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WO vixen rail...no safety stop

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12 replies to this topic

#1 mewmartigan

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Posted 18 August 2019 - 12:02 PM

So the saddle on my new CEM40 leaves something to be desired. My Z103 actually slid in the saddle during a goto so I figured I had better screw in a safety stop.

 

The underside of the vixen rail on my Z103 has no threaded hole for a safety stop screw. So, those of you with a WO rail, what method are you using for a safety stop?

 

Thanks!


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#2 John Fitzgerald

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Posted 18 August 2019 - 12:11 PM

The scope holding rings on my Vixen style rails are screwed to the rails from the bottom using socket head cap screws, not countersunk.  The heads of the screws are the safety stops.  If they were countersunk, I would drill or thread a bolt hole at least near the upper end of the dovetail for a safety stop.  If on an eq mount, then on both ends.


Edited by John Fitzgerald, 18 August 2019 - 12:13 PM.

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#3 markb

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Posted 18 August 2019 - 12:36 PM

Drilling and threading the rail for a pair of M4 thumbscrews is easy, and they are easily removable.

 

I avoid SAE for consistency in my threaded fasteners, but IIRC 6-32 thumbscrews are super cheap and available since they were used for pc computer cases.

 

Incidentally, the locking screws on old serial connectors are 4-40, and lots of extended shaft thumb screws in 4-40 are therefore easy to get. One made my etx125 finder instantly removeable.

 

A button head screw can also be used for a never-removed safety, and its looks will not offend, but thumbscrews work great.

 

With either, buy the drill and tap set, usually very inexpensive, to avoid weak threads or broken taps (HD, Lowes, Amazon). Reverse the tap a 1/2 turn every couple of turns to clear the chips. Keep the tap straight, their hardness makes them relatively easy to snap.

 

I have been buying Irwin taps and drills and am satisfied so far. I avoid chinese unbranded on taps due to the unmitigated disaster of broken taps, tough to remove without damage.


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#4 mewmartigan

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Posted 18 August 2019 - 07:19 PM

The scope holding rings on my Vixen style rails are screwed to the rails from the bottom using socket head cap screws, not countersunk.  The heads of the screws are the safety stops.  If they were countersunk, I would drill or thread a bolt hole at least near the upper end of the dovetail for a safety stop.  If on an eq mount, then on both ends.

Yes, mine are countersunk. Maybe I can just find a longer screw so it sticks out a bit.

 

Drilling and threading the rail for a pair of M4 thumbscrews is easy, and they are easily removable.

 

I avoid SAE for consistency in my threaded fasteners, but IIRC 6-32 thumbscrews are super cheap and available since they were used for pc computer cases.

 

Incidentally, the locking screws on old serial connectors are 4-40, and lots of extended shaft thumb screws in 4-40 are therefore easy to get. One made my etx125 finder instantly removeable.

 

A button head screw can also be used for a never-removed safety, and its looks will not offend, but thumbscrews work great.

 

With either, buy the drill and tap set, usually very inexpensive, to avoid weak threads or broken taps (HD, Lowes, Amazon). Reverse the tap a 1/2 turn every couple of turns to clear the chips. Keep the tap straight, their hardness makes them relatively easy to snap.

 

I have been buying Irwin taps and drills and am satisfied so far. I avoid chinese unbranded on taps due to the unmitigated disaster of broken taps, tough to remove without damage.

I probably need a tap set anyway but I was hoping to avoid drilling the rail. Thanks for the info though.



#5 junomike

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Posted 18 August 2019 - 08:58 PM

A longer screw (or possibly the same one) with added washers (underneath the screw head) should move the screw head out enough for the Saddle body to catch should it loosen.



#6 John Fitzgerald

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Posted 18 August 2019 - 09:04 PM

A longer screw (or possibly the same one) with added washers (underneath the screw head) should move the screw head out enough for the Saddle body to catch should it loosen.

!!!  WARNING!   If you use a longer screw, make sure it doesn't poke into the telescope tube.  Many rings are threaded all the way through, and there's nothing to stop a too long screw from denting the OTA.


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#7 Xeroid

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Posted 19 August 2019 - 09:49 AM

Got a Big Surprize when I received my Sbony vixen style rail: no threaded holes for the stop screws!!

