Main shaft shim, spacer

[toaster12]

I have put together my 700 but in no way could I fit the spacer on the mainshaft. The smallest is 0.8mm and the gap between the bearing and shaft is 0.2mm.

So at the moment I am running without a spacer. There is absolutely no way that I can compress the bearings to create a gap large enough to use a spacer.

So the question is , is the spacer needed in this situation? Do I just fly and keep an eye on the end play until I can fit a spacer?

[mk1spitfire]

think my mate filed it down

[derelict]

i had a tiny bit of play without the spacer... and with the smallest spaced i was having a hard time putting the bolt into the maingear... put i've worked it through somehow ;-)

so i seem to be fine with the smallest spacer.... but one thing i've noticed is that the head turns quite hard allthough everything seems to run smooth. i don't know if it's coming from the tail gearing, anti-rotation bearing, main shaft bearings ? what ever... maybe it "loosens" after a few flights.

Try to mount the smallest spacer somehow just for the piece of mind... i don't know if a no spacer shaft will cause any troubles !

Cheers

Marcel

[helis101]

I had the same problem with the shim being to thick, what i did is sand the shim with a dremel till it would fit correctly. Or find thinner shims i hear that they are needed.

[toaster12]

well i've just checked with feeler gauges I have a gap of less than 0.06mm !!!!!!!!

A shim of that size is going to do nothing apart from get chewed up and spat out!!

Why is is needed? The step sits on the shim that sits on the bearing! without the shim it just sits on the bearing.

At the moment it will just stay as it is and will just have to keep an eye on it.

[helis101]

well i've just checked with feeler gauges I have a gap of less than 0.06mm !!!!!!!!

Why is is needed?
Shim is to eliminate any vertical play in the shaft, if there is any vertical play it will effect pitch inputs.

[stmpngrnd]

Shim is to eliminate any vertical play in the shaft, if there is any vertical play it will effect pitch inputs.
thanks for coping my RR post word for word. rather than copy you should link to other posts.

[helis101]

thanks for coping my RR post word for word. rather than copy you should link to other posts.Sorry buddy i didnt mean to steal your thunder just thought that you worded it perfectly. :thumbup:

[toaster12]

I wasn't going to say anything :shock:

I really don't think 0.06mm is going to affect anything that much!!

[stmpngrnd]

Sorry buddy i didnt mean to steal your thunder just thought that you worded it perfectly. :thumbup:
no worries..just had to call it out on principal.;)

[cbdane]

no worries..just had to call it out on principal.;)

I think you meant principle. ;)

[stmpngrnd]

I think you meant principle. ;)

darn..I dumb thumbed the keyboard..now I've lost all my thunder!:oops:

[Finless]

Well OK guys keep the RR trash over there... copy and paste or whatever no one here gives a rats arse!

As for .06.. If you can grab the head and feel up and down play then find a way to remove it. It will effect pitch and cyclic input (and I didn't copy that from any RR post). I too have to admit the smallest shim made it a beach to get the main gear bolt in but I went with it and so far so good...

I kind of knew this would start appearing because no way can Align get the frames to bearing blocks and main shaft hump consistent every time. They need to supply more spacer options in my opinion!

By the way because the main shaft hump is kind of rounded if you do decide to dremel a spacer you ONLY need to do it around the center hole area of a spacer... Super easy.... I thought about that as well but even though mine was tight it was OK in the end.

Bob

[mewsikman]

Its really a two person job, one to push the head down while the other one has a hex driver and rubber mallet to hit the bugger in.....

NOTE: DO NOT HIT IT HARD IT WILL GO IN WITH GENTLE TAPPING

[toaster12]

That's 1/2 of 1/2 a mm!!!

With my body weight on the shaft and the 0.8 mm spacer there is no way to move the shaft.and gears enough to put the bolt through.

I'll have to fly it as is, 'til some smaller spacers are available.

[sonofcar]

That's 1/2 of 1/2 a mm!!!

With my body weight on the shaft and the 0.8 mm spacer there is no way to move the shaft.and gears enough to put the bolt through.

I'll have to fly it as is, 'til some smaller spacers are available.
I grinded mine down to about 0.4mm and it then fit with just the right amount of pressure. No play and no bind in the bearings.

