21 replies to this topic

[apfever]

No need to change any original accessories, no need to take the OTA apart to get the captive rings off, completely reversible non permanent, better ring stability, easier control for rotating tube, walks the dog and does brain surgery. Hasn't anybody else done this yet? Where's the string on it? It's so simple you could probably do it by rubbing two sticks togehter but I'll use a band saw and drill, maybe drill press since it's handy and beside the saw.

It is 4:53 Mountain Time and I just thought of this so I'll be back with a first super rough proto type in whatever time it takes. The super ooper duper single part version should work even better. OOps, 4:55 now, I'll get busy.

[fjs]

You have my attention, I have to see this.

Caveat: I have no such mount.

[sarastro]

Don't tease us like that!
I have a Polaris mount.
And a drill press.
But no band saw....

[apfever]

WOW, did I mention how nice this can look? As a matter of fact, it can look pretty darn sweet on the scope. It works GREAT!!! Sorry about the miserable fail. It will require a couple of small standard 1/4 -20 bolts and the longest time for me was digging through the bolt bucket. Rough proto was about 10 minutes and included some finer fit sanding.

I really stink at documenting so I'm trying a series of pictures now.

[apfever]

OK.

I have 4 different OTA that go on my Polaris; Orange C80, C6 newt., C4.5, and Tasco 8V. All of these have these style rings in the photo, the C6 is exempt. The broken blue arrow points to the tube crushing side that slips over the saddle tang and impales the OTA onto the small poorly felted rail corners. The solid blue arrow points to the solid thick accessory flat on the 'top' of the rings. Both locations are tapped for standard 1/4-20 bolts.

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[apfever]

I noticed that the solid accessory flat part of the rings will hold the OTA off the rail saddle if bolted to the top of the saddle tangs.

It is difficult to see in the photo. Here I have the solid flats of the orange C80 rings bolted to the top of the saddle tangs. The arrows point to a completely clear gap between the OTA and felt contact points. The Tasco 8V and C4.5 also clear the saddle rails when mounted this way. The C6 newtonian is mounted in a similar way and the OTA is held off the saddle also, but in hinged rings. Thus the C6 on Polaris mount has no crush issue.

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[apfever]

Here is where I spent as much time looking for a bolt, as I did making the super uber duper part.

The mount saddle tangs have screw in inserts that the original clamp knobs push against so they can crush the tube onto the saddle. Remove those inserts. They come out fairly easy (usually). The threaded hole in the tang is larger than 1/4-20 and a standard 1/4-20 bolt can go through the saddle tang into the ring accessory flat. You need to get a SHORT 1/4-20 bolt so it will secure the OTA ring without bottoming out and without going through the ring into the OTA. I found a couple of short bolts shown by the arrows. One is a wide pan head and one is a shouldered thumb screw. A couple of standard 1/4-20 clamping knobs would work great, with the thread ground to length.

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[apfever]

Here is the sad resulting situation so far. The original rings are now mounted upside down, on top of the saddle. The OTA is loose, sliding back, and resting with the focuser on the table.

The original clamping knobs are now on top. They will not reach the OTA, and even if they did they would damage **EDIT - EDIT** out of it. Fitting a block into each ring is all fine and dandy but it won't increase surface contact much over the felt (would still be better though), and they'd tend to fall out easy. soooo....

edit: getting pictures.

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[apfever]

The block is oak, but experiment. I had this long stick which was already the right width to fit between the sides of the ring notch. It was too thick to fit between the ring and OTA so I just bandsawed it by eye. It was still a hair thick by one hole so I sanded it on the edge sander. This stick was also already cut at a 45 on one end so I did some quick sanding to round both ends, just for some quick looks.
The holes were centered side to side by eye. The distance between holes was measured to match the distance between the holes in the mount saddle tangs. I drilled these at 17/64", which is 1/64" over 1/4". I drilled over size for some wiggle room since this is a quickie rough in. Carefull layout should use 1/4" to match the 1/4" clamping threads. The holes were drilled to a depth just short of going through, and leaving plenty of support below the clamp knobs threads.

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[RacerX69]

Don't tease us like that!

^^^^ Whut he said. ^^^^

I have a Polaris mount.

I do not, but I am still interested.

And a drill press.
But no band saw....

