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May 24, 2012, 07:49 PM
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beenflying's Avatar
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Discussion

250DFC Head Upgrade


I received my 250DFC head today. Looks really nice. The parts look so small compared to the 450DFC and especially the 500DFC, I have.

The new DFC Pro shaft (has the fixed flange) is so small, it fits across the standard Align plastic parts box.

I'm interested to see how the 250 flies with the Align head, as the rotor housing is a lot wider than the Tarot/Microheli rotor housing. The Tarot head I'm using, actually seems to have an excessive amount of teeter, using the 2 o-rings provided (the same as the Microheli head). I've never tried the single damper Tarot released later, which looks like it would be much stiffer.

There is definitely no ability for the blade arms to flex and the blade holder arm bears have no slop, so there will be virtually no teeter ability with this head.

I'm surprised the provided dampers feel reasonably soft. I thought the DFC head required very stiff dampers, to take the load off the blade arm pushrods ball link, at the swashplate.

I'll report back after fitting the head.

Here are some pictures of the head, packaging and instructions.
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May 24, 2012, 07:52 PM
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beenflying's Avatar
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Fitting the 250DFC head is very similar to the 450DFC head I fitted a while ago. Addition parts are required to complete the DFC head if you are not replacing an Align 250 FB/FBL head. These parts are available in one part set:
1/ Feathering shaft and screws/washers (H25015)

All screws require thread lock including the small threaded hub that screws into the end of the arm. The blade holder arm screw is a 2mm collar screw and unfortunately the thread is a little on the short side. This means that when you do up the screw the metal rotor grip arm bearings can still move along the collar screw. I've seen some use additional washers but I decided to force the screw further into the blade grip until there was only the slightest bit of play. This also means the threaded part of the screw is not right on the edge of the blade grip arm, so it will be less likely to bend or snap. Perhaps this is what Align intended.

The threaded hub must be screwed all the way into the bottom of the metal pushrod. This is not used for adjustment, like some believe. The ball link is then screws onto the other end of this and again must be screwed on a far as possible or you wont be able to get zero pitch at center stick.

The feathering shaft is a better fit in the dampers than the 450DFC. Make sure you put a small amount of grease on the feathering shaft, so it slides smoothly in the dampers. On the 250 I use a toothpick to put thread lock into the ends of the feathering shaft. I then fit one feathering shaft end screw/washer onto the feathering shaft and then put on the first blade grip. I fit the spacer and then push the feathering shaft though the rotor housing, with both dampers installed. I then fit the other spacer and then the other blade holder. Add the other screw/washer and tighten with two 1.5mm hex drivers.

The 250DFC head also comes with a 250 Pro like main shaft. This has a permanent collar, like the 450 pro. So don't fit the rotor housing to the shaft until you have fitted the swashplate. I waited until the shaft was in the main bearings.

I find the screw in the bottom of the shaft in the 250 to be a real pain. My Rx servo plugs are under the main shaft. So, to get access to the main shaft screw, I have to remove a servo plug to feed a torx driver through where the servo plug used to be.

The 250 Pro shaft is a good fit in the 250. I had a tiny bit of up/down play but not enough to worry about. Better that than too tight and causing the bearings to bind. I used my existing main shaft screw, because I prefer the torx screws. Don't forget to grease the bottom of the main shaft, because the shaft itself is the center of the one way bearing, so the rollers lock and roll on the shaft.

I now fitted the swashplate and the head. I also fitted the same HK CF/GF blades that I was using on the Tarot head. I prefer these over the Align CF blades. This time I removed the two unused balls on the upper part of the swashplate. They just looked too out of place on the 250 compared to the 450.

