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Portaball Users - Sing Their Praises

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#26 5u4

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Posted 23 May 2017 - 06:49 PM

Have a 8" f6 that I bought used & it's a scope that gets used a lot as it's so simple to set up. Just grab the scope with one hand & the base with the other, plop it down & you're ready to go. The electrical system gave up the ghost long ago, but don't care about that.

 

It has a ZOC mirror, so not going to do much better there, at least for an 8". It has a 1.25" helical focuser, but it's fine with me. A 24 Pan is as low as I care to go anyway & it handles the weigh of a 12mm Delos just fine, but don't think I'd want to go with an eyepiece any heavier as that's pretty much the weight limit.

 

No Dobson's hole is a plus + you can position the eyepiece anywhere you wish. Can tear it down for easy transportation if need be, but I just leave it set up as I live in the country & don't take it anywhere anymore.


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#27 gwlee

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Posted 23 May 2017 - 08:21 PM

How are they for balancing eyepieces?  How limited are you in terms of eyepiece selection?  I currently have simpler designs as far as eyepieces go, but I am just curious as to what can be used.  Examples would be helpful.

 

Thank you. 

When i ordered my 8"f6, you were required to specify the 1.25" eyepieces you wanted to use, and Peter balanced the scope for these EP. I specified 24mm Panoptic, 13mm Nagler T6 and 7mm T6, and the scope came balanced for these EPS and worked with 1.25" EP of similar weight, such as TV 32 Plossl. However, the focuser's set screw was not compatible with the safety undercut on TV EPs, which was a big disappointment.  Not sure how the new owner does things, but reducing the focal length (from f6 to f5.5) probably allowed him to use a 2-inch focuser and achieve balance. 



#28 gwlee

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Posted 23 May 2017 - 08:33 PM

 

 

How are they for balancing eyepieces?  How limited are you in terms of eyepiece selection?  I currently have simpler designs as far as eyepieces go, but I am just curious as to what can be used.  Examples would be helpful.

 

 

I have a set of TeleVue Nagler Type 6's and 19 and 24 Panoptics that I use exclusively in the Portaball-8.  Its a perfect combination.  Lightweight, wide-field, good planetary.  

 

Stay away from 2" eyepieces in the PB-8.  

 

Seems like the 8" would be a dynamite planetary scope with pretty good deep sky.

 

Yes, my thoughts exactly when i ordered my 8" f6. The ZOC optics were excellent, but the shakiness of the f6 structure and the rough focuser made it difficult to get full benefit of the optics. New scopes are f5.5 and new focusers are feathertouch, so these problems should have been mitigated or perhaps entirely corrected. If so, i would consider buying another one. 


Edited by gwlee, 23 May 2017 - 08:36 PM.


#29 gwlee

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Posted 23 May 2017 - 09:10 PM

The optics are obviously unimpeachable. But I do find that cool down takes real time. I typically blast the primary with a portable 12 volt fan for a half hour before beginning to view. 

I found that my 8"f6 PB took longer to cool than an 8"f6 Orion Dob that i owned at the same time. I SPECULATE the difference was because it's ball tightly enclosed a lot of other stuff along with the mirror that had high thermal mass, such as the rechargeable battery and fan required to cool the thing.

 

Although the PB took slightly longer to cool with it's fan running than the Orion took without a fan, the added complexity and cost of the fan/battery/switches/wires/battery charger freed me from the Dobson's hole, and the weight of the PB was still about 7 pounds less than the Orion Dob.  


Edited by gwlee, 23 May 2017 - 10:17 PM.


#30 skaven

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Posted 09 September 2017 - 12:12 PM

I'm glad to have found this thread, as I just took delivery of a 12.5" f/5 Portaball a few months ago and I am curious how other Portaball owners are lubricating/waxing the sphere to achieve acceptable stiction for smooth movements at high power.  I'm really frustrated with the stiction on my Portaball and could use any advice.

 

Dave's recommendations in the instructions, and over the phone, is to use a PTFE-bearing marine polish (StarBrite is what he recommends) to polish the sphere.  The tubing in the base is made of PTFE, so it seems fairly obvious that a polished fiberglass surface with some embedded PTFE should glide smoothly over the PTFE tubing.

