Teeter block centering

jdalexa

Gold Member
Joined
Mar 30, 2004
Messages
629
Location
Woodland, CA
Aircraft
Cessna 140
Total Flight Time
850
After talking to Ernie today, it's apparent that I need to work on the centering of my teeter block between the towers to get the 1-per shake out. Anyone know where I can find the thin washer-like shims to be used for this?
 
Plastic Milk containers work

Plastic Milk containers work

I believe that even plastic milk juggs works.oh,that's for the outside under the teeter bolt/n nut
 
Now that I think of it, that's a good solution. Get a hollow punch kit and punch them out from soda cans. Off to find a hollow punch kit now.
 
Washers

Washers

jdalexa said:
Anyone know where I can find the thin washer-like shims to be used for this?
Sure...

See McMaster-Carr Catalog Page 3031.

Assuming you have a 3/8" diameter teeter bolt, you'll want McMaster-Carr part number 3088A931, 19-Piece Plain Steel Shim Assortment, $7.60.

Regards,

John L.
 
Exactly what I am looking for. It's not the bolt I need to shim, but the sleeve that goes into the bearing and that the teeter bolt goes through. It requires a 5/8 i.d. shim.

Went out tonight with the calipers and indeed, the teeter block is .013 off center within the towers. I hope that correcting this will take more of the 1-per-rev stir out of the system.

Thanks much John. Appreciate the info. One never stops learning with these things. It constantly amazes me how much difference .010 or .015 will make when it comes to the rotor system.

gyropilot said:
Sure...

See McMaster-Carr Catalog Page 3031.

Assuming you have a 3/8" diameter teeter bolt, you'll want McMaster-Carr part number 3088A931, 19-Piece Plain Steel Shim Assortment, $7.60.

Regards,

John L.
 
I carry a little pair of scissors and a sheet of ex-soda can metal with my rotor-assembly hardware. Keeps me ready for sudden shimming.
 
John,

It is NOT centering the teeter block between the towers that solves the problem.

It is centering the blade and hub mass (not necessarily the block) between the teeter blocks. The teeter block needs to move toward one of the teeter towers as required to center the mass and stop the shake. In fact, the teeter block will probably not be exactly centered, unless the blades and hub happen to be perfectly made and balanced chord wise, which would be unusual, as seldom is anything perfect.
 
I just love the way John Landry pulls these parts numbers out of the air. Hell of a resource having a "professional shopper" among us. I've been thinking for 6 months that someone must have some type of shim assortment like this and John just pops it up. Thanks John.
 
John, if you can wait for mail delivery, I’ll stick a handful of shim washers in an envelope and send to you.

Send me your postal address.
 
ToddP said:
I just love the way John Landry pulls these parts numbers out of the air. Hell of a resource having a "professional shopper" among us. I've been thinking for 6 months that someone must have some type of shim assortment like this and John just pops it up. Thanks John.
Hey! Don't I get credit for coming up with a part number first? A soda can! (maybe a beer can will work better!)
 
The trouble using beer cans.........

The trouble using beer cans.........

.......is that you have to drink the beer first. Then you try and cut the shims and you use all the can without success. You drink another can but you are now less handy with the scissors and you cut your finger still without suitable shimns so it is another can etc. etc. ect!!!!! :D

Aussie Paul. :)
 
Ken,

Yeah... that makes sense. Centering it is a start and then start working one way or the other. I forsee a lot of time up and down the ladder.
 
C. Beaty said:
John, if you can wait for mail delivery, I’ll stick a handful of shim washers in an envelope and send to you.

Send me your postal address.

That would be awsome! Thanks much!

1761 Losoya Dr
Woodland, CA 95776
 
Teeter block centering (update)

Teeter block centering (update)

I came across some hollow punches and punched some soda cans to make field expedient shims. The teeter block is now centered within the towers and what a difference!!!! I'm able to take my hands off and leave them off. Still some stir and now a higher frequency shake is manifesting - probably stringing error.

Still, a huge improvement. I'll try for more tomorrow.

Then off to get some night time in the pattern toward the commercial rating and eventual CFI. Whooo... been a while since I've flown night. Very funky.
 
Last edited:
Out-of-string amounts to a combo of out-of-balance and off-center lift. It's one-per-rev, and should make the stick circle at the same RPM as the rotor.
 
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