I could see straight away that I had a lot of positive pitch. I did up the ball links on the DFC arms until the ball links didn't really want to go any further and shortened the servo pushrods until they didn't want to go any further and still had a small amount of positive pitch. Knowing I couldn't screw any ball links down any further I decided to lower the servos slightly using the ZYX application (this is easily done with the provided all servos up/down cyclic trim). The other option would have been to remove the servo pushrods and grind them down a bit, but I decided I would live with the slightly off center zero pitch until I saw how it flew. I should add that my pushrods are still the HK250GT ones, and had I been using Align ones, this might not have been a problem.

I had to dramatically reduce the ZYX's collective pitch range, from the 66 I had for the tarot/microheli head, to 50. At 50 I had +/-12.5 degrees. I also lowered the cyclic limits until I had 12 degrees of maximum travel. I couldn't move the cyclic balls in any further, because the ball link would have fowled with the top of the DS410 servo case, where one of the gear set pins is supported.

I have to say I wasn't expect the heli to fly very well with these new settings. I was expecting I would have to at least lower the cyclic gain from their current setting of 40.

The tracking difference between the two blades was 0.2 degrees, so I made no adjustment to the DFC arm ball links.

The next morning was the time for the test flight. I was expecting the wet dog shake as soon as the skids got light on the ground, but instead it lifted off into a perfectly steady hover. I was also expecting the cyclic to be super sensitive, so I'd set the DR's to 80%. Instead it was incredibly docile, so I landed and set them back to 100%.

Amazingly the heli flies just like before with the very long microheli blade arms. I'm even more impressed with the ZYX now. The difference with the DFC head is the responsiveness of the heli. With nothing like the teeter it had before, and the lower CoG, it responds very quickly to any cyclic change. I have to say I was pleasantly surprised and feeling so comfortable with it, I started throwing the heli around a few minutes into the flight. Other than the power, it felt a lot more like the Gaui X2 (fitted with T250SE dampers), and also using the ZYX.

So again, another nice upgrade from Align. Also another good option for FB to FBL conversion. The feathering shaft used is the stock Align 250 shaft that is available from many suppliers, unlike the Tarot/Microheli FBL head. I got my upgrade kit for $32.79 from Infinity Hobby. It's only available in silver.
Last edited by beenflying; Jun 04, 2012 at 01:50 AM.
May 24, 2012, 08:27 PM
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mhills51's Avatar
Looks sweet! What controller are you going to use?
May 24, 2012, 08:35 PM
Registered User
Do you use the existing servo linkage rods?
What servo's are you using?
May 24, 2012, 09:09 PM
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beenflying's Avatar
Thread OP
Quote:
Originally Posted by mhills51
Looks sweet! What controller are you going to use?
My 250 currently flies really well, with the Tarot ZYX. I'll just be removing the Tarot/Microheli mixed FBL head and fitting the Align DFC one, along with the DFC main shaft, of course.
Last edited by beenflying; May 24, 2012 at 09:38 PM.
May 24, 2012, 09:13 PM
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beenflying's Avatar
Thread OP
Quote:
Originally Posted by clearprop88
Do you use the existing servo linkage rods?
What servo's are you using?
Yes the servo to swashplate linage rods are still used, as is the feathering shaft and screws. So the only thing you need to complete this upgrade is the feathering shaft and feathering shaft end screws/washer. These parts are marked as optional on the instruction diagram.

I'm using Align DS410's. The heli happily flies with 40 gain on the Tarot ZYX, using these servos, and I could probably go higher.
May 25, 2012, 06:06 AM
Registered User
Hi there.
Is everything you need included?? or are there other parts you need to buy ??
May 25, 2012, 06:17 AM
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beenflying's Avatar
Thread OP
If you don't want to pull your old Align style head apart, you will need the feathering shaft and the feathering shaft end screws and washers. These are all included in the Align part # H25015:
http://www.readyheli.com/H25015-Alig...t_p_32936.html
Jun 04, 2012, 01:16 AM
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beenflying's Avatar
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I've updated the second post with the mini review. I hope you enjoy it.
Jun 04, 2012, 06:40 AM
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lcc014's Avatar
Quote:
Originally Posted by beenflying
I've updated the second post with the mini review. I hope you enjoy it.
BF, thank you so much. Very detail review When you forced the collar screw into blade grip, did it really go in further until minimum play was achieved ?

