Dial Indicating Fan Hubs ( Important)

[marked23]

...and a new fan.

I bent my fan... the flat'ish part where the blades stick out from. You could eyeball it and see the bend. I carefully bent it back good enough that it again looks straight to the eye.

Can I still fly this fan?... is the flatness of the flat part that important?

(anybody want to buy an unfinished fury extreme? :cry: )

-Mark

[I3DM]

Hey guys,
can anyone post a picture of an engine in a vice with the dial indicator on it ? it would sure help everyone understand the process better.
thanks.

[Dr.Ben]

I hadn't come by lately to read a few of these posts. RE the one where the runout was good until shifting all of a sudden to 0.003", you can bet that it was tightened too much, too fast. When I'm doing this, I typically tighten the fan down in as many as a dozen or more individual increments. It takes a little while, but still a lot less time than starting over from sctratch. My latest effort yielded a TIR of less than </= 1/4 thou in 30 minutes. It is a good fan assembly for sure on a nice, straight crank.

Ben Minor

[WayneBrown]

A few pics of the setup..

[DavidH]

That is exactly what I use. A six inch flat drill press vice. A dial indicator with a stand and magnetic base. Looks identical to the setup I use.

David

[ErichF]

Hey, Lamer...Looks like you got to the Harbor Freight. I got a flyer in the mail today, with those same tools on sale

So ya up for some flying this week? I'm up an running, and can fly after work this week, or all day Sunday.


Erich

[WayneBrown]

I've got to meet Rodney for parts and GV-1 help on Sat. If everything goes well, I'll fly Sunday too!

[Ninjak2k]

Excuse a newbies ignorance please. How do you dial the fan if you've locked the crank? I'm guessing you remove the crank lock, turn the fan to dial it, and then relock to tap the face and tighten the nut. Is that right?

In other fan dialing threads I've seen (though for different helicopter fans), people were dialing the fan from the side, not the top face as seen in the above images. Does this method accomplish the same thing? Will the collets ensure alignment side to side if the top face is dialed true?

Thanks,
Dan

[ErichF]

The beauty of MA fan hubs is that you don't have to lock the crank when tightening the fan nut. It's a lot like putting a prop on a plank fan. Just use a big shop rag to grip the fan with your hand and squeek down the nut, little by little, while tapping every so often on the high spots to keep alignment.

If you go to the Miniature Aircraft Forum, DavidH wrote a great post detailing the process.



Erich

[WayneBrown]

Originally Posted by Ninjak2k

Excuse a newbies ignorance please. How do you dial the fan if you've locked the crank? I'm guessing you remove the crank lock, turn the fan to dial it, and then relock to tap the face and tighten the nut. Is that right?

In other fan dialing threads I've seen (though for different helicopter fans), people were dialing the fan from the side, not the top face as seen in the above images. Does this method accomplish the same thing? Will the collets ensure alignment side to side if the top face is dialed true?

Thanks,
Dan

You don't need to 'lock' the crank during the dialing in process but you do need to 'Support' the crank while tapping on the fan to prevent premature bearing failure. You only lock the crank once you've applied a large enough amount of torque where you cannot grip the outer edge of the fan while tightening.
I used a piece of 1" Dowel cut to reach from the back of the crank counterweight to about 1 1/2" outside the back of the crankcase. Resting the dowel on a tabletop, then placing the crankcase over the dowel will support the bearing at the counterweight.
MA fans are CNC machined, the top face of the fan is truer than the side, or at the base of the blades. My fan has flats opposite each other making the side measurement impossible.

[Dr.Ben]

Wayne has it right. The only thing that you have to watch for if you do the tapping on a workbench is if the bench isn't sturdy or the surface has some "give" to it. When this is the case, the force of the tap ends up being absorbed by the table rather than by the shifting of the fan. You'll tap yourself silly to no avail. Though I end up doing a lot of deep knee bends, I do my tapping on a concrete/linoleum floor. The firmer the surface on which you tap, the lighter to have to tap. Also, keep the dowel length as short as reasonable. When you get to a length approaching 12 inces, the wood of the dowel itself starts to absorb the force of the tap just as a nonsolid work surface does.

WRT to the final tightening of the fans, I get mine pretty darn snug (alright, darn tight) because sometimes you can improve the final product by a 1/4 thou by making really sure the nut is really seated. I've never been thrilled about transfering this kind of force all the way through the crank to a crank lock, especially the milled out intake area, so I use a 6 inch piece of flat aluminum bolted to the fan's face as a handle. As mentioned earlier, the design of the MA fans allows you to do this without having the fans slip on the engine's crank. A ten inch socket handle provides plenty of leverage for the socket. No need for a two foot breaker bar here <g>.

