Spinner Wobble/prop balance

[edneff]

I have a very slight wobble on the tip of my spinner. I just used the dynavibe and checked my prop balance and it is off by .19

Question: Could the imbalance be caused by the spinner wobble?

follow up: Could the prop imbalance be fixed by dynamically balancing (adding weights to the back plate)? or should i attempt to fix the wobble first?

[Tom Martin]

Fix the wobble first. Take all top or bottom spark plugs out so that you can move the engine freely. Mark the centre of the spinner as best you can with a small black dot. Now set a step latter close to the spinner with a pointer, (scrap aluminum) aimed at the dot. Rotate prop to see how the dot moves.
Make adjustments in holes to get spinner centred then fill slotted holes with epoxy to make it permanent. It may be necessary to adjust the front baffle as well. It is well worth the effort to get the spinner as close as you can get to being entered.

[edneff]

Thanks Tom.

I'll try that and report back. I'm surprised that the low mass of the spinner could unbalance the prop.

[13brv3]

If you still have access to the balancer, you could always take the spinner off, and make another run. I do imagine you can dynamically balance out the wobbly spinner, but I'm sure everyone would agree that fixing the spinner first is the best approach.

BTW, I've seen some of the most wobbly spinners on certified planes. Some are really off, to the point of being amusing.

Cheers,
Rusty (picking up my ACES 1015 tomorrow)

[VA Maule]

Does your spinner have a forward bulkhead or just the rear backing plate ? If no forward bulkhead removed a spark plug from each cylinder for easier rotation and check backside of backing plat for runout with a dial indicator,might be bent. Without a forward bulkhead it doesn't take much of a bump into, someone lean on or against it even lightly to get it off center.

[edneff]

I checked the offset at the center of the spinner as described in above posts. My prop has a front bulkhead, and the rear bulkhead *looks* ok, although I did not check it with a dial indicator as suggested.

The offset was extremely slight, between 1/32 and 1/16 of an inch...

I have decided to let sleeping dogs lie for now, and perhaps do a dynamic balance at the next condition inspection.

There is no noticeable vibration, and in fact many folks have commented on how smooth the whole setup is.

thanks for all the helpful suggestions.

Ed

[tgmillso]

I'm totally kicking myself now that I read this thread. I spent hours yesterday trying to align the spinner using the dot and pencil clamped to a ladder method suggested in the instructions. Using a dial indicator on the circumference a couple of inches aft of the tip makes so much sense. Shame this post didn't appear a day earlier.
Tom.

[Raymo]

Originally Posted by tgmillso

I'm totally kicking myself now that I read this thread. I spent hours yesterday trying to align the spinner using the dot and pencil clamped to a ladder method suggested in the instructions. Using a dial indicator on the circumference a couple of inches aft of the tip makes so much sense. Shame this post didn't appear a day earlier.
Tom.

I used the dot/pencil method and my spinner is spot on. Didn't take long.

[rvbuilder2002]

Originally Posted by edneff

I checked the offset at the center of the spinner as described in above posts. My prop has a front bulkhead, and the rear bulkhead *looks* ok, although I did not check it with a dial indicator as suggested.

The offset was extremely slight, between 1/32 and 1/16 of an inch...

I have decided to let sleeping dogs lie for now, and perhaps do a dynamic balance at the next condition inspection.

There is no noticeable vibration, and in fact many folks have commented on how smooth the whole setup is.

thanks for all the helpful suggestions.

Ed

If the Dynavibe resolved to an IPS value of .19, I guarantee there is a high enough vibration that would be beneficial to resolve whether you think you feel it or not, but I agree that the amount the spinner is out of track is not worth bothering to correct.

[Walt]

Originally Posted by edneff

There is no noticeable vibration, and in fact many folks have commented on how smooth the whole setup is.

I can't tell you how many times I've heard the above statement, the comment I usually hear after balance is "wow I can't believe the improvement".