Study for a 203x1000 newtonian dobsonian base

[N3ptune]

This thread is experimental, because it's impossible for me now to assess how serious I am about building my own Dobsonian base for my current 203x1000. My goal would be to have a fast option to get out when the sky is medium only, EQ5 is bad at that, Dobson should be far better to move 360 degrees around at will to easily escape the clouds. That's my goal. 

I can see me using the device... but there is a courage problem

- I would like to have quality "Alt" rotation at the base, the scope has to be stable at the base, not wobbly, and it has to have a minimum of resistance, friction. There is the lazy Suzan option or another odd option using a vinyl record, which one is best?

- I would like to keep my existing rings and dovetail on the scope, they always remain on the scope. It's really important not to add anymore procedure when it's time to choose between EQ5 or DOB  so it's possible to simply take the bag with the scope and rings inside and then put the scope either on the EQ5 or on the DOB. Can it be done? I believe so... with a level of difficulties probably, but especially scared about the balancing part. (This technique would spare me from buying a new set of rings for the dob too)

- The "azimutal" part has to be solid and the scope well balanced too, really smooth and very well balanced. I don't want the instrument to fall on the floor.

I am intimidated a bit..

[DRT]

Whilst this sounds like an interesting project I doubt that you will find a solution that meets all of your success criteria that would be cheaper than just buying on of these:

https://www.firstlightoptics.com/dobsonians/skywatcher-skyliner-200p-dobsonian.html

 

[N3ptune]

Yeah that's an option, for a used one maybe, but they are almost 600$ cad here now, years after years chinese are getting better salary.

[Chris]

It can be done, as you know I've built a Dob base for a 150p f/5. I used a vinyl record for the azimuth bearing, it's almost tradition to use a space themed record such as Pink Floyd, Dark side of the Moon  The record works ok but I think a lazy Susan would be better as people seem to upgrade to this.

Going from an EQ5 to Dob base and back and fourth could be done, but you would have to accept the alt bearings being stuck to the rings, so maybe bolt a dovetail 90 degrees to these for using the EQ5, might look a bit odd but should be ok.

If I can find my build thread I'll link it to you  

Good luck with the project if you pluck up the courage, anyone can to anything given enough time I feel, that's how I get by  

[N3ptune]

13 hours ago, Lockie said:

It can be done, as you know I've built a Dob base for a 150p f/5. I used a vinyl record for the azimuth bearing, it's almost tradition to use a space themed record such as Pink Floyd, Dark side of the Moon  The record works ok but I think a lazy Susan would be better as people seem to upgrade to this.

Going from an EQ5 to Dob base and back and fourth could be done, but you would have to accept the alt bearings being stuck to the rings, so maybe bolt a dovetail 90 degrees to these for using the EQ5, might look a bit odd but should be ok.

If I can find my build thread I'll link it to you  

Good luck with the project if you pluck up the courage, anyone can to anything given enough time I feel, that's how I get by  

Hello Lockie thanks for your ideas and support.

I think a Lazy Suzan should be less expensive then a Pink Floyd vinyl nowadays I need to call my local bearing store to see their inventory and prices. I would be interested to see you base too especially the 2 white pads red arrow, are they plastic or Teflon ?  And what about the interior, there must be some kind of clip on the inside to prevent the wheels from falling sideways? If you have a picture of the inside could be interesting to see.

Thanks.

 

[Chris]

Hi, the white pads are Teflon, I bought quite thick Teflon so I could easily countersink the screw heads which attach them.

Yes there are just a couple of pegs on the inside to keep the bearings running true, but you could also have them on the outside, I just put them on the inside for neatness. 

Sadly I don't have any more pics that I can find, I sold the scope when the next project idea popped into my mind....I do stupid things like that unfortunately.

[N3ptune]

@Lockie ok. 

- I just bid on a 8" skyliner 200p, about 5 minutes ago   for fun.  To see if life wants me to get a second telescope for a descent price. Where did you bough your tefflon strips Lockie?

 

[N3ptune]

I offered 200$ for this kit, I am waiting for a report on the condition of the mirrors and overall mechanic.

Thoughts?

https://www.kijiji.ca/v-passe-temps-bricolage/longueuil-rive-sud/telescope-8-sur-base-dobsonienne/1283701287

[N3ptune]

My Dobson project is having a little boost today, I measured my telescope with precision and I want to build a base around the dovetail and the rings, I have some ideas. I will put the progress of my conception in here and we will see what happens. This is my work so far no Dobson yet. 

