View Full Version : exi 250 budget build???
04-07-2010, 10:48 AM
one more little negative....well more just annoying. The plastic ball link end on the linkage rods are really fragile. I was turning them inwards to shorten em up to spec and one side just kind of broke. Well it didnt break but it definitely cracked. I'm just going to leave it on there as this is pretty much my parts/budget bird so its kind of whatever but just to let you guys know. The frame does seem pretty awesome though, no complaints about that... forget to mention this earlier, they also include a bag of bolts and nuts for mounting your servos, which I though was pretty cool.
04-07-2010, 01:10 PM
Information outdated. Removed.
04-07-2010, 11:12 PM
Oh yes, I forgot to mention, those ball links are friggen garbage, mine all replaced with... you guessed it Align. The plastic that EXI uses must me the ground up milk jugs that we ship back to China! (just kidding, if they were made of that, they wouldn't break) Did your kit come with the new tail gear made of metal or the plastic one? If its the plastic one, make sure that you have a spare belt laying around. It allows way too much side to side travel causing wear on the belt. Keep us posted. Like I said before, mine flew well stock, but the parts wear very quickly over the Align stuff so just be prepared.
04-07-2010, 11:42 PM
I have a HK250GT that I have been flying indoors over the winter. Very low cost to get in the air and after a bit of chasing the vibrations out, it has been great. The tail belt stretches out immediately and needs replaced. I got an align belt and a kevlar but am still using the align. Since the GT is all metal on the frame components and tail gears, no apparent wear to the belt. I am using HXT900 servos on cyclic and a HXT500 on the tail with an XM G401B Gyro. HH gain is 64 on the DX6i. The trick with that setup is putting some foam tape to keep the frame from vibrating the side of the gyro as it is a tight fit upside down on the gyro tray. Also the 37mm align tail blades seemed to help get rid of the original tail wag I had with the high head speed. I also had to loctite everything and use some balanced EXI 205 glass blades. The control links also take a little tinkering to get to the proper length. I recall cutting a couple of mm off one to keep from splitting the link when it got to the end of the threads. I set the HK to the align manual lengths. Also used a swash leveler to fine tune the setup.Seems to me getting it in the air for $150 is worth a bit of tinkering and it flys just great. I also have an EXI 450 Carbon V2 that I really like, so the 250 should be good. Might take a little work to get right, but you can really save on the electronics. BTW, I used a left over 3900 KV motor from an ESKY King 2 with a Turnigy Plush 25A esc that really cranks the little blades on the 250.
04-08-2010, 08:14 PM
just for my personal view and what i read so far.
250 is a small heli and require high level of precision. clone are cheaper in general and does not offer that amount of precision.
Just Take Note on the Feathering Shaft. Feathering Shaft for 250 is held by a M2 screw. The Shaft diameter is only 2.5mm. The screw thread is even thinner. If the precision level for the clone is not high, you don't have a lot of screw thread to hold the M2 screw.
I read stories about Feathering Shaft and Main Shaft snap into pieces, probably because of material used. And Blade "shooting" off because of not enough thread.
If you were to get clone. I strongly advise that you replace Feathering shaft and Main Shaft with original.
There has been talk about modding Feathering Shaft to use Bolt instead, but 250 is just too small for it.
04-08-2010, 08:59 PM
Information outdated. Removed.
04-08-2010, 09:11 PM
Feathering shaft failure was the first crash on my EXI. Replaced with Align.....
04-09-2010, 12:53 AM
Are you an Align employee or a clone? Lol. Thank you for the tip.
Neither. I just happen to live in china currently and read local chinese heli forum.
04-09-2010, 04:48 AM
Information outdated. Removed.
04-09-2010, 05:14 AM
hihi, no clue for most of your questions. I suspect regardless of the brand, they come from a few factories. so I suspect not a lot of diff between each clone. Beside, there isn't much 250 clone out there compared with 450.
and seriously, will you trust cloned flybarless system ? i mean, if there is any problem, we talking about a bird that can fly to any direction.
I buy some cloned parts mainly because align don't make them or it is non-critical, like alu battery holder, landing skid rod.
I think best is to avoid clone if possible.
