49 replies to this topic

[TayM57]

Televue thumbscrews are captive generally I believe (mushroomed out at the end), so removing it as a temporary solution for a nylon screw likely isn’t possible.

Oh I didn't know that.

[helpwanted]

The screw leaving a mark on the barrel is really no big deal. It’s like when you buy a brand new car, the first time you get dinged in a parking lot it upsets you, but the car still works and still looks beautiful. You’re probably the only person that would notice where that nick is. 
if the screw leaves a mark in the barrel, that probably means you’re turning it too tight, and that’s OK too, just like the mark on the barrel does not hinder the performance of the eyepiece. 

[scotsman328i]

Oh I didn't know that.

Actually Tay, I had to take images a few minutes ago of my Powermate to show Agena to fix the issue. The screw on the 2” Powermate body is mushroomed and does not come out. It is the screw on the 1.25” adapter that is removable.

[Bill Weir]

Go get a yogurt, cottage cheese, etc type container out of the recycle bin and cut an appropriate sized strip and insert it. It will do until the brass replacement is sent. I’ve done this before when I’ve made make do extension tubes out of central vac tubing. 

 

Bill

[scotsman328i]

Go get a yogurt, cottage cheese, etc type container out of the recycle bin and cut an appropriate sized strip and insert it. It will do until the brass replacement is sent. I’ve done this before when I’ve made make do extension tubes out of central vac tubing. 

 

Bill

I could, but we are in the middle of pollen season in Charleston, SC. EVERYTHING is under 2” of yellow dust. I have time for the rings to come in before I’m out viewing again. I just want to fix the issue for when pollen season ends.

[Jethro7]

Very disappointing! I also received a 2x Powermate about two weeks ago. Same issue…no brass compression rings! I will be calling TeleVue on Monday myself asking for them to send me 2” and a 1.25” brass compression rings for it. The slots are in there as they are machined to fit the compression rings. No one can tell me Televue doesn’t have compression rings sitting around the shop there. 

 

Thanks. See attached picturI have no doubt that this is the real thing. It has a good amount of heft and the machining is done very well.

 

You can see what are indentations for where I assume the rings should go but, alas...

 

The place I bought this from said thet the lad time for the missing parts could take up to 2 weeks.

Hello,

Yep, the compression are missing. I can't imagine in any way that Tele Vue would do away with the compression rings. So someone was sleeping on the Job. Just call TeleVue on Monday, TeleVue should just send the compression rings out.

 

HAPPIER SKIES TO YOU AND KEEP LOOKING UP Jethro

Edited by Jethro7, 15 March 2025 - 04:33 PM.

[scotsman328i]

Hello,

Yep, the compression are missing. I can't imagine in any way that Tele Vue do away with the compression rings. So someone was sleeping on the Job. Just call TeleVue on Monday, TeleVue should just send the compression rings out.

 

HAPPIER SKIES TO YOU AND KEEP LOOKING UP Jethro

Thanks Jethro, Agena is handling it. They’re getting me the OEM compression rings for the 2x Powermate asap come Monday.

[Enyo]

Hmm, my 26 year old 5x Powermate never had a compression ring nor my 23 year 4x Powermate but my newer 3x does. 

 

Anyone know if the rings were used way back in the day or are they were a later addition to the Powermate line.

[Starman1]

Why not give the customer what is stated on the website? Why not receive the same product that everyone else historically received WITH compression rings? I have Naglers and Ethoi. I really don’t want them marred by set screws. A compression ring also holds an eyepiece more securely and safely than a set screw.

Uh, no, this is false and indicates a common misconception.

The brass split ring that is in there does NOT compress all the way around the barrel at the same time.

What happens is that the brass ring directly under the screw will move inward until it contacts the eyepiece, while the ends of the split ring slide around the perimeter of the groove.

The ends do not contact the eyepiece.

 

Compression ring is a misnomer.

