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Does anyone know of a source for undersized needle bearings to fix a
weakness in my Losmandy G11 mount? Specifically, 1.247" ID / 1.500 nominal
OD. For the benefit of those who may encounter the same problem, I have
described it below:

With a nominal vertical load, the RA and/or DEC shafts on my G11 mount tend
to 'hang' about .002"-.003" below the axis centerline when the clutches are
relaxed. When the clutches are tighten, the shaft end plate initially
'locks' to the nylon clutch surface slightly below center. When the axis is
rotated far enough that the weight overcomes the grip of the nylon surface,
the axis 'shifts' into a 'more' aligned position. This is normal behavior on
four different mounts that I have examined. Besides introducing tracking
errors, this misalignment distorts the worm/wheel spacing by a small amount,
and causes the backlash to vary as the axis is rotated through 360 degrees.
Changing the load on the mount, or loosening and retightening the clutches
can completely upset prior backlash adjustments. If you are not adjusting
your worm/wheel spacing for absolute minimum backlash, you may never
encounter this aspect of the problem.

The needle bearings on both the RA and DEC are set back about 2" from the
'business end' on each axis. As an experiment, I pressed an additional
1.250" ID needle bearing into the opening so that the shaft was supported
nearly to the end of the opening. Additionally, the shafts I have seen
measured 1.2470" dia instead of an optimal 1.250". I wrapped some .0015"
stainless steel shim stock around the undersized shafts as a temporary fix
to remove the bearing slop.

Well, it was like night and day. That simple change eliminated the
'shifting' on each axis, improved tracking and GOTO pointing accuracy
dramatically, there was no more slop in either axis, and best of all, the
backlash can be adjusted to virtually zero through a full 360 degrees of
rotation.

Anyone else have a similar experience?

Neal

--- In Losmandy_users@..., "Neal Barry" <nbarry@b...> wrote:

Does anyone know of a source for undersized needle bearings to fix a
weakness in my Losmandy G11 mount? Specifically, 1.247" ID / 1.500

nominal

OD. For the benefit of those who may encounter the same problem, I

have

described it below:

I wrapped some .0015"
stainless steel shim stock around the undersized shafts as a

temporary fix

to remove the bearing slop.

Well, it was like night and day. That simple change eliminated the
'shifting' on each axis, improved tracking and GOTO pointing

accuracy

dramatically, there was no more slop in either axis, and best of

all, the

backlash can be adjusted to virtually zero through a full 360

degrees of

rotation.

Anyone else have a similar experience?

Neal

I have the same problem with my G11 but only in the lower dec bearing
set (the upper set appear to be OK) The shaft is 1.250, but the ID of
the bearing set is oversized. The symptom is that I can slightly rock
the field of view by putting pressure on the OTA. This is
particularly
annoying at high power. The RA axis appears to be OK. It seems to be
an
ongoing variability in out of tolerance bearings. How old is your
mount?? And why isn't this caught by Losmandy??

I think QA may be an issue under backorder pressures to get the units
out. When I received my mount, the RA setting circle wouldn't rotate.
To make a long story short, disassembly of the RA axis revealed that
the nylon clutch washer was missing. This caused the setting circle
ring to be bound up. It seems to me that this should have been caught
by the most cursory of final inspections. Things like this don't
inspire confidence in an otherwise first rate product.

Bill

I talked to Scott losmandy today about these issues and he is aware of Neal's fix.Scott says the ra will seem better at those tolerances because the bearings are so close (short distance) but the slop in dec occurs because of the longer distance between bearings ie.smae angular shift but much less actual movement in ra at the end.Like shaking a shot stick vs a long one.
Scott says the bearing housing holes are not necessarily perfectly aligned.I gather they are bored separately from each end towards centre.As a result,two bearings with a little play still works but if a third was introduced not in reasonable alignment or if the two bearings were slightly out of line but zero slop the the shaft could torque and bind.
Scott told me that the worm and gear set should be capable of 2 to 3 arc secs of per and that the rest is cotributed by all the other parts in the system including this dec slop and to lesser extent ra slop.
My bearing guy looked at Neal's memo and some Losmandy drawings.He concluded that the easiest and best fit was to buid up the shaft to 1.50 with chrome.Then we'd have to make certain the setting circle gear and all the bearings will stil fit.
What I would love to find is if someone (California?)
with good hi tech machine shop could make us some sleeves,say titanium or nickle-chromium that are 1.247
id and 1.50 od and 1.5long so we could slide theseonto our shafts and into the needle bearings.The tolerance can be exact I'm told because unlike beraings that can be preloaded,the needle bearings have built in slack already.
(he also says we won't find a 1.247 bearing.)
I asked Scott if he had any ideas or would consider his shop doing hand fitted retros but he's no inclined.
I guess its up to us.
The other alternative is to machine out the bearing housing,buil new shafts and install better bearings at proper tolerances.
The saga continues.....keep looking to the stars

