Spuhr binds parallax ?????

Dthomas3523

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Manufacturers might have a tendency to ‘test’ things with a desired outcome in mind.

Seems pretty easy for us to grab x brand mount and install y brand scope with housing pushed up against it....and applying some of Ken’s numbers, tighten it down with same overall force as directed by 25”lb Spuhr caps.

Bottom line, I find it hard to believe Spuhr has the market cornered on squeezing parallax parts.
I can find multiple threads with this issue about spuhr. Almost zero about any other brand it rings, at least not in the frequency of spuhr.

There are several high end optics manufacturers that will advise against spuhr mounts if you call them. Spuhr is a good product overall, so no one wants to ruffle feathers between manufacturers.

I have personally had parallax issues with spuhr and taken the same optic and jammed my arc rings against the turret housing without issue.

I’m not saying spuhr is “bad” at all. I’m actually saying the opposite. Because if the combination of one piece mount AND the abundant surface area if the rings, it’s almost too perfect and doesn’t mesh well with an optic that has a little bit of stacked tolerances inside of it. Tolerances that would be acceptable by the manufacturer and work fine in any other mount.
 

Hoyt7mm

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Assuming that at least part of the issue lies in the Spuhr not allowing for any mfg misalignment between ocular and object tube... when having issues, is it more often/only when the scope is mounted without anything else?
IE - are people still having issues when using rosin or bedding the Spuhr base with epoxy? I would think doing either of those 2 might help correct some of the misalignment, or at least provide a little bit wider margin for error.

Edit to clarify
 
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ofelas

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I’m not exactly sure what “too precise” means.

Never used the Spuhr 6 screw rings, but I have zero issues with Badger 6 screw rings & Near Mfg 8 screw rings, both of which, especially the Near Mfg, put the caps extremely close to the bell/ turret section flange in my applications.

I do run a Near Mfg mount in another application that has the scope pushed forward so the erector flange is butted up against the front ring cap as well.

Never heard of a Near Mfg mount/rings causing issues when butted up against a non flanged center section either.
658F25F0-35BC-4B6E-9258-9CF1E760D996.jpeg
 

craigos

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have a spuhr and Kahles (same as above) on my JP, slapped it on, torqued to specs and never had an issue. Run zco, kahles, NF, S&B on all my spuhrs and nadda an issue
 

SN13

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I want you guys to think about something.

When you torque a small bolt, you can get ALOT of Compression strength. Hundreds of pounds are possible from one small bolt.

Each bolt is additive.

When you have more bolts, you increase the chance of Bolt Crosstalk. Where by tightening one, you loosen another because you've reduced the stretch on that screw by compressing the plate nearby.

This means if you go too high you may be applying MORE than the needed in-lbs because the plate is already compressed.

You can test this by torquing all 6 screws to 10in lbs. Keep going until the torquing stops (Go over and over and over until you're not tightening anymore)

Now, remove one central screw from both sides, and try to remove the remaining 4 corner screws with the torque driver still at 10in lbs.... You can't move the bolts, you have to increase the torque higher to get the bolts to release... The torque you show now, is what those bolts are holding now. Even though you haven't tightened them any more, you'll see they are now like 16 in-lbs.....

Now think of something else......


A #6-40 bolt makes 371lbs of Tension with 10 inch lbs of torque. (https://www.futek.com/bolttorque/american)

Now you have SIX per ring. . . . That's 2,226 LBS OF TENSION..... But over how much surface area?

A 1" LONG ring, 1.338" Diameter (34mm) has a surface area of:

Pi*d*l
3.14*1.338*1= 4.20 Square Inches.

2,226 lb / 4.2 si = 530 PSI.

WHY?

That's 10 INCH POUNDS.... and you guys are torquing to 20?

I asked my Civil Engineer Friend who designs structural bridges, how he would handle this, given that if you don't apply at least a minimum torque to a screw to induce stretching, then it really doesn't count for compression holding.

His answer: Reduce the number of bolts used.

I.E. Take out the center two. and if that's STILL too much, take out the 4 corners and ONLY use the center two.



I don't know if these Manufacturers even do these calculations.... Has anyone seen the "Data" ?
 

ofelas

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SN13 - that techno stuff is far above my pay grade, but it got me thinking - maybe that’s why Richard Near’s 8 screw Classic rounded front caps are actually two rings with a slight gap + 4 screws each.

Not that I’ve had an issue with his flat accessory 8 screw caps either...

CB199C12-40E1-4188-9679-3A39215BAD1A.jpeg
 
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SN13

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SN13 - that techno stuff is far above my pay grade, but it got me thinking - maybe that’s why Richard Near’s 8 screw Classic rounded front caps are actually two rings with a slight gap + 4 screws each.