 

The binding system that closely resembles the name "compression ring" is the "Twist-Lock" binding, which could also be described as a collet.

 

The purpose for the split ring is NOT improved binding, it is to prevent marring of the eyepiece barrel finish by the thumbscrew.

 

Theoretically, IF the split ring pressed into the undercut on the eyepiece barrel, it could produce a more secure binding.  But that is no different than a thumbscrew entering the undercut on the barrel.

 

All that doesn't mean I don't agree that the split ring should be there.  This is merely an error on the part of Tele Vue's supplier and will be promptly taken care of.

Any retailers with stock like the ones described should also be in contact with Tele Vue.

[Starman1]

Hmm, my 26 year old 5x Powermate never had a compression ring nor my 23 year 4x Powermate but my newer 3x does. 

 

Anyone know if the rings were used way back in the day or are they were a later addition to the Powermate line.

Yes, split rings were added later.

There was a time when none of their Barlows, PowerMates, diagonals, etc. came with the split-ring binding.

 

We should actually stop calling them compression rings, since they don't compress anything.

The screw compresses the ring, which then springs back with the screw no longer presses on the ring.

The only part of the split ring that actually touches the eyepiece is the part under the screw.

[scotsman328i]

Uh, no, this is false and indicates a common misconception.

The brass split ring that is in there does NOT compress all the way around the barrel at the same time.

What happens is that the brass ring directly under the screw will move inward until it contacts the eyepiece, while the ends of the split ring slide around the perimeter of the groove.

The ends do not contact the eyepiece.

 

Compression ring is a misnomer.

 

The binding system that closely resembles the name "compression ring" is the "Twist-Lock" binding, which could also be described as a collet.

 

The purpose for the split ring is NOT improved binding, it is to prevent marring of the eyepiece barrel finish by the thumbscrew.

 

Theoretically, IF the split ring pressed into the undercut on the eyepiece barrel, it could produce a more secure binding.  But that is no different than a thumbscrew entering the undercut on the barrel.

 

All that doesn't mean I don't agree that the split ring should be there.  This is merely an error on the part of Tele Vue's supplier and will be promptly taken care of.

Any retailers with stock like the ones described should also be in contact with Tele Vue.

Ok, that’s fine. In that case…

 

“I’ll take the non marring of $700 eyepieces for $100, Alex.”

[betacygni]

Ok, that’s fine. In that case…

“I’ll take the non marring of $700 eyepieces for $100, Alex.”

I’ve actually taken the compression ring out of some of my visual backs for heavy duty usage. To me the compression ring is vanity over function. They tend to sometimes catch on the eyepiece (undercut) when inserting or removing and don’t hold as well in heavy duty applications. The old fashion set screw marring is actually creating a better mechanical connection than just the friction of a brass ring that doesn’t dig into the eyepiece at all. To me it’s all a bit silly to try to protect an invisible in use part of the eyepiece, especially when this protection comes with a couple negatives (admittedly minor in diagonal/powermates, more significant in visual backs). I’ve always greatly respected Takahashi for sticking with the superior set screw and ignoring the compression ring fad in their visual backs and accessories.

Edited by betacygni, 15 March 2025 - 04:28 PM.

[scotsman328i]

I’ve actually taken the compression ring out of some of my visual backs for heavy duty usage. To me the compression ring is vanity over function. They tend to sometimes catch on the eyepiece (undercut) when inserting or removing and don’t hold as well in heavy duty applications. The old fashion set screw marring is actually creating a better mechanical connection than just the friction of a brass ring that doesn’t dig into the eyepiece at all. To me it’s all a bit silly to try to protect an invisible in use part of the eyepiece, especially when this protection comes with a couple negatives (admittedly minor in diagonal/powermates, more significant in visual backs). I’ve always greatly respected Takahashi for sticking with the superior set screw and ignoring the compression ring fad in their visual backs and accessories.

Cool. I’ll still take a non-marring BCR over a set screw anyday. 