 

However, my experience in this area has been VERY bad.  The stiction is TERRIBLE, with the sphere sticking quite hard to the base.  It requires a firm shake to break the sphere loose and get it to start moving.  Once moving, the movement is smooth and easily controlled, but that initial "bump" to get things moving means that it's virtually impossible to achieve any sort of fine movement (such as centering Saturn in a 5mm orthoscopic eyepiece).

 

I have experimented with several different waxes/polishes/lubricants but have not yet found one that works well.  To improve readability, I use a scale in the list below rating stiction, with 1=terrible stiction (extremely jerky movement, impossible to perform fine pointing), to 5=perfect stiction (slight pressure on the UTA causes small, smooth movement).

  • Baseline: sphere and base cleaned with Simple Green, no polish/wax applied.  Result: 1 -- the scope is virtually impossible to use.
  • Cleaned the sphere and base with Simple Green, then waxed the sphere with StarBrite marine polish (wipe on and let dry to a haze, then wipe to a polish with a microfiber cloth).  Result: 2 -- hardly better than without waxing at all
  • Cleaned the sphere and base with Simple Green, then waxed the sphere with Turtle Wax (wipe on and let dry to a haze, then wipe to a polish with a microfiber cloth).  Result: 2 -- same as the StarBrite.
  • Cleaned the sphere and base with Simple Green, then did a "thick paste" application of StarBrite (wipe on and let dry to a haze, then wipe lightly to a haze with a microfiber cloth).  My theory being that perhaps some wax needs to be left on the surface to act as a lubricant.  Result: 3, quickly degrading to 1 -- the wax gums up in the base and ultimately makes things worse.
  • Cleaned the sphere and base with Simple Green, then sprayed a thin coat of RZ-50 (a PTFE-bearing dry-film lubricant) on the base.  Result: 4.  Hey!  This seems to work pretty good!  Only problem is, the RZ-50 is quickly rubbed off through abrasion with the base, and gums up, meaning after an hour or two, I'm back to level 2.

So right now my best solution for stiction is the RZ-50, but it's extremely labor-intensive. I have to clean the entire sphere with mineral spirits to remove all the gummed-up RZ-50, then apply a fresh coat...every night I want to observe.  This is unsustainable.  There has to be a better way.

 

I purchased a 5 foot long piece of fresh, new PTFE tubing, with a thicker sidewall (1/4" OD, 5/32" ID) to see if perhaps a stiffer tubing the base would help.  It will also let me run some experiments with the surface finish on the tubing in the base: I can try a sanded versus a smooth finish (I've heard that sanding the PTFE pads on dobsonian telescopes can improve stiction).

 

What are other Portaball owners doing about the stiction problem?  Reading this thread, it seems that using StarBrite is sufficient, and that most users don't seem to have trouble with stiction.  Perhaps I'm doing something wrong?  Does the StarBrite require multiple applications?  Am I preparing the surface properly before applying the polish?  Should the sphere's surface be shiny/polished or matte?  Is there anything that has to be done to the base to ensure good stiction?  Am I just expecting too much out of this system?



#31 skaven

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Posted 09 September 2017 - 12:18 PM

I've had a 12.5" F5 for a couple of years. It's a 2003 model and has required some work.

 

[...]

 

I also got one of the new all-aluminum tripods. It has more stiction than the original, but the aluminum vibrates and makes it a pain to use at high power. I may try to fit some wooden legs. 

 

How was the old base (which you indicate had better stiction characteristics) designed?  A simple hardwood ring?  What is the bearing surface on which the sphere slides?  More PTFE tubing?  Or fiberglass-on-wood?



#32 skaven

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Posted 09 September 2017 - 12:27 PM

How are they for balancing eyepieces?  How limited are you in terms of eyepiece selection?  I currently have simpler designs as far as eyepieces go, but I am just curious as to what can be used.  Examples would be helpful.

 

Thank you. 

I have the 12.5" PB and I'm able to use everything from University Optics Orthscopics (tiny, lightweight) all the way up to my 30mm Explore Scientific 82 degree (which is a "hand grenade").  No problems at all with balance.  Dave did a great job of adding just the right amount of ballast (lead shot embedded in epoxy) in the base of the sphere, to ensure that I could use my full range of eyepieces without any issues.



#33 TG

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Posted 09 September 2017 - 01:09 PM



I'm glad to have found this thread, as I just took delivery of a 12.5" f/5 Portaball a few months ago and I am curious how other Portaball owners are lubricating/waxing the sphere to achieve acceptable stiction for smooth movements at high power.  I'm really frustrated with the stiction on my Portaball and could use any advice.

