rt3232

My Feedback: (6)

Did a search and nothing much on eather prop's or spinners

So first how meany of the gasser guys that are using wood props of any brand are checking there balance and/or reblancing??

Secound how meany are checking the balance of there 3" or larger spinners and re balancing??

Reason for the Questions, I have found over the years some of all brands of props are well out of balance and need/have to be rebalanced, So hear the firet questionis just a curiosity thingy.

I have used big spinners befor but never payed much attention to them, but at the moment I have a 3.5 dia spinner that acts like it has an oz. of lead stuck in one side, (using a du-bro balancer) and I did not save the package so I don't have a clue on the brand.

So can you drill holes in the back plate? what is the procedure to balance one? also I found that just rotating the spinner on the back plate will change the heavy point, and how critical is the spinner balance/

Cheers Bob T

pe reivers

first, the spinner must run true.
secondly, the position of the prop on the spaiiner must not change the way the prop tracks.
finally, if the prop is well balanced, a slight spinner unbalance will be no big vibration source if spinner + backplate is balanced separately on a long spindle.

Campgems

Bob, are the prop relief cuts the same on both sides of the spinner. Other than this obvious cause of unbalance, the only other thing it could be is that the ID and ODof the spinner cone are not concentric.. The first is easy to fix, the second is all but impossible without making a special jig for a lathe to re-machine the spinner. It would be less expensive to turn it into a paper weight though as the cost of materials for the jig would be more than the cost of a new spinner.

Don

rt3232

My Feedback: (6)

Hi Pe/Don

The props are balanced so they will hold position 6/12, 3/9 etc. and at this point I am inclined to run the spinner as/is. I am still breaking in the engine on the bird. One of the things I have noticed is the whole engine seams to be viberating, A little back ground. Engine is mounted on 3/4 dia. oak dowel stand offs 17/8 long on to 1/2 ac ply plate, with full lenght bolts thru blind nuts, backed up with an a/c stop nut, and by hand you can see a slite flex in the ply see pic's The plate is mounted to the fuse (laminated) side panels the come thru the main 1/4ac ply fire wall, and everything is gusseted and pinned.

The suggestion to use the spinner as paper wieght just may be in the cards.

Will check every thing after I get a maiden if the weather ever cooperates

Cheers Bob T

pe reivers

Run the engine without the spinner first. Then with spinner, so you will know if it adds to the vibration that is natural to any internal combustion engine.
After that, you may want to index the prop/spinner combo (try different locations in relation to one another) and see if there is a position with least vibration.

rt3232

My Feedback: (6)

Pe

I hear ya load and clear, been there and done that , and that is why I have doubled checked the props and questioned the spinner as the vib's seam to be at a different throtle setting. But magnitude seams to be about the same, so will watch and check things for cracks or outher signs of change.

Thanks for the suggestions and help as they jog this old mans memory

Cheers Bob T

Campgems

Bob, is it an optical illusion, or is the upper standoff not parallel with the lower? From the photo, it looks like the firewall end is lower than the engine end.

Assuming you have one of the Wheel type DuBro balancers, you should be able to check the balance of the spinner. Use the flat side of the spoon into the cavity of spinner and the point of the taper into the center hole. That should give you good alignment for a balance check. The back plate could be checked in a like fashion.

Don

rt3232

My Feedback: (6)

Don

I think it is an optical illusion, becouse when I made the stand off's they measure 1.875 =/- .005 had them clamped in my machine vise and ran an old end mill across them on my drill press and the hole also drilled on the press, and another thing I am running the engine in my shop with out the wings on, so on next day off the bird goes together and will see what it look like.

As for the spinner you get what you pay for, it was about half the price of a Dave Brown and about 1/3 price of a true-turn. Picked this up a Toledo this year from a new Chinese vender, back plate looks ok but the spinner shell is what is off, and the balancer is a wheel type unit, So I think is is paper wieght time for this one.