[N3ptune]

Has anyone tried this kind of Lazy Suzan before and are they good? stable?

https://www.amazon.ca/Shepherd-Hardware-9549-1000-Lb-Capacity/dp/B00004YOKA/ref=sr_1_9?ie=UTF8&qid=1502660144&sr=8-9&keywords=lazy+susan

[brantuk]

I made the parts and built a rocker box similar to this one: http://dobstuff.com/lbrockerbox.htm

It's really quite easy - I recommend using 18 plyboard with teflon pads and a formica running track for the az axis (I used a circular bottom board). An M8 or M10 bolt through the middle will provide a solid joint and easy adjustment. You can use the furry side of velcro for the alt axis. Cutting the alt axis is the hardest part - I routed a hole of the correct diameter dead center of a measured board - then cut it in two identical parts. Hth

 

[mapstar]

6 hours ago, brantuk said:

I made the parts and built a rocker box similar to this one: http://dobstuff.com/lbrockerbox.htm

It's really quite easy - I recommend using 18 plyboard with teflon pads and a formica running track for the az axis (I used a circular bottom board). An M8 or M10 bolt through the middle will provide a solid joint and easy adjustment. You can use the furry side of velcro for the alt axis. Cutting the alt axis is the hardest part - I routed a hole of the correct diameter dead center of a measured board - then cut it in two identical parts. Hth

 

First pics I've seen of your base and it looks just the job 

[N3ptune]

@brantuk very interesting concept with the formica and tefflon pads, I will consider this option over a lazy suzan, it can be done easily and we have Formica scrap parts at the job too. (: thanks for sharing

[brantuk]

1 hour ago, mapstar said:

First pics I've seen of your base and it looks just the job 

Thanks Damian - I have all the pics for a build thread but, would you believe, it's not totally finished yet lol. Just needs the alt brake install plus priming and painting (same colour as my red moonlight focuser upgrade), but not had chance to do it yet due to illness. It works very nicely though - dead smooth and super lightweight.

1 hour ago, N3ptune said:

@brantuk very interesting concept with the formica and tefflon pads, I will consider this option over a lazy suzan, it can be done easily and we have Formica scrap parts at the job too. (: thanks for sharing

You're welcome N3ptune - if you need help sourcing any of the bits let me know and I'll post up some links. Some of my astro club mates have used the lazy susan method (particularly on smaller dobs) and it works very well too - but once you get up to 16"+ dia mirrors things start to get heavy and formica/teflon provides a more controllable and solid solution (imho).

[N3ptune]

12 hours ago, brantuk said:

Thanks Damian - I have all the pics for a build thread but, would you believe, it's not totally finished yet lol. Just needs the alt brake install plus priming and painting (same colour as my red moonlight focuser upgrade), but not had chance to do it yet due to illness. It works very nicely though - dead smooth and super lightweight.

You're welcome N3ptune - if you need help sourcing any of the bits let me know and I'll post up some links. Some of my astro club mates have used the lazy susan method (particularly on smaller dobs) and it works very well too - but once you get up to 16"+ dia mirrors things start to get heavy and formica/teflon provides a more controllable and solid solution (imho).

I am interested in you brake concept @brantuk  It would be a great option for the tube pivot axis, to secure the position.

These images are my daily progress, it's a container capable of holding the scope with the rings and dovetail (my scope is stored with the rings inside it's bag, for the EQ5) I am trying to figure out what part to use in order to lock the top holder (H shape) on one side, maybe some kind of special clips like those found on a toolbox or something else.

The Formica and pads seems like a better idea then they Lazy Suzan, I think they would provide a better stability with the center bolt and the pads, more precision too.

 

 

[brantuk]

I find that with the alt brake, it will work much better if the scope is properly balanced first. Then you only need the minimum of friction to lock and hold it in place. My rebuild was for a Lightbridge rocker box, so fortunately I have a brake which I just transferred from the original box to the new one. However - if you look at that "dobstuff" link I provided above - there's a design for a simple brake right at the bottom of the page.

That's an interesting design for the tube holder - very elaborate. Another way to do it might be to bolt a dovetail to the top and bottom of the tube rings then fix a circular wooden alt axis to each dovetail - just an idea, but it'd be a lot less work.

[dyfiastro]

I am in the process of building a basic dob mount for an 203/1000 as well.
I wanted something that I could use away from home but easy enough to convert back for obsy use.
Here is the basic design that I went with, the entire thing was put together using off-cuts from old bits of furniture etc...

I am just in the process of painting it all up but pretty happy with the result.
I went for the traditional record for the azimuth bearing due to having a scratched one laying around. a better alternative may be added later if required.
The Alt bearings are drainage pipe end caps that bolt directly to the the scope rings.
In total the entire thing has cost me about £9 and the base can be moved in one piece or split if required.

[N3ptune]

14 hours ago, brantuk said:

I find that with the alt brake, it will work much better if the scope is properly balanced first. Then you only need the minimum of friction to lock and hold it in place. My rebuild was for a Lightbridge rocker box, so fortunately I have a brake which I just transferred from the original box to the new one. However - if you look at that "dobstuff" link I provided above - there's a design for a simple brake right at the bottom of the page.

That's an interesting design for the tube holder - very elaborate. Another way to do it might be to bolt a dovetail to the top and bottom of the tube rings then fix a circular wooden alt axis to each dovetail - just an idea, but it'd be a lot less work.