 

Dave's recommendations in the instructions, and over the phone, is to use a PTFE-bearing marine polish (StarBrite is what he recommends) to polish the sphere.  The tubing in the base is made of PTFE, so it seems fairly obvious that a polished fiberglass surface with some embedded PTFE should glide smoothly over the PTFE tubing.

 

However, my experience in this area has been VERY bad.  The stiction is TERRIBLE, with the sphere sticking quite hard to the base.  It requires a firm shake to break the sphere loose and get it to start moving.  Once moving, the movement is smooth and easily controlled, but that initial "bump" to get things moving means that it's virtually impossible to achieve any sort of fine movement (such as centering Saturn in a 5mm orthoscopic eyepiece).

 

I have experimented with several different waxes/polishes/lubricants but have not yet found one that works well.  To improve readability, I use a scale in the list below rating stiction, with 1=terrible stiction (extremely jerky movement, impossible to perform fine pointing), to 5=perfect stiction (slight pressure on the UTA causes small, smooth movement).


  • Baseline: sphere and base cleaned with Simple Green, no polish/wax applied.  Result: 1 -- the scope is virtually impossible to use.

  • Cleaned the sphere and base with Simple Green, then waxed the sphere with StarBrite marine polish (wipe on and let dry to a haze, then wipe to a polish with a microfiber cloth).  Result: 2 -- hardly better than without waxing at all

  • Cleaned the sphere and base with Simple Green, then waxed the sphere with Turtle Wax (wipe on and let dry to a haze, then wipe to a polish with a microfiber cloth).  Result: 2 -- same as the StarBrite.

  • Cleaned the sphere and base with Simple Green, then did a "thick paste" application of StarBrite (wipe on and let dry to a haze, then wipe lightly to a haze with a microfiber cloth).  My theory being that perhaps some wax needs to be left on the surface to act as a lubricant.  Result: 3, quickly degrading to 1 -- the wax gums up in the base and ultimately makes things worse.

  • Cleaned the sphere and base with Simple Green, then sprayed a thin coat of RZ-50 (a PTFE-bearing dry-film lubricant) on the base.  Result: 4.  Hey!  This seems to work pretty good!  Only problem is, the RZ-50 is quickly rubbed off through abrasion with the base, and gums up, meaning after an hour or two, I'm back to level 2.


So right now my best solution for stiction is the RZ-50, but it's extremely labor-intensive. I have to clean the entire sphere with mineral spirits to remove all the gummed-up RZ-50, then apply a fresh coat...every night I want to observe.  This is unsustainable.  There has to be a better way.

 

I purchased a 5 foot long piece of fresh, new PTFE tubing, with a thicker sidewall (1/4" OD, 5/32" ID) to see if perhaps a stiffer tubing the base would help.  It will also let me run some experiments with the surface finish on the tubing in the base: I can try a sanded versus a smooth finish (I've heard that sanding the PTFE pads on dobsonian telescopes can improve stiction).

 

What are other Portaball owners doing about the stiction problem?  Reading this thread, it seems that using StarBrite is sufficient, and that most users don't seem to have trouble with stiction.  Perhaps I'm doing something wrong?  Does the StarBrite require multiple applications?  Am I preparing the surface properly before applying the polish?  Should the sphere's surface be shiny/polished or matte?  Is there anything that has to be done to the base to ensure good stiction?  Am I just expecting too much out of this system?

skaven, I'm not sure what the base ring of the Portable is like: does it contact the ball at three points or continuously? I own a StarStructure TL dob and it doesn't use the traditional laminate on bearings. Instead, it uses the hook part of velcro on bearing surfaces, the other surface being either HDPE or PTFE, not sure which. Velcro seems to have the perfect stiction behaviour and the movement is ultra smooth and stiction free.

 

I'm not sure if you can use this info but if possible, it might be worth a try to buy a strip of industrial strength velcro, cut it to size and use that on the base.

 

Tanveer.



#34 areyoukiddingme

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Posted 09 September 2017 - 01:49 PM

 

I've had a 12.5" F5 for a couple of years. It's a 2003 model and has required some work.

 

[...]

 

I also got one of the new all-aluminum tripods. It has more stiction than the original, but the aluminum vibrates and makes it a pain to use at high power. I may try to fit some wooden legs. 

