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Sep 18, 2019, 09:45 AM
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Help!

APCE adapter ring too large for pusher mode


APCE props have a precision face with adapter rings provided to match the diameter of the motor adapter shaft. That face is designed to work in tractor mode where the precision face matches the precision shaft face, insuring axial alignment even if the adaptor is slightly loose. In tractor mode the precision face is on the outboard side and if the adapter is loose alignment may not be true axial.

The looseness in this case is because the ring rests on the adapter threads with a clearance of less than 1mm, allowing the prop to shaft to be less than axial. I've observed non-axial alignment on my test system as evidenced by more than normal vibration.

Is there a way of modifying the rings or shaft so that they provide a snug true axial fit?
Last edited by aeromodel03; Sep 18, 2019 at 07:03 PM. Reason: add information
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Sep 19, 2019, 09:46 AM
I'd rather be Flying
davecee's Avatar
Quote:
Originally Posted by aeromodel03
APCE props have a precision face with adapter rings provided to match the diameter of the motor adapter shaft. That face is designed to work in tractor mode where the precision face matches the precision shaft face, insuring axial alignment even if the adaptor is slightly loose. In tractor mode the precision face is on the outboard side and if the adapter is loose alignment may not be true axial.

The looseness in this case is because the ring rests on the adapter threads with a clearance of less than 1mm, allowing the prop to shaft to be less than axial. I've observed non-axial alignment on my test system as evidenced by more than normal vibration.

Is there a way of modifying the rings or shaft so that they provide a snug true axial fit?
Being able to flip a prop over and reverse direction is quite an advantage electrics have over an ICE engine, but as you found out there is sometimes a bit of more work to do. I've used APCe tractor props in pusher mode quite a lot.

When using an APCe tractor prop as a pusher, make sure you drill out the "non precision" hole on the "front" of the prop (if necessary) so it doesn't touch the prop shaft at all.

The adapter ring should never be loose on the prop shaft at all, either as a tractor or a pusher. If necessary, use an adapter ring slightly too small for the portion of the prop shaft that it is adjacent to. Ream the adapter ring to the proper size. You will probably have to glue the adapter ring in place to be able to ream it. I use just a couple small drops of CA for that.

Another technique I've used to tighten up any slop between the prop shaft and a "very slightly" too big prop hole is to place a a sufficient number of wraps of masking tape around the shaft to fill the gap. I wouldn't use this method to fill a large gap. I've seldom used over one full wrap, never over two. I'll cut the width of the tape down as necessary. It actually works very well.

Or, you could buy APCe pusher props which are designed to be used with the base toward the motor, just like other pusher props.
Sep 19, 2019, 10:06 AM
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Davecee


Thanks for the reply. I will try the "ream out a ring glued with CA" first.
Bill


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