 

Phooyie, will use JB Weld to fill in and then tap a thread hole.

Attached Thumbnails

  • Sbony.JPG

Edited by Xeroid, 19 August 2019 - 09:49 AM.


#8 Nippon

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Posted 19 August 2019 - 11:52 AM

I don't know why some manufacturers don't provide a provision for stop screws. Losmandy and Stellarvue send stop screws with their dovetails. This is a bit off topic but users of Losmandy D style rails on dual type saddles that can use either the D and V type need to insure their stop screws stick out enough so they can't just pass through the space created by the Vixen part of the saddle.


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#9 RandallK

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Posted 19 August 2019 - 02:15 PM

So the saddle on my new CEM40 leaves something to be desired. My Z103 actually slid in the saddle during a goto so I figured I had better screw in a safety stop.

 

The underside of the vixen rail on my Z103 has no threaded hole for a safety stop screw. So, those of you with a WO rail, what method are you using for a safety stop?

 

Thanks!

I have the same set up as you. I discovered that on the Z103 there are holes on each side of the upper and lower tube rings. The ZWO came with 4 "extra" knurled top bolts that will fit into these holes. I put 2 in the top ring just the other day. That should catch it if it does a major slip (again).  I now use a hex key on the saddle knobs to get a better grip. Not over tighten but just a bit more than the torque you can get with those tiny knobs!


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#10 mewmartigan

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Posted 19 August 2019 - 02:59 PM

I have the same set up as you. I discovered that on the Z103 there are holes on each side of the upper and lower tube rings. The ZWO came with 4 "extra" knurled top bolts that will fit into these holes. I put 2 in the top ring just the other day. That should catch it if it does a major slip (again).  I now use a hex key on the saddle knobs to get a better grip. Not over tighten but just a bit more than the torque you can get with those tiny knobs!

Ah, good idea. I will put some screws in those left/right holes on the tube ring.

 

For the saddle I ended up putting rubber non-slip stickers from Lowes where it contacts the rail. You can see them in the pic here. We'll see if it helps. I've seen people talk about ADM or someone hopefully doing a replacement saddle but then what happens to the usb/power panel? It seems integrated to the saddle and I love that thing.

 

https://photos.app.g...A6RRJS5hu9Hmzv7


Edited by mewmartigan, 19 August 2019 - 03:12 PM.


#11 Lighthound

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Posted 19 August 2019 - 03:24 PM

post-222684-0-23873600-1566226145.jpg

 

Plenty of room to drill and tap on the corners.


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#12 markb

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Posted 19 August 2019 - 07:40 PM

It can be a little tricky to do, but I have tapped existing holes, even tapped sections of preexisting machined cuts, without drilling. No clamping is done, so it just has to be secure enough to act as a safety stop.

This may require having a full set of taps to allow matching tap to cut width.

A full tap set is not needed to drill and tap a threaded fastener of your own choice, as single, matching, tap and correct numbered drill pairs are inexpensive and readily available locally and from amazon.

I hesitate to reveal that I have abandoned tap handles in favor of a slow speed drill. You have to be vigilant about chip clearing, and immediately stop if resistance increases. Holes tend to have better formed threads with this unapproved method, and my tapped holes go straighter.

As to the red rail pictured , it can may a bit unsightly to do so, but I agree, tap two corners and insert allen head machine screws or the more unobtrusive button head screws. They can be very short as they are not clamping any loads.

I see many folks don't want to 'scar ' their rails with drills, so another alternative is to JB weld or E6000 (my most versatile and toughest adhesive, but still removable down the road) a very short machine screw with a proteuding head into an existing opening, sans tapping.


Edited by markb, 20 August 2019 - 10:03 AM.

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#13 John Fitzgerald

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Posted 19 August 2019 - 09:05 PM

Unless it's smaller than about #10, I put the tap in the drill press, clamp the work in the X-Y drill press vise, unplug the drill press, and turn the chuck by hand.  That way, it goes in straight, you can feel resistance, and back it up every half turn or so.  It's a floor model press, with a 5/8" chuck, so plenty to grip.  On the really small taps, I turn them with a t-shaped tap holder, by hand.  It's easy to start tapped holes crooked in aluminum, so one has to be careful to stay perpendicular to the work.


Edited by John Fitzgerald, 19 August 2019 - 09:07 PM.

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