 

How was the old base (which you indicate had better stiction characteristics) designed?  A simple hardwood ring?  What is the bearing surface on which the sphere slides?  More PTFE tubing?  Or fiberglass-on-wood?

 

 

The older base is a wood ring/wood legs with aluminum inserts, and the contact ring is of a smaller diameter. That ring appears to be the same plastic substance as found on the new base (but for all I know it is different).

 

I have used turtle wax on my sphere just once, and it has had excellent stiction for more than 1 year. But it's starting to get a touch grabby, so I think I'll do a new coating. Last time I applied the wax, I let it dry for about 1/2 hour, and then spent perhaps 5 minutes polishing it off with an old t-shirt. 



#35 areyoukiddingme

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Posted 09 September 2017 - 01:51 PM

 

How are they for balancing eyepieces?  How limited are you in terms of eyepiece selection?  I currently have simpler designs as far as eyepieces go, but I am just curious as to what can be used.  Examples would be helpful.

 

Thank you. 

I have the 12.5" PB and I'm able to use everything from University Optics Orthscopics (tiny, lightweight) all the way up to my 30mm Explore Scientific 82 degree (which is a "hand grenade").  No problems at all with balance.  Dave did a great job of adding just the right amount of ballast (lead shot embedded in epoxy) in the base of the sphere, to ensure that I could use my full range of eyepieces without any issues.

 

I drew the line at the explore scientific 17/90 + paracorr 2. That started to exceed the scopes stiction at around 30 degrees or so. But that's one very heavy eyepiece. I have no trouble with either 21 Ethos or 31 Nagler with Paracorr at any angle.



#36 skaven

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Posted 09 September 2017 - 02:38 PM

skaven, I'm not sure what the base ring of the Portable is like: does it contact the ball at three points or continuously? I own a StarStructure TL dob and it doesn't use the traditional laminate on bearings. Instead, it uses the hook part of velcro on bearing surfaces, the other surface being either HDPE or PTFE, not sure which. Velcro seems to have the perfect stiction behaviour and the movement is ultra smooth and stiction free.

 

I'm not sure if you can use this info but if possible, it might be worth a try to buy a strip of industrial strength velcro, cut it to size and use that on the base.

 

The base is a machined aluminum ring with a depression cut into the inner circumference that accepts a 1/4" diameter PTFE tube.  So the sphere rests on a circle of PTFE (tubing), supported by aluminum.  The contact surface is thus very small -- probably no wider than 1mm at any given spot around the ring (but of course it makes contact all the way around the ring).

 

Given the design, it's not possible to swap out "pads" like you can on a dob.  The only options are to alter/augment the surface of the sphere (wax, lubricant, etc) and to alter the bearing material (change out the PTFE tubing for something else, or perhaps sand the surface of the tubing).



#37 skaven

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Posted 09 September 2017 - 02:40 PM

 

The older base is a wood ring/wood legs with aluminum inserts, and the contact ring is of a smaller diameter. That ring appears to be the same plastic substance as found on the new base (but for all I know it is different).

 

I have used turtle wax on my sphere just once, and it has had excellent stiction for more than 1 year. But it's starting to get a touch grabby, so I think I'll do a new coating. Last time I applied the wax, I let it dry for about 1/2 hour, and then spent perhaps 5 minutes polishing it off with an old t-shirt. 

 

Hmm..perhaps it's my application process?  When I applied the wax, I only let it dry for a couple minutes (just until it formed a haze).  Perhaps I should let it sit longer before polishing.



#38 areyoukiddingme

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Posted 09 September 2017 - 03:28 PM

Sounds like that is worth a try. I recall the polishing process required some pretty substantial elbow grease to get it polished off.

 

I see that there are tons of different products. I used the turtle wax super hard shell liquid wax.



#39 TG

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Posted 09 September 2017 - 09:42 PM


skaven, I'm not sure what the base ring of the Portable is like: does it contact the ball at three points or continuously? I own a StarStructure TL dob and it doesn't use the traditional laminate on bearings. Instead, it uses the hook part of velcro on bearing surfaces, the other surface being either HDPE or PTFE, not sure which. Velcro seems to have the perfect stiction behaviour and the movement is ultra smooth and stiction free.

I'm not sure if you can use this info but if possible, it might be worth a try to buy a strip of industrial strength velcro, cut it to size and use that on the base.