Thanks again for you help

Cheers Bob T

Lowvoltage

OK. While the subject of balance is being discussed, I balanced a Zinger 22-10 prop for a G-62 with just the pilot hole in the prop. After I reamed it to 3/8" the balance was off by a bit. I know it was due to the prop reamer, but how do you keep the reamer in line with the center of the prop when you use the reamer by hand? It should have followed the pilot hole all the way through the prop. Perhaps Ishould have knocked the horizontal bar out of the reamer and used the reamer in my drill press. I know how hard it is to balance a big prop using a balancer that is made for smaller props ie. the Top Flight magnetic balancer won't even hold this prop, but it is great for spinners and backplates.

Joe

Campgems

Bob, maybe a salvage. If you can locate the light area, go in with some 80 grit and really sand down a section of the inside there. Then lay in a thin coat of epoxy and check the balance again before it fully hardens. If it is then heavy, scrape some out and check again, If it is still light dab on a little more epoxy. You don't have to worry about it slinging off as it is captured. You should be able t o salvage the cone. This assumes the ODruns true and the back plate is OK.

We have a guy in the club that builds scale. He has a complete machine shop, and he turns some very interesting spinners. Works of art, they are. I have a small shop also and I a amazed at what he can turn out. His last project was hydraulic shock absorbers on the landing gear of a Ryan he built. Not just scale looking but fully funcitional.

Don

Campgems

That is the solution. Make sure you support the prop on the driven face, IEthe back of the prop. Make a platform for your drill press that will support the center of the propand have a hole for the reamer to go through. Then tape a piece of wood on the column for the prop to catch on so the edge isn't damaged. Use the stepped reamers andmake just one pass to the right side. Turn the drill press off and loosen the chuck and pull it off the reamer. Then turning by hand remove the reamer from the prop. NEVER turn the reamer backward, it kills them.

Keeping the prop tight to the platform so it doesn't twist is the key to a good ream. Some guys like to drill the props, but the drill will drift and will not center on the pilot hole. The pilot end of the reamer keeps things straight. Last, use as slow a speed as possible on the drill press. Always ream from the front to the back of the prop. The back is what registers the prop, so reaming from the back looses the registration.

Don

Lowvoltage

Thanks Don. Lessons learned. I didn't want to take the time to set up the drill. Next time Iwill.

Joe

pe reivers

Bob,

If vibration shifts to different rpm, that is because the resonant rpm of the system changes, not necessarily because there is more or less vibration due to imbalance. It is only natural that resonant rpm changes if you make changes to the mass distribution, like adding a spinner. This is exactly what I think is going on after reading your post.

tony0707

HI
DO BALANCE all props-spinners and wheels as much as is possibleout of balance causes vibrationthat will damage radio equipment over time-put your hand on the side of the fuse with the engine runningi think you will be very surprised at the amount of vibrationwith the stuff all balanced
reducing vibration should increase airframe longevity" IF " you don't hit the ground
ENJOY BEST REGARDS TONY

rt3232

My Feedback: (6)

Don

May try the epoxy thing, but for now, I will just pick up another spinner brand that I have more confidence in.

And again Thanks for your suggestions,

Cheers Bob T

rt3232

My Feedback: (6)

Pe

I am in total agreement with you, and like I said just need some one to jog the old gray matter, and as I have told Don at this point I am just going to pick up another spinner. I will post the differance.

I do Thank you for your help

Cheers Bpb t

dinorc

Hi rt3232,
I always balance the prop first both horizontally and vertically, then I go to the "spinnah" : I mark both the backplate and the spinner and from that time on I always mount them that way (marks aligned).... before and after balancing; of course the spinner is already cut for the prop I intend to use and the backplate is drilled. When the whole "thingah" is installed, and if I used enough patience to really balance things the only vibrations left should be due to other reasons.
OK guys, start balancing again!
Dino

rt3232

My Feedback: (6)

Dinorc

Prop's are balanced to hold all positions 6/12, 3/9 and in between and as I said in a previous post for the spinner I have repalceced it an new one is spot on for me, and I do index my spinners, So now if mother nature will just ccoperate with my days off we will try to get some pic's and a maiden on the new bird

Cheers Bob T