[Olimad]

 

 

All that doesn't mean I don't agree that the split ring should be there.  This is merely an error on the part of Tele Vue's supplier and will be promptly taken care of.

Any retailers with stock like the ones described should also be in contact with Tele Vue.

 

I am sure that what I am going to say will be wrongly interpreted and I respect your knowledge and also the quality of TV. but

 

On the one hand, we can not say that the Quality Check of TV is also what makes TV so premium (QC of their products in the US before sending them for sale all over the world and this has an impact on their prices in Europe - seen in a lot of threads in this forum) and OTOH that It is merely the fault of TV suppliers.

And also that the different sellers should be in contact with TV - No, after having knowledge of this little problem TV should contact all their resellers with this stock to check if wether or not there is this little problem.

Or should any resellers also check every TV products before selling them? That would mean QC by manufacturers, QC by TV in the US and also QC by the resellers ? After knowing the little problem, TV responsability is to contact their other resellers, not other way around.

For the customers, that is merely TV responsability.

 

Having said that, an error can happen to every one (that is what makes us human), we are not talking about a sector of activity that when an error occurs, It puts someone s life ar risk.

It is a small and easy to fix error, nothing to do with intrinsic optical quality. Time delaying but no big deal.

Edited by Olimad, 16 March 2025 - 04:06 AM.

[Polyphemos]

…

 

The old fashion set screw marring is actually creating a better mechanical connection than just the friction of a brass ring that doesn’t dig into the eyepiece at all.

….

Actually, this is incorrect. Set screw marring is an indication of a poor mechanical connection.

 

This happens when the local stress created by the poor surface quality of the set screw exceeds the shear strength of the barrel material. When your diagonal rotates and a scratch is made on the barrel, flaws on the set screw contact surface have acted like the cutting tool on a metal lathe. The set screw machined the scratch.

 

If the set screw contact surface is worked to remove these destructive surface flaws - a simple matter of rubbing it against a whetstone in a circular motion until the set screw contact surface is uniformly abraded to a matte finish - the contact area of the set screw tip increases dramatically, local microscopic stresses at the contact point decrease dramatically, and it becomes practically impossible to scratch a barrel.

 

I put this to a test a couple of days ago when I clumsily banged my arm sideways into the eyepiece mounted on my Orion ST80, forcing the diagonal to rotate 180 degrees in the process. The diagonal barrel was secured in the visual back with a single small diameter (3mm) set screw, which while plenty secure under normal circumstances wasn’t up to my forcefully knocking it with my forearm. I removed the diagonal to survey the damage caused by the set screw and there was absolutely none. The semi-polished set screw surface was incapable of cutting the diagonal barrel under any normal circumstances. A further benefit is that because the barrel surface won’t fail and yield in shear the set screw is far more effective in keeping parts from moving. I routinely observe through a horizontally oriented eyepiece.

 

Better set screws come with better finished and/or rounded surfaces, but the contact point is almost invariably not sufficiently smooth and the contact point surface area too small to be optimally effective. These I rework the same way as any common set screw.

[turtle86]

Cool. I’ll still take a non-marring BCR over a set screw anyday. 

Me too.

[betacygni]

Actually, this is incorrect. Set screw marring is an indication of a poor mechanical connection.

 

This happens when the local stress created by the poor surface quality of the set screw exceeds the shear strength of the barrel material. When your diagonal rotates and a scratch is made on the barrel, flaws on the set screw contact surface have acted like the cutting tool on a metal lathe. The set screw machined the scratch.

 

If the set screw contact surface is worked to remove these destructive surface flaws - a simple matter of rubbing it against a whetstone in a circular motion until the set screw contact surface is uniformly abraded to a matte finish - the contact area of the set screw tip increases dramatically, local microscopic stresses at the contact point decrease dramatically, and it becomes practically impossible to scratch a barrel.