The base is a machined aluminum ring with a depression cut into the inner circumference that accepts a 1/4" diameter PTFE tube. So the sphere rests on a circle of PTFE (tubing), supported by aluminum. The contact surface is thus very small -- probably no wider than 1mm at any given spot around the ring (but of course it makes contact all the way around the ring).

Given the design, it's not possible to swap out "pads" like you can on a dob. The only options are to alter/augment the surface of the sphere (wax, lubricant, etc) and to alter the bearing material (change out the PTFE tubing for something else, or perhaps sand the surface of the tubing).

OK, if you are going the polish route, I would highly recommend SailKote, a dry sprayable lubricant with marine applications. It dries clean, unlike graphite lubricants which make a mess.

Tanveer

#40 skaven

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Posted 09 September 2017 - 10:41 PM

 

OK, if you are going the polish route, I would highly recommend SailKote, a dry sprayable lubricant with marine applications. It dries clean, unlike graphite lubricants which make a mess.

Tanveer

 

 

Interesting -- I'll have a look.  The SailKote product description seems to specifically call out its superior durability compared to dry-film Teflon (PTFE) lubricants, so that might just be the ticket!



#41 Pierre Lemay

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Posted 09 September 2017 - 11:44 PM

I have made many ball scopes using both fiberglass and aluminium hemispheres (see my website for examples). They all rest on three contact points: either aluminium, steel or plastic rollers or a combination of. Whichever combination of contact points The hemisphere rests upon, a 5 minute application of simple turtle wax on the hemisphere followed by a one minute "polish" of the dried paste yields perfect movement everytime. I repeat after a few months, as required.  Without the wax, scope movement is impossible. 

 

My ball telescopes have won numerous awards and anyone who has moved them around will testify how smooth the movement is, whether its 90 F or -40 outside. I'm not sure what the problem with the Skaven's portaball is but for my ball scopes, it's really simple to make the scope move smoothly with simple car wax. 


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#42 Jon Isaacs

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Posted 10 September 2017 - 08:57 AM

No ball scopes here. With standard Dobs, I have tried about everything, Sailkote, Turtle Wax, Armor All, dry, various lubes.

 

What I found that really works, that transforms a sticky scope to a scope with excellent motions, simple bar soap.  I wet the soap and rub it over the lamnate's contact surface a few covering the entire surface. I let it dry a few minutes..

 

This is a standard old time carpentry technique for wooden drawers and the like.

 

Jon



#43 mdsohio

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Posted 10 September 2017 - 10:25 AM

I don't own a Portaball or any kind of ballscope, so I wont offer any advice in that regards, but one thing I noticed in this whole discourse was your constant and non-altering use of simple green. The common denominator here if you will. quote:"Baseline: sphere and base cleaned with Simple Green" No one else has mentioned it as well. Maybe its the issue, especially since others have had better experience with the same products you said you tried? Something to consider. For the record, lots of folks have tried John Issacs ideas on bar soap and it reportedly has worked well for everyone that has posted.
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#44 skaven

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Posted 10 September 2017 - 06:43 PM

No ball scopes here. With standard Dobs, I have tried about everything, Sailkote, Turtle Wax, Armor All, dry, various lubes.

 

What I found that really works, that transforms a sticky scope to a scope with excellent motions, simple bar soap.  I wet the soap and rub it over the lamnate's contact surface a few covering the entire surface. I let it dry a few minutes..

 

This is a standard old time carpentry technique for wooden drawers and the like.

 

Jon

Wow, great idea! I hadn't considered that, but I do get the impression that soap (even gummed-up soap on the ring) would have very good stiction characteristics.  I wonder if maybe something like paraffin wax would behave similarly?

 

The thing with ball scopes like this is that the friction is not really the issue.  It's actually OK if there is a fairly high coefficient of friction, because it helps ensure that the scope doesn't "drift" once you have it pointed somewhere.  But it's critical that the stiction be as low as possible.

 

A good example of the movement characteristics I'm looking for, is on the focus knob of my C6 SCT.  The knob has quite a bit of friction...it takes quite a bit of force to move it, and and resists moving very fast.  However, a light touch will slowly adjust the focus, without any jerking or really any noticeable stiction at all.  I presume this is accomplished with a fairly thick, sticky grease on the threads.

