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Old Dec 01, 2009, 06:40 PM
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Build Log
HK450MT Build Project

Well, here I am again getting sucked into the helicopter side of RC. I just can't stay away very long and with the plethora of inexpensive 450 clones and electronics I had to give one a try. Enter the HK450MT.

The HK450MT is an updated version of the HK450 clone of a Trex 450SA that was mostly plastic parts. This new one is mostly metal and looks really nice so far.

My setup will be:
- Turnigy Typhoon 2215H
- TURNIGY Plush 30amp Speed Controller
- HXT900 x3 on Cyclic
- Hobby King 401B AVCS Digital Head Lock Gyro
- Spektrum AR6100 RX
- 3S 2200mah 20C Lipo
- Dx7 Tx

My tail servo is TBD. I have several to try before I settle on one.

Stay tunned as I will get some photos up and some initial thoughts on the progress thus far.
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Old Dec 03, 2009, 05:05 PM
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I'm well on my way into the build and I have a few items to note so far.

When installing the elevator CCPM servo into the frame (HXT900 Servo) I originally had it mounted from the outside with the tabs resting up against the outside of the frame. When I went to setup the linkage rod to the swash, I did not have a pure vertical line so I started to think about how I could get a pure vertical rod orientation and I noticed the servo needed to have the tabs on the inside of the frame to achieve this. I could not get the bottom portion of the servo to go through the frame slot without crushing and hanging up on the servo wire exit at the bottom of the case. I did not want to split the frame in order to get this installed, so I backed out the servo case screws far enough to remove the top portion of the case with the tabs. I then joined the two halves in the frame with the tabs on the inside and tightened the case screws back in. Now the linkage rod is vertical. The newer position puts the servo gear case closer to the tail belt pulley gear than before, but I think it has enough clearance to proceed.

Second thing I encountered was the OEM main gear had a slight warp in it from the factory. I'm not sure how much vibration this could cause, but I took it apart from the One-way gear mount and heated it up with a hair dryer and then weighted the ends down that were warped and left it there overnight. After inspection it seems to be better, so I'm going to try using it.
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Last edited by cactus; Dec 04, 2009 at 12:17 AM. Reason: Photos
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Old Dec 03, 2009, 05:14 PM
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I must note that my selection of components and this kit reflects my intention to build a stable and predictable 450 size helicopter for casual sport flying. I have owned larger and much more expensive CP birds in the past but the cost was a hindering factor in progressing further in flight skills. Cheaper gear removes some of the scare factor for me and will allow me to work on smooth scale like flight and some backwards stuff once I can do it better in the sim.
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Last edited by cactus; Dec 03, 2009 at 05:21 PM. Reason: Better explanation.
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Old Dec 05, 2009, 08:19 PM
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I finished getting the swash plate servos setup through the entire pitch range and checked it for level using an hex key wire-tied to the shaft above the swash.

Moving on the the rest of the head setup, it came with the push rods in nearly the perfect length so far.

The fly bar paddles and weights came nearly perfectly balanced in weight between the two with the paddles registering the same weight on my scale.
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Old Dec 06, 2009, 01:20 AM
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I'm on hold until I can get a replacement swash plate. The one that came with this head was junk and manufactured with a lop-sided bearing pressed in.
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Old Dec 07, 2009, 12:29 AM
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I got the tail pitch control rod installed and the servo in position ready to start the Gyro setup. I ordered an Align SA swash plate off EBay and it should be here in a few days.
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Old Dec 10, 2009, 01:10 AM
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Hey, I just put one of these together myself. I wanted to let you know that the Align Trex-450 SEv2 Manual works for the HK-450. It can be helpful when building, for example, the Elevator servo is shown the way you found you had to have it. It may help save you some time/frustration!

It is available in PDF format at this link:

http://www.heliguy.com/i/Trex450SE-V2Manual_ebook.pdf

Hope this helps, sorry about your Swash Bearing!

PS Feel free to delete this comment from your build log, I wont be offended, Good Luck and welcome back to the hobby.
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Old Dec 10, 2009, 01:20 AM
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I might have to try the SE V2 manual instead. I'm going by the 450SA one and it has some differences for sure. My swash has not come in yet, everything is delayed due to the weather. I did get some wire management done tonight as well as mounting my new carbon tail fins I got off of another ezoner.
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Old Dec 10, 2009, 11:34 AM
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I printed the SA manual first myself. I found the SEv2 manual to be closer. For example; correct flybar length, and all of the screw sizes/types matched up.
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Old Dec 15, 2009, 12:06 AM
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Align swash arrived today. I have it setup on the shaft and so far it is spinning true. I'm going to recheck it for level throughout the entire pitch range and then put the rest of the head back on for flybar setup and linkage leveling.
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Old Dec 17, 2009, 12:49 AM
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I got the head put back together and the fly bar setup. Tail setup and gyro tomorrow night.
Installed some new gear that I purchased separate from the HK kit:
- Align SA Swash.
- Swapped out the white landing gear for black ones.
- CF tail fins replace the metal ones from HK.
- Wire mesh protection kit for servo wires.
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Old Dec 18, 2009, 11:36 AM
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Last night I worked on getting the CCPM geometry setup so I get +/- 10 degrees of pitch mechanically and check for CCPM interactions as per the Finless Bob CCPM Part2 video on Helifreak.com. I have several issues to resolve after trying this:

1. I am not getting an even pitch range from full + to full -. The - side is 3-4 degrees more than the positive in relation to the value I have for pitch in the CCPM setup in the DX7.
2. I am getting some CCPM interaction in both ELEV and AILE. What is weird about this is I can have the stick centered and the swash level and all the locations on up the head look level (eyeball method on the upper head) but the fly bar will tilt around slightly as I transition up and down in the entire pitch range.

Leading up to this I had done the following:
- 90 degree centered the servo arms at mid stick. Had to use a slight amount of sub-trim to get them perfect.
- Ball links on the servo arms to the swash are vertical.
- I checked the swash for level at low, center and high using the allen key method on the shaft with the head removed.
- I checked the rest of the head above the swash for level and set the blade grips for 0 pitch at mid stick.

I must have some improper length ball links somewhere or just have not adjusted the servo end-points enough...
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Old Dec 19, 2009, 01:38 AM
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Thanks Cactus,
Good build log.

I must admit that once I get one of my blades setup to plus and minus 10 degrees and then track the other blade to it, I don't worry about the fine interactions. I figure I am going to crash it soon anyway and my 450 T Rex flys fine.

I am watching your log with interest as I have just ordered the HK 450.
Cheers
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Old Dec 19, 2009, 01:50 AM
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Aussie, I am going to take a different approach to getting the CCPM setup. I have one of those swash leveling tools coming soon and I'm planning on doing it all with that and not bother with the bubble leveling on the paddles.

As far as my pitch is concerned, I'm going to try and get it closest to +/- 10 degrees as I can mechanically. I'm not going to be flying it anytime soon, so I might as well take my time on the build and get a smooth sport flyer out of it for spring time.
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Old Dec 29, 2009, 12:39 AM
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CCPM Setup Take 2

I went through my pitch range again with the EXI swash level tool and I found a few tiny adjustments on the bottom and top of the range. I made the changes in the ATV for the ELEV on the Dx7 and that fixed a majority of the interaction I was getting before.

I also smoothed out the ELEV ball link as it was sticking a bit at the swash.
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