jimmy

From: "Bill Faatz" <faatz1@...>
Reply-To: Losmandy_users@...
To: Losmandy_users@...
Subject: [Losmandy_users] Re: G11 Fix - Source for undersize needle bearings?
Date: Tue, 15 Aug 2000 23:47:41 -0000

--- In Losmandy_users@..., "Neal Barry" <nbarry@b...> wrote:

Does anyone know of a source for undersized needle bearings to fix a
weakness in my Losmandy G11 mount? Specifically, 1.247" ID / 1.500

nominal

OD. For the benefit of those who may encounter the same problem, I

have

described it below:

I wrapped some .0015"
stainless steel shim stock around the undersized shafts as a

temporary fix

to remove the bearing slop.

Well, it was like night and day. That simple change eliminated the
'shifting' on each axis, improved tracking and GOTO pointing

accuracy

dramatically, there was no more slop in either axis, and best of

all, the

backlash can be adjusted to virtually zero through a full 360

degrees of

rotation.

Anyone else have a similar experience?

Neal

I have the same problem with my G11 but only in the lower dec bearing
set (the upper set appear to be OK) The shaft is 1.250, but the ID of
the bearing set is oversized. The symptom is that I can slightly rock
the field of view by putting pressure on the OTA. This is
particularly
annoying at high power. The RA axis appears to be OK. It seems to be
an
ongoing variability in out of tolerance bearings. How old is your
mount?? And why isn't this caught by Losmandy??

I think QA may be an issue under backorder pressures to get the units
out. When I received my mount, the RA setting circle wouldn't rotate.
To make a long story short, disassembly of the RA axis revealed that
the nylon clutch washer was missing. This caused the setting circle
ring to be bound up. It seems to me that this should have been caught
by the most cursory of final inspections. Things like this don't
inspire confidence in an otherwise first rate product.

Bill





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Losmandy_users-unsubscribe@...

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Hi Jimmy

Most of Scott's business comes from the movie industry - heavy duty
tripods for camera support, etc. The telescope mounts are a sideline
and because Scott is an observer himself. I would think the extra hours
required to hand fit mounts would cut into his real bread and butter
work.

Considering the difference in price points for Scott's mounts vs ( AP,
TAK, Mountain, Parallax ) as well as his primary business model, I am
not terribly surprised there is no time for fine fitting work.

-David

James,

Is it possible to find out what shim stock is needed to take up the play and instead of placing it
around the shaft, place it around the OD of the bearing and press the bearing into the housing. It
might squeeze the bearing enough to take up the play.

Don

I talked to Scott about that and he says the press fir of the bearings requires a press.It is tight.The issue is the bearing have play and with the built in .oo3 there's juust too much.

jimmy

From: "Donald J. D'Egidio" <djd52@...>
Reply-To: Losmandy_users@...
To: <Losmandy_users@...>
Subject: Re: [Losmandy_users] Re: G11 Fix - Source for undersize needle bearings?
Date: Wed, 16 Aug 2000 15:23:08 -0400

James,

Is it possible to find out what shim stock is needed to take up the play and instead of placing it
around the shaft, place it around the OD of the bearing and press the bearing into the housing. It
might squeeze the bearing enough to take up the play.

Don

----- Original Message -----
From: "James A. Thibert" <thibertj@...>
To: <Losmandy_users@...>
Sent: Wednesday, August 16, 2000 4:36
Subject: Re: [Losmandy_users] Re: G11 Fix - Source for undersize needle bearings?

