Ball links loose, length of links

[Ty89m]

I was prepared to use the reamer on the uniball links, but all of them are quite loose on the balls, they don't pop on or off easily, but not as tight as the Finless bob videos show... Doesn't seem to be much lateral play, a SMALL bit, so should I order new ones or will it be fine?

[Ty89m]

Any word on how much lateral play is acceptable? It's a very small bit of play, and the balls are still very hard to get on and off, links are a bit too small for my ball link wrench, but it's doable... not much fun though ha! Should I be concerned?

[CrashAddict]

Well, The links only go on one way MSH pointing out. I didn;t use the sizer on any links except when I did the tail. They were way to stiff. The rest of it did not look like Finlesses Video but the tail did. I dont have anything I would call "Play" though. Not sure what you mean. As for ball link pliers, the JR ones fit all balls for removal. Not quite as good for installing but they work.

[spykez]

Originally Posted by Ty89m

I was prepared to use the reamer on the uniball links, but all of them are quite loose on the balls, they don't pop on or off easily, but not as tight as the Finless bob videos show... Doesn't seem to be much lateral play, a SMALL bit, so should I order new ones or will it be fine?

Unless the quality of the kit has changed, my msh linkages have always appeared tighter to put on and stiffer than what finless recommends as 'ideal' in his ball links 101 video. But they work just fine pretty much.

Leaving them the without touching them for the most part on average seems to be about right.

You might get the odd really stiff one, which will be really too stiff, ok loosen it up a bit, but I think the danger is over reaming and the linkages not lasting long enough.

Running them tighter than what finless recommends has been fine for me - on the head FBL.

Now if flybarred, you possibly might want to reconsider what I said and err on being loose like finless recommends, maybe. Also I do tend to err on making my tail action silky smooth, so those linkages you may want to look at - although in my experience if the tail isn't smooth it's usually cos I f'ed up somewhere else other than the linkages.

[Ty89m]

Hmm, I ended up trying two different bags of the long links, and 90% of them were VERY loose on the ball, they still weren't easy to pop off, but just flopped around, much looser than Finless recommended. Managed to get a few of them that were a bit stiffer. The loose ones didn't have much lateral play, so weren't too sloppy, so probably would've been ok.

[scott s]

They flop around is ideal. Just as long as there is no up and down play and they hold. If you have ever used a "rocket city link or the Quick rc links they snap on hard and hold like mad but flop around like crazy = no friction = IDEAL. As I posted before With the msh reamer I think it is almost impossible to over ream unless you realy go nuts so if you have a tight one by all means ream it! I use an align ball link remover and works for removing the links but you must use a little caution and get it lined up just right. It is worthless for snapping them on however as the msh mini balls and links are a size of their own lol.

[Ty89m]

Yeah, ha, trying to get the links on the servo arm balls with my Heli-Max pliers was a true test of patience... Links are probably my least favorite thing to deal with so far ha!

Rather than start another thread, I got the head build up last night (FBL) and am curious how everyone gets the thrust bearings out to re-grease/replace. That doesn't look like much fun...

[CrashAddict]

It all comes apart quite easily. You just need the right size poker. Once the grips are off (2 bolts) You just pull the grips off and insert your poker into the back of the grip and the bearings pop right out. Wood dowel is best. Don't hammer on em. Pressss... Gently.

[CrashAddict]

As for the length. Well, I have something to say on THAT subject. If you search here you will find many threads discussing the lengths. Everyone used manual spec on the servo to swash links and then you have a number of lengths used for swash to grips. What I did was take the difference in length of the pushrods for the low FBL hub and the stock length and deduct that from the manual spec. It was too short. In fact, unless you want to use a lot of VBAR trim, you need to make them 2mm longer which makes the 35mm link too short. I bought some 40mm turnbuckles and cut them down to 37mm and the length was perfect however, I didn't like the turnbuckles and ultimately went back to the 35mm pitch links. Be carefull to thread the ends on even on both sides otherwise there isn't enough meat catching. My upper links are at 21.1mm which is just a turn too short but the VBAR trim evened it out fine.

