GF grip fasteners coming loose / how hard do I need to tighten these things?

[Ron61]

Do you understand?

[1sascha]

I think what Ron means is the points on the rusks are meeting when your tighten the screw. This shouldn't be happening. Since they're tightening against each other rather than against the shaft individually. His cure was to file off a bit of the point of each rusk.so that they'd stop meeting when tight.

I guess what you are saying is that the spring washer's "open ends" touch each other under pressure and so they will push on each other rather than pushing against the screwhead and grip fastener... thus allowing the screw (and in consequence the grip fastener and the grip) to come loose over time.

Do you understand?

fixative.jpg

I got all that - that's why I quoted it in my now-deleted post. What you describe is almost *exactly* what I did when I realized the fastener was coming loose over time. Well, I didn't use an extension on the Allen key (didn't want to over-torque things), but I did use an Allen-key's long side as my lever (like in your pic, but minus the extension-tube) instead of this screw-driver bit-holder:



^ That's exactly what I've used before - doesn't provide nearly as much leverage as an "Ikea-style" Allen-key.

I went to the Ikea-style key because I thought more torque might solve the problem. That's also why I asked about Loctite in my original post, since that was one way I could think of to, perhaps, secure the screw more reliably.

Re. the spring washer: The ends don't need to overlap, but I guess they shouldn't face each other directly to prevent them from touching each other "head on". Correct?

So... this is what it should look like more or less?





S.

[Ron61]

I repeat once again - a spring washer is not needed in places where the screw, bolt works in tension.
This is exactly our case. And even banned.
But this is a joystick, and not the lower belt of the floor truss, on the strength of which people's lives depend.
We have it as a spacer to make it easier to turn the screw.
In your case, I recommend grinding off 0.5 mm from the inner surfaces of the clamps.

[Drano]

@Sacha. In Ron's pic where he shows the "crackers". See the gap between them? That's supposed to be there when tightened against the shaft. The thinking is that yours may be a mil too long and need to be shortened a bit. Just enough that they don't meet at the pointed end. File a bit off the pointed ends so that the gap is there when you tighten the screw. You WON'T be able to see this inside the grip. Just give it a try. If it works as it should, he's right, you shouldn't need a lock washer. If yours are a smidge long it won't matter if you have a lock washer as it's not right. They don't tighten against each other. They tighten against the shaft on both sides.

[1sascha]

Sorry if I seem a bit thick and/or pedantic here, but:

Oh.. so we're talking about the fastener itself being too "long" (its two parts touching each other when tightened down) - I thought you guys were talking about the spring washer's "ends" touching.

That's kinda weird, because both the grip fastener that came with my stick/MCG grip and the one that came with my 100mm extension had the spring washer installed from the factory. Honestly: I wasn't even aware that they were there, because I'd never taken the fasteners apart until VKP Operator over on the HOTAS Discord pointed out to me that there was a spring washer in there and that *it* might be the problem.

My point being: If the spring washer isn't needed or in fact could cause the fastener to not function properly .... why even put it there at the factory?

I'm confused...

In your case, I recommend grinding off 0.5 mm from the inner surfaces of the clamps.

Got it.

I don't have the necessary file here, but I'll pick one up from a local HW-store tomorrow and give that a go. My fastener is still coming loose after nearly every flying session and I'm starting to worry I'm about to strip the screw-head from all the tightening I have to do on that fastener.

EDIT: Whoops... I should've looked at Ron's edited version of my fastener-pic a bit more closely ... he did put a line in there, showing me what to do. My bad ...




S.

[Drano]

While you're there, might want to pick up a new lock washer. Especially if yours looks flat. Don't go bonkers with the file either. It's probably just a tiny bit of material that's causing the problem.

[Drano]

While you're there, might want to pick up a new lock washer. Especially if yours looks flat. Don't go bonkers with the file either. It's probably just a tiny bit of material that's causing the problem.

[rtrski]

There is a simple rule for bolts and growers - if the bolt is in tension, break - the grower is not installed, it is prohibited.
If the bolt is shearing, a grover is placed to prevent the nut from unwinding. We have the first case.

I think he's saying if a bolt is being used "in tension" - to hold two things together against its own AXIS length - then a washer is not only not needed - it is actively counterproductive. (This is something I've read elsewhere, that washers - especially lock washers - don't do much of any good, even per outfits such as NASA.)

If the bolt is "in shearing" - intended to hold two pieces of something together that would otherwise slide against one another in the plane that the bolt axis is the "normal vector" to - then a washer to increase surface area being gripped, and even a lock washer to help maintain tension of nut to thread, is an engineering good thing.

