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HK 450 GT Pro build

Started by gauravag, February 16, 2010, 03:42:01 PM

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vinay


ujjwaana

Grrr!!!! This only came after I already spent on my dearly $23 on the Turnigy DS480 Servo!
Futaba 8FG Super | HK-450v2 | FA-22 Raptor |AXN Floater-Jet | FunJet | Black Horse Edge 540 | Amp Master 015 | 2.3M Big Brother

gauravag

Ok, I downloaded the Bob Finless Videos from helifreak.com today and also the manual from the align website.
The first task I did was to open up the rotor grips in order to grease the thrust bearings and also locktite the screws.
What i saw surprised me ! The screws on the rotor grips were very loose, with absolutely no locktite on them and the thrust bearings were also dry. I packed them with TT Bearing grease and assembled the grips back.
Had anyone overlooked or assumed this was built correctly, it would have led to a disaster, and possibly injuries.

I am not sure if i should open all screws/nuts to check for locktite. I think i will just check everything for tightness and not dismantle everything. Experienced fliers, please tell me what other joints are critical.

I also lubed the one way bearing. it was dry and tight. After lubricating it became free.

Thats all so far ! The quality looks superb. Makes me wonder how HK has got it all so cheap. I hope it flies well too !

Vinay, your post about MG-14 has me worried. I have only 3 of them and hope they do not put up an act when i get them on my heli .

vinay

#28
Welcome to the world of cheap helis.  ;)

make sure u loctite after leveling the swash plate and checking the speed of the servo travel. I ended up loctiting the screws 3 times. Ofcourse I cleaned them each time. what a pain. you dont do the same mistake. also i had different speed on one servo coz it came in a different parcel/order :D. hope yours are fine. I saw that many on RCGroups are facing the same issues with the servos.

I took 12 hours just mouthing the servo and leveling the swash plate and setting the equal travel. This is for my HK 450 V2 plastic heli. The quality of the head is better than 450 MT. ;D except its plastic in 2 places.

gauravag

Quote from: vinay on March 23, 2010, 07:05:36 PM
make sure u loctite after leveling the swash plate and checking the speed of the servo travel. I ended up loctiting the screws 3 times.

Vinay, Which screws are you talking about here ? Surely not the ones on the feathering shaft, that hold the main rotor grips together ?
Not sure how swash levelling would affect this ...

vinay

I am speaking of the frame screws, which you will be removing to mount the servos.

anwar

Quote from: gauravag on March 23, 2010, 06:56:22 PM
The first task I did was to open up the rotor grips in order to grease the thrust bearings and also locktite the screws.
What i saw surprised me ! The screws on the rotor grips were very loose, with absolutely no locktite on them and the thrust bearings were also dry.

Align is very clear about this. They specify multiple times in the manual to remove factory assembled pieces and double check everything for thread lock and lubrication.

I was not sure about the HK stuff, so I asked around the US forums, and everyone said just open up and rebuild just to be sure.  I mean if Align (which costs a lot more) asks to double check, I guess it is a no-brainer that the HK ones would definitely need that.
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vinay

On my MT everything came thread locked. so hard that it was hard to remove. But I had checked every screw by tightening it further before maidening it. Its bad to know about the inconsistency. removing the Philips on the head required a 2mm #0 screw driver (the align TREX 250 Philip screw driver is a perfect fit)

gauravag

Ok, i checked the entire head. Luckily except for the main head screws that pack the thrust bearings and the grips, rest all were lock-tited and snug.
After checking the rotor head, i proceeded to install the mg-14 cyclic servos. Put my throttle at center stick, exact 50, then attached the arms to all three servos. Made sure they were all perpendicular ( had to do a very slight subtrim on a couple ).
Put in all the servos. At this point i must say that the Finless videos at Helifreak kind of take all the fun out from the build.
Though i had printed out the manual , i never needed to consult that as watching the videos while building helped me get all the servos setup in about 30 minutes !

Now, on i went to the tail section. Again checked all screws for lock tite, and rebuilt the tail rotor grips.
Threaded the belt through the boom, and attached it to the tail rotor assembly and then to the main body.
Lastly installed the boom supports.

Regarding the quality of the kit, so far I have nothing really to complain for. The screw quality is nice, everything fitted properly, and nothing missing so far. I think over time things would become more apparent, when we will need to replace components or rebuild .