[Ty89m]

Perfect, yeah I searched and found a lot of different lengths being mentioned for swash to grips. I also used the manual suggested 17mm length for the servo to swash links. I have the Xtreme Trex500 turnbuckles I may try, can't remember how long the are though. Isn't the ultimate goal to have the swash level, and in turn 0 pitch at mid stick? Thanks for taking the time to share your thoughts.

[CrashAddict]

Yeah that 17mm is what I used first, it was too short. I guess it would kill MSH to put a sheet of paper in with the Low Hub.

The ultimate goal is zero pitch at midstick, yes. On the vbar, when you put it in calibration mode, its going to swing your servos to where they will be at mid stick for you so you are leveling to the Mini V. Now, I have my arms at perfect 90's and all three servo to swash links are the same length but at midstick, it was visibly not level. Kind of freaked me out as to why. I found two issues. One was that not all of the servo arms are exactly the same. The biggest diference was the holes are not exactly on center on the arms plus by the time you get the ball on the servo arm, they are not exactly the same height. Close but not perfect. The second issue was that the control balls on the swash are not all level with each other. So, thats why on here I asked if I should adjust the links to level the swash or use trim to level it. Consensus was to use the VBAR trim and keep the links the same which is what I did.

[Ty89m]

Thanks for the insight, I should be setting it up shortly and hope all goes smoothly. Should I level the swash with the rod lengths or use the trim in the Vbar/sk540 setup?

Also, I had a helluva time screwing the links onto the rods and getting both ends in equal distances, I ended up having one link screwed on further than the other, tried to make the threads showing even on both ends, but just couldn't quite do it. Seems like there's still plenty of threading in each link, so hopefully all works well and they hold.

[CrashAddict]

Well, I don;t know what the SK540 is like. I know once you see the trim needed from 17mm in the VBAR you will probably open them up a bit. You can even them up then. I dunno, every build seems a bit different. At 21 mm, I have like one rod down 1 tick another up 5 and another up 16 or so to get it level. Then you have to set zero pitch which is another adjustment, and then you have to set level at the top and bottom of travel and then the collective setting and cyclic. Lots of clicking and trimming to do. But I think 17 will be too short. Probably will work it is a lot of travel ad will eat into your positive collective I would think.

[scott s]

The 17mm between the plastic links on the servo to swash rods is correct. This places the antirotation pin at the center of the antirotation bracket at mid stick collective. If you mess with this to much when you dial in a lot of cyclic on fbl unit and 12 to 13 degrees collective you run the risk of the antirotation pin binding at top or bottom of the antirotation bracket when giving large elevator inputs and large collective inputs at the same time. There is no reason to alter this except a turn or possibly 2 to get swash level . Then simply adjust your swash to grip links to get 0 collective pitch at mid stick. I use infinity turnbuckles for rex 500 which are 34mm for swash to grip and they work out just fine, The rods supplied with low head are 35mm same as servo to swash rods. yes this is with low fbl head. Do not over think this guy's LOL!

[Ty89m]

Thanks Scott, I'll keep the servo to swash rods at 17mm (measuring between links like the manual suggests) So, I haven't installed the complete head, and am curious about using my FastLad swash leveler. Should I use it during the SK540 setup? Would this be the time to adjust the servo to swash links a turn or two to get swash level, or would I do this in the SK540 setup using the servo trims? I understand the idea of the swash leveler, but not sure how to go about using it, or in other words, what to adjust to get it level at low, med, and high stick....

[CrashAddict]

17mm is too short.
Im not even close to hitting the top of the anit rotation bracket. Bottom maby.

It would only be right if something else is off. There are a lot of dimensions here and everyone is all over the map.

I'm curious as to how it looks at mid stick for you on 17mm as far as zero pitch goes. If your anywhere near close, Ill pull my head apart and redo it for the fifth time.