I have a table saw, worm drive Skill saw, drill press, cutting torch, wire feed welder, brake lathe with flywheel grinding attachment, 4 post lift, and about $200,000 worth of SnapOn, MAC and Crapsman tools.

Maybe I can pick something up here that will help me mount the Byers drive to my Edmund equatorial mount.

Without crushing Mrs. Racer.

[apfever]

Installed.

Making the holes deep in the wood allows the clamping knobs to hold it in place when loosening for tube rotation. By drilling 1/4" holes, as deep as possible, the holes and clamping knob threads act as a centering and ring support by tying both rings together at the top. The stick should be cut for a close slip fit in the ring notch and it will act as a brace between the rings.
Light Bulb: this can also hold those floppy rings in place when the OTA is off the saddle.

Surface area of contact is going to get real large in the next entry....

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[apfever]

Ideally, you need to round the bottom of the stick to match the radius of the OTA. This quickie is still flat and only contacts the OTA on the center line. Rounding the sick to fit the OTA curve will provide superior contact suface to anything stock. Fitting the curve will also allow the stick to have taller contact with the sides of the ring notches.

You might want to increase the radius a hair for some felt, but go minimal. The idea is to have as much stick as possible slip fit the ring notches.

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[RacerX69]

Nice job!

[apfever]

You can router this, black stain, hammer tone black, shape, and pretty up any way you like. Too easy.

This was way quick and crude. Even so, the slightest turn of the clamp knobs and the OTA goes from smooth slip and rotation to rock solid. Also, ...Sheesh.. it just keeps getting better so I'll stop with this...The knob location is a heck of a lot nicer for ergonomics when shifiting the OTA, annnnnnnd, the rings don't get loose on the saddle when shifting the OTA, and....

I'm open to comments, please, really, before I do actual field work. What am I missing? Seems this should have been done long ago.

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[apfever]

Oh, Racer,

I'm afraid you might need a good stable 2,000 pound screw cutting lathe with a 16" throw and long bed. The older the better. You didn't mention one of those. It would be great for curve fitting the stick.

[fjs]

Hey, O.K. I got you. That is a pretty setup, and nice invention! Maybe come in handy if I ever find a Polaris... If not, thanks for the superb entertainment value.

[RacerX69]

Oh, Racer,

I'm afraid you might need a good stable 2,000 pound screw cutting lathe with a 16" throw and long bed. The older the better. You didn't mention one of those. It would be great for curve fitting the stick.

I had access to a very old leather belt driven metal lathe when I worked at the electric utility fixing trucks. It had ( I think ) a 16" throw, the bed was about 8 feet long or so, it had all the screw cutting gearing, adjustable tailstock, etc.

I still have a nice assortment of cutting tools I picked up at Boeing surplus when it was still open in Kent, WA. Parting tools, and various cutters I had ground and made for various machining jobs I did. THe "community" tooling that was shared was always dull and damaged, by ignorant and inconsiderate fellow mechanics.

There was also several drill presses, one was originally set up for use in a shop with central drive power to operate off of a belt, but converted to electric power. There was also a Walton drill press with the infinitely variable drive.

And a few years before I retired they bought a Chinese clone of a Bridgeport mill.

All of the machining and fabricating stuff was supposed to be for company use only, but more "home projects" were run through there than anything else.

I sure miss all that stuff.

And I had a chance to buy a real Bridgeport mill at Boeing surplus for $1,500, and a nice lathe for about the same amount, but I didn't have any way to move them, and at the time, no shop to put them in.

*sigh*

[Ducky62]

I have a Vixen Polaris R100S 100mm f/6. They "fixed" the tube crushing problem by using a heavier gauge tube than found on the C4.5, 8V etc. That thing is built like a tank.

[starman876]

nothing like giving your scope a woody

[DocFinance]

Nice mod. I don't think the spacer is really necessary, though. I use my polaris with the cheapo EQ2 rings all of the time and it dampens just fine.

[Nick Will]

Very nice. Going to give it a try. I got some nice birds eye pine, some 6" PVC for the radius and lots of Velcro nap for tube contact medium.
Now all I need is time.
Thanks again Ap for blazing a trail

[Masvingo]

Brilliant write-up Neil, highly entertaining! Makes me want to rush out and get a Polaris mount!