I talked to Scott losmandy today about these issues and he is aware of
Neal's fix.Scott says the ra will seem better at those tolerances

because

the bearings are so close (short distance) but the slop in dec occurs
because of the longer distance between bearings ie.smae angular shift

but

much less actual movement in ra at the end.Like shaking a shot stick vs

a

long one.
Scott says the bearing housing holes are not necessarily perfectly

aligned.I

gather they are bored separately from each end towards centre.As a
result,two bearings with a little play still works but if a third was
introduced not in reasonable alignment or if the two bearings were

slightly

out of line but zero slop the the shaft could torque and bind.
Scott told me that the worm and gear set should be capable of 2 to 3 arc
secs of per and that the rest is cotributed by all the other parts in

the

system including this dec slop and to lesser extent ra slop.
My bearing guy looked at Neal's memo and some Losmandy drawings.He

concluded

that the easiest and best fit was to buid up the shaft to 1.50 with
chrome.Then we'd have to make certain the setting circle gear and all

the

bearings will stil fit.
What I would love to find is if someone (California?)
with good hi tech machine shop could make us some sleeves,say titanium

or

nickle-chromium that are 1.247
id and 1.50 od and 1.5long so we could slide theseonto our shafts and

into

the needle bearings.The tolerance can be exact I'm told because unlike
beraings that can be preloaded,the needle bearings have built in slack
already.
(he also says we won't find a 1.247 bearing.)
I asked Scott if he had any ideas or would consider his shop doing hand
fitted retros but he's no inclined.
I guess its up to us.
The other alternative is to machine out the bearing housing,buil new

shafts

and install better bearings at proper tolerances.
The saga continues.....keep looking to the stars

jimmy

From: "Bill Faatz" <faatz1@...>
Reply-To: Losmandy_users@...
To: Losmandy_users@...
Subject: [Losmandy_users] Re: G11 Fix - Source for undersize needle
bearings?
Date: Tue, 15 Aug 2000 23:47:41 -0000

--- In Losmandy_users@..., "Neal Barry" <nbarry@b...> wrote:

Does anyone know of a source for undersized needle bearings to fix a
weakness in my Losmandy G11 mount? Specifically, 1.247" ID / 1.500

nominal

OD. For the benefit of those who may encounter the same problem, I

have

described it below:

I wrapped some .0015"
stainless steel shim stock around the undersized shafts as a

temporary fix

to remove the bearing slop.

Well, it was like night and day. That simple change eliminated the
'shifting' on each axis, improved tracking and GOTO pointing

accuracy

dramatically, there was no more slop in either axis, and best of

all, the

backlash can be adjusted to virtually zero through a full 360

degrees of

rotation.

Anyone else have a similar experience?

Neal

I have the same problem with my G11 but only in the lower dec bearing
set (the upper set appear to be OK) The shaft is 1.250, but the ID of
the bearing set is oversized. The symptom is that I can slightly rock
the field of view by putting pressure on the OTA. This is
particularly
annoying at high power. The RA axis appears to be OK. It seems to be
an
ongoing variability in out of tolerance bearings. How old is your
mount?? And why isn't this caught by Losmandy??

I think QA may be an issue under backorder pressures to get the units
out. When I received my mount, the RA setting circle wouldn't rotate.
To make a long story short, disassembly of the RA axis revealed that
the nylon clutch washer was missing. This caused the setting circle
ring to be bound up. It seems to me that this should have been caught
by the most cursory of final inspections. Things like this don't
inspire confidence in an otherwise first rate product.

Bill





To unsubscribe from this group, send an email to:
Losmandy_users-unsubscribe@...

________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at




To unsubscribe from this group, send an email to:
Losmandy_users-unsubscribe@...

To unsubscribe from this group, send an email to:
Losmandy_users-unsubscribe@...

________________________________________________________________________
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Hello Everybody
I took 4 G11 R.A. axes and measured the movement. Then I placed a
3rd bearing in the housing and measured again. I all cases the
movement was cut in half.
Also, if you press the needle bearings in to tight, they will lock up.
Scott

--- In Losmandy_users@..., "James A. Thibert" <thibertj@h...>
wrote:

I talked to Scott about that and he says the press fir of the

bearings

requires a press.It is tight.The issue is the bearing have play and

with the

built in .oo3 there's juust too much.

jimmy

From: "Donald J. D'Egidio" <djd52@b...>
Reply-To: Losmandy_users@...
To: <Losmandy_users@...>
Subject: Re: [Losmandy_users] Re: G11 Fix - Source for undersize

needle

bearings?
Date: Wed, 16 Aug 2000 15:23:08 -0400

James,

Is it possible to find out what shim stock is needed to take up

the
play

and instead of placing it
around the shaft, place it around the OD of the bearing and press

the

bearing into the housing. It
might squeeze the bearing enough to take up the play.