Not that I’ve had an issue with his flat accessory 8 screw caps either...

View attachment 7387061
Having isolated dual-rings in the front would prevent bolt Crosstalk. As you're only dealing with corner screws but TWICE. So yea, that would prevent the over-torque because of the crosstalk...
 

ofelas

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I suppose I should worry about bolt crosstalk in my other application’s non isolated 8 screw Near front saddle/caps, but no issues with them.
 

SN13

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The proper way to tighten a Rectangular Bank of Bolts is this:

Right Center, Left Center, Left Rear, Right Rear, Right Front, Left Front.

It's a spiral outward pattern. But If you return to the FIRST screws again, you'll note they are not torqued to spec.

Now one thing I'm not CLEAR on is if the provided torque specs are based on doing the proper spiral pattern to minimize crosstalk and account for the compression that happens and keeps the central screws tight enough, or if it's based on multiple passes....

Multiple passes are likely to cause overtorque at spec'd In-lbs
 
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SN13

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I suppose I should worry about bolt crosstalk in my other application’s non isolated 8 screw Near front saddle/caps, but no issues with them.
Does that non isolated 8 screw have a Torque pattern specified? How do you handle the Torquing? Once or repeated? What In-lbs?
 

samb300

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All the fastener math is great, but the truth of the matter is I had binding on my TT regardless of what bolt pattern I used, at HAND TIGHT. And by hand tight I mean sub 10 in-lb...like a mouse fart would be able to loosen each screw. So maybe only using 4 screws at the corners and going to 10 in-lb on those 4 would cause it not to bind, but it's hard to feel confident in a mount with screws that loose, especially when the rear cap could have all 6 at 25 in-lb with no issue.

I will also say that when I re-mounted my Gen2 Razor in a lower Spuhr, it tried it at 15 and 20 in-lb. Both settings had me chasing a wandering zero. It wasn't until I torqued all 12 to 25 in-lb that the zero held.
 
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ofelas

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18-22 in-lbs on all 10 screws, with 20 recommended for my scope tube and caliber by Near.

In no particular order; I torqued once and it’s GTG.

Same procedure with my Badgers & Era-Tacs; I’ll put my success down to well machined rings & mounts, then, coupled with straight scope tubes.

Any rings and mounts shouldn’t be this finicky as far as potential binding goes.

Personally, I think this whole “too precise” bit is hogwash.

Does that non isolated 8 screw have a Torque pattern specified? How do you handle the Torquing? Once or repeated? What In-lbs?
 
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SN13

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All the fastener math is great, but the truth of the matter is I had binding on my TT regardless of what bolt pattern I used, at HAND TIGHT. And by hand tight I mean sub 10 in-lb...like a mouse fart would be able to loosen each screw. So maybe only using 4 screws at the corners and going to 10 in-lb on those 4 would cause it not to bind, but it's hard to feel confident in a mount with screws that loose, especially when the rear cap could have all 6 at 25 in-lb with no issue.

I will also say that when I re-mounted my Gen2 Razor in a lower Spuhr, it tried it at 15 and 20 in-lb. Both settings had me chasing a wandering zero. It wasn't until I torqued all 12 to 25 in-lb that the zero held.
Interesting.

And thanks for posting the torque order. that comes with the rings...

Can you advise if you repeat torque or do it one time?
 

SN13

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18-22 in-lbs on all 10 screws, with 20 recommended for my scope tube and caliber by Near.

In no particular order; I torqued once and it’s GTG.

Same procedure with my Badgers & Era-Tacs; I’ll put my success down to well machined rings & mounts, then, coupled with straight scope tubes.

Any rings and mounts shouldn’t be this finicky as far as potential binding goes.

Personally, I think this whole “too precise” bit is hogwash.
So to confirm, you do ONE torque and do NOT return to the bolt to tighten again. Good.

Also, I agree with you on the "Too Precise"....
 

SRPowah

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This reminds me of the vertical split ring shit show that transpired a couple years ago... No one really knew an answer, they just knew there was a pattern. Plenty of vertical ring people called BS there because their rings have worked forever and disregarded those with complaints.

With how many god damn Spuhr mounts I see on this forum, I do think it is a minority that has issues or else everyone would be telling everyone to avoid them like the vertical split rings. That doesn't mean there isn't a problem somewhere.

What are the odds of getting someone in the industry getting involved to speak up, instead of just end users?
 
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Sixfivesavage

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Anyone who's been around a bit will remember that badger has a set of rings specifically designed to combat this issue because it was so prevalent with the Premier scopes. That's the reason there's a wider ring up front...go figure.
 

