a dob mod of my own ?

[vindictive666 (John)]

hello all

i had to make a slight adjustment to my dobs movement the other day

i found out that ive got to have both of the springs on to have a smooth up and down motion if i try it with just the one it gets too easy to move the slightest breeze or touch will move it. (i dont know if there is an other thing i could try ?)

the next problem i had was the left and right movement (is or was a real pain)
it has a central bolt straight thru with washers and a lock nut. i had to tighten the nut so tight that it bent the wahers that came with it, that would last only a couple of rotations before even (yep) the lock nut came lose.
so i invested in a spring washer and new washers x2.
(my base is made up with the rollerbearing type plate)
and it seems to tighten up well now i havent had a chance to test it out observing yet Clouds and actually had some rain today (friday morning) so hopefully ive got a well behaved movement for now

also i have a question in regarding the up and down movement is there another adjustment i can make on the dob besides the tension springs ?

[rmcpb (Rob)]

One modification to the spring system is to try using some key rings between the springs and the attachment onto the base. If one spring is too loose and two too tight by effectively lengthening the springs using the keyrings the tension can be finely tuned to achieve a smooth motion. The jump from one spring to two is huge and very coarse.

Its a matter of trial and error to get it right but the system can be very finely tuned using this method.

As for the side to side motion, try using one of those teflon lock nuts instead of the spring washer. Again, it can be very finely tighened to the correct tension to allow easy movement with no slop and will not move once set.

Good luck.

[slice of heaven]

Theres a site for I found for mods for the gso scopes. Their selling them and they also have a link for gso dob mods. Dont know the link but the company was dba astronomy or db astronomy.I only buzzed through it quickly but there was suggestions on improving the dob's movement by using felt to firm up the movement. Do a search or if I find the link I'll let you know.They were selling the scopes as a brand called Hardin.


Geoff

[slice of heaven]

Found the link but how do I add it to a post.
Geoff

[vindictive666 (John)]

edit your post and copy and paste

or just put it in the quick reply

[slice of heaven]

http://www.speednetllc.com/dbaastron...ods%20fixs.htm

Thanks , I'm totally computer illiterate, thats why I have kids.

[vindictive666 (John)]

thanx slice
iam gonna save that page its whats iam after
iam going to see if my mods work first if not then ive more options

[Starkler (Geoff)]

For the altitude motion springs I used split rings as used on keychains. These I attached to the spring via a nylon cable tie.

It takes a bit of trial and error but I find that as the dynamic friction reduces with less spring pressure , the static friction doesnt appear to follow .

[ballaratdragons (Ken)]

Vin666,

I believe you have the same scope as me. GS 12" Deluxe Dobber.
The one with the Crayford focuser and cooling fan.

I have the correct Nylock nut (nylon locking insert) and I also use a spring washer which should not be necessary and yet the nut still comes loose turning the Azimuth anti-clockwise. You are not alone.

I also have to use both tension springs to stop any movement from the slightest touch!

I think these must be GS 12" bugs, but I am working on solutions. I will let you know if I find any easy fixes.

[vindictive666 (John)]

thanks bd

thatll be appreciated

have you checked the link earlier in this post ?

http://www.speednetllc.com/dbaastron...ods%20fixs.htm


has a coupe of good ideas

[RAJAH235]

Vin & Ken, I suggest you try 'Clear Nail lacquer' as a locktite type substitute, as well as the 'nylock nut'. It's cheaper. See pic. for another idea for your prob. re; the alt. brg. being too loose and not being able to adjust the springs correctly. A brake band, that is adjusted via the wing nut. I have to adjust mine when it gets wet or I use the big E/Pc.
HTH. L.

[bytor666]

I can say one thing about this. I also have a 12" gso scope . I use the tension springs along with 7 1/2 LBS of counterweights at the back end (underneath the tube,opposite the focuser and other heavy stuff,finderscope& telrad), plus I have just the bolt and a locking nut that reaches it with space to spare on the bolt and mine doesn't come loose no matter which way I turn it. I find that the tension springs work excellent when I switch from light to heavy eyepieces, and I also put magic supersliders in between the round pieces of wood on my dob mount. I then use a small amount of vasoline on the magic sliders to add just the right amount of "glide" when I turn the mount in azimuth.
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mark
12" gso scope