RunRyder - mx400 pro head issue

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e-Ark X-400 - MX400 > mx400 pro head issue

Turner0022
Senior Heliman
Location: Old Hickory Tn

has anyone had problems with head screws backing out ? now that im a little more agressive in my flying , flips and rolls , im crashing cause the screws are backing out and causing me to crash !its so agravating.... i finnaly get to fly a little 3d and the heli wont hold up . what should i do ? will lock tight help? its metal parts screwing into plastic parts.

HBK2~Raptor 50v2~Dragonus~blade 400 radix blades

12-17-2007 10:40 PM

SLC
Senior Heliman
Location: Johnson City, Tn

head screws

Those 2 screws are a problem even on the MX-450 with it's all metal head. Most of the slop on the head is caused by these screws being to loose . The problem is if there tight enough where they won't back out, they bind the flybar where it can't move freely.
The only fix that works well is this part http://www3.towerhobbies.com/cgi-bi...?&I=LXMRF4&P=7. The difference between this part and what comes with the Mx-450 is there is a bearing on each side instead of a brass bushing. You can tighten the flybar screws down without binding the flybar.
As for your plastic head I personly don't think there is a good fix other then the part mentioned above.
Merry Christmas
Scott

12-17-2007 11:03 PM

copperclad
Elite Veteran
Location: ..

hi turner

sorry , regular locktite won't work for plastic to metal , but they do make a metal to plastic product loctite 425 is made for plastic

http://68.72.74.113/PRODUCTS/425.htm

it is a cyanoacrylate adhesive , when i built a raptor a while back they had me use medium thick CA for all metal to plastic fasteners , i would get some slow cure medium thick CA and give it a try , HTH , dana

12-17-2007 11:08 PM

SLC
Senior Heliman
Location: Johnson City, Tn

Hi Copperclad
I'm all for trying a easy/ cheap fix myself but this problem has creeped up in this forum since the MX's came out.
I can't really say for sure if the CA won't work as I never had the plastic head and tryed the fix myself, but I can say for sure that red loc tight won't hold for more then 10 flights or so on a metal head . I thought I had the problem fixed and low and behold after about 10 flights I noticed my blades went way out of track , checked the screws and they had backed out. I did the red loc tight again and cleaned everything well with finger nail polish remover with the same results after a few flights.
Merry Christmas
Scott

12-17-2007 11:40 PM

copperclad
Elite Veteran
Location: ..

hi SLC
thanks for the headsup , i have no experience with the head and history of problems that you mention , i just answered the CA as regular loctite will attack some plastics and is not any good on the rest , but for metal to plastic , loctite sells CA , so CA would be the stuff to try if it was a standard metal to plastic application

what i can say after hearing that RED loctite won't work even if properly cleaned , on a metal to metal , is that there is an issue , of some kind , with a proper metal to metal , using RED locktight should be permanent , without heat to unscrew you will shear the fastener with RED loctite , if it isn't holding there is something else going on , like an undersize screw for the load , or some kind of loading issue

are you talking about the two screws that form the flybar pivot , they are the only ones i can see that look like they could be flaky

again thanks for the headsup , i have been having a riot with my 450MX and will start keeping a close eye on it , thanks again , dana

12-17-2007 11:57 PM

copperclad
Elite Veteran
Location: ..

hi SLC
i just did a search and see it is the flybar pivot screws you are talking about , i will keep an eye on them , thanks , dana

i just looked at the drawings in my manual , and the seesaw on my machine , and i am thinking the screws are too short or too small in diameter or both ( so they are just catching by a couple of threads ) , the first thing i would try is replace them with new screws that go all the way into the center , just short of hitting the flybar , loctite them in and if they come loose , go up to the next size screw and the same deal , all the way in , i know this means finding longer screws and probably shortening them to the right length , and to up a size means a drill and tap and new bearings or spacers besides the screws , and of coarse helimax should have done this right from the getgo , but that is the type of thing they would iron out and about the second , third or forth version , hopefully

looking at mine they are still tight , so either they are the right length or you guys are more aggessive than me in the air

12-18-2007 12:08 AM

SLC
Senior Heliman
Location: Johnson City, Tn

red LT

Hi Copperclad

Quote
are you talking about the two screws that form the flybar pivot , they are the only ones i can see that look like they could be flaky

Yes thats the screws.

Quote
without heat to unscrew you will shear the fastener with RED loctite , if it isn't holding there is something else going on , like an undersize screw for the load , or some kind of loading issue

you said that way better then I could have

You should be able to tap the flybar and it move free to it's end point with very little force.
When I used the red loc tight I put it on the screw and tightened holding the flybar with my other hand moving it up and down, when I felt the flybar binding just a tad I stoped and backed off the screw just a touch.