 

Obviously a thick, sticky grease is a no-go for a ball scope for many reasons, but maybe something like bar soap or paraffin wax would be a suitable substitute that wouldn't be as messy?

 

I don't own a Portaball or any kind of ballscope, so I wont offer any advice in that regards, but one thing I noticed in this whole discourse was your constant and non-altering use of simple green. The common denominator here if you will. quote:"Baseline: sphere and base cleaned with Simple Green" No one else has mentioned it as well. Maybe its the issue, especially since others have had better experience with the same products you said you tried? Something to consider. For the record, lots of folks have tried John Issacs ideas on bar soap and it reportedly has worked well for everyone that has posted.
Mike

Simple Green is a very effective degreaser, which is why I have been using it: it strips all the wax and oils off so I have a fresh, clean surface to try another product with.  But you're totally right -- it very well could be leaving some kind of residue that I'm not accounting for.

 

Today I cleaned the sphere with mineral spirits, and found that it removed the old gummed-up RZ-50 *much* better than the Simple Green had been.  I then applied a coat of StarBrite wax, let it dry for about half an hour, then buffed it off with a microfiber cloth.  While I was at it, I pulled the PTFE tubing out of the base and gave it a good cleaning with mineral spirits.

 

When I reassembled the scope, I found that the movement was *much* more "slippery" than it has ever been -- even with the RZ-50.  However, I'm still not convinced that the stiction has improved.

My heavier PTFE tubing should be arriving tomorrow, so I can experiment with that as well.  I'm going to try to avoid applying spray-on film lubricants if I can avoid it, since every time I've done that it eventually gums up in the base.



#45 Jon Isaacs

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Posted 11 September 2017 - 05:28 AM

Wow, great idea! I hadn't considered that, but I do get the impression that soap (even gummed-up soap on the ring) would have very good stiction characteristics.  I wonder if maybe something like paraffin wax would behave similarly?

The thing with ball scopes like this is that the friction is not really the issue.  It's actually OK if there is a fairly high coefficient of friction, because it helps ensure that the scope doesn't "drift" once you have it pointed somewhere.  But it's critical that the stiction be as low as possible.

A good example of the movement characteristics I'm looking for, is on the focus knob of my C6 SCT.  The knob has quite a bit of friction...it takes quite a bit of force to move it, and and resists moving very fast.  However, a light touch will slowly adjust the focus, without any jerking or really any noticeable stiction at all.  I presume this is accomplished with a fairly thick, sticky grease on the threads.

Obviously a thick, sticky grease is a no-go for a ball scope for many reasons, but maybe something like bar soap or paraffin wax would be a suitable substitute that wouldn't be as messy?

 

 

A few thoughts:

 

For a focuser, light and easy a la Feathertouch is unbeatable, there is no momentum to worry about and you can focus without jiggling the mount and causing vibration.... 

 

But, as you say, with a Dob, you want significant friction and zero stiction.  The large altitude bearings on premium Dobs are about higher tracking forces.  

 

My intuition is that paraffin wax would not reduces the stiction the way soap does.  Rub your finger across a bar of soap, rub it across some wax.. 

 

I don't know how soap would work the Portaball, it's got a lot of surface but a unique contact area. But the soap has worked well for me regardless of the surfaces, Teflon-Ebony Star, Teflon-Glassboard and Teflon-Aluminum.  

 

JOn



#46 skaven

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Posted 12 September 2017 - 03:03 PM

My new PTFE bearing tubing came in the mail yesterday.  It looks and feels much more like the "virgin teflon" pads that are commonly used by Dobsonian telescopes.  The tubing currently in the base (as provided by Dave) is the "translucent" variety that looks and feels more like regular plastic tubing.  I'm going to experiment with it this weekend to see if the new tubing I purchased (non-translucent, thicker sidewall) makes for a better bearing surface.


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#47 GeneT

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Posted 12 September 2017 - 08:51 PM

Back in the late 80s at Astrofest, a fellow from Michigan (I think) brought a 10" or so ball scope that was built around a spun aluminum ball. It really got Pete Smitka's mind spinning. The next year he brought his first Portaball. The rest is history. He was quite a character. Very smart and loved to joke around. I was very saddened by his passing. Thankfully, he sold Mag1 to Dave Juckem before he died. Dave had been making the ball and upper tube assembly and other fiberglass parts for Pete. As an aside, Dave himself had built several novel telescope designs that won awards at Astrofest. His specialty was and is fiberglass components. He's used that technology making parts for homebuilt airplanes and a novel clamshell observatory for his personal scopes.