Ben Minor

[DavidH]

Any of these dial indicators should be fine.

http://www.harborfreight.com/cpi/cta...emnumber=33675

http://www.harborfreight.com/cpi/cta...itemnumber=623

http://www.harborfreight.com/cpi/cta...temnumber=1717

Here is the bases

http://www.harborfreight.com/cpi/cta...temnumber=5646

http://www.harborfreight.com/cpi/cta...temnumber=5645

This vise to hold the motor and support the dial indicator

http://www.harborfreight.com/cpi/cta...emnumber=30999


Any of the above will work fine. As for the dial indicators, the dial test indicator is probably a little more accurate. But any of them will do the job correctly.

Any combination of above will run you $25 to $50. Go to the dial indicator thread that is a sticky in this forum. Scroll down and look at the pictures and you will see how the above setups are used.

David

[tnreefguy]

I also check the outside diameter runout of the fan even if the fan it lateraly straight it could still be egg shaped.

[DavidH]

Doesn't really matter if the outside of the fan hub is not exactly round. Need to check the run out in the inner circumstance of the fan hub where the uni-ball rides. IT is important that part of the hub has as runout less than .002

David

[darkfa8]

David, how are you supporting the cracnkshaft/counter weight on that 6" vise?

During this procedure do you have any sort of threadlocker applied to the crank threads?

i'll be indicating a hub assembly for a Tiger 50. I had a friend mill the serated face off of the prop drive washer also.

[DavidH]

Originally Posted by darkfa8

David, how are you supporting the cracnkshaft/counter weight on that 6" vise?

During this procedure do you have any sort of threadlocker applied to the crank threads?

i'll be indicating a hub assembly for a Tiger 50. I had a friend mill the serated face off of the prop drive washer also.

I don't have to support the crankshaft. The motor is sitting horizonital in the vise jaws. But when it is vertical, the fan holds the crankshaft in place.

I have never used threadlocker on a crank shaft nut.

Why would you mill off the face of the drive washer if it is used? If the drive washer is used, I would want the ridges to grip into the fan when tightened.

David

[darkfa8]

milling the serations was advised to make for more accurate and more quickly dialing in the hub. Since the serations are not a true flat surface, rotating the hub would produce varying results.

I expect the milled surface to allow for even better results. I'll try it and see how it goes.

No threadlock, hmm, I'm sure you're aware that a lot of people, manuals, etc beat it into you that it's imperitive to use loctite on the crank nut. How come you're not using it and haven't had it come loose in flight?

I suppose if you dial in things as close to perfect as possible, there aren't any induced vibrations, enough so to loosen the nut?

[DavidH]

No threadlock, hmm, I'm sure you're aware that a lot of people, manuals, etc beat it into you that it's imperitive to use loctite on the crank nut. How come you're not using it and haven't had it come loose in flight?

Quiet a few of the top pilots taught me a few years ago that loctite is not needed on the crankshaft nut. YS Performance will tell people not to use loctite when they have sent engines in for repair.

I just torque the nut moderately when I do the final tightening. I use a small 1/4 inch ratchet that is 6 inches long and hold the motor in my hands when tightening the nut. Have not had one come loose since I quit using loctite about 10 years ago on the crankshaft nut.

David

[darkfa8]

regaurding supporting the crankshaft.. i meant so during the "tapping" the fan/hub while tightening... so as not to transfer the tapping to the bearings...?

i'm gonna go over to Harbor Freight and buy the same setup you have. Should be about $24 w/tax

[sumonzu]

Originally Posted by Dr.Ben

I hadn't come by lately to read a few of these posts. RE the one where the runout was good until shifting all of a sudden to 0.003", you can bet that it was tightened too much, too fast. When I'm doing this, I typically tighten the fan down in as many as a dozen or more individual increments. It takes a little while, but still a lot less time than starting over from sctratch. My latest effort yielded a TIR of less than </= 1/4 thou in 30 minutes. It is a good fan assembly for sure on a nice, straight crank.

Ben Minor

How did you all do this? I tried several times from scratch but since the begining (withouth tightening) I can't almost move the fan even tapping several times. Where I'm wrong?
Any suggestion is welcome.