If you want to see the slop these little screws cause grab the main blade grips and work them back and forth and watch the seesaw around those 2 screws.

12-18-2007 12:22 AM

copperclad
Elite Veteran
Location: ..

hi SLC
LOL , i was editing more info into my post above before i got to your response , and just jumped back in to say , you are right , if the screws are just holding by the last two threads , no bonding agent ( loctite ) will work , this is what i ment by , other issues , the screws are too short , and will have to be replaced with longer screws before you will get positive results with loctite , HTH , dana

12-18-2007 12:27 AM

copperclad
Elite Veteran
Location: ..

hi
looking at my manual , they look to be 2mm screws , i am wondering if a set of the longer washout arm screws ( 4102-010 ) would be close to the right length , or hobby shop them for some 2mm panheads

the seesaw is 7mm diameter and the flybar is 2mm , leaving 5mm , split that and there is 2.5mm of material on each side , so you would want 2.5mm of threads to engage the seesaw , this would be enough to all but reach the flybar , from what i can see the screw should be just under 6mm overall , so a 2mm X 6mm panhead would need to be shortened a touch , dana

the picture in the manual , makes the stock screws look to be about 4mm , which would only have 1/2mm into the seesaw , and that would explain why thread lock isn't working

12-18-2007 12:52 AM

Turner0022
Senior Heliman
Location: Old Hickory Tn

wow now thats results on a question ! my head is mostly metal i guess i need to just finish it out . metal to metal and lock tight all screws . i was flying so nice a couple of tight flips then its like it blew up in mid air ! the screw backed out causing the pitch to flip into neg and shooting straight down landing on the skids from 30 ft up, broke skids , bent shaft , broke 1 rod , stripped main gear and 1 servo . the better i get the more i crash if that makes any scense.....that old saying if you dont crash you aint flying hard enough ... that sure gets expensive!!! thanks for the replys !!! happy hollidays

HBK2~Raptor 50v2~Dragonus~blade 400 radix blades

12-18-2007 01:56 AM

SLC
Senior Heliman
Location: Johnson City, Tn

a fix

There was someone that posted a fix like your talking about Copperclad I can't recall if it was here or another heli site.
Get 2mm screws longer the the stock ones , can't remember the lenth. Remove the flybar,loc tight and install the screws making sure there not to tight , the screws have to long enough to hit the flybar if it was not removed. Use a drill bit the same diameter as the flybar and drill out the ends of the screws. Reinstall the flybar.
I never tried this but I'm sure it would work as long the drill didn't walk on you and hollow out the alumimum. The loc tight would be optional in my opinion because the screw ends would be half round and couldn't move anyways.

Hi Turner0022
Glad some of this helped you and sorry to here about your crash.

12-18-2007 02:35 AM

whodaguy
Heliman
Location: Saskatoon, SK - Canada

SLC speaks the truth about the head upgrade. I put one in at the begining of summer and it has made a world of difference. The price is well worth it when matched up against the price of a crash. As in any application of this sort some type of thread lock must be used. I use a popular blue type from a tube. It works best for me. I coat the threads with a small paint brush, I believe its called a liner brush. That way I am sure of adaquate coverage and I also am sure that it is applied only to the part that I want it. I am not familiar with any thread lock solution for metal to pastic or vice versa...

I have recently converted my MX400 to CCPM and am just in the process of fabricating a better battery mount as well as waiting for a new cowl to "Align" up with all of my modifications.

I bought the MX because at the time it was in my price range and affordable to fly. I still feel it is a good heli and I am very satisfied with it. It flys the way I want it to and thats important to me.

Whodaguy.....................

12-18-2007 12:45 PM

copperclad
Elite Veteran
Location: ..

hi
YES , i run blue LT on all metal to metal threads , one thing it also does that is important , if the screw is put in without it and starts to loosen , because of the vibration , will hog out an aluminum thread pretty quick , so you run into a problem , if a screw has come loose a couple of times , depending on the aplication , there can end up being very little thread for it to bite into , my understanding is 2mm screws come in stock lengths , of 4mm , 6mm , 8mm and i am guessing they are running a 4mm screw because the 6 is a touch too long , great thread , i was about to get blindsided on these two screws , because i hadn't picked up on this yet in my reading , thanks again , dana

12-18-2007 01:04 PM

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e-Ark X-400 - MX400 > mx400 pro head issue

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