I can thread my prop down the shaft of the engine, but it will not slide down the threaded shaft. Is this a good fit, or should the prop be reamed out a little?

I hope all of my future props fit as good as yours!!! I would leave it alone. You are assured a good tight fit with no 'play' . Scott

If you can get it on like that then you're fine. You don't need to do anything else to it. You should only ream it out when you can't get it on the shaft of the engine.

ken

Thanks, thought so, but just not sure.

You guys are the best

It may be hard to get it off after the engine runs for a while.

Yeh, maybe a pinch of vazoline on them threads might help. Scott

I agree with danny, I had a few like that and after you tighten the prop nut down it also squeezes the prop a bit and it can be a bit tough to get off later. Tough but not impossible.

I've spent some serious time getting props off my 25fx.

as long as you can get your prop.adjusted at roughly 9/3 oclock position when it is tight that is a good fit.and missleman is right when you thread them on the wooden props tend to mush down and are a bear to get off.

They should not be so tight that you have to thread them on. That puts stress on the hubs that they are not designed for.

I just used a 1/4" drill bit, seemed to work perfectly. I tried to slide the prop onto the shaft of the drill bit (opposite side of the blades) and it was a snug fit-it would slide on if you turned the prop, just like the fit that was on the engine shaft. I put the bladed side of the bit in the prop, and 'threaded' the prop onto the drill bit, and was able to slide the prop back off the drill with only a very slight turning of the bit. Now prop just slides over threads of shaft, and needs only a slight push to get the prop fully down to the end of the shaft. Should be a perfect fit

Also how tight do you make the prop? I have a 10mm socket on the end of a screwdriver handle, and made it 'snug', not cranking it, but making it tight...good enough?

Fatorangekat,
While it's possible to use a drill to open up the hole on a prop in a hand drill is possible, it's not recommend. The best way to open up the hole in the prop is to use a reamer to widen the hole. This is because it will keep the hole in the center of the prop and not throw the prop out of balance. If you must use a drill to open up the hole then you should use a drill press to do it with. this way you can secure the prop so that it doesn't pull off center when you start drilling out the hole.

For your second question. No, "snug" is not tight enough. If you just snug it down it's a pretty sure bet that the prop is going to get thrown when you try to start the engine. When you put the prop on you need to get it as tight as possible. I recommend using a box end wrench so that they wrench doesn't slip and round the nut. Then get a good leather glove for one hand to hold the prop with so that it doesn't cut you hand, or use a good rag and wrap around the prop. Then to tighten the nut down use the prop to help you tighten it. Grab the prop and the wrench with the hand in the glove (or rag) and pull them together to tighten the nut. This leverage will get the nut tight enough to keep the prop from being thrown. Don't worry about stripping out the nut or shaft as they are both made of steel and aren't going to strip. This is how I secure my props and I haven't thrown a prop from any plane in over 8 years.

Hope this helps

Ken

Thanks Ken, I'm glad I asked!

Yes, tighten it right down. I use a 10" adjustable wrench myself.
When you get a chance get a prop reamer, it will come in handy in the future.
This one in case you want to fly smaller than 40 size:
http://www3.towerhobbies.com/cgi-bin...&I=LXK248&P=ML
This metric one is what I use, most engines that have larger than 1/4" shafts are mostly metric.
http://www3.towerhobbies.com/cgi-bin...&I=LXEGH6&P=ML