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Re: [Losmandy_users] PE and bearing mods: Necessary in this case?


Dec 24, 2000

 


----------------------------

#1643 Dec 24, 2000

Hi all,

Had a chance last night to test the RA worm bearing(ABEC-5)and third

shaft bearing mods. About 18 arc sec PE,same as before mods.



Mark Butler



----------------------------

#1679 Dec 26, 2000

Just what is expected from upgrading bearings? Most os the PE comes from

deformities in the worm so even perfect bearings will not reduce the PE! The

bearings should help reduce high frequency components in PE, the "fuzzy"

bits, not the gradual trends. By reducing the high frequency stuff guiding

becomes easier as slower deviations are "easy" do guide while faster stuff

is not.



mbutler wrote:

> Hi all,

> Had a chance last night to test the RA worm bearing(ABEC-5)and third

> shaft bearing mods. About 18 arc sec PE,same as before mods.

>

> Mark Butler

>

>

> To unsubscribe from this group, send an email to:

> Losmandy_users-unsubscribe@egroups.com



--

Rob Watson

home.pacbell.net/watsonrm/



----------------------------

#1680 Dec 26, 2000

Hi Rob,



I think we have reached the same conclusion. The worm bearings and their

adjustment, plus the step accuracy of the motor and it's reduction gearing

have to be the main sources of the rapid changes in the data I have been

seeing. An averaged trend line is showing a sinusoidal curve well within

the stated accuracy of the gear machining. The trick here is to find a way

to reduce the fairly rapid fluctuations to ease the load on the autoguider

and the PEC.



My ideal would be to see a graph that showed a close approximation in

amplitude between the RA and Dec tracks. Perhaps a bit unrealistic, but I

think things can be improved considerably from where they stand today. I

would love to see some guiding data recorded with the Gemini system.



-Marty



> Just what is expected from upgrading bearings? Most os the PE comes from

> deformities in the worm so even perfect bearings will not reduce the PE!

The > bearings should help reduce high frequency components in PE, the "fuzzy"

> bits, not the gradual trends. By reducing the high frequency stuff guiding

> becomes easier as slower deviations are "easy" do guide while faster stuff

> is not.

>

> --

> Rob Watson

> home.pacbell.net/watsonrm/

>



----------------------------

#1682 Dec 26, 2000

Most of my high frequency points are random and were greatly reduced by lapping.

I did not see any impact in upgrading the worm bearing from the stock to ABEC-7.

I was able to get the worm to fit closer to the gear upon bearing upgrade by

0.001". This may not seem like much but without the upgrade the worm so adjusted

is locked in place and unable to turn!



Marty Niemi wrote:

> Hi Rob,

>

> I think we have reached the same conclusion. The worm bearings and their

> adjustment, plus the step accuracy of the motor and it's reduction gearing

> have to be the main sources of the rapid changes in the data I have been

> seeing. An averaged trend line is showing a sinusoidal curve well within

> the stated accuracy of the gear machining. The trick here is to find a way

> to reduce the fairly rapid fluctuations to ease the load on the autoguider

> and the PEC.

>

> My ideal would be to see a graph that showed a close approximation in

> amplitude between the RA and Dec tracks. Perhaps a bit unrealistic, but I

> think things can be improved considerably from where they stand today. I

> would love to see some guiding data recorded with the Gemini system.

>

> -Marty

>

> > Just what is expected from upgrading bearings? Most os the PE comes from

> > deformities in the worm so even perfect bearings will not reduce the PE!

> The

> > bearings should help reduce high frequency components in PE, the "fuzzy"

> > bits, not the gradual trends. By reducing the high frequency stuff guiding

> > becomes easier as slower deviations are "easy" do guide while faster stuff

> > is not.

> >

> > --

> > Rob Watson

> > home.pacbell.net/watsonrm/

> >

>

>

> To unsubscribe from this group, send an email to:

> Losmandy_users-unsubscribe@egroups.com



--

Rob Watson

home.pacbell.net/watsonrm/



----------------------------

#1684 Dec 26, 2000

--- In Losmandy_users@egroups.com, Rob Watson watsonrm@p...> wrote: > Most of my high frequency points are random and were greatly

reduced by lapping.

