Quick mainshaft shim question.

[rcmarty]

Got my kit yesterday and have been drooling at it as i finished up a quote for a job.

I have a quick question on the main shaft shims.

Manual shows places for 1 x .5mm and 3 x 1mm shims.

I got : 3 x .5mm and 1 x 1mm

I'd assume spacing between the main and tail gear would take priority over the lower stack.
Should i go 1 + .5 between gears and 2 x .5 below ?

I do i need to get my hands on some 1mm ?

Thanks , martin

[AusAnt]

Glad you got it so quickly. My kit came with 3 x 1mm and 1 x 0.5mm. There's a little bit of vertical play with that setup, which the manual says is normal. I'm not sure if the additional 1.5mm will make any difference.

[rcmarty]

Yup picked it up last night at the post office.

Ken is great , got me into the next kit quite fast.

If you still got a bit of play with the proper stack , then i'm going to be another 1.5mm short. Hope ken has some spares in stock.

I'm also going to put a cross bar on the back 2 canopy mounts.

Did you get your's running yet ?

I've started today , locktiting bolts and assembling misc stuff out of order

Martin

[dahld]

You can probably get away with 1.5mm spacing instead of the recommended 2mm between the main gear and the tail drive belt pulley. Just make sure when it's all together, the main gear doesn't kiss the the smaller belt pulley, that sits just above and to the rear of the main gear. It normally has about 2mm of clearance.

That will leave you with 1mm of shims for under the main gear (instead of the recommended 1.5mm), which again, you can probably get by with, as some vertical play in the gear is required anyways. Of course in the end, make sure you pinion is well adjusted vertically to match the herringbone gears.

If you want, PM me with an address, and I'll put some in the mail to you, as I've got about a billion of them (-: That way you can eventually get it back to specs. Or, if anyone has them in stock, it's part # 4517, and I'm sure if you said you were shorted the shims, they'd send them for free.

(-: Dave Dahl

[rcmarty]

Ken (rcflightstore.com) has a set in stock. I'll get him to put a set in the mail for me.

No real hurry right now , Moving on the 9th and i haven't bought packs yet.

Hoping to sell of some more stuff soon.

Thanks for the offer dave , if i find myself short (or ken happens to sell them before i get an order in) , i'll give you a pm

Thanks , martin

[AusAnt]

Sounds good. Mine will be a few weeks - I have servos coming in another 2 weeks and batts by then too, so prob another 3 or 4 weeks till she's in the air, depending on Vancouver weather....

[flymustangs]

I just got to that part in the build and I also received 3 X 0.5mm shims and 1 X 1mm shim. I'm wondering now if something was changed/updated so it doesn't match the manual now.

[rcmarty]

That might be a possibility.

aus mentined that he still has a bit of play with the 3x 1mm and a .5

I'm going to order up a spare set of shims (4517) so it should have plenty to choose from.

I'm going to dry fit what i have and see how it looks.


Dave .. Are the lower shims there to help load the shaft when inverted ? (just a thought)

I'm thinking that the top bearing and the bottom one (if shimmed right) would share the load when inverted.

Martin

[flymustangs]

I just tried 1.5mm spacing between the main gear and the tail drive belt pulley and it will not work. With 1.5mm of shims the main gear just touches the smaller belt pulley. I'm not even sure 2mm would be enough.

[rcmarty]

I was down tinkering also.

Even i grabbed the wrong ones (can't blame them too much as there hard to tell) and thought i had 1.5 mm worth.

Turns out i had 2 of the .5's for 1mm total. Maingear rubs on the taildrive gear.

Then i took it down again and put 2mm's worth in there and it clears fine. I'm guessing 3/5 of a mm worth (love the german specs ) and i wouldn't expect any issues in flight.

Then for giggles i put the last .5 on the bottom of the maingear and popped on the bottom bearing block.
I slid down and went half a screw hole past the holes.

3mm hole , 1/2 past is darn close to 1.5 mm.

So the proper shims + what aus said ( a little bit left (.5)) sound bang on to me (again german specs).

I'm thinking the 4517 shim kit is going to be popular.

I'm off to get mine.

Martin

[dahld]

I think the kit builders are just picking the wrong shims from the bins. The size of the shims and the way the manual depicts it is correct.

@ rcmarty,

It is actually the middle and top bearings that support the heli upright and inverted. There are no vertical loads on the main gear at any time. It floats between the bottom bearing and the tail drive pulley.

(-: Dave

[AusAnt]

I just checked mine (been down building too) and mine has about 0.5 to 0.75mm vertical play judging by eye (I think closer to 0.5). Nothing seems to rub at either extremity, so that seems about right.

[rcmarty]

Thanks dave

I was tinkering a bit with it and i can see the logic now.

I think once assembled according to the manual it will be good to go.

There might be a little bit of vertical play ( ~.5 as mentioned above) but the heringbone drive system should self center that.


I ordered up a set of shims so i'll have some spares to play with after it's all done.

Hoping there is at least 3 of the 1mm in there. The description doesn't spec the suppiled parts , just that you get 8 as the picture shows.

Martin

[rcmarty]

Originally Posted by AusAnt

I just checked mine (been down building too) and mine has about 0.5 to 0.75mm vertical play judging by eye (I think closer to 0.5). Nothing seems to rub at either extremity, so that seems about right.

If it's closer to the .75mm then another .5 shim would be perfect , as long as it doesn't apply any pressure it will be good to go. Reducing the amount it can 'float' is going to be better. If it gets tight then your better off without it and relying on the pinion to center the gear.

A bit of speculation at this point as i don't have my shim kit yet.

Martin

[flymustangs]

Ready Heli doesn't have these in stock. I sent them a message and I'll see what they say. I'm sure they'll figure something out in typical Ready Heli fashion.

[rcmarty]

ken at rcflightstore.com has a set.

He does live inventory so it shows at least one set in stock.

(not very often his computer gets it wrong )

http://rcflightstore.com/product_inf...oducts_id=4569

Martin

[belgoheli]

I have built my XXtreme using the shims as suggested. The axial play is indeed there but I found it hard to tell wether this .5 or .7 or even more.

The real question stays: does the gea

[belgoheli]

Sorry guys , the reply went out by mistake. To finish off the query, the real question remains does the gear wear or not with this setting??

[flymustangs]

RH did reply and said they would send a set. The bad news is that it will be at least seven days before they have them in stock.

[rcmarty]

same theory as the logo 600/500 stuff.

The space need to minimal to keep the maingear in alignment with the pinion gear.

Large differences will cause issues with the pinion and maingear and may accelerate wear on one side of the herringbone.

Given the size of the gear and .75 mm , we should be good.

Getting the fit even better would be a bonus.

My situation with 1.5mm short + the .75mm standard play , i can see it being too much.

Martin