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Rotating rings ?

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#26 Charlie Hein

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Posted 26 March 2004 - 12:20 AM

Here is my take on Stacy's original idea. I used UHMW plastic channel and a hose clamp.

-Dave


Dave, that's a great idea! Where can you get the plastic channel?

Charlie

#27 Rushwind

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Posted 26 March 2004 - 04:34 AM

ooo... I *like* the plastic channel! I may have to upgrade. Does it come in black? (:

Jimbo

#28 Stacy

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Posted 26 March 2004 - 01:35 PM

Those are some great ideas! :smash:

#29 BCB

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Posted 26 March 2004 - 02:49 PM

Hmmmmmmmmmm

I like the plastic channel myself..

Things have been REALLY hectic at work lately, and I haven't had the time to get round to fabbing the one I had in mind. That plastic channel would make my life alot simpler, that's for sure.

On another note, it seems that tube rotation is affecting my secondary collimation by quite a bit.. (combination of a plastic top-end ring, and having the spider mounted to a thin walled tube that flexes wherever it wants to when rotated in the rings)

I like this scope, but am starting to think something a bit bigger (ap fever:D) and beefier might be better, than trying to work all the darn bugs out. LOL

#30 Charlie Hein

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Posted 28 March 2004 - 05:32 PM

Ok, I've been on a parts-gathering spree this afternoon. I've acquired the tapered screw for the front ring's hinge, and a "stop nut" to keep it from loosening up ($0.75 for the stainless steel version at Ace Hardware). I found the nylon spacer that goes into the front ring's tensioner to keep it from completely closing ($1.25 for a package of two at Lowes'). A trip to the local bicycle store was interesting. It turns out that the QC seat releases they sell come with a ring to go around the seat post that the tensioner goes through. The bike shop in question routinely robs this ring from the package in order to use it to mount baby seats to mommie's bikes, so they had a number of useless(to them) tensioners laying around in the tops of the bike mechanics' tool boxes, one of which they cheerfully refused to take any payment for whatsoever after handing it to me (freebie!).

So far, this has been a real cheapie project, and I've been feeling pretty good about that. I still have not come up with the ring, though. Although I know that there are hose clamps out there that come in length, and can be cut down to the size you need (an 8" Orion OTA is going to need one about 32" long, BTW), none of the hardware stores in my area seem to stock them. I've scoured all the hardware stores in the area, and nobody seems to carry anything even remotely like the plastic channel, either. It would be really helpful to know what the plastic channel was originally designed to do.

Better yet, if anyone has about a yard of the stuff that they'd be willing to part with, I'd be motivated to make a deal... if I do manage to find the channel on my own, I'll be sure to let y'all know!

Charlie

#31 Rushwind

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Posted 28 March 2004 - 05:49 PM

Charlie,

You might find that it saves you some search effort to use two smaller hose clamps, and attach them end-to-end; Dave's rig is a 5", so he could probably use a 5.5" hose clamp (which was in stock at my local hardware store), but I went with 2 of those for my Orion 8" OTA.

Jimbo

#32 Charlie Hein

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Posted 29 March 2004 - 12:03 AM

yep, had that length at all local hardware stores as well... the plastic channel is the big "sticker" in this whole deal... it's just that I can actually remember *seeing* the channel Dave has a picture of somewhere... I just can't remember what it was doing when I saw it! It would be *so* helpful to know who to contact to get a yard of that channel... I know that I'm obsessing on this, but I have to know... :grin:

Charlie

#33 Stacy

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Posted 02 April 2004 - 08:51 PM

it's just that I can actually remember *seeing* the channel Dave has a picture of somewhere... I just can't remember what it was doing when I saw it!


Happens to me all the time Charlie. It's probably in your shop or garage somewhere! I searched a bit on the Web but have come up empty so far … Maybe Dave will tell us where he found that stuff!

Regards,
Stacy

#34 BCB

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Posted 03 April 2004 - 06:48 AM

Just fired him a PM almost BEGGING him to tell us what it is, and where he got it.. :D

#35 Guest_**DONOTDELETE**_*

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Posted 03 April 2004 - 08:03 PM

Ok, I found the post!

