how sharp is too sharp

After going through the forums I have learned that my props not being balanced has caused me $ in struts, flex shafts (thought I was "immune" from having to balance them, just like getting copd from smoking lol). So, I started balancing them during these last few weeks.

A couple of questions though:

1) how sharp is too sharp? right know I have them to where you can actually shave the hair off your forearm (like my hunting knives)

2) have a magnetic sharping tool, if I put the prop in one direction on the shaft (balanced blades always come up horizontal) then turn the prop on the balancing shaft (same location as before) its then out of balance. This is without doing working on the prop between switching the prop directions. Done this several times with different props.

Do I do my best to get the best compromise between the 2 directions the prop is on the shaft? or am I doing something wrong in my methodology?
I'm not stupid, but this has me baffled.

I've tried searching for anything about this, but have come up empty handed. Maybe just incorrect wording in the search engine (silly me)

Thanks for any insight,
John

Balancing is a difficult thing at first, because you have to learn where to remove material, based on on the prop settles on the mag pin. Sometimes it’s the backside rib, others it’s the blade area out towards the tip. Sometimes it’s at the tongue. It just takes time learning. You’ll waddle for a while in one area and feel it never changes much. That’s when you have to work other areas. Here’s a couple of tips:

1) If the prop blade fails vertical down, then it’s outside heavy, meaning the outside blade area by the tip or the spine.
2) If the prop wants be be almost horizontal, it’s usually at the tongue or up by the hub.

Just two tips to start you off. I’m not sure a blade can be “too sharp”. But it can be too polished. I like to polish out the front side (wet 1000 grit), the side you don’t remove material from. I leave the backside polished with about a wet (oiled) 400 grit. I always use wet sanding practices to hold the toxic grit down and not float around. Good luck!

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Originally Posted by CraigP

Balancing is a difficult thing at first, because you have to learn where to remove material, based on on the prop settles on the mag pin. Sometimes it’s the backside rib, others it’s the blade area out towards the tip. Sometimes it’s at the tongue. It just takes time learning. You’ll waddle for a while in one area and feel it never changes much. That’s when you have to work other areas. Here’s a couple of tips:

1) If the prop blade fails vertical down, then it’s outside heavy, meaning the outside blade area by the tip or the spine.
2) If the prop wants be be almost horizontal, it’s usually at the tongue or up by the hub.

Just two tips to start you off. I’m not sure a blade can be “too sharp”. But it can be too polished. I like to polish out the front side (wet 1000 grit), the side you don’t remove material from. I leave the backside polished with about a wet (oiled) 400 grit. I always use wet sanding practices to hold the toxic grit down and not float around. Good luck!

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You don’t remove material from the front side of the prop? As in the side that faces the front of the boat?



I don’t waste a bunch of time trying to get the balance perfect on props. I’m in the camp that believes with all the water hitting the prop that it dampens vibrations. Out in air with nothing touching it balance is extremely important. I could see you having some issues if your driving the boat in a lot of chip, the prop coming out the water a lot and spinning high rpms...but that’s usually not the case because going fast in chop usually ends up flipping the boat.

Let me put it to you this way. I’ve ran many many props. I’ve sold many props. And they were not meticulously balanced, but they were close. And I never had an issue nor has anyone I sold a prop to had an issue. I will point out that when I sell a prop its much closer to perfect than my personal props are, ONLY because my customer may check it and think that it’s not ok to run. If I sell one of my personal props I always resharpen and rebalance it. If your having driveline issues, unless your not balancing the prop at all, you’ve got other problems.


Now to answer your question. Yes, your prop can be too sharp. Let me elaborate. If you make the cutting de too thin and sharp it will fold over on you and/or you will dull it very quickly. I do like my props sharp but don’t over do it.

I’ve always considered the pushing face of the prop as the front side. Not the way it is mounted on the boat.

KFX, you’re confusing sharpness as thin. You don’t need to thin the blade to sharpen it. It’s like knives, some people make the knife too thin, thinking it is very sharp. But the best and strongest knives have an angle in to the knife edge, and it’s that angle in that you work to maintain the sharpness. The most efficient angle in has been found to be 12 degrees per side, or 24 degrees inclusive. But with a prop, you want a zero degree on the front side and about 18-20 on the back side.

