-home-made-dobsonian-base.html

[JamesF]

I had your 6" dob base in mind, Moonshane. That's partially the reason for asking for more photos -- it's good to see how different people approach things different ways.

James

[Moonshane]

defo James

I often see other peoples' designs and think oh, yeah, of course!!

whichever way you go, my main advice would be bearings (alt and az) of approx the same size and not less than 12" diameter. makes for a much more stable mount and even motion.

[Rusty Strings]

I agree with the above advice on the alt bearing. The originals on mine were plastic drain stoppers from a builders merchant. They were about 4" in diameter and while they were fitted I had the usual dob balance issues and it was never very smooth. So, I made the far bigger birch ply ones, 16" diameter, lined with laminate and the balance problems have gone and it moves like a dream.

The rest of the mount is made from 3/4" MDF. I do have access to a workshop with a table router so building it wasn't to tricky once the design was finalised.

The original azimuth bearing was a 12" LP and 3mm PTFE squares which was later replaced with a sheet of ebony star lumpy laminate and bigger PTFE squares and is much smoother.

What would I do different? Make it entirely out of birch ply as the MDF is unnecessarily heavy.

As requested, so more images. The first few are with the original alt bearings.

[jimmyjamjoejoe]

What was the LP?

[Peter Drew]

An easier but less elegant method is to make an open ended square box with triangular internal strengthening gussets and a removable top face. The Dob altitude rings are easily fitted to the sides. Just take the top off, drop the OTA in and replace the "lid", a bit of foam rubber or felt will give enough grip.

[perkil8r]

Superb. Thanks very much, certainly given me some ideas to go off. I think I am going to design a mongrel from a few of the above ideas. Certainly looks easy enough and a lot simpler than I had originally thought, especially the bearings. Would adjustable feet be an advantage or a hinderance?

[Moonshane]

might be worth it but may also reduce stability. mine are fixed

[Rusty Strings]

The feet on mine are adjustable so the mount is level when I use it with the wixey angle gauge.

[perkil8r]

I'm thinking if I do this (which I intend to, but how soon is another question) I intend on fixing a compass and a level to the base. I'm thinking adjustable feet, but the Jury is still out on that. On the subject of the az bearing, I am thinking of using 2 rings of teflon or nylatron (sp) is there any important reason for not using 2 complete rings instead of squares set in 3 or more positions around the dia?

[JazzyF]

Thank you perkil8r so much for this post. I registered because of it, and the inspiring replies, so thank you all. Especially to John (Rusty), as like the OP, I have a 200PDS OTA coming from  astroboot which was a very good price and if you don't mind John, I will be copying your design for a dob mount for it. I hope that's allowed :-)

Jim