Glad you all like the channel idea. So far it is working great. I bought the channel at McMaster Carr (www.mcmaster.com). I copied the URL below but it might not work:

http://www.mcmaster....409668295717965

It is UHMW plastic channel. I bought some 1" wide by 1/8" thick strips to cover the channel to clean it up.

Like I said, it seems to be working great so far. However, the image doesn't stay centered when I rotate the tube (not a fault of the plastic ring but the tube holder). I may experiment with a new set of tube rings.

-Dave

#36 Guest_**DONOTDELETE**_*

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Posted 03 April 2004 - 08:05 PM

I had to cut the channel down to fit between my tube and mounting plate.

As far as I know, it doesn't come in black. And it may be a pain to paint too.

I used one large pipe clamp to hold it together.

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#37 Guest_**DONOTDELETE**_*

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Posted 03 April 2004 - 08:06 PM

And another picture....

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#38 Charlie Hein

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Posted 03 April 2004 - 08:57 PM

I had to cut the channel down to fit between my tube and mounting plate.


So did you glue the flat piece over the channel opening? If so what kind of glue?

Charlie

#39 Guest_**DONOTDELETE**_*

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Posted 04 April 2004 - 08:51 PM

Ahhh, there's a trick!

If I get a chance, I'll take another picture showing what I did. I drilled a small hole on each side of the channel into the edge of the cover strip and used small nails (brads) to hold it in place.

-Dave

#40 Rushwind

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Posted 05 April 2004 - 02:20 AM

However, the image doesn't stay centered when I rotate the tube (not a fault of the plastic ring but the tube holder). I may experiment with a new set of tube rings.


I've been meaning to bring this up; my image doesn't stay centered when I rotate the tube, either. I was beginning to wonder if it was a "feature". What would one have to do to make sure that the image stayed centered after rotation? Is it about making sure that the hose clamps are square with the tube? Maybe putting in a rigid spacer like Stacy did?

Inquiring minds want to know. :question:

Jimbo

#41 Guest_**DONOTDELETE**_*

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Posted 05 April 2004 - 09:54 AM

Jimbo,

On an EQ mount, the optical axis of the tube has to be orthogonal to the declination axis (I doubt mine is). Also, when we loosen the tube holder, the tube can wiggle around. So one needs to properly align the tube and keep it that way even when rotating to prevent the image from moving.

It's similar for an alt-az mount but I can't think of how to explain it.

-Dave

#42 Charlie Hein

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Posted 05 April 2004 - 12:24 PM

I found a source for hose clamps long enough to go completely around almost any size OTA. A clamp to fit up to a 10" OD tube is cheap enough ($2.42), but adding shipping and a "handling" charge gets the cost up to about $7.00. Not the cheapie solution I had envisioned, but I don't have to do any more hunting for it!

Charlie

#43 Charlie Hein

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Posted 05 April 2004 - 12:33 PM

However, the image doesn't stay centered when I rotate the tube (not a fault of the plastic ring but the tube holder).



Well Dave, now we know why they want so much for the rotating rings! :grin: Seriously, thanks for the info on the channel!

I think the simple work-around for this is to simply rotate the tube before lining up on target. If rotating the tube is your first task, it doesn't matter too much if the tube flops around a bit when it's loose.

Charlie

#44 Charlie Hein

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Posted 05 April 2004 - 12:50 PM

Ahhh, there's a trick!

If I get a chance, I'll take another picture showing what I did. I drilled a small hole on each side of the channel into the edge of the cover strip and used small nails (brads) to hold it in place.

-Dave


I see... did you do it just on the ends of the channel, or at intervals along the edge?

This gets me thinking - Is the cover required for extra rigidity, or did you mainly do it for aesthetics?

I'm assuming that the material is flexible enough to easily hand bend around the tube... would it be easy/advisable/worthwhile to put a notch-tab arrangement on the ends of the channel so as to fit one end inside the other for additional rigitity, or is it rigid enough once tightened up with just the squared off ends butted up against each other?