Would you specify the lapping conditions, i.e. type and size of

grit/lubricant and for how many turns





> I did not see any impact in upgrading the worm bearing from the

stock to ABEC-7. > I was able to get the worm to fit closer to the gear upon bearing

upgrade by > 0.001". This may not seem like much but without the upgrade the

worm so adjusted > is locked in place and unable to turn!

>

> Marty Niemi wrote:

>

> > Hi Rob,

> >

> > I think we have reached the same conclusion. The worm bearings

and their > > adjustment, plus the step accuracy of the motor and it's

reduction gearing > > have to be the main sources of the rapid changes in the data I

have been > > seeing. An averaged trend line is showing a sinusoidal curve

well within > > the stated accuracy of the gear machining. The trick here is to

find a way > > to reduce the fairly rapid fluctuations to ease the load on the

autoguider > > and the PEC.

> >

> > My ideal would be to see a graph that showed a close

approximation in > > amplitude between the RA and Dec tracks. Perhaps a bit

unrealistic, but I > > think things can be improved considerably from where they stand

today. I > > would love to see some guiding data recorded with the Gemini

system. > >

> > -Marty

> >

> > > Just what is expected from upgrading bearings? Most os the PE

comes from > > > deformities in the worm so even perfect bearings will not

reduce the PE! > > The

> > > bearings should help reduce high frequency components in PE,

the "fuzzy" > > > bits, not the gradual trends. By reducing the high frequency

stuff guiding > > > becomes easier as slower deviations are "easy" do guide while

faster stuff > > > is not.

> > >

> > > --

> > > Rob Watson

> > > home.pacbell.net/watsonrm/

> > >

> >

> >

> > To unsubscribe from this group, send an email to:

> > Losmandy_users-unsubscribe@egroups.com

>

> --

> Rob Watson

> home.pacbell.net/watsonrm/







----------------------------

#1705 Dec 27, 2000

I had posted the process I used before, about a month or so ago. Check the

egroups for message #1239 for my description of lapping.



havriliak@... wrote:

> --- In Losmandy_users@egroups.com, Rob Watson watsonrm@p...> wrote:

> > Most of my high frequency points are random and were greatly

> reduced by lapping.

> Would you specify the lapping conditions, i.e. type and size of

> grit/lubricant and for how many turns

>

> > I did not see any impact in upgrading the worm bearing from the

> stock to ABEC-7.

> > I was able to get the worm to fit closer to the gear upon bearing

> upgrade by

> > 0.001". This may not seem like much but without the upgrade the

> worm so adjusted

> > is locked in place and unable to turn!

> >

> > Marty Niemi wrote:

> >

> > > Hi Rob,

> > >

> > > I think we have reached the same conclusion. The worm bearings

> and their

> > > adjustment, plus the step accuracy of the motor and it's

> reduction gearing

> > > have to be the main sources of the rapid changes in the data I

> have been

> > > seeing. An averaged trend line is showing a sinusoidal curve

> well within

> > > the stated accuracy of the gear machining. The trick here is to

> find a way

> > > to reduce the fairly rapid fluctuations to ease the load on the

> autoguider

> > > and the PEC.

> > >

> > > My ideal would be to see a graph that showed a close

> approximation in

> > > amplitude between the RA and Dec tracks. Perhaps a bit

> unrealistic, but I

> > > think things can be improved considerably from where they stand

> today. I

> > > would love to see some guiding data recorded with the Gemini

> system.

> > >

> > > -Marty

> > >

> > > > Just what is expected from upgrading bearings? Most os the PE

> comes from

> > > > deformities in the worm so even perfect bearings will not

> reduce the PE!

> > > The

> > > > bearings should help reduce high frequency components in PE,

> the "fuzzy"

> > > > bits, not the gradual trends. By reducing the high frequency

> stuff guiding

> > > > becomes easier as slower deviations are "easy" do guide while

> faster stuff

> > > > is not.