I have owned about a dozen reflectors and SCTs over the years. My largest was a 20 inch Obsession. It was an excellent telescope, but too much hassle for me to pack up, drive to a site, unload, and reload in my vehicle. I own a Honda CRV, and there is plenty of room for the telescope, eyepiece case, and all the other accessories, with a lot of room to spare. All this would fit in an auto as small as a Honda Civic. I once thought an Obsession 18 Ultra Compact would be the answer, but I just plain did not like the telescope. About 22 years ago, I bought a 12.5 inch, F5 Portaball. For me it is the perfect telescope. It is easy to load, set up, and very fun to use. I bought a Tom O platform for it, but now rarely use the platform. Just locate, view, and nudge along. The ball design makes it very easy to follow an object, and you can twist the focusser to be in exactly the right position for maximum ease of viewing. In short, the Portaball is my keeper telescope. I am 74 years, old and have no difficulty on loading, and setting up the Portaball. It provides excellent images and is a joy to use.


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#48 skaven

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Posted 15 September 2017 - 11:04 AM

My new PTFE bearing tubing came in the mail yesterday.  It looks and feels much more like the "virgin teflon" pads that are commonly used by Dobsonian telescopes.  The tubing currently in the base (as provided by Dave) is the "translucent" variety that looks and feels more like regular plastic tubing.  I'm going to experiment with it this weekend to see if the new tubing I purchased (non-translucent, thicker sidewall) makes for a better bearing surface.

Here's a comparison of the two PTFE tubings.  The translucent one is the one that was shipped by Dave in my base.  The opaque one, with thicker side-walls, is the new tubing I purchased from fluorostore.com.

 

It's hard to tell without fully assembling the scope and actually pointing at something, whether the new tubing is better or worse (or the same) as the existing tubing.  My hope is that the thicker sidewall results in a stiffer bearing surface that has less of a tendency to "stick" when the scope comes to rest.

 

If I don't notice any improvement, I will try the soap.

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#49 SkyRanger

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Posted 17 September 2017 - 07:06 AM

My 8" PB is at PB World Headquarters for refurbishing.  It will come back with a new CZ quartz mirror, an upgraded cell, a completely upgraded electrical system, and a FT focuser, which replaces the old helical.  I am keeping the original struts and the original secondary cage.  I'll let you know what I think when I receive the scope in a few weeks.

 

GG



#50 Don H

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Posted 17 September 2017 - 12:05 PM

 

My new PTFE bearing tubing came in the mail yesterday.  It looks and feels much more like the "virgin teflon" pads that are commonly used by Dobsonian telescopes.  The tubing currently in the base (as provided by Dave) is the "translucent" variety that looks and feels more like regular plastic tubing.  I'm going to experiment with it this weekend to see if the new tubing I purchased (non-translucent, thicker sidewall) makes for a better bearing surface.

Here's a comparison of the two PTFE tubings.  The translucent one is the one that was shipped by Dave in my base.  The opaque one, with thicker side-walls, is the new tubing I purchased from fluorostore.com.

 

It's hard to tell without fully assembling the scope and actually pointing at something, whether the new tubing is better or worse (or the same) as the existing tubing.  My hope is that the thicker sidewall results in a stiffer bearing surface that has less of a tendency to "stick" when the scope comes to rest.

 

If I don't notice any improvement, I will try the soap.

 

I wonder if just using three short strips 120 degrees apart might be better than having it run around the entire rim?

 

By the way, I remember when Peter first brought a PortaBall to AstroFest. I was an instant fan and spent quite a while talking to him about the design. He said to come by at night, so we went over and tried it then, and several subsequent Septembers. I made it to AstroFest every year for about 20 years or so, beginning in the late 80s. I have toyed with the idea of building one like it with one of my mirrors, since I could not really afford to buy the real thing. So far, it has not happened. I got the same idea when I saw Dave Kriege bring his first Obsession, and was able to make several truss scopes of different sizes. But the ball scope remains to me the ultimate solution for portability and ease of use. My 12.5 inch mirror is only an inch thick and is an f/5.9, both of which tend to be less than optimal for balancing in a sphere. But I still entertain the notion to make one or hope to someday buy  a used PortaBall if I ever get some king of financial windfall.

 

Regards,

Don




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