 

I put this to a test a couple of days ago when I clumsily banged my arm sideways into the eyepiece mounted on my Orion ST80, forcing the diagonal to rotate 180 degrees in the process. The diagonal barrel was secured in the visual back with a single small diameter (3mm) set screw, which while plenty secure under normal circumstances wasn’t up to my forcefully knocking it with my forearm. I removed the diagonal to survey the damage caused by the set screw and there was absolutely none. The semi-polished set screw surface was incapable of cutting the diagonal barrel under any normal circumstances. A further benefit is that because the barrel surface won’t fail and yield in shear the set screw is far more effective in keeping parts from moving. I routinely observe through a horizontally oriented eyepiece.

 

Better set screws come with better finished and/or rounded surfaces, but the contact point is almost invariably not sufficiently smooth and the contact point surface area too small to be optimally effective. These I rework the same way as any common set screw.

The set screws on my feathertouch focusers are pointed to gouge into the material. This presumably is to prevent rotation of heavy loads. Doing a bit of set screw research does indeed confirm this, gouging is best for strength. Time to sharpen all my set screws! 

 

Source: https://www.mcmaster...rew-points.html

[TayM57]

Only on CN can a thread about a missing part segue into a conversation about semantics regarding compression rings/split rings, and whether a set screw is a better way of securing an eyepiece vs a split ring.

 

Shades of the great undercut debate.

Edited by TayM57, 16 March 2025 - 12:21 AM.

[scotsman328i]

Only on CN can a thread about a missing part segue into a conversation about semantics regarding compression rings/split rings, and whether a set screw is a better way of securing an eyepiece vs a split ring.

 

Shades of the great undercut debate.

Haha Tay, NO ONE beats a dead horse quite like CN! 

[Polyphemos]

The set screws on my feathertouch focusers are pointed to gouge into the material. This presumably is to prevent rotation of heavy loads. Doing a bit of set screw research does indeed confirm this, gouging is best for strength. Time to sharpen all my set screws! 

 

Source: https://www.mcmaster...rew-points.html

That’s not how it works best for our relatively light loads. Gouging is analogous to taking a heavier cut during machining, which requires more torque. We’re trying to avoid cutting all together, and are instead relying on increasing friction to prevent movement. When we want to stop our cars we apply our brakes; we don’t drop an anchor. If you need to rely upon gouging or deforming your components to prevent them from moving you’ve made a fundamental error in choice for the retention system.

 

My recommendations, while founded in sound mechanics, are entirely practical and based on dozens of reworked set screws and grub screws from M8 to M1.5 with 100% success in preventing or entirely eliminating damage while improving retention effectiveness. We can dig deeper into the theory, but you can prove its efficacy for yourself in a few minutes and you need nothing more than a medium-fine whetstone or some 800 grit sandpaper and a drop of oil.

[davidgmd]

I like compression rings, even though they occasionally catch on an undercut. If it bothered me significantly, I’d remove the compression rings and use nylon-tipped set screws.

[scotsman328i]

I called Televue today and told them of my situation with the missing BCRs. They already have the 2” and 1.25” BCRs in the mail, along with a spare orange dust cap. They are aware of the situation and are working on correcting the issue with their suppliers and retailers. 

[turtle86]

I like compression rings, even though they occasionally catch on an undercut. If it bothered me significantly, I’d remove the compression rings and use nylon-tipped set screws.

 

My thoughts and experiences exactly.

[turtle86]

I called Televue today and told them of my situation with the missing BCRs. They already have the 2” and 1.25” BCRs in the mail, along with a spare orange dust cap. They are aware of the situation and are working on correcting the issue with their suppliers and retailers. 

 

That is great news.  Tele Vue generally has excellent QC but no one is perfect.

[scotsman328i]

That is great news.  Tele Vue generally has excellent QC but no one is perfect.

Definitely! It was no big deal, just wanted the rings and I’ll put them in the Powermate. Easy peasy.