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Prop Question

Old 08-18-2011, 12:13 PM
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MetallicaJunkie
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Default Prop Question

What is the standard prop hole size for lets say 22 inches on up(xoar, menz, etc..) is it 10,11, or 12mm? i need to order a reamer and want to make sure i get the right one
Old 08-18-2011, 12:16 PM
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Tired Old Man
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Default RE: Prop Question

10mm.
Old 08-18-2011, 12:23 PM
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MetallicaJunkie
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Default RE: Prop Question

thanks!!
Old 08-18-2011, 03:45 PM
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vertical grimmace
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Default RE: Prop Question

The best ream to buy is a long tapered one from the hardware store. Not only is it a valuable tool in the shop, you will always have exactly the size you need. So long as you are careful not to go to far. I even mount mine in a drill press occasionally. I have never liked the specific sized reams. They can be tricky to center.
Old 08-18-2011, 04:10 PM
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MetallicaJunkie
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Default RE: Prop Question

i went today and all they had were stepped drills, with too many increments to use for a prop
Old 10-29-2011, 01:20 AM
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Default RE: Prop Question

This looks like a newer post so looking for help. I have a G38 that I do not know the history. It came on a Dynaflite PT19. Awesome flyer, fun. But the engine is driving me crazy. It is fickle to start. Does not always start, when it does, runs great. Two main issues:

1) Flying along, all is well and it will start sputtering, running rough then cold turkey quit. Get it on ground and sometimes will start again, sometimes not.

2) Just won't start at times.

I had carb rebuilt, spark looks good, changed fuel, plug.

It honestly acts like when I once had a prop strike and sheared the key on the shaft, making timing all wacky of course. Tries to start, pops, but just is not consistent. It almost seems like the timing goes in and out. Anybody think this is at all possible? I also replaced all fuel tube, but maybe need to revisit the tank.
Old 10-29-2011, 04:40 AM
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Default RE: Prop Question

Good props (Menz, Mejzlik, Biela) don't need a 10mm reamer. The center hole is properly sized by the manufacturers. All you need is a drill jig for the prop bolt holes.
Old 10-29-2011, 05:19 AM
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Default RE: Prop Question

I have the standard 10mm-12mm reamer made for RC applications and used it once. What I found is that the angle of the reamer to the prop hub may not be at 90 degree, at least at the beginning. I did not like the way the prop has a slight large hole at one side.

Maybe operating the reamer on a drill press is a better procedure?
Old 10-29-2011, 07:17 AM
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Default RE: Prop Question

The G-38 issues sounds like fuel delivery. Go back through the plumbing. It's possible to have a weak sensor fade with heat accumulation but there is no definition establishing magneto or electronic ignition. Timing is fixed with either one. If it's right at the start of a flight it will be right at the end of a flight, unless external scrws are visibly loose. So fuel delivery is the likely cause. Although the carb has been rebuilt it could have had something overlooked so include it in the fuel system checks.
Old 10-30-2011, 08:18 AM
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ec121
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Default RE: Prop Question

Don't use a reamer. Go to Harbor Freight and get one of their 115 piece drill sets. They are of reasonable quality,not expensive, and have all of the letter, number, and fractional drill sizes you will ever need on a model airplane. There will be a metric equivalent somewhere in all those drill bits.
Old 10-30-2011, 09:12 AM
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Default RE: Prop Question

Well, that is exactly I did for my other props. Drill with a 10mm standard drill bit on a press. The only drawback is that the bit will not center on the existing hole unless the prop is allowed to move a little bit at the very early stage. It becomes dangerous as the prop is hold by hand and the drilling could complete the entire length of the hub in a fraction of a second. The prop is basically pulled up instantly and can cut the fingers.

With a reamer, the centering is guaranteed and you just need to push the press handler down very slowly. The prop can be secured on a drill jug.
Old 10-30-2011, 07:06 PM
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ec121
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Default RE: Prop Question

Don't know about all that. I clamp my props in a drill vise and let the prop rest against the upright on my drill press. Never had one break through the steel upright, and the vise is too heavy to let the drill lift it before it breaks through.
Old 10-31-2011, 01:11 AM
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Default RE: Prop Question

I've rarely found a need to ream out the center hole on Vess, Xoar, etc.

I just clamp my PSP prop drilling guide on from one side to drill the prop mounting holes, then
re-position to the other side and tighten the PSP down again, which makes any tight center holes just right.
(The center guide on the PSP will relieve the props center hole somewhat)

Better snug than loose.

As for props pulling up while drilling, that happens when feeding the drill bit in far too fast.

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