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General control line discussion => Open Forum => Topic started by: Dick Pacini on April 01, 2013, 01:28:46 PM
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I ordered an assortment of props from a couple of suppliers. I bought two M/A Glass-filled nylon props in 11X5. They are so sharp, I could have carved the ham with them yesterday. The web-site advises cleaning flash off with a knife. These props are sharper than my knife! I think I will sand the edges a bit to increase safety during handling. :X
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I almost always use a heavy leather glove. The trick with a sharp trailing edge prop is either to hit it backwards, or flip it forward without hooking your finger over the trailing edge.
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I always "deburr" them with some 400 grit wet & dry, not enough to round the edge but to remove the fine sharp mold flash that is like a razor. I have heard people advise against it saying it will effect the efficiency of the prop but in reality I don't believe anyone could begin to tell the difference.
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I know all too well about sharp APC props...even when the girl who's plane it's on says its sharp and not to turn it over...
After learning that lesson, I am way more careful around those props. After getting a Brian Eather three blade ready to go, I turned the prop over and felt it was sharp, so I made sure to dull the trailing edge of the prop just to protect the fingers
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I know all too well about sharp APC props...even when the girl who's plane it's on says its sharp and not to turn it over...
I remember that story. Every young man wants to impress the girl. I'm sure she was impressed.
(don't feel bad, we've all done something along those lines -- the one I remember best involved my first bike with toe clips, a stop light, and a pretty girl passing by).
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I don't tempt fate with props when starting. I use an electric starter or a chicken stick. I am building an electric now, so even better.
James
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Yet another advantage to electric systems. No flipping.
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I use an old pocket knife to debur the edge. It knife dulls quickly, so I sharpen it after a few props. Scrape the flashing with the blade at 90 degrees to the prop. It is also a good way to balance them. Work on the heavy side a little more.
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I found out the hard way that APC and master airscrew props are very sharp. These days I take the edge off with a razor blade, cutting more off the heavy side to balance. Next to be even safer I paint a red tip on them.
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Yet another advantage to electric systems. No flipping.
Yes, I love my electric starter. ;D :##
I inspect and sand all of my non-wood props to some extent. Usually just enough to remove any molding or flash lines and clean them up, only takes a few minutes per prop. I always check the balance too, on all props. y1
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I ordered an assortment of props from a couple of suppliers. I bought two M/A Glass-filled nylon props in 11X5. They are so sharp, I could have carved the ham with them yesterday. The web-site advises cleaning flash off with a knife. These props are sharper than my knife! I think I will sand the edges a bit to increase safety during handling. :X
I scrape and sand the TE of the prop until it's reasonably safe. I have used so many APC 9-4 props over the years that I can judge when it's safe enough and get the whole thing done in about 10 seconds.
The 20FP starts well flipping forward so that's what I do, and I only very rarely cut my finger any more.
Brett
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"Rarely" is a pretty good record, but just once is reason enough to use a chicken-stick. F.C.
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I remember that story. Every young man wants to impress the girl. I'm sure she was impressed.
(don't feel bad, we've all done something along those lines -- the one I remember best involved my first bike with toe clips, a stop light, and a pretty girl passing by).
This is the response I got, "God you're stupid! I told you the prop was sharp!" LOL We then proceeded to patch up my finger with CA...
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Way to go to build brownie points with the new girl! I learned along time ago about sharp edges on props, even the old nylon blades we used to swear by. A few swipes with sandpaper and remember not to slide the finger along the blade.
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"Rarely" is a pretty good record, but just once is reason enough to use a chicken-stick. F.C.
Mostly it's because I can't remember the right procedure to back-bump the 20, so I just flip it forward. Its pretty amazing, that little guy will start on the first flip after sitting idle for years, pretty much every time.
Brett
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Its pretty amazing, that little guy will start on the first flip after sitting idle for years, pretty much every time.
Brett
I'll trade you two Fox .15's for it
Larry Buttafucco Stunt Team
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I always "deburr" them with some 400 grit wet & dry, not enough to round the edge but to remove the fine sharp mold flash that is like a razor. I have heard people advise against it saying it will effect the efficiency of the prop but in reality I don't believe anyone could begin to tell the difference.