Guthwine

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Try to mount it with the mount the rings as far away from the turret as possible (towards the bell). I knew a guy where this helped with that issue.
 

ken226

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Try to mount it with the mount the rings as far away from the turret as possible (towards the bell). I knew a guy where this helped with that issue.
I've had this issue with other brands of rings and mounts, and that fixed it too.

But

Did you see the pic of @deersniper scope and mount, on the first page? He won't be moving that mount further forward.

It's easy to see how this occurs. If the outer tubes inside diameter falls close to its MMC tolerance limit, the focus lens group carrier tubes outside diameter falls close it's MMC tolerance limit, and/or the scopes tube has a wall thickness too thin for the clamping force applied, or some combo of those factors, and the scope ring ends up over the moving parts, it binds.

I've had it bind using Tally rings, Seeking rings and Warne rings. I've had it happen on IOR, , Vortex and Bushnell scopes.



I've never had it happen on a Leupold, Nightforce or US Optics scopes. I haven't owned many scope brands, the IOR this happened on was mine. The rest were customers guns. On all of them, it was easy to move the front ring until I found a spot that didn't bind. I've never used a Spuhr mount.
 
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MysizeisMAGNUM

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What I’m seeing is the same stuff I see on projects I oversee. Multiple company’s and the outer limits of tolerances. The Spuhr you have probably would pass all the Q.C, within the Specs needed for most 34mm tubes.

Your scope same deal, passes QC within the required spec to safely torque in most mount manufacturers. Coating or machining of the tube might be on the higher end of spec but still passes the within the allowable tolerances.

When you pair the two manufacturers it’s not working because each product you have is probably on the limits of spec and both manufacturers are close to allowable tolerance. Together they’re not working. It happens in so many industries, thankfully the product we’re buying on this level will swap them out or you’ll settle with a different mount.
 
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psychosniper

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I have eight Spuhr ISMS mounts currently in use. Seven are 34mm and one is 36mm. Out of all eight, I have one 34mm that the rear cap (A-40) does not torque down with an even gap between the front of the cap to base vs rear of cap to base. It was causing a slight rough spot in the magnification ring from one of my Coyote Brown M7Xi’s. Switching the caps did not change anything so I decided to sacrifice the mount and proceeded to lap it in search of the problem. It was surprising to see how uneven the contact area was after using the lapping bar. After the first cycle, 50% contact was showing so I continued lapping until I felt it was at least 80% contact between front and back. I tried the M7Xi again and found that it did slightly lessen the roughness but did not eliminate it.

I then switched that mount to a cerakoted T5Xi 5-25. It has the same uneven gap but does not induce binding of any nature. I put that M7Xi in a different Lot# Spuhr and no problems whatsoever. I also have a M5Xi 5-25 in a Spuhr from the same lot as the one that caused the binding with the M7Xi. No issues with an uneven cap or binding from that one. I figure that particular mount must have been slightly crooked on the lathe or had a problem in the tooling, not sure. I’ve moved on to the other nuisances of life.
 
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918v

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When u lapped it, was it torqued down on the rifle? Maybe the pic rail Is bowed and in turn causes the Spuhr to bow which in turn causes the maintube to bow.
 
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psychosniper

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Rail is not bowed but that was also my first thought when I noticed it. I’ve checked it with a straight edge and mic in multiple locations.

When I first mounted the M7, the Spuhr was torqued to the pic rail of my Defiance Deviant LA. I’ve had five different optic/Spuhr combinations mounted to this action with no issue prior so it wasn’t a worry. This is when I first noticed the issue. I removed the scope from the Spuhr and the Spuhr from the Deviant action rail. I then torqued the Spuhr to my Targets USA tracking fixture to repeat the install. Same results. I then repeated all these steps installing them on my AXSA. Same results. I then put the Spuhr back on the tracking fixture and proceeded to lap. I repeated the mounting process to the Deviant and AXSA with the M7 and the issue was still there but to a lesser extent but ended up the same between the three rails. I then swapped the M7 with the T5 and tried it on all three rails with no issues. I have used the hell out of this tracking fixture to mount, lap, and diagnose optics. I’ve had probably thirty different optic/mount combinations on this fixture. Never had an issuer before this particular Spuhr and haven’t had another one since.
 

SanPatHogger

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I have a Remington 700sa, Talley rings and a cheap Athlon scope. My parallax knob got loose in the center and tight at both ends of travel when the scope rings were tight. Ended up tightening the rear rings to 15 and the fronts to 12 to keep things smooth. I was thinking about lapping them.
I see you lapped the rings and it got a little better. What about simply lapping more?
 

Rlb40x

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I have a gen1 razor in a spur mount and when both were new I set torque at 24 in lbs and it took my parallax out.
I first called vortex and they asked what mount? Then the tech said torque to 15 in lbs, which seemed light to me but it worked fine after that.
Lesson learned.