600 My T-Rex 550 Rebuild

[PLANETGETLOW]

What did you sell? I don't have a big enough 'fleet' for that to worry me

I sold my Blade 270 cfx and a Gaui X3. Together they both paid for the 550. I'm going to just try and stay above 450 sized helis.

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Yeah, the joys of upgrades and conversions! The motor moiunt from the later version of the 550 would probably have solved the pinion problems, though i'm not sure if the frames changed too at which point it probably becomes a new heli rather than an upgrade.


The DFC head sits lower and the swash sits lower on the shaft too, so you will need shorter links on the swash servos. The links from the 550DFC 'should' fit, I think.

Mine has a 600DFC on it

 

[Heliman450]

Hi all, just remembered that I took a photo of what was probably the cause of my last crash. It's the Ex-Bus cable to/from my Spirit Pro to the Jeti REX7 Rx. It looks like the single (signal) wire has been used to pull out the plug and in so doing has damaged the plastic such that the connection doesn't make fully unless it's pushed down as an extra step.

I have to plead guilty on this as nobody else has been involved in making/breaking the connection other than me, although not many times. Not something I'll be doing again in the future! Not that it would have helped in this case, but I'm also going to buy a glue gun to make sure that the connections don't come out during flight. Just as well I planned to do the change to a DFC rotor head anyway and the cost of my mistake wasn't more than just a new set of blades plus the new main gear and motor drive pinion.

 

[Smoggie]

That's the culprit alright! The locking clip 'thingy' has broke off the plug, it happens occasionally.

 

[Heliman450]

Yeah, the joys of upgrades and conversions! The motor moiunt from the later version of the 550 would probably have solved the pinion problems, though i'm not sure if the frames changed too at which point it probably becomes a new heli rather than an upgrade.


The DFC head sits lower and the swash sits lower on the shaft too, so you will need shorter links on the swash servos. The links from the 550DFC 'should' fit, I think.

Hi Steve, I looked in on the ShopAlign website and checked out the parts. The DFC mounting plate mentions a 2mm frame thickness. Not knowing what the width of the plate actually is I decide to get the Dremel out and try the modification rather than order, wait and find out that nothing else fits for the same width between the side frames. It seems to have worked fine and I didn't need to take much off the slots, just enough to move the motor back and mesh the gears properly.

I'll do some experimentation and measuring with my trusty digital calliper to reach a solution on the size for the rods.

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That's the culprit alright! The locking clip 'thingy' has broke off the plug, it happens occasionally.

It's actually still there but has folded upwards. Of course it's a bit difficult to see with a black plug and no macro lens for my phone camera.

 

[Smoggie]

I think they made the side frames thicker at V2 of the 550 which if i recall was when they added the slant gears. The motor mount could still fit though because the distance between the inside faces of the frames stayed the same.

 

[Heliman450]

Hi all,

Picture attached of step 1 of my experimentation. I came to the conclusion that I need three linkage rods of around 32.0mm long. I checked out 亞拓家電網路購物 and part #88 shows H55049 as the part number and in the pack are three rods 32.0mm long, result! I removed the pitch linkage rods and took them apart. The minus 1.9 degrees was increased to plus 0.3 with a small adjustment to increase their length. My cardboard packing holds the swashplate at 11.75mm above the frame and with the servo arm(s) at the mid position the distance between centres is 48.2mm (5.3mm less than previously at 53.5mm). Now I've only got to wait until Tuesday to buy the rods

 

[Smoggie]

For a small reduction like that you could most likely get away with trimming down the links.

 

[Heliman450]

For a small reduction like that you could most likely get away with trimming down the links.

Hi Steve,

You're probably right there. I measured the depth of the hole in the ball link and it's 10.0mm. There's 8.0mm of thread on each end of the linkage rods, so about 2mm off each end would work. I've got nothing to lose on that even if the links get messed up. I'll do just that tomorrow when I go to my workshop.

 

[Heliman450]

Hi there! I cut the link rods down, but unfortunately they failed my own quality control inspection. They just aren't tight enough for my liking, maybe I could have used them to go through the setup process but after waiting so long to this point I can wait until tomorrow.

What with the DX6 binding problem and the list of other non-RC related troubles it looks like nothing I touch works at the moment

 

[Heliman450]

Hi all, no video of the event (it was all over a bit quick) but the tail link rod pulled out of the link. What were you thinking???

Fortunately, there was no damage done but I need to investigate further why it happened. Of course I'll go through the set up again but I can't explain at the moment why it happened other than the threading of the new ball link wasn't tight enough. I can't do anything more today so I just dropped it off at the workshop for tomorrow.

It sounds amazing. I can only explain that due to the different main drive gear and motor pinion (bevelled). The whistling noise that was always there has disappeared to be replaced with a very deep sounding hum. I must video it next time out if only for the audio

Bye for now!

