SLIGHT WOBBLE ON ORION XT8 DOBSONIAN MOUNT?

I have just purchased an Orion SykQuest IntelliScope XT8 Dobsonian
telescope. It seems excellent and I know that it is recommended by
many for beginners such as myself. Yesterday I assembled it. The only
question arising so far is what is the allowable wobble between the
two baseplates; namely the top baseplate and the ground baseplate?
When I hold the top baseplate perfectly horizontal, there is a small
gap between the bottom of the top baseplate and the tops of the three
Teflon bearing pads on the ground baseplate. This leads to a small
amount of wobble in the top baseplate and the supported telescope. I
have followed the assembly instructions rigorously, for example the
brass bushing on the azimuth axis screw sits in the hole on the
azimuth encoder disk and the brass bushing extends slightly above the
top surface of the top baseplate. I note that the top fender washer on
the axis screw sits on top of the brass bushing and not over it as the
hole in the washer is not big enough to accomodate the brass bushing.
The top fender washer is thus not applying any appreciable direct
pressure on the top surface of the top baseplate. Maybe this slight
wobble is how it should be, but everything I read about Dobsonians
tells me that they are incredibly stable. Any advice would be much
appreciated. Very many thanks.

Sounds like you got a washer that's to small, should be able to get a better
fitting one at a hardware store.


--


"And for the second time in four million years, the monolith awoke."
Arthur C.Clarke 2062dyssey three

SIAR
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Telescope Buyers FAQ
http://home.inreach.com/starlord
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"Jan Drozd" wrote in message
m...
I have just purchased an Orion SykQuest IntelliScope XT8 Dobsonian
telescope. It seems excellent and I know that it is recommended by
many for beginners such as myself. Yesterday I assembled it. The only
question arising so far is what is the allowable wobble between the
two baseplates; namely the top baseplate and the ground baseplate?
When I hold the top baseplate perfectly horizontal, there is a small
gap between the bottom of the top baseplate and the tops of the three
Teflon bearing pads on the ground baseplate. This leads to a small
amount of wobble in the top baseplate and the supported telescope. I
have followed the assembly instructions rigorously, for example the
brass bushing on the azimuth axis screw sits in the hole on the
azimuth encoder disk and the brass bushing extends slightly above the
top surface of the top baseplate. I note that the top fender washer on
the axis screw sits on top of the brass bushing and not over it as the
hole in the washer is not big enough to accomodate the brass bushing.
The top fender washer is thus not applying any appreciable direct
pressure on the top surface of the top baseplate. Maybe this slight
wobble is how it should be, but everything I read about Dobsonians
tells me that they are incredibly stable. Any advice would be much
appreciated. Very many thanks.


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Thanks for this advice. I will check this out tomorrow (it is late
evening here in UK), but I am not sure it is the problem (if indeed
there is a problem). I also understand that there is a Yahoo forum for
these type of scopes. I will also check this out. I have also sent
request to technical help at Orion. Many thanks.


"starlord" wrote in message ...
Sounds like you got a washer that's to small, should be able to get a better
fitting one at a hardware store.


--


"And for the second time in four million years, the monolith awoke."
Arthur C.Clarke 2062dyssey three

SIAR
http://starlords.netfirms.com
Telescope Buyers FAQ
http://home.inreach.com/starlord
Bishop's Car Fund
http://www.bishopcarfund.netfirms.com/

"Jan Drozd" wrote in message
m...
I have just purchased an Orion SykQuest IntelliScope XT8 Dobsonian
telescope. It seems excellent and I know that it is recommended by
many for beginners such as myself. Yesterday I assembled it. The only
question arising so far is what is the allowable wobble between the
two baseplates; namely the top baseplate and the ground baseplate?
When I hold the top baseplate perfectly horizontal, there is a small
gap between the bottom of the top baseplate and the tops of the three
Teflon bearing pads on the ground baseplate. This leads to a small
amount of wobble in the top baseplate and the supported telescope. I
have followed the assembly instructions rigorously, for example the
brass bushing on the azimuth axis screw sits in the hole on the
azimuth encoder disk and the brass bushing extends slightly above the
top surface of the top baseplate. I note that the top fender washer on
the axis screw sits on top of the brass bushing and not over it as the
hole in the washer is not big enough to accomodate the brass bushing.
The top fender washer is thus not applying any appreciable direct
pressure on the top surface of the top baseplate. Maybe this slight
wobble is how it should be, but everything I read about Dobsonians
tells me that they are incredibly stable. Any advice would be much
appreciated. Very many thanks.