Oh ok I see the brake concept there coming from dubstuff, it gives me ideas. My concept clearly is complex compare to what I see, all that because, I want to keep the rings and dovetail on the tube. Your option to use a second dovetail on the top could work to.

5 hours ago, dyfiastro said:

I am in the process of building a basic dob mount for an 203/1000 as well.
I wanted something that I could use away from home but easy enough to convert back for obsy use.
Here is the basic design that I went with, the entire thing was put together using off-cuts from old bits of furniture etc...

I am just in the process of painting it all up but pretty happy with the result.
I went for the traditional record for the azimuth bearing due to having a scratched one laying around. a better alternative may be added later if required.
The Alt bearings are drainage pipe end caps that bolt directly to the the scope rings.
In total the entire thing has cost me about £9 and the base can be moved in one piece or split if required.

Nice nice, good work, but I see your tube is supported by only 1 ring, there is no visible stress on the tube? Otherwise it's a nice piece of gear, simple and inexpensive, wise.

[dyfiastro]

1 minute ago, N3ptune said:

Oh ok I see the brake concept there coming from dubstuff, it gives me ideas. My concept clearly is complex compare to what I see, all that because, I want to keep the rings and dovetail on the tube. Your option to use a second dovetail on the top could work to.

Nice nice, good work, but I see your tube is supported by only 1 ring, there is no visible stress on the tube? Otherwise it's a nice piece of gear, simple and inexpensive, wise.

Thanks
This is very much still in the beginning stages but Looking at the standard 200p dobs there only seems to be a single point of contact as well. I do intend using at least one more and maybe 2 more if I can get some cheap enough.
The extra rings will also then be used as stoppers so I am able to rotate the tube easier without altering the pivot / balance point.
The tube ota in the photo has gone back to my mate and I am waiting for mine to arrive, once its here I will be able to progress further.

[N3ptune]

25 minutes ago, dyfiastro said:

Thanks
This is very much still in the beginning stages but Looking at the standard 200p dobs there only seems to be a single point of contact as well. I do intend using at least one more and maybe 2 more if I can get some cheap enough.
The extra rings will also then be used as stoppers so I am able to rotate the tube easier without altering the pivot / balance point.
The tube ota in the photo has gone back to my mate and I am waiting for mine to arrive, once its here I will be able to progress further.

Good ill be please to follow your project here, we will make this thread very rich in information. (; Has for me, I am launching the 3D software right now and ill be modelling another even more complex idea.

I invented my own rotating ring too for the 200p, so far it's really really really useful and working very well.

https://drive.google.com/open?id=0B0OZ0oXfzDlFSG1FMUZoV2RDTk0

 

[N3ptune]

Tonight I modified the width of the wood to reduce the size of my box.. has much has possible. Also i started to think about the base and I came up with a a strong shape. The name of the project is :

N3ptune's secure Dobson base (For the skywatcher 200p)

The goal is to be able to swap from the Dobson mount to the Equatorial mount without removing the rings and dovetail on and off the tube, the rotation of the tube should be possible too. I think the conception has some interesting safety features or potential too. (; 

[N3ptune]

I woke up this morning and this Dobson project is over.

I just can't visualize me using it for the following reasons:

#1. The first one being, this device has no tracking capabilities and this is not very good for sketching. An equatorial platform isn't an interesting option for me either.

#2. The box is big, heavy and will take too much space inside the house. Especially for a second mount.

#3. It's too much things to handle to go outside and I need a special Dobson chair too which are expensive and another thing I don't want to store at home.

If i can pick another smaller telescope for guest like 127mm - 130mm, then I will build a smaller Dobson mount for it but I am giving up for the 203mm. 

Thanks for your help here and see you here later! (for a smaller project)

[DRT]

I use the OTA from my 12" F4 Dob on a Skywatcher AZ-EQ6 in Alt-Az mode. The mount copes with it well but the eyepiece can be quite high when pointing near zenith.

Worth considering?

[N3ptune]

5 hours ago, DRT said:

I use the OTA from my 12" F4 Dob on a Skywatcher AZ-EQ6 in Alt-Az mode. The mount copes with it well but the eyepiece can be quite high when pointing near zenith.

Worth considering?

That is a very nice setup, with this massive tube you must capture some very nice DSO details and a lot of faint stars, very nice. But do I understand what I see? (not sure) You have wheels attached on both sides of the rings, maybe to install on a Dobson mount and there should be a dovetail bolted on one ring to be able to mount the tube on the AZ-EQ6?

Are these wheels made of alloy?

 

 

[DRT]

Yes, the tube rings and the bearing rings are part of the Dobsonian mount. There is a Losmandy plate attached to the ring that is attached to the AZ-EQ6.

You can see the Dob mount here: http://www.orionoptics.co.uk/MOUNTS/dobsonianmount.html