Scott, I was under the impression that this is how link length is best determined.

Set your swashplate to mid stick and set blade incidence to 0 degrees. Measure distance between the balls and that's your link length

Is that right?

[scott s]

Originally Posted by CrashAddict

17mm is too short.
Im not even close to hitting the top of the anit rotation bracket. Bottom maby.

It would only be right if something else is off. There are a lot of dimensions here and everyone is all over the map.

I'm curious as to how it looks at mid stick for you on 17mm as far as zero pitch goes. If your anywhere near close, Ill pull my head apart and redo it for the fifth time.

Scott, I was under the impression that this is how link length is best determined.

Set your swashplate to mid stick and set blade incidence to 0 degrees. Measure distance between the balls and that's your link length

Is that right?

If you follow the manual the servo to swash links are measured between the inside ends of the plastic links, right where they screw on the rods!!! RTFM, LOL! and I am only joking here so don;t roast me.

I have built 3 stretched mini protos with low fbl head. 2 for me and 1 for a fellow club member and I assure you that 17mm between the plastic links on the swash to servo rods is correct. Actually on the 2 links for the aileron servos when the plastic links are aligned correctly to snap on they measured 17.11 mm. I used a digital caliper to measure between the links. The last one I built the swash set perfectly level with swash leveler on with only having to turn elevator link up 1 turn and just a small bit of tweaking on the trim function in my hc3sx fbl unit.
Here are photos and antirotation pin is dead center and swash is perfectly level in photo and stick is exactly at 50 midstick shown on pitch curve monitor in my jr9303. 0 degree collective at mid stick with 34mm long turnbuckles from infinity hobby. There is no arguing with me here on this one LOL! 17.11 mm between the links on 2 aileron servo rods and 17.2something (can't remember) on elevator servo.
2nd picture is not blurry, sorry about the first one being a bit out of focus

[CrashAddict]

I understand we are measuring between the grips. (Using the large grips) and Using 17mm as speced in the manual for servo to swash. This establishes the hight of the swash at mid stick. We are on the same page on all of that.

It is the Swash to Grip length I was talking about since that is not in the manual. The size listed in the manual for swash to grip is for the regular head. For the Low FBL you get the shorter 35mm rods. So, the size in the manual (31.1) for that is too long. 48.8mm rod is used so if you subtract 35 from 48.8 you end up with 13.8mm difference. If you subtract 13.8 from 31.1 you end up with 17.3mm for the measurement between the grips for the swash to grip links. What I am saying is that is way to short. You won;t be close to zero pitch with that length.

[scott s]

Originally Posted by CrashAddict

I understand we are measuring between the grips. (Using the large grips) Using Manual for servo to swash. We are on the same page.. It is the Swash to Grip length we are talking about since that is not in the manual.

JEEZ! Just adjust the dang swash to grip links to be what ever they need to get 0 degree collective at exactly mid stick. You can use a ruler to "eyeball" the length needed to get them close and go from there. I use turnbuckles so I just preadjust them short and dial it in on the heli without unsnapping them in a matter of minutes. The rods without links on for swash to grip for low head are 35mm same as servo to swash.
The rod length for the fbl modded standard head swash to grip is in the manual. It's length is 48.8mm and the distance between plastic links on that rod is 31.1mm give or take to get 0 degrees at mid stick.
The low fbl head comes with the appropriate 35mm long rods for swash to grip. Use turnbuckles as it makes life much easier on the swash to grips!!

[scott s]

Ty89m, There is more than likely a function in the sk540 where you trim all your servos so the arms are at 90 degrees to the servos. this probably should have been done before instaling the servo block assembly because it is a bitch trying to eyeball the servo horns and change them once everything is in the frame. then you use swash leveler and get as close to level adjusting links as you can (they snap on one way so full turns are needed. Any small minor distances between leveler and swash that can't be achieved with the links are tweaked using the trim function in the fbl unit to get it perfect. A degree or 2 servo arm deviation from 90 degrees makes no difference at all