Pictures to come soon !

gauravag

Ok a bunch of questions for Anwar/Vinay and others who are experienced here :

- The Tail servo plate seems to be designed for a large servo with 4 screws. I have a small micro servo, so any ideas on how to mount this ? Last resort for me would be to build a Plywood mounting plate and use that to mount the servo . Even then the height would be less, thus the linkage rod would be bent, unless I raise the servo by using another plywood mount

- This may be a little tough to explain. I have the main shaft installed. There is no play in the main shaft that goes through the bearings. However the main gear has a little up-down play . The tail drive gear is sold. Just the main gear slides up and down a little. Is that OK ?

- Need to solder the 3.5mm connectors on the motor and ESC. Since I am new to brushless electronics, I see 3 wires on the motor and ESC. Which goes where ? Or should i just plug any, and get the correct direction of rotation ?

I guess thats it for now.
Thanks !

vinay

1) I cant comment w/o a pic of the servo holder.

2)Don't know. Not able to understand where the play is. If I still understood properly then you need to slightly push the shaft upwards till there is no play and pull down the holder(the hub that is present at the center of the main shaft) and tighten it.

3)The 3 wires of ESC can connect to any 3 wires on the motor. if the motor turns in the non desired direction, then just interchange any 2 wires, this will reverse the direction.

anwar

1. The Align original tail servo mount was able to take all types of servos (I do remember using micro servos and mini servos on that mount).  I am not sure if I used both holes to mount the servo though, might have used only one hole on one of the types.

2. You need to ensure there is no up-down movement of the main gear.

3. Amen to Vinay ;)
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vinay

I am so much pissed off with MG14s. >:(

Once I learn hovering and FFF, I will leap to Hitecs and GY 401, or Probably sparten. I didnt want to use these costly ones as a beginner. Airtronics is no less of a troubler.

anwar

Lots of questions ;)

Many people are happy with the MG-14s (at least as per online reviews/reports).  You just need to get couple more, so that they all match up (instead of investing heavily on other metal gear ones) ?

Are you not happy with the HK401 gyro ? 

What is wrong with Airtronics ? Do you mean the radio ?
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vinay

#39
1) Ya many are happy. But there a few who suffered a bad fate, and I fell into the same category.  Nope Iam not investing on other metal gear servos for the 450s. I will some how manage with the existing stuff. But for a 500 or 600 size heli in the future it will be Hitec/branded servos only.

2)Gyro I dont know. I never flew for a month now. Rajesh was the person to fly my heli last. Since then never flown. So cant comment.

3)Ya RDS is kinda radio that is good, but with its own limitations. You cant correct the mistakes that cheap servos cause. Its good to fly. In fact many DX7 owners on the net say RDS is better for Helis compared to DX7 due to its crispness and extra channel. But RDS rather demands more correct physical setup on the Heli rather than offering to fix things using programming. It does offer enough programming to fix, but still when I change modes it kinda acts weird - believe me, I have tried everything.

I am setting up my Plastic HK 450, and noted that once the Rx is swithced off for some time and switched on, the servo travel is reducing for one of the servo (MG14) - This I am able to find out using a swash plate leveler - the travel is reduced by 1 mm. This reduced servo travel is correcting out 1 min after RX is turned on. To blame the RX or servos? :headscratch: These are some of the few problems I am facing.

Many satisfied people that you may see on RCG/RCU/WFlyer regarding MG 14s are the ones who dont care much for precision/ Lucky ones/ Good radios? Infact many people eyeball for leveled swash plate and start flying.  ;D and the servo gets 5 *****

I can fix all the issues that MG 14s are causing using RDS itself, but it is going to take 3 to 4X the time as I have to correct things physically and lil programatically. Its like building a tower out of a deck of cards . Infact this second heli Iam building should end up as a perfectly setup 3D heli, inspite of all the problems. Thats my goal  :thumbsup:

I never had any issues seting up the HK 450 MT using HXT 900s and I had done it in 3 hrs for the servos mounting part :giggle:


kartikshah

Quote from: vinay on March 27, 2010, 10:17:48 PM

You cant correct the mistakes that cheap servos cause.

I am setting up my Plastic HK 450, and noted that once the Rx is swithced off for some time and switched on, the servo travel is reducing for one of the servo (MG14) - This I am able to find out using a swash plate leveler - the travel is reduced by 1 mm. This reduced servo travel is correcting out 1 min after RX is turned on. To blame the RX or servos? :headscratch:

I can fix all the issues that MG 14s are causing using RDS itself, but it is going to take 3 to 4X the time as I have to correct things physically and lil programatically. Its like building a tower out of a deck of cards . Infact this second heli Iam building should end up as a perfectly setup 3D heli, inspite of all the problems. Thats my goal  :thumbsup:

I never had any issues seting up the HK 450 MT using HXT 900s and I had done it in 3 hrs for the servos mounting part :giggle:



Cheap servos can't be fixed by radios, if they could then no one would buy or make high/costly servos....
The problem lies with the servo, either its under load or hunting...... the best is to change the same servo to another place and check or put another servo...... hope this helps.......