Don

----- Original Message -----
From: "James A. Thibert" <thibertj@h...>
To: <Losmandy_users@...>
Sent: Wednesday, August 16, 2000 4:36
Subject: Re: [Losmandy_users] Re: G11 Fix - Source for undersize

needle

bearings?

I talked to Scott losmandy today about these issues and he is

aware of

Neal's fix.Scott says the ra will seem better at those

tolerances

because

the bearings are so close (short distance) but the slop in dec

occurs

because of the longer distance between bearings ie.smae angular

shift

but

much less actual movement in ra at the end.Like shaking a shot

stick vs

a

long one.
Scott says the bearing housing holes are not necessarily

perfectly

aligned.I

gather they are bored separately from each end towards

centre.As
a

result,two bearings with a little play still works but if a

third was

introduced not in reasonable alignment or if the two bearings

were

slightly

out of line but zero slop the the shaft could torque and bind.
Scott told me that the worm and gear set should be capable of 2

to 3 arc

secs of per and that the rest is cotributed by all the other

parts in

the

system including this dec slop and to lesser extent ra slop.
My bearing guy looked at Neal's memo and some Losmandy

drawings.He

concluded

that the easiest and best fit was to buid up the shaft to 1.50

with

chrome.Then we'd have to make certain the setting circle gear

and all

the

bearings will stil fit.
What I would love to find is if someone (California?)
with good hi tech machine shop could make us some sleeves,say

titanium

or

nickle-chromium that are 1.247
id and 1.50 od and 1.5long so we could slide theseonto our

shafts and

into

the needle bearings.The tolerance can be exact I'm told because

unlike

beraings that can be preloaded,the needle bearings have built

in
slack

already.
(he also says we won't find a 1.247 bearing.)
I asked Scott if he had any ideas or would consider his shop

doing hand

fitted retros but he's no inclined.
I guess its up to us.
The other alternative is to machine out the bearing

housing,buil
new

shafts

and install better bearings at proper tolerances.
The saga continues.....keep looking to the stars

jimmy

From: "Bill Faatz" <faatz1@l...>
Reply-To: Losmandy_users@...
To: Losmandy_users@...
Subject: [Losmandy_users] Re: G11 Fix - Source for undersize

needle

bearings?
Date: Tue, 15 Aug 2000 23:47:41 -0000

--- In Losmandy_users@..., "Neal Barry" <nbarry@b...>

wrote:

Does anyone know of a source for undersized needle bearings

to fix a

weakness in my Losmandy G11 mount? Specifically, 1.247" ID

/
1.500

nominal

OD. For the benefit of those who may encounter the same

problem, I

have

described it below:

I wrapped some .0015"
stainless steel shim stock around the undersized shafts as a

temporary fix

to remove the bearing slop.

Well, it was like night and day. That simple change

eliminated the

'shifting' on each axis, improved tracking and GOTO pointing

accuracy

dramatically, there was no more slop in either axis, and

best of

all, the

backlash can be adjusted to virtually zero through a full

360

degrees of

rotation.

Anyone else have a similar experience?

Neal

I have the same problem with my G11 but only in the lower dec

bearing

set (the upper set appear to be OK) The shaft is 1.250, but

the
ID of

the bearing set is oversized. The symptom is that I can

slightly rock

the field of view by putting pressure on the OTA. This is
particularly
annoying at high power. The RA axis appears to be OK. It seems

to be

an
ongoing variability in out of tolerance bearings. How old is

your

mount?? And why isn't this caught by Losmandy??

I think QA may be an issue under backorder pressures to get

the
units

out. When I received my mount, the RA setting circle wouldn't

rotate.

To make a long story short, disassembly of the RA axis

revealed
that

the nylon clutch washer was missing. This caused the setting

circle

ring to be bound up. It seems to me that this should have been

caught

by the most cursory of final inspections. Things like this

don't

inspire confidence in an otherwise first rate product.

Bill





To unsubscribe from this group, send an email to:
Losmandy_users-unsubscribe@...

______________________________________________________________________
__

Get Your Private, Free E-mail from MSN Hotmail at

To unsubscribe from this group, send an email to:
Losmandy_users-unsubscribe@...