I could imagine if your angled bolt parts in that rusk assembly are a tiny bit too long the flat faces might meet before you have good pressure of the angled faces against the metal grip shaft they're intended to hold, which is what the rest of this thread seems to be coming to conclusion on.

I've had my Gunfighters (originally MK II, upgraded to III but of course that didn't alter these parts) for many years now and have never had a slipping issue I can recall. BUT I also do not use an extension, or super strong springs, on either side. I think it's a deceptively simple mating approach that can work really well, but of course part supply tolerances matter so my experience is only a single (and very old now) anecdote.

[1sascha]

EDIT: Possibly forgot to add that this sort of thing doesn't seem related to the extension being installed. It happened before I even owned the extension, with just the MCG Pro mounted directly to the gimbal.

Well... it happened again and just as always towards the end of a long flying session. Roughly three hours of everything working fine and then "misfires" started to happen. So I'm more or less convinced the pad's not at fault. If the pad was the cause of this, why would it work flawlessly for a long period of time and only then start to act up? Especially since the fastener was loose again when I checked it once button 29 started to misfire.

I also really hope it's not at fault because I wouldn't know what to do if I had to re-solder the pad - never held a soldering iron in my life and I sure as hell don't own one.

Ground off a bit more from the problematic fastener and it's definitely shorter now than before - I checked its length with my calipers and it's about a half to a full mm shorter now overall, plus the screw now protrudes from the rear end of the fastener when tightened down (it didn't do that before and on the second fastener it also doesn't do that). I also swapped the two fasteners, using the problematic one now for the grip to extension connection and the newer one that came with the extension to connect the extension to the gimbal. I figure that the lower connection is probably under more stress - plus the newer fastener never came loose on its own so far, so ...

This is what the problematic fastener's back now looks like (after I filed it down/shortened it), mounted to hold the upper connection (grip to 100mm extension):

... and here's what the newer fastener that I didn't shorten looks like holding the lower connection (100mm extension to gimbal):

Problem went away again after I re-tightened the lower fastener a bit - let's see if it'll stay that way.

then a washer is not only not needed - it is actively counterproductive.

Yeah, that's what I thought he said... which is why I was wondering why the washer is even there in the first place - if it's counter-productive, why even include it from the factory? I haven't taken it out yet, but if this problem persists, I might try that. Or go with my last-ditch solution of putting some Loctite on that screw and see if that'll hold it.

I'm also pretty sure I'll soon need a new screw for that problematic fastener. I've had to loosen/tighten it so many times that by now the screw-head feels a bit worn out.


S.

[rtrski]

I think he answered that in another post - makes the screw easier to turn for the user, so tradeoff between ease of installation at slight cost of possible tightness, or at least no advantage to possible tightness.

...But this is a joystick, and not the lower belt of the floor truss, on the strength of which people's lives depend.
We have it as a spacer to make it easier to turn the screw.

Totally off the rails thought - what does the exterior of your mounting shaft look like? I wonder if it has been gouged or grooved by attempted tightening, and thus the 'rusk' angled parts can't get as good a surface mate. Or is a tiny bit under outer diameter spec? Wonder if a single wrap of tape or something might give just a little more dia for the angled parts to grab hold of? (Please don't try based solely on my suggestion - at least run it by VKB official supporters first...I can also imagine that making things even worse since it would no longer be metal to metal contact, and/or mucking up the pin and pad contacts if it got out of hand...)

I can't think of the last time I even worried about that attachment, and I keep my left hand stick permanently 'angled' (my own variation of the OTA mount, by just putting the whole gimbal at an angle). And on the right side, my MCG Ultimate is often dangling pointing forward, since I have a motorized actuator on the mount plate to pivot it out of the way of my elbow for mouse access... let me know if you want me to mike out (measure with digital calipers) my grip shafts as a comparison...

Overall setup: https://i.imgur.com/FtxaIEp.jpg

Pivot actuation for right side (sorry for shaky-potato-cam): https://i.imgur.com/KBmXKVX.mp4

While this attach system is deceptively simple and elegant - it does seem to introduce a fair amount of concern and use issues across the general gamut of consumers. The only 'minor' modification they've made over the years to my knowledge is that flat side for the Kosmosima version, so the fastener can't just rotate freely during initial insertion, the angles have to be in the right place. I almost wonder if one more slight machining operation to put a feature into the shaft exterior to either side that the rusk parts intentionally grip (with less of a chamfer cut into them) might improve this whole mess, or just make it worse. (Disclaimer - I am sooooooo not a mechanical engineer!!!) Certainly be more expensive to exterior machine that larger part than the little assembly bits...