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anwar

Quote from: vinay on March 27, 2010, 10:17:48 PM
Many satisfied people that you may see on RCG/RCU/WFlyer regarding MG 14s are the ones who dont care much for precision/ Lucky ones/ Good radios? Infact many people eyeball for leveled swash plate and start flying.  ;D and the servo gets 5 *****

What ever the case is, there is one thing to be remembered. *As long as the behavior is consistent*, people should not bank on perfectness of the swash plate or other items when it comes to flight stability.  I get this time and again on the field, with people complaining that "the heli drifts, but the one on the sim does not, so this must have some more setup to be done" !  The reality is that perfect setups are next to impossible (or are impossible) in physical terms, while it is very easy on the sims.  When one adds other variables like wind, it gets even worse.

The important thing is that YOU fly the heli (or plane), and do not let the aircraft fly you ! Use the help of things like trim etc to make it behave better, but then *your thumbs are the ones that makes the rules in this game*. Always remember that aspect.  Of course if it drifts wildly, or the behavior changes periodically (like a servo changing its range of travel arbitrarily in the middle of a flight etc), then there is something to be dealt with.  Otherwise, be sure to train your thumbs to deal with the minor imperfections, and leave the desire for perfectness at the sim itself.

In short, I felt that there is nothing wrong with eyeballing the swash and start flying :)  May not be the best way for an *absolute* beginner (who has not trained himself using wind etc on the sim) but for others, that is a good enough start, and that is probably why these servos get 5 stars !

Over time, they make small corrections to their setup, that the brand of servo becomes an afterthought.

I do agree with Kartik that the behavior should be consistent.
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vinay

Quote from: kartikshah on March 27, 2010, 11:06:56 PM
Cheap servos can't be fixed by radios, if they could then no one would buy or make high/costly servos....
The problem lies with the servo, either its under load or hunting...... the best is to change the same servo to another place and check or put another servo...... hope this helps.......

Karthik, I tried chaning the servo as well, but even that servo was not good enough. I agree There is a reason why a HItec costs 35 $ for a metal gear and the HXT MG 14 costs 7 $ per metal gear. Though I can buy 5 servos and of HXT and pic the best ones out of them at the price of 1 hitec. THe point is, the pain thats caused in picking/fixing/trying. I have spent almost 20 hrs to setup the servos and level the swash plate properly.

Coming to RDS, there is no EPA on individual cyclics in CCPM mode. But the link you gave me last time regarding RDS Master-Slave Mixing helped me a lot in correcting the travel of each servos. But when I change modes - say from 2 to 1, then for some reason there is a slight readjustment of one servo - which theoretically should not be happening. I noted that the other factors like individual trims were all setup neutrally across all modes, but still this weird behavior. DX7 could have easily solved this using individual EPA. But the price I got this RDS for - NO COMPLAINS!  ;D - or the ones RCD deal with Extra 7 ch Rx. I would any day recommend RDS. Neither am I feeling guilty that I brought RDS.

Anwar bhai, I do agree that pure perfection is not required unless hard core people like Tareq flies the Heli for his 3D stunts. But its in my nature to keep things as perfect as possible, be it RC or Office. A slight 1/2 mm variation in the swash plate was making me feel that I was setting up the Heli improperly. Though I know it wont cause any problems during normal hovering and FFF, I would still have the feeling that I didn't do something properly.

Anyways, I finished setting up the Swash plate and setting up the pitches of the blades as clean and neat as possible. So the setting up head ache is over.

Fixed the motor as well with the paper trick and the gap came out perfecly.