To unsubscribe from this group, send an email to:
Losmandy_users-unsubscribe@...

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__

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Hi all,

Yes, .003 is probably too much. I've never had any luck compressing needle
bearings that far. They tend to distort and bind.

There was one suggestion on either the SBIG or STC-USER list. Someone stated
that they had the shafts built up with chrome plate and then reground for a
close fit. They did this successfully on two different G11s.

(BTW, thanks for all the feedback on my initial post.)

Neal

--- In Losmandy_users@..., scott@l... wrote:

Hello Everybody
I took 4 G11 R.A. axes and measured the movement. Then I placed a
3rd bearing in the housing and measured again. I all cases the
movement was cut in half.
Also, if you press the needle bearings in to tight, they will lock

up.

Scott

Hi Scott

I'm confused as to what you are saying. Did you add another bearing
set in addition to the original two, and if so where?? What about the
Dec axis...would this be the same?? Are you recommending this as a
fix?? Also, how would I press in the bearings too tight if the
bearing
set OD is correct for the housing bore??

Bill

Hello Bill
I added a 3rd bearing to the R.A. axis, right next to the pressure
plate and clutch pad. This would help, and as for the DEC. axis, yes,
but you might have trouble getting the DEC axis through all the
bearings. Some people where talking about a shim on the out side of
the bearing to make the press tighter.
Scott

--- In Losmandy_users@..., "Bill Faatz" <faatz1@l...> wrote:

--- In Losmandy_users@..., scott@l... wrote:

Hello Everybody
I took 4 G11 R.A. axes and measured the movement. Then I placed a
3rd bearing in the housing and measured again. I all cases the
movement was cut in half.
Also, if you press the needle bearings in to tight, they will lock

up.

Scott

Hi Scott

I'm confused as to what you are saying. Did you add another bearing
set in addition to the original two, and if so where?? What about

the

Dec axis...would this be the same?? Are you recommending this as a
fix?? Also, how would I press in the bearings too tight if the
bearing
set OD is correct for the housing bore??

Bill

If I'm reading this correctly, it's how my older GM100 is already
configured, that is, there's a bearing against the worm gear as well as
ones at either end of the shaft housing. Scott, am I right about this?

Paul Sterngold

--- scott@... wrote:

Hello Bill
I added a 3rd bearing to the R.A. axis, right next to the pressure
plate and clutch pad. This would help, and as for the DEC. axis, yes,
but you might have trouble getting the DEC axis through all the
bearings. Some people where talking about a shim on the out side of
the bearing to make the press tighter.
Scott

--- In Losmandy_users@..., "Bill Faatz" <faatz1@l...> wrote:

--- In Losmandy_users@..., scott@l... wrote:

Hello Everybody
I took 4 G11 R.A. axes and measured the movement. Then I placed a
3rd bearing in the housing and measured again. I all cases the
movement was cut in half.
Also, if you press the needle bearings in to tight, they will lock

up.

Scott

Hi Scott

I'm confused as to what you are saying. Did you add another bearing
set in addition to the original two, and if so where?? What about

the

Dec axis...would this be the same?? Are you recommending this as a
fix?? Also, how would I press in the bearings too tight if the
bearing
set OD is correct for the housing bore??

Bill

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--- In Losmandy_users@..., scott@l... wrote:

Hello Bill
I added a 3rd bearing to the R.A. axis, right next to the pressure
plate and clutch pad. This would help, and as for the DEC. axis,

yes,

but you might have trouble getting the DEC axis through all the
bearings. Some people where talking about a shim on the out side of
the bearing to make the press tighter.
Scott

Hello Scott

My specific problem is slop in the lower dec bearing. Again, my shaft
dia is 2.250, so I don't have the undersized shaft problem. Are you
saying to...

1. Press out the existing lower bearing (how do I do that) and
reinsert it with a shim between the housing bore and the OD of the
bearing...

2. or pressing in a new bearing with the correct nominal dimensions
below the present one? If so, what bearing do I need to obtain? Can I
get a correctly sized one from you?

3. Is there enough room to do this? It sounds like a possible
binding problem because the upper and lower bore centerlines may not
be
coincident.

4. What about wrapping shimstock around the dec shaft? Or would that
cause radial runout when dec shaft is rotated?

Bill