Charlie

#45 Charlie Hein

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Posted 05 April 2004 - 02:34 PM

I bought some 1" wide by 1/8" thick strips to cover the channel to clean it up.


Dave,

Sorry to keep bugging you on this, but I have another question... I'm getting confused about the size of the channel. If the strip you bought to cover the channel is 1" by 1/8" thick, then how wide/thick is the channel itself?

...can you supply the part numbers for the pieces you got?

I'm ready to get the parts, just want to make sure I get the right stuff.

Charlie

#46 Guest_**DONOTDELETE**_*

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Posted 05 April 2004 - 10:52 PM

Hi Charlie,
No bother at all! The part number for the channel is 8672K31. They also sell the hose clamps. I think I purchased 45945K38 for my tube (Type 316 Stainless Steel Nonperforated Worm-Drive Hose and Tube Clamp).

I nailed the strips at the ends only. The stuff is easy to bend and machine with standard woodworking tools. I added the strip for aesthetic reasons. I doubt you would need to notch the ends, except to make it look nicer.

Yep, I try to orient the tube first then line up on target. It works for now but I may try to make rotating rings using the UHMW plastic as the bearing.

I'll try to get some more pictures tomorrow.

Let me know if you need anything else!

-Dave

#47 Charlie Hein

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Posted 06 April 2004 - 12:30 PM

Hey, Dave- thanks for the reply. I'm glad that this isn't too annoying for you - not everyone is as patient, and I want to let you know that I appreciate it!

I think that you accounted for everything except for the part number of the 1" plastic strip you used for the cover. Once I get that I'll order the plastic parts and get this puppy constructed!

Meanwhile, I've been thinking about the rigidity issues I've noticed with the stock Orion tube rings. With the tube out of the rings, they seem a little "floppy", for lack of a better term. I can see that when they're loosened, they will tend to move around a bit.

Stacy put an aluminum bar between the two rings along the top where a camera piggybacks onto the rings to try and address that issue. Maybe he could comment on how well this stiffens up the whole works.

If more stability is needed, I was thinking that maybe we could drill and tap along the rings next to the hinges and also next to the ring openings on each "half" of the rings, and add four additional supports to really stiffen things up... if we were to go this route, we might even consider drilling and tapping next to the extrusions in the top half of the ring where the cameras piggyback and put in a couple of supports there rather than taking up the piggyback mount with the support bar. If two holes per side were drilled and tapped, it stands to reason that you'd then have a very stiff ring assembly to turn against. Perhaps some careful grinding on the spacer that keeps the front ring from closing entirely would help keep the tube in line - or maybe we could just add another quick release to the front ring to lock the tube down tight after turning...

...hey, it just a thought!

Charlie

#48 Guest_**DONOTDELETE**_*

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Posted 06 April 2004 - 03:43 PM

Charlie,

I think the strip model number is 8702K19.

My tube holder also seems a little 'floppy' when loose. My problem seems to be centered on the hinge. I think my holder is smaller and stiffer than your holder. It appears that your holder is like to individual rings. Maybe you can get some small pieces of thin aluminum plate and curve them to fit on the outside between the rings. Should eliminate any twisting. I think your idea will work too. I would try to fasten each end of the support with more than one fastener, that way the rings won't twist.

-Dave

#49 Charlie Hein

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Posted 06 April 2004 - 08:26 PM

Charlie,

I think the strip model number is 8702K19.

My tube holder also seems a little 'floppy' when loose. My problem seems to be centered on the hinge. I think my holder is smaller and stiffer than your holder. It appears that your holder is like to individual rings. Maybe you can get some small pieces of thin aluminum plate and curve them to fit on the outside between the rings. Should eliminate any twisting. I think your idea will work too. I would try to fasten each end of the support with more than one fastener, that way the rings won't twist.

-Dave


Good idea, Dave... maybe Stacy will chime in on how well the single stiffening bar works before I go to a lot of trouble.

Also, thanks for the part number on the strip, it sure makes for a clean installation!

Charlie

#50 Guest_**DONOTDELETE**_*

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Posted 06 April 2004 - 10:20 PM

Charlie,

It's out of focus, but here is a picture showing the nails I used to hold the strip in place.

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