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Are my guts wrong?

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#1 doole

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Posted 22 November 2020 - 09:10 AM

My guts are telling me that it's probably a pretty bad idea to leave your gear all set up in the living room with the weights and everything on, as attractive as that is, and as much as your life partner loves it. They're telling me that will leave little divots in the bearings all over the place and add all sorts of periodic error. Are they right?



#2 AstroBrett

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Posted 22 November 2020 - 09:15 AM

Your gut feeling about your life partner is spot on. Regrading the bearings, I've never experiences a problem, or ever heard of that being an issue. They would be pretty poor bearings if that was the case.


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#3 alphatripleplus

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Posted 22 November 2020 - 09:23 AM

When you say "all set up", are you thinking of leaving the scope on the mount with the counterweights balanced, or just the counterweights and no scope? I would not leave it set-up with just counterweights.

 

If you leave a scope fully set-up in an observatory, there should be no issue, so I don't see an issue doing so inside your home. I used to do that in a sun room. However, to get the scope outside, you will have to do some disassembly and that is where you want to be careful transporting the mount without the scope or weights attached.


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#4 jrcrilly

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Posted 22 November 2020 - 09:43 AM

If this were an issue, everyone with an observatory would be experiencing it. I have had no problems in 20 years.


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#5 wrvond

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Posted 22 November 2020 - 10:01 AM

My telescope room:
 
794A7F90 84B8 434D 832B 2B9C9A886A9C
 
 
Not shown:
 
Monster parallelogram with binoculars mounted
 
XT10g

Edited by wrvond, 22 November 2020 - 10:02 AM.

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#6 Astrola72

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Posted 22 November 2020 - 10:10 AM

Might leave divots in the flooring, but not in the bearings. Your guts are wrong, about the setup, not the life partner. There you've obviously got it right!

 

Joe


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#7 CltFlyboy

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Posted 22 November 2020 - 10:11 AM

Ditto. All the years in this hobby and I've never heard of metal fatigue caused by a parked scope.

 

 

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#8 StarBurger

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Posted 22 November 2020 - 10:17 AM

Your scope will not suffer but someone else might. 

I left my full AP rig temporarily set up in the living room over night. It stands 6 feet high on a heavy tripod, white OTA, shiny legs and away from any furniture.

I woke up to see the whole shebang on the floor next day. Focuser was trashed and luckily that was all.

My wife owned up to accidentally stumbling into it. Periodic error ?

Well there were some divots, but not in the scope....


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#9 Lee D

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Posted 22 November 2020 - 10:32 AM

 

My telescope room:
 
 
 
 
Not shown:
 
Monster parallelogram with binoculars mounted
 
XT10g

 

I looked at that photo and wondered "What on earth is on the front of that SCT?" Apparently it's a clock on the wall. :)


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#10 coopman

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Posted 22 November 2020 - 10:46 AM

Me too, derangedhermit.



#11 Andynator

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Posted 22 November 2020 - 10:48 AM

Mine are usually put away due to lack of room. But when I am using equipment several days in a row I will leave it set up. Bring the tube in the house and lay it on the couch. Lock down the mount clutches and remove the counterweight. Reassemble indoors and remount the optics.

The only difference is, I turn the tube and lock in place parallel to the floor. Once everything is dried out, I put the caps on and leave it like that. Probably just OCD but trying to keep dust from settling on the mirrors/lenses.
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#12 SonnyE

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Posted 22 November 2020 - 10:49 AM

I looked at that photo and wondered "What on earth is on the front of that SCT?" Apparently it's a clock on the wall. smile.gif

Thanks!

You saved me from asking it it was for enhanced light gathering,

Or a return to fringe, for dew shedding.....

 

Just an optical delusion.... crazyeyes.gif


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#13 TOMDEY

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Posted 22 November 2020 - 11:03 AM

Good question --- but not to worry.

 

This comes under the heading of Hertzian Stresses, which address deformation of materials under point (or line or edge) contact. Think of a pneumatic tire contacting the road. If static geometric zero-force contact occurs at a point, the moment a surface normal loading force is introduced, the tire (and road) must deform elastically. Otherwise, the contact area pressure would be infinite, which is impossible. If the Hertzian Elastic Limit of either mating material is exceeded, then it permanently deforms... what we colloquially call fractured (brittle material), dented (malleable material) --- permanently ruined.

 

Bearings (Ball, cone, etc.) present no-load zero-area contact; and rely on Hertzian Deformation to bear the normal load. As long as that load is never exceeded, the bearings are fine. This explains why bumping your mount can permanently damage it. The impulse event of a shocking bump (e.g. dropping the gizmo onto a concrete floor) can ruin it. As long as that has never happened to your mount, it's fine.

 

This also explains why "scratch and dent" evidences are always of concern, and result of half-price sales at the appliance store. It's not cosmetic, but rather potential hidden damage that devalues the item. Evidence of an impulse event.

