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Re: PE harmonic


Feb 22 11:16 AM

 


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

#28915 Feb 22 11:16 AM

Recently I have used PEMPRO again to measure and set up PE in my G11

with gemini lvl 4 and noticed the 76 second harmonicthat has +- 2-3

arcsec error is there any chance any progress on this issue, is it

possible to use sleeve bearings or something, has anyone made a

commercially available part? when I get rid of the worm error there it

is , plain as day....



Thoughts?



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

#28919 Feb 23 1:45 AM

Hi,

surely the bearings are a real source of erratic behaviour in PE and

subsequent high order harmonic growth.

I don't know personally any type of commercially available upgrade,

but in the meantime I'm still asking if the source could be the radial

tensioning of the bearings other than the bearings themselves... What

about this idea?

The way to go could be easily explained by two PE graph made using two

different mounts:

One with the whole bearing set replaced with higher grade one; the

other with the standard bearings but with the bearing houses slightly

reworked in order to delete any sort of tensioning source.



Just an idea to have a better know-How on the tweaking looking for top

notch performances.



Best,

Stefano

--- In Losmandy_users@yahoogroups.com, "glacy31" glacy31@...> wrote:

>

> Recently I have used PEMPRO again to measure and set up PE in my G11

> with gemini lvl 4 and noticed the 76 second harmonicthat has +- 2-3

> arcsec error is there any chance any progress on this issue, is it

> possible to use sleeve bearings or something, has anyone made a

> commercially available part? when I get rid of the worm error there it

> is , plain as day....

>

> Thoughts?

>



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

#28921 Feb 23 4:53 AM

I minimised it on my G11 (though not eliminated it) by not

overtightening the bearing blocks, and then subtly adjusting their

angles with a 3/4" spanner until the error diminished.



The total PE is now around 2.5 to 3 arc secs after uploading a PEC

table with PEMPro.



Changin the bearings did nothing for me, and minimum error does not

seem to co-incide with the outer edges of the bearing blocks being

alaligned.



I added a 3.14 cycle harmonic to PEMPro, this shows the error nicely,

and means you can eliminate it from the generated correction curve.



Mark

--- In Losmandy_users@yahoogroups.com, "glacy31" glacy31@...> wrote:

>

> Recently I have used PEMPRO again to measure and set up PE in my G11

> with gemini lvl 4 and noticed the 76 second harmonicthat has +- 2-3

> arcsec error is there any chance any progress on this issue, is it

> possible to use sleeve bearings or something, has anyone made a

> commercially available part? when I get rid of the worm error there

it

> is , plain as day....

>

> Thoughts?

>



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

#28924 Feb 23 8:57 AM

Hi Stefano,



you wrote

> but in the meantime I'm still asking if the source could be the radial

> tensioning of the bearings other than the bearings themselves... What

> about this idea?



I do not think it is the radial tensioning. I would say it is the axial

tensioning of the ball bearings in order to avoid the worm moving

axially between the ball bearings and so introduce another sort of

backlash apart from the play that the worm has to have with the main

gear.



To avoid the axial movement in the original design you have to push the

blocks together and so the balls of the ball bearings will run on the

shoulders of the rings of the ball bearing and I guess from that part

of the rings the stickyness of the movement could come.



I therefore when I designed my wormblocks I am using 2 thrust bearings

one in each block to avoid the axial movement of the worm. Of course

now I got the problem of the flat races on which the balls of the

thrustbearings run. This is a very critical adjustment now but easier

manageable then the asjustment of the original wormblocks.



Here is an image of how the RS-Wormblocks look alike from the inside



www.rainerehlert.com/astro/worm/PPWB01.jpg



and assembled like this



www.rainerehlert.com/astro/worm/PPWB02.jpg



and on the mount like this



www.rainerehlert.com/astro/worm/GM-8-RSWormblock.jpg



The whole unit is held down by the 2 spring loaded screws and so far I

have not observed that the worm climbs up the main gear.



regards Rainer



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

#28925 Feb 23 12:37 PM

Rainer,

I've already seen your beautiful project about G11 worm and gear. It's

really very interesting and well built - my congratulations.