04-09-2010, 07:19 PM
I keep wondering why a question on a budget build always turns into a bashing of perfectly good helicopter kits? In my experience, the HK250GT is actually a better kit that the original Trex 250. I have not closely examined a SE kit, so no comment there. The HK has very nice carbon frames and cnc work, all metal support pieces, most importantly the bearing holders and anti rotation guide. The canopy pins screw into the metal base of the AR guide which is solid enough to support both the frames and the pins if you crash. The Align blades are much better as well as the belt, but both of these are easily replaced. I have also had great success with the low cost 9 gram HXT900 servos. I am putting MG90S metal gear ball bearing servos on my second kit that is currently in the mail. I already use these on my 450s. They are super and cost a whopping $5.00 each. The HXT's are under $4. You need to pay more attention when you use these components, like getting a digital servo tester, but they either work well or test out bad. I have had a few bad servos, but nothing major. Also, for most people learning and doing mild 3D, any of the various G401B AVCS gyros work just fine. I must have ten of those. I had one go bad, the rest hold the tail in most conditions, assuming you know how to set up the tail and eliminate vibrations.
Come on guys. For those of us who have LHS who sell nothing but e-flite, the HK's, EXI's and CopterX kits make fine flying helicopters that don't make me feel like I am playing catch with plasma TVs. My HK250GT runs 4300 RPM headspeed and hovers hands off indoors for $165 including the Spektrum receiver...:lol:
04-10-2010, 12:55 PM
I'm not bashing, just stating fact about what has transpired since I purchased my EXI 250. I have the EXI 450 (Trex Clone) and it flies better than my blade 400 ever did in its best day even after upgrades. Having both the Trex and the EXI, there are + and - 's for each. What facts that I have concluded is that the EXI components start out very nice, but seem to wear faster than the Align versions. My EXI has the best of both worlds now and flies like a champ. But I still would (hindsight being 20/20) wait to buy the Trex kit the next go around. It all comes down to what you are willing to give up, more money or slightly less quality parts. Either way if you are happy with what you have that is all that matters because you are the one flying it and enjoying it. :Bang
04-11-2010, 05:47 PM
RP, not talking about your posts, good info. BTW, just flew 13 batteries through my HK250GT today, flying so sweet. As you said, once you get it right, they all fly good. Out of curiosity, which parts wear out on the EXI?
One thing I did find on the HK, the bearings are in need of lube. Makes a huge difference. Also the belt likes some silicone from time to time.
Another upgrade the HKGT needs is bearings for the flybar seasaw. I bought some but have not gotten around to replacing the bushings. Waiting for the next time I have it apart. One nice thing, four bearings were about $1.25.
If I could get an Align SE without the esc and motor. I might do that. As it is, I am in the air including an AR6100e for $60 less than the SE basic kit.:cheers
04-11-2010, 08:28 PM
Swash wore fast, cyclic links as well. Feathering shaft and of course the tail pulley. Check page 3 of this thread I have a more detailed explanation. Great to hear that somebody flew today!! :thumbup:
04-12-2010, 08:13 AM
I've just built up a HK250GT. I have no experience of the Trex 250 but the quality of the GT feels pretty good to me.
Only things I've switched to are Align blades and belt. I've since tuned a few things including the tail servo horn since taking these pics. Amazing the difference changing the servo arm length from 6.5mm to 4.5mm makes on these tiny helis!
Now for a maiden flight.
04-18-2010, 09:38 PM
Well it looks good. How does it fly? What kind of power do you get out that turnigy motor? I have seen those on the H K web sight but never pulled the trigger in getting one. Also, do those servos center well? I have those Hitec HS-55's on my EXI and have some trim issues with it from time to time. My Align digital's are right on all the time, maybe time for an upgrade!
07-04-2011, 03:17 PM
I just built an EXI 250. CF frame, CF blades, Sg90 servos (including tail), gz401 ($12 e-bay gyro, works like a charm for sport flying and mild 3D), volcano series 30A ESC, Gens Ace 1000 mAh 3s, and AR6200 receiver. THis heli flies well, I love it and it was cheap to build, I am thinking about digital servos (as t-pros are known to strip often) but for the mean time this will do.
ESC 30A 12.50
1000 mAh 3S 11.50 ( x 5, I like to fly for at least 35-40 min)
AR6200 Rx 55.00 (e-bay, nitro hobby)
TPro Sg 90 2.25 ( x 4)
CF blades 12.00
EXI Kit 59.00
Helium 3500kv motor 12.50
GZ 401 gyro 12.00
This brings the total to 185.50 for a decent budget build. Much cheaper than the T-rex 250 kit, its not as agile as my Gaui 200, but it did not cost 380 either! Five stars to the EXI 250, only three to the EXI 450 (feathering shaft, main shaft, tail slider & linkage, and flybar were bent form the factory; lots of replacing parts before it got off the ground).