 

When JMI shipped my 16-inch Binoscope to me, the crate comprised a recording accelerometer on the outside. That was to assure that the shipper would babysit the delivery, and the recipient could file a claim upon arrival, if the accelerometer got tripped. (It was fine, and so was the scope).    Tom

 

[I worked on the design and build or alignment sensors that had to maintain centi-arc-sec accuracy for a decade. To assure this, we built three passive interferometers into the tiny device. It worked fine, for the life of the mission. The interferometers reported that the Hertzian condition was never violated.]

 

 

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#14 wrvond

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Posted 22 November 2020 - 11:03 AM

I looked at that photo and wondered "What on earth is on the front of that SCT?" Apparently it's a clock on the wall. smile.gif

 

Unfortunate placement. smile.gif

 

 

smclock.JPG


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#15 csauer52

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Posted 22 November 2020 - 11:04 AM

Your scope will not suffer but someone else might. 

I left my full AP rig temporarily set up in the living room over night. It stands 6 feet high on a heavy tripod, white OTA, shiny legs and away from any furniture.

I woke up to see the whole shebang on the floor next day. Focuser was trashed and luckily that was all.

My wife owned up to accidentally stumbling into it. Periodic error ?

Well there were some divots, but not in the scope....

You actually slept through that?


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#16 wrvond

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Posted 22 November 2020 - 11:05 AM



Good question --- but not to worry.

 

This comes under the heading of Hertzian Stresses, which address deformation of materials under point (or line or edge) contact. Think of a pneumatic tire contacting the road. If static geometric zero-force contact occurs at a point, the moment a surface normal loading force is introduced, the tire (and road) must deform elastically. Otherwise, the contact area pressure would be infinite, which is impossible. If the Hertzian Elastic Limit of either mating material is exceeded, then it permanently deforms... what we colloquially call fractured (brittle material), dented (malleable material) --- permanently ruined.

 

Bearings (Ball, cone, etc.) present no-load zero-area contact; and rely on Hertzian Deformation to bear the normal load. As long as that load is never exceeded, the bearings are fine. This explains why bumping your mount can permanently damage it. The impulse event of a shocking bump (e.g. dropping the gizmo onto a concrete floor) can ruin it. As long as that has never happened to your mount, it's fine.

 

This also explains why "scratch and dent" evidences are always of concern, and result of half-price sales at the appliance store. It's not cosmetic, but rather potential hidden damage that devalues the item. Evidence of an impulse event.

 

When JMI shipped my 16-inch Binoscope to me, the crate comprised a recording accelerometer on the outside. That was to assure that the shipper would babysit the delivery, and the recipient could file a claim upon arrival, if the accelerometer got tripped. (It was fine, and so was the scope).    Tom

 

[I worked on the design and build or alignment sensors that had to maintain centi-arc-sec accuracy for a decade. To assure this, we built three passive interferometers into the tiny device. It worked fine, for the life of the mission. The interferometers reported that the Hertzian condition was never violated.]

 

Uhhhhh what he said...

 

;)


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#17 StarBurger

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Posted 22 November 2020 - 12:15 PM

You actually slept through that?

Well no I didn't. During the night and day there are all kinds of destructions occurring from food burning on the stove, gravity suddenly being turned on without warnings given, items becoming invisible or appearing from nowhere and other paranormal activity only when wifey is at home.

I have come to ignore it all and just shrug. "I'll see what the damage is later"...


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#18 SonnyE

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Posted 22 November 2020 - 12:27 PM

Well no I didn't. During the night and day there are all kinds of destructions occurring from food burning on the stove, gravity suddenly being turned on without warnings given, items becoming invisible or appearing from nowhere and other paranormal activity only when wifey is at home.

I have come to ignore it all and just shrug. "I'll see what the damage is later"...

Like selective hearing, you have also developed selective awareness....  lol.gif



#19 wrvond

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Posted 22 November 2020 - 12:57 PM

Well no I didn't. During the night and day there are all kinds of destructions occurring from food burning on the stove, gravity suddenly being turned on without warnings given, items becoming invisible or appearing from nowhere and other paranormal activity only when wifey is at home.

I have come to ignore it all and just shrug. "I'll see what the damage is later"...

In our house, when the smoke detector goes off, we know dinner is ready.  ;)


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#20 Eddgie

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Posted 23 November 2020 - 09:53 AM

My guts are telling me that it's probably a pretty bad idea to leave your gear all set up in the living room with the weights and everything on, as attractive as that is, and as much as your life partner loves it. They're telling me that will leave little divots in the bearings all over the place and add all sorts of periodic error. Are they right?

Bearing material is extremely hard and there will likely be no damage at all leaving weight on the bearings. 

 

You will find observatory mounts that have been left in place for decades with no damage at all. 


Edited by Eddgie, 23 November 2020 - 09:57 AM.

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#21 doole

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Posted 23 November 2020 - 10:09 AM

Thanks again, kids. Great info. Again.




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