[toaster12]

Unfortunately, I don't have a workshop to grind down a spacer to half it's thickness. or even a quarter! Remember I have less than 0.06mm not 0.6mm of play.

In fact, I don't have a shed or a garage!!

I know you're gonna say use a dremel, but how are you're gonna hold it to get an even surface!!

I appreciate what everyone has said, but I do not have those facilities available to me. I believe align should release 0.4, 0.2 and 0.1mm spacers as well. I may then stand a chance!

[Dr_Crash]

Guys,

Please note that I too had the same problem everyone else is talking about. It appears that during the machining process the edge of the cut became slightly flared. This will not allow your shim to fully seat.
http://barrets.smugmug.com/photos/331375962_MMMTg-M-1.jpg

What you need to do is lightly file the edge line just next to the heat treat area.
http://barrets.smugmug.com/photos/331376011_jKTpj-M-1.jpg

This will now look smooth. It doesn't take very much. There are very tight tolerances between shim and main shaft.
http://barrets.smugmug.com/photos/331375918_bicAa-M-1.jpg

Now you should be able to fully seat your shim. The .8mm shim was perfect on my TREX 700.
http://barrets.smugmug.com/photos/331376054_aFUXc-M-1.jpg

Have fun and fly hard.

Chris

[stmpngrnd]

Unfortunately, I don't have a workshop to grind down a spacer to half it's thickness. or even a quarter! Remember I have less than 0.06mm not 0.6mm of play.

In fact, I don't have a shed or a garage!!

I know you're gonna say use a dremel, but how are you're gonna hold it to get an even surface!!

I appreciate what everyone has said, but I do not have those facilities available to me. I believe align should release 0.4, 0.2 and 0.1mm spacers as well. I may then stand a chance!
I just used the sanding drum while pressing the shim down on my work table with my finger. You're not applying a whole lot of pressure with the dremel so it's ok. It never felt like it was going zing out of my grasp. I would do about a 1/3 of the washer and then rotate. probably went are about 4 to 5 times and mine came out relatively even..between .6 and .65 all the way around. If fit perfect after that..and yes it was pushed all the way to machined collar.

[toaster12]

Thank you to all for their tips and advice, finally I have a spacer fitted and no play in the shaft.

Yes, the spacer did not lay flat against the machined collar! A little bit of careful filing cured that.

Then a little bit of sanding took the spacer down to 0.6

Then pressure on the main shaft and some little taps with a mallet and the jobs done.

Couldn't have done it without your help, so many thanks again.

[Mercuriell]

Well I had no play with no shims so didn't put one in :) - after 6 maiden flights yesterday still no play. If you have some play it might help to loosen the bearing blocks on the mast just to give a tiny bit of slack to get the shim in.

[Finless]

Dang John... I didn't know you were getting a 700? Congrats!

Bob

[Animal]

I also only had a small gap to fill. but it was to much slop for me. so i wanted to find a better way to beat this cat.
What i did was loosened all 8 screws holding the main shaft bearing blocks. Insert the shaft with the thinest shim. Attach the main gear, then tighten down the main bearing block screws making sure the main shaft still rotates freely.

after i was happ with alignment i went back and one by one loctited all the screws.

[rcmadpilot]

I am sure glad that you all were able to get your's in. Mine is so tight that even the smallest shim doesn't work. I tried all your tips and I am still can't get mine in. :mad:

[Mercuriell]

Dang John... I didn't know you were getting a 700? Congrats!

Bob

This is one nice heli - I reckon the build took me around 5 hrs (~20 for the Strat:shock:) and the hardest part was getting that fuel tank in lol. It has been very aggressively priced here in Oz pitching in at ther same price as the 600N basic and $300 cheaper than the NSP. I really can't see any upgrade space for it either (except maybe I'll put a QUK tail on)- the parts are real good quality and a thoughful and elegant design :) I maidened her on Sat and she flies like a dream - can't wait till the engine loosens up! This bird is definitely gonna relegate the 600N to the sidelines (actually been loaned to my mate who's too idle to build his Strat!) and the Stratus gonna be reserved for Sunday best !

After two more flights (8 in all) noted just under a thou float in the main shaft so I reckon that 0.8mm shim will fit in just nicely now - I'll find out tonight!

You'd know this already Bob but I've found to my delight that the 90 engines are easier to start and tune up than the 50s!