By the way, even if I still know the issue related to the not well

placed bearing blocks, I'd like to know more about the possibility not

so remote of outer ring radial tensionig of the bearings. I've noticed

that mine are really hardened in their houses, even too much in

respect to the necessary - this sounds a bit strange to me.



Probably I'm wrong, but I'm just curious about this issue.



Thanks and compliments once more.

Best,

stefano

--- In Losmandy_users@yahoogroups.com, "Rainer" rsbfoto@...> wrote:

>

> Hi Stefano,

>

> you wrote

>

> > but in the meantime I'm still asking if the source could be the radial

> > tensioning of the bearings other than the bearings themselves... What

> > about this idea?

>

> I do not think it is the radial tensioning. I would say it is the axial

> tensioning of the ball bearings in order to avoid the worm moving

> axially between the ball bearings and so introduce another sort of

> backlash apart from the play that the worm has to have with the main

> gear.

>

> To avoid the axial movement in the original design you have to push the

> blocks together and so the balls of the ball bearings will run on the

> shoulders of the rings of the ball bearing and I guess from that part

> of the rings the stickyness of the movement could come.

>

> I therefore when I designed my wormblocks I am using 2 thrust bearings

> one in each block to avoid the axial movement of the worm. Of course

> now I got the problem of the flat races on which the balls of the

> thrustbearings run. This is a very critical adjustment now but easier

> manageable then the asjustment of the original wormblocks.

>

> Here is an image of how the RS-Wormblocks look alike from the inside

>

> www.rainerehlert.com/astro/worm/PPWB01.jpg

>

> and assembled like this

>

> www.rainerehlert.com/astro/worm/PPWB02.jpg

>

> and on the mount like this

>

> www.rainerehlert.com/astro/worm/GM-8-RSWormblock.jpg

>

> The whole unit is held down by the 2 spring loaded screws and so far I

> have not observed that the worm climbs up the main gear.

>

> regards Rainer

>







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

#28926 Feb 23 1:30 PM

Hi Stefano,



The only way to find it out is test the ball bearings inside and

outside the blocks with the help of a ball bearing manufacturer which

do have the testing facilities to do this sort of measurments.



Maybe we have a member here who works in a ball bearing factory :-))



regards Rainer





>

> Rainer,

> I've already seen your beautiful project about G11 worm and gear.

It's > really very interesting and well built - my congratulations.

> By the way, even if I still know the issue related to the not well

> placed bearing blocks, I'd like to know more about the possibility

not > so remote of outer ring radial tensionig of the bearings. I've

noticed > that mine are really hardened in their houses, even too much in

> respect to the necessary - this sounds a bit strange to me.

>

> Probably I'm wrong, but I'm just curious about this issue.

>

> Thanks and compliments once more.

> Best,

> stefano

>



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

#28928 Feb 24 12:38 AM

Hello Rainer,

the way you showed would be the best solution at all. By the way, I've

no possibilities, at the moment, of testing seriously my bearings :-(



By the way, who's that lucky boy? ;-)



Stefano

--- In Losmandy_users@yahoogroups.com, "Rainer" rsbfoto@...> wrote:

>

> Hi Stefano,

>

> The only way to find it out is test the ball bearings inside and

> outside the blocks with the help of a ball bearing manufacturer which

> do have the testing facilities to do this sort of measurments.

>

> Maybe we have a member here who works in a ball bearing factory :-))

>

> regards Rainer

>

>

>

> >

> > Rainer,

> > I've already seen your beautiful project about G11 worm and gear.

> It's

> > really very interesting and well built - my congratulations.

> > By the way, even if I still know the issue related to the not well

> > placed bearing blocks, I'd like to know more about the possibility

> not

> > so remote of outer ring radial tensionig of the bearings. I've

> noticed

> > that mine are really hardened in their houses, even too much in

> > respect to the necessary - this sounds a bit strange to me.

> >

> > Probably I'm wrong, but I'm just curious about this issue.

> >

> > Thanks and compliments once more.

> > Best,

> > stefano

> >

>



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