 

[trainrider06]

Hehe I had a link come out of my rear servo at about 20 feet in the air, it just went buuuurrrrrppp, then tailed straight into the ground! That was a very ugly result especially since it went into concrete......

 

[Smoggie]

Were they new links and rods Phil?

They come in different thread sizes, 1.5mm, 2mm, 2.5mm and 3mm. Possibly your ball link was a larger size than the rod causing sloppy fit?

 

[Heliman450]

Were they new links and rods Phil?

They come in different thread sizes, 1.5mm, 2mm, 2.5mm and 3mm. Possibly your ball link was a larger size than the rod causing sloppy fit?

Ah Ha! I didn't realise that the tail ball links were so varied in size. My 550 has the carbon rod, which does seem to be a very small diameter on the twisty bits at each end. I used a pair of new ones out of a pack but nothing was mentioned about it containing various sized holes. I haven't picked up anything from the assembly instructions or on the Shop website where I've been checking out the different part numbers.

When I did the tail conversion to 600 size, I also had two 600 metal rods, but decided to go with the carbon rod. Am I correct in thinking that the links don't have their own threads and the hole is smooth the thread being cut by whatever rod goes in (of course the correctly sized rod). When I start on my checks tomorrow, I'll begin following your lead on sizes. I was considering dumping the carbon rod, too.

There are some links in the pack with a 'collar' around them and they look more substantial than the others. Where are they supposed to go?

Once again, thanks!

 

[Smoggie]

Yes, the plastic ball links come un-threaded so you can use them on left or right hand threads such as found on turnbuckles.

The ball links with the metal collar are for the DFC links, like shown in this pic:


But for some reason they aren't always fitted

 

[Heliman450]

OK, I meant the ones with a plastic 'collar' or ring around them, not the metal-collared ones.

 

[Smoggie]

The one with the plastic collar moulded in is for use on the swash bellcrank that's used only on the 600. You can see one in the photo i attached in my last post.

 

[Heliman450]

The one with the plastic collar moulded in is for use on the swash bellcrank that's used only on the 600. You can see one in the photo i attached in my last post.

Gotcha!

 

[Heliman450]

Hi all, here's the follow-up on my investigations into the failure of my tail rotor link..............

The holes in the links don't fit so clearly into sizes as Steve listed below. However, there are 8 different numbers shown on the new links in my possession (more than one bag's content). The numbers are: 04, 06, 07, 08, 09, 10 and 14. I have varying quantities of each, the majority being #08.

My carbon tail rod had a #07 at the servo end and a #08 on the rotor end (the one that failed). I replaced both with a pair of #06 and they needed noticeably more force to screw the links on. I think this will resolve the issue. Only thing to do now is go through the tail rotor setup again.

Sorry that I couldn't provide any information about which link to use on which rod as the bag contents cover a number of heli models. As the numbers increase so does the size of the hole.

BE VERY CAREFUL WHEN SELECTING WHICH ONE YOU USE AND MAKE SURE THEY ARE TIGHT ENOUGH!

 

[Heliman450]

Hi again, continuing on the ball links' issue. I'm putting together a table listing all the dimensions I can find in the manuals I've downloaded and will share it in due course. As Steve mentioned earlier on, the rods appear to be listed as 1.96 and 2.5 mm diameter. The 3.0 mm comes from only one place as far as I can see so far and that's the 'A' Frame shaped 'anti-rotation' device shown in the picture Steve provided in thread #54, which is secured with a M3 set screw according to the 700 assembly instructions I reviewed. I found this package that seems to include most of what my T-Rex 550E (hybrid) needs.

I intend to buy a pack to see exactly what the 19 ball links have moulded into them, particularly the 14 apparently identical ones.

亞拓家電網路購物 - 600PRO連桿é H60222

Finally on this for now. There's nothing I can yet find for the carbon tail rod links other than '600 Ball Link'. There's no size shown for the threaded ends, however, without measuring them it looks like they are 1.96 mm diameter so falling into the category needing a #04/06/07. It looks like the lower numbers are ok to fit a 1.96 mm rod. I'm not even going to use the #07 in this location.

Bye now!

 

[Heliman450]

Hi all, after trawling lots of manuals checking out what's what, I came up with the diagram below, which shows the link rods very well. Since the advent of flybarless, Align seem to have decided to remain with the rods from the swashplate designated as 'Rod D' and everything above being simplified to 'Rod A' doing away with everything in between.

Note that almost every heli is different in some form or another due to the various layouts of the link rods and be extra careful as they aren't consistent in the way they've put the manuals together so one needs to check very carefully for the particular model you're working with. This is made especially difficult if, like me, you have a hybrid that's been changed from the original model. Add to the mix that they have combined bits into a spares pack covering various models you might not have enough of the ball links you need for your needs.

The majority of the rods seem to have a diameter of 1.96 mm so having a good supply of the 04/06 & 07 is a good start.

View attachment T-Rex Link Rods.pdf

Bye now!