> > > >

> > > > --

> > > > Rob Watson

> > > > home.pacbell.net/watsonrm/

> > > >

> > >

> > >

> > > To unsubscribe from this group, send an email to:

> > > Losmandy_users-unsubscribe@egroups.com

> >

> > --

> > Rob Watson

> > home.pacbell.net/watsonrm/

>

>

> To unsubscribe from this group, send an email to:

> Losmandy_users-unsubscribe@egroups.com



--

Rob Watson

home.pacbell.net/watsonrm/



----------------------------

#6279 Oct 5, 2001

Dear all,



I have posted a graph of my PE on my G11 on my web site:

astrophotonut.tripod.com/g11pe.htm



This was taken using CCDTRACK and the ST4 over a period of 10

minutes. As you can see from the graph, the RA axis shows a very

reproducable curve, having a peak to peak error of 18 arc secs over a

period of 240 seconds. The interesting thing is that it is

relatively smooth. Will a replacement of the worm bearings smooth

this out more or is this about as good as it gets?

Also, the dec axis shows two peaks very much away from the rest of

the data. During actual guiding with CCD track, the ST4 lost the

star and just before this there was a wild swing in the dec value.

Is this just seeing related and what parameter would correct for this?

Would this G11 behavior be good enough for CCD work?

Thanks for any comments



Tom



----------------------------

#6280 Oct 5, 2001

Tom,



Try getting a tracklog that is much longer, maybe an hour, then look to see is those DEC spikes are happening at regular intervals... If they are mechanical, then they'll be in regular periods, if it is seeing or wind moving the scope around, then the spikes will be random. Your R.A. graph looks like some of mine (I have 4 worm gears, of which I have tried 3), They are mostly O.K. but those big swings in R.A. (like the ones you have around 100 & 340 seconds) seem to cause the most issues (and trailed stars) for me. I'll be posting all of my curves later...



Frank





---------------

>Is this just seeing related and what parameter would correct for this

>Would this G11 behavior be good enough for CCD work?BR>

>Thanks for any commentsBR>



----------------------------

#6286 Oct 5, 2001

Hi Tom

I'm going to assume that this is an UNGUIDED pe curve,taken with an ST-4

using a PC so you can turn your

DEC and RA corrections off but still plot a graph from the coordinates

posted by the CCD.

(otherwise,if this is guided,you go lotsa problems)



Given that these curves are UNGUIDED,they look pretty darn good.There is a

bit of a problem diagnosing just two periods in RA.

From the double peaks,1 halfway up and down each cycle I'd say you might

have some slack in the worm between bearings.Not much but maybe push the

outboard bearing in towards the motor.



In DEC you have a big spike in each cycle.Since there is no correcting going

on,you are not even going outside 1 tooth.(Given 360 teeth and therefore 1

tooth equals 1 degree then 1 tooth also equals 3600 arcsecs)

You might want to move your DEC a few teeth and see if the same spike

occurs.If it does then your DEC is probably off balance a bit.Might be

slacking off a bit as it moves in 1 direction then jumps a bit when the worm

and tooth make good contact again.



In either event,I'd do some more testing before doing mods.

Good skies...clear eyes



JImmy



www.frenchriverobservatory.com







----Original Message Follows----

From: tom_b@...

Reply-To: Losmandy_users@yahoogroups.com

To: Losmandy_users@yahoogroups.com

Subject: [Losmandy_users] PE and bearing mods: Necessary in this case?

Date: Fri, 05 Oct 2001 16:01:45 -0000



Dear all,



I have posted a graph of my PE on my G11 on my web site:

astrophotonut.tripod.com/g11pe.htm



This was taken using CCDTRACK and the ST4 over a period of 10

minutes. As you can see from the graph, the RA axis shows a very

reproducable curve, having a peak to peak error of 18 arc secs over a

period of 240 seconds. The interesting thing is that it is

relatively smooth. Will a replacement of the worm bearings smooth

this out more or is this about as good as it gets?

Also, the dec axis shows two peaks very much away from the rest of

the data. During actual guiding with CCD track, the ST4 lost the

star and just before this there was a wild swing in the dec value.

Is this just seeing related and what parameter would correct for this?

Would this G11 behavior be good enough for CCD work?

Thanks for any comments



Tom







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