[1sascha]

Looks fine to me.

I think this is under control now.

1. I've swapped the two fasteners and now have the problematic (but now shortened one) up top, connecting the grip to the extension. That makes it much easier to check up on it (no dust-cover in the way) and I think the lower fastener (extension to gimbal) is probably under more stress, so I figured the newer fastener would be better suited for this position (it has never come undone so far).

I managed to get through a long flying session last night without any problems. The fasteners were *maybe* a tiny bit looser afterward, but I might just be overly paranoid here and I don't have any means to measure torque anyway. The point is: No misfires, no nothing ... the stick just worked as it's supposed to.

Of course, this is just a sample size of one (evening), so I'm glad that:

2. VKB have contacted me and will send replacement fastener(s?). They also offered to send a replacement contact pad, but also said mine doesn't look like it needs replacement or fixing. So they're sending that "just in case". Which, while not really needed at this time, is a huge load off my mind because it means I won't have to take up soldering if things do go bad in the future..


Thanks, VKB!

S.

[1sascha]

And just to put this one to rest:

A few days ago I received two replacement fasteners from VKB (along with a new contact pad) and swapped both the old fasteners out. Been...err... two or three 4 hour + sessions now and both fasteners seem to be holding fine. I've checked them before and after each session, and they never seem to have come loose. I also haven't had any more misfires from any of the buttons or any other malfunctions during my flying sessions. I think it's still a good idea to keep checking the fasteners regularly, but so far, the problem seems to be fixed.

Not sure if I would want to tackle replacing the pad, since I can't seem to find instructions on how to do it, but I don't think it's really necessary at this point since there have been no more malfunctions.

Thanks for all the input guys!

Sascha

[fallout9]

I'll send you a walkthrough for replacing the contact pads board on your base when the time comes, just buzz me.
Glad to hear the issue has been fixed, thanks for the update!

[1sascha]

... and just one more added "tip", already mentioned on discord:

I finally went to the HW-store and bought me one of these



and I would recommend something like it to any GF-owners. This particular one wasn't super expensive (under €6), but it does come from a reputable brand and works *so* much better than either my screwdriver/bitholder set's 2.5mm or any of the Ikea-style Allen keys I have lying around here.

No fumbling for correct fit, the driver will just slide into the screw and sit there "locked". Plus it's so much easier to work on the screw near the gimbal's dust-cover... with shorter drivers I was always fighting the dust-cover while trying to get the driver to lock into the screw. And the length of the driver and T-handle mean you can apply lots of torque very easily and tighten things down reliably. Ever since I locked the fasteners with the new T-handle driver, their screws haven't moved *at all*.
And I didn't have to use the long bit as a lever (which allows you to apply even more torque) - simply using the long part as my driver and the handle as, well, a handle enable me to apply enough torque to lock things down.

In fact, I think I'll run off to the store today to grab me the same thing in 3 mm for the screws on my UCM-mounts.



S.

[Drano]

Hey just wanted to check in on this thread as I just took my stick apart yesterday. I have the OG Gunfighter base with the clutch adjustments that point down. I have it mounted to a plate I made wth holes drilled in it so I can access them without taking it apart but the pitch bolt was spinning and wouldn't tighten up. So a minor tear down. Been a while.

Just wanted to pass along that both of the rusks that hold the stick to the 200mm extension and extension to the base were still tight. Bet it's been a year since I've had them apart. I fixed the bolt spinning and adjusted the pitch clutch. Figured out I really didn't need to take the base apart to do that. I can put a tiny straight screwdriver between one of the nut sides and the gimbal to stop it spinning wth the dust cover loose. Next time. But it's always a good thing to check up on your mechanical stuff now and then small as it might be.

I also released tension and rotated both bearings a half turn. Grease was fine. I use a very thin layer of Rotanium blue automotive grease on the cams and nyogel on the clutches. I do not have any signs of wear on my avia cams.

I did find two problems under the hood. The screw that holds the roll clutches together had worked loose but hadn't dropped off yet. Tightened that. The other was more concerning and will keep an eye on it. My base has the pogo pins facing up instead of the later marks that had contact pads there. One of the pins was stuck down. I was able to free it with dabs of contact cleaner and gently pulling with a tiny tweezer in my ifixit kit. It's springing up now.