Man O Man, just GREAT! Makes my day when I can find a modeler that I can AGREE with! #^
I even flip some .60-.75 and .90 machines, especially if recently warmed up. Hold blade and turn for the "BUMP", flip and off it generally starts fine. However no matter the prop, it gets a sanding on the back edge. I have never done one that has reduces ability to fly the machine, enough for me to tell.
Back in the late '70s to mid '80s when I did some pylon racing, Quarter Midget, Sport, Q-500, and Scale War Bird, I worked on props a lot especially for 1/4 midget and Q-500. Make a good one and the next one just like it would be horrible.
Guys if you are short on experience with props, I suggest you balance and get rid of those razor-like trailing edges. It ain't pretty when they have to cut off your ring to get to the flesh to sew it up while the doctor, a former RCer, asks why you stick your hand in the prop. HB~> Had it not been for that ring I would probably have lost two fingers, but the ring caused the APC to break at the hub, killing the 1.20 4 stroke. %^@
I or you could ask why I was so stupid, but I cannot find a good answer. Stuff happens. Ya''ll do be careful and do prepare for out thar' on the flight line.
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I spent 7 hours in the emergency room last night due to a run in with an APC Prop.
Mike
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Yep..........
Mr Griffin also learned that just because the prop is on an electric motor you still want to keep your fingers away from it. Thank God that he only hit the back of the prop and not the tip so he still has fingers on that hand!
Since these "spinning scaples" are turning somewhere in the 9-10000 rpm range we all have to remember that we have to keep our fingers, wrists, necks and arms away from them!
Eric Rule
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Mike, that is a bummer, just what you need added to your plate right now. Hope things improve better soon, you are due for a break. As far as prop injuries go, it has been said before but most major prop injuries are due to a moment of carelessness after the engine has started. An electric starter will not protect you from that. :(
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This was due to just not thinking and being careless after being around this for lots of years. It reminds you that no matter how long you have been around this, you can NEVER take it for granted. As Eric said, I was extremely lucky and the Doc in the ER said just a millimeter or two deeper and I would have been into the ligaments and tendons....Never let your guard down around these spinning razors..
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I spent 7 hours in the emergency room last night due to a run in with an APC Prop.
Mike
So sorry for you, Mr. Mike. I sincerely hope you have a quick recovery and all goes well for you.
It can happen so quickly. Hang in there.
NOW to make you SMILE:
Years ago we had a club member whose wife was a school teacher for 3rd (IIRC) graders. Once in the Spring she brought out her students for a couple hours and a Jetero hosted hot-dog lunch. We did airshow for the kids. I was behind the wing tweeking a needle valve. SWISH and a knuckle was scratched but was bleeding some. We took care of it, and I was flying again. No Big Deal! Next Day teacher asked what the children learned from the airplane flying.
ONE YOUNG FELLOW stated: "I learned "... THAT OLD MAN COULD BLEED A LOT!" LL~ LL~ LL~ LL~ LL~
Lets all hope no one else has to demonstrate "bleeding" any more .
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Hoss you made my day. I laughed until my belly hurt. Thanks for sharing that....and thanks for brightening my day.....
Mike
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after going from racing to stunt i had to remember that the prop was 12 in long not 6 in ,it was hard on finger tips for a while HB~>
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My faveorite "chicken stick" is an 8 inch piece of an old RUBBER garden hose. Better it take the beatings!
Ward-O y1
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The really bad injuries seem to come from reaching around or through the prop. The only thing I do from in front of the airplane is starting the engine, then everything else is done from behind the prop arc, like setting the needle, especially on the bigger displacement engines. As far as electrics, I would think they could be worse. It's possible to stall an IC engine, but an electric motor at full song and current draw must be relentless and would act like a blender! I shudder to think about it!
Type at you later,
Dan McEntee
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I always "deburr" them with some 400 grit wet & dry, not enough to round the edge but to remove the fine sharp mold flash that is like a razor. I have heard people advise against it saying it will effect the efficiency of the prop but in reality I don't believe anyone could begin to tell the difference.
Foam fingernail files are handy for this. Like mini sanding blocks they seem to last and are available in 400 grit.