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.779 / Virus Database: 526 - Release Date: 10/19/04

The only
question arising so far is what is the allowable wobble between the
two baseplates; namely the top baseplate and the ground baseplate?

None.

When I hold the top baseplate perfectly horizontal, there is a small
gap between the bottom of the top baseplate and the tops of the three
Teflon bearing pads on the ground baseplate.

Snug the center bolt up until the two surfaces mate properly, if it gets to
tight back it off a bit. Some people add a center "bearing" cut from stacked
milk carton "washers. I did a sweet mod on my XT-8. My Starsplitter 10" uses
FRP for for bottom bearing that rides on the teflon. I had a construction
frined cut me a round, I drilled holes where the three bolts pass through the
base and for the center post and glued it on with contact cement. Now it is as
smooth in AZ as the starsplitter is. I'd like to find a way to get the ALT axis
moving more smoothly now. It would be perfect then.
rat
~( );

email: remove 'et' from .com(et) in above email address

Very many thanks for this useful information. However, as I have the
XT8 IntelliScope with the azimuth encoder board and disk between the
ground and top baseplates I think that one solution for this set-up
may be to increase the height of the three Teflon bearing pads,
perhaps by putting a shim of some sort under each bearing pad, or
getting thicker bearing pads.

t (Ratboy99) wrote in message ...
The only
question arising so far is what is the allowable wobble between the
two baseplates; namely the top baseplate and the ground baseplate?

None.

When I hold the top baseplate perfectly horizontal, there is a small
gap between the bottom of the top baseplate and the tops of the three
Teflon bearing pads on the ground baseplate.

Snug the center bolt up until the two surfaces mate properly, if it gets to
tight back it off a bit. Some people add a center "bearing" cut from stacked
milk carton "washers. I did a sweet mod on my XT-8. My Starsplitter 10" uses
FRP for for bottom bearing that rides on the teflon. I had a construction
frined cut me a round, I drilled holes where the three bolts pass through the
base and for the center post and glued it on with contact cement. Now it is as
smooth in AZ as the starsplitter is. I'd like to find a way to get the ALT axis
moving more smoothly now. It would be perfect then.
rat
~( );

email: remove 'et' from .com(et) in above email address

The problem appears to have been solved. Orion technical support in
the USA has been incredibly helpful, a really first class plus
service, and sent three shims to me here in England. I have put these
under the three Teflon pads and the wobble seems to have gone. All
else seems to be working fine.
Jan

(Jan Drozd) wrote in message om...
Very many thanks for this useful information. However, as I have the
XT8 IntelliScope with the azimuth encoder board and disk between the
ground and top baseplates I think that one solution for this set-up
may be to increase the height of the three Teflon bearing pads,
perhaps by putting a shim of some sort under each bearing pad, or
getting thicker bearing pads.

t (Ratboy99) wrote in message ...
The only
question arising so far is what is the allowable wobble between the
two baseplates; namely the top baseplate and the ground baseplate?

None.

When I hold the top baseplate perfectly horizontal, there is a small
gap between the bottom of the top baseplate and the tops of the three
Teflon bearing pads on the ground baseplate.

Snug the center bolt up until the two surfaces mate properly, if it gets to
tight back it off a bit. Some people add a center "bearing" cut from stacked
milk carton "washers. I did a sweet mod on my XT-8. My Starsplitter 10" uses
FRP for for bottom bearing that rides on the teflon. I had a construction
frined cut me a round, I drilled holes where the three bolts pass through the
base and for the center post and glued it on with contact cement. Now it is as
smooth in AZ as the starsplitter is. I'd like to find a way to get the ALT axis
moving more smoothly now. It would be perfect then.
rat
~( );

email: remove 'et' from .com(et) in above email address