Also noted that the Plastic HK the Feathering shaft screws were not at all tight. After removing I found out weird things:

1)There was grease on the screws. No wonder the thread lock did not hold - I removed the grease from the screws using Colin, Slightly heated up feathering shaft with torch lighter to evaporate any grease. Inserted removed screws many times to remove any oil and cleaned the screws again with colin. I used lots of blue anabond. I think next time when I remove the screws I need to heat up a lot.  ;D

2)Though this is a V2 version the trust bearing in the feathering shaft are different. The trust bearings here are ordinary bearings(There are 6 bearings totally inside the head - 3 on each sides.) Not the ones that was in my HK 450 MTs head or as in Align manual(3 part bearing). Weird.  :headscratch:

I feel this ones is better. You can tighten up as much as you want and it stays cool, unlike the MT/Align bearing where they started making clicking noise when tightened too much.

gauravag

Some more progress.
1. The play was not in the rotor head, rather the main gear. Figured out that there was a brass collar that goe on the gear to prevent this. I installed that and all is good now.

2. I am still stumped as to how to mount the micro rudder servo. Will try to post a picture later today. The heli has an aluminium servo mount, designed for a full size servo with 4 holes, and the tail pushrod comes up a little high as well. If nothing else I would make a plywood mount/adaptor here. Hopefully somebody can suggest me a better/easier way here 1

3. MG-14 servos. I was able to setup mine without any problems. I have the swash levelled. and the servos all seem to work OK. BTW I do not have any swash leveller tool, so just eyeball it.
Vinay, though I like perfection too, but when you are learning, i think giving hours on end to get the swashplate "exactly" level is no good. Just get it as accurate as you can and go fly !
What good would it be if you have it exactly level, only to find that you need to trim it because of CG/other interactions.
At this point, i think having more of stick time, thank bench time is what we beginners should aim at.

Now, regarding good quality servos/equipment, I have always used Futaba ( and lately Hitec ) servos. Though expensive they have never failed for me. With these cheap servos, i am not sure how long they would lost, or how much damage they would cause. Just a simple short circuit could fry the Rx, ESC, and other electronics !
Since i wanted to try a cheap setup, i went for these, and so far been pretty happy.

Now i need the 3.5m connectors before I can continue. Also once the rudder servo issue is resolved, i should be in good shape soon !

-Gaurav

vinay

Quote from: gauravag on March 28, 2010, 12:13:00 PM
Just get it as accurate as you can and go fly !

Thats the problem with staying in bangalore and working for a SW company.  ;D

anwar

#45
Quote from: gauravag on March 28, 2010, 12:13:00 PM
2. I am still stumped as to how to mount the micro rudder servo. Will try to post a picture later today. The heli has an aluminium servo mount, designed for a full size servo with 4 holes, and the tail pushrod comes up a little high as well. If nothing else I would make a plywood mount/adaptor here. Hopefully somebody can suggest me a better/easier way here 1

This is what is confusing me, as I have never seen a tail mount for a 450 class heli that can ONLY take FULL size servos alone.  They can always take MINI and MICRO servos.  By MINI servos, I mean the ones like the popular Futaba s9650 (which is often paired with the GY401 gyro, and that is the setup I use).  So you either mount the micro servos with the only one of the two holes, or mount a mini servo using both the holes. 

You need to post pictures for us to see what the issue is.
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anwar

Quote from: vinay on March 28, 2010, 10:29:57 AM
But its in my nature to keep things as perfect as possible, be it RC or Office.

Attention to detail :) May the force be with you :thumbsup:

If you are doing the tinkering yourself, it is a good thing. 

Quote from: vinay on March 28, 2010, 10:29:57 AM
Slightly heated up feathering shaft with torch lighter to evaporate any grease.

Isopropyl alcohol on a tissue paper would be the common method for cleaning screws.
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kartikshah

#47
@ vinay,

another link and you can post your problem there and there should be a solution as thousands are using it without a problem, as maybe you have missed out something while mixing.
http://www.helifreak.com/showthread.php?t=170415
* Multiplex EasyStar II * JR XG8 * Phoenix Tiger 60 * 1/8 Truggy * Multiplex Xeno Uni *

vinay

Thanks Karthik for the link, but they again link to the same post as before.

I have leveled the swash plate for full range from -10 to +10 on mode 2 and -2 to +10 on other modes.

Its clean and level on mode 2 throughout the entire range. But when I change to other modes (Normal,1,3), then below Center throttle stick, one of the servos(the bad servo - Aileron Servo) moves down slightly faster than the other two (1 mm at -2 degrees). Basically this was my complaint before, but who the heck cares as this is the pitch I use to keep the Heli pushed to the ground in the Normal mode ;D. And the 1 mm deviation should not cause the Heli to topple over.  ;) As I get the throttle stick to move up(-0.5 degrees), the servos correct them self. So I dont think its going to be an issue anyway. As some people dont even level the swash plate to that precision.

vinay

So hows it going? busy with raptor 50?