Ching-Ho Cheng
Jun 04, 2012, 04:15 PM
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beenflying's Avatar
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Quote:
Originally Posted by lcc014
BF, thank you so much. Very detail review When you forced the collar screw into blade grip, did it really go in further until minimum play was achieved ?

Ching-Ho Cheng
You're welcome. Thanks. Yes, I just applied a lot more force to the hex driver, while holding the the blade holder arm between my thumb and first finger, and wound it in till it came to a pretty hard stop. I didn't check but perhaps there is a small unthreaded part on the lead in to the threaded hole and this is a very tight tolerance to the unthreaded part of the screw.

I should add that the MIP Thorp hex driver I used is a very good fit in the Align hex screws and the handle has a very good grip as well. I highly recommend these hex drivers (orange handle in the 2nd and 6th picture above).
Last edited by beenflying; Jun 04, 2012 at 04:22 PM.
Jun 04, 2012, 05:51 PM
AMA Member # 458448
lcc014's Avatar
Quote:
Originally Posted by beenflying
You're welcome. Thanks. Yes, I just applied a lot more force to the hex driver, while holding the the blade holder arm between my thumb and first finger, and wound it in till it came to a pretty hard stop. I didn't check but perhaps there is a small unthreaded part on the lead in to the threaded hole and this is a very tight tolerance to the unthreaded part of the screw.

I should add that the MIP Thorp hex driver I used is a very good fit in the Align hex screws and the handle has a very good grip as well. I highly recommend these hex drivers (orange handle in the 2nd and 6th picture above).
BF,

Great to know that we can use this method to minimize the play/gap. I also use MIP hex driver but only the 0.9mm size. I use Hudy drivers for other sizes. Sometimes, I found the Align screw is on the soft side. I could not over-tighten too much. Otherwise, screw head would strip especially true with the 0.9mm screw head in 250.

Thanks,

Ching-Ho Cheng
Jun 04, 2012, 06:04 PM
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beenflying's Avatar
Thread OP
Quote:
Originally Posted by lcc014
BF,

Great to know that we can use this method to minimize the play/gap. I also use MIP hex driver but only the 0.9mm size. I use Hudy drivers for other sizes. Sometimes, I found the Align screw is on the soft side. I could not over-tighten too much. Otherwise, screw head would strip especially true with the 0.9mm screw head in 250.

Thanks,

Ching-Ho Cheng
Yes, I stopped using my Align 0.9mm and 1.5mm drivers. Both were too undersize for my liking, and it was too easy to strip out the screw heads. Since using the MIP and ALZRC drivers, I haven't had a screw head strip. The 0.9mm were the worst. I couldn't even normally tighten an Align 0.9mm hex screw, with the Align hex driver, without it stripping out. I also now have the MIP Thorp 0.9mm driver.
Jun 04, 2012, 06:10 PM
AMA Member # 458448
lcc014's Avatar
Quote:
Originally Posted by beenflying
yes, i stopped using my align 0.9mm and 1.5mm drivers. Both were too undersize for my liking, and it was too easy to strip out the screw heads. Since using the mip and alzrc drivers, i haven't had a screw head strip. The 0.9mm were the worst. I couldn't even normally tighten an align 0.9mm hex screw, with the align hex driver, without it stripping out. I also now have the mip thorp 0.9mm driver.
Jun 06, 2012, 01:30 AM
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beenflying's Avatar
Thread OP
Any one else tried the 250DFC head yet? I'd be interested to know what color the LED was, on a microbeast, at the 6 degrees setting.

It would be nice to see a DFC swash plate come out for the 250, as well. My one has a bit of play in it. If I replace it, I'd rather fit a DFC one.


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