To the OP, this is one of those artsy-fartsy questions. You’re going to get about a million opinions on this. I recommend you go to the Internet, there’s some good reference documents to get you going on the right foot.

I'm one of the guys who thins the prop gradually over the width of the blade. not everything i do is perfectly balanced, but i get it pretty close and its good imo, as long as I've spent some time giving it that nice gradual sharp edge

John balancing props is a time consuming process and very important to the performance of our boats.If you re not familiar to it there are people here like dasboat that can help you with this task but obviusly you can get some tries to it.Gill

An unbalanced prop will burn up a strut bearing or sleeve. Couple runs no but a dozen 1 mile heats full of throttle stress into and out of turns will bake the bushings.

Thanks to all for the response's helping me out on this. Just I did watch a lot of videos posted on utube. Just did find what I was looking for.

Craigp: never thought of the tips you gave. Yea, I only wet sand. May start with files to start if way out of balance though.
T.S.: I ran the boats just about every weekend available without balancing (about once a month) I had to replace crap.

Thanks again yu'all,
John

Hey John, I too use files to bring the blade into it’s final shape/weight/balance. I use 3in1 oil on the files to keep the filings contained and not free to go anywhere. I balance my blades pretty close, they are spinning incredibly fast, so for me, that’s just common sense. I maintain about a 12 degree angle from the edge to the meat of the blade on the backside. This gives me a honing edge to true up the edge every once in a while. So the edge from the side looks like a single angle edge. I use the files to do all that... The sandpaper is just for final finish.. I too learned much off the Internet! I messed up my first prop, a Grimm Racer blade, by putting an edge angle on the front and back faces, or more like a knife. That blade cavitated so bad it wouldn’t even push the hydro up on plane! Since it was bad anyway, I tried a fix by removing material on the front edge, effectively thinning the blade. It ran much better, but was still cavitating coming out of a turn. So leave that front face alone! Have fun!

Hello Craig,
I'm with ya on only sharpening from the "backside" and the wet/dry paper 600grit and 1000rit (wet though) is for the finishing/polishing. Have a bunch of different riffle files that I use (with cutting oil)
Have a bunch of "plastic" props, should they be done? don't think it can happen. Unless you sharpen it like a knife, so you don't get residual plastic hanging on and not just rolling over. If you understand what I stating.

Thanks,
John

PS: plan on heading to the FE internationals in Leonard, MI and watch and learn.

I’ve tried using 1500-2000 on plastic props, to mixed results. You have to move the paper really slow, or heat is generated and causes those “fuzzies” on the edge. I just got one tiny Revolt with plastic... A file on plastic was a train wreck!

I have a set of small hobby files from Lowe’s, they work great! BTW, working props into finish condition is a real PIA, and I don’t really like doing it. So I got my favs, and just keep them in good order. My hands ache after working a prop! A grinder would go so much faster, but I don’t want that toxic dust first in the air, then resting on surfaces.

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Originally Posted by CraigP

I’ve tried using 1500-2000 on plastic props, to mixed results. You have to move the paper really slow, or heat is generated and causes those “fuzzies” on the edge. I just got one tiny Revolt with plastic... A file on plastic was a train wreck!

I have a set of small hobby files from Lowe’s, they work great! BTW, working props into finish condition is a real PIA, and I don’t really like doing it. So I got my favs, and just keep them in good order. My hands ache after working a prop! A grinder would go so much faster, but I don’t want that toxic dust first in the air, then resting on surfaces.

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you can always sent them to me Craig !!! or anyone !!

Members may find this useful. Words have meaning.

https://www.miwheel.com/resources/terms/


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Ok guys first hand experience here, listen up,
Just got out of the hospital (12 days, 6 in ICU) for guess what? beryllium copper poisoning. Stupid me: got a little itty bitty belt sander just to work on the props, decided to try and see if it would work, started the sander up and touched the prop to it a couple of times. Couldn't have touched the prop more than 10 maybe 15 seconds total in different positions. Next day was calling 911 because I couldn't breath. On oxygen 24 hrs a day, 9 different meds, going to take 10 t0 12 weeks before wheezing starts to go away.

Here's a few items about that stuff:

You can build up a tolerance (but depends on your body) but not worth trying that one,
You never, never get rid of it and will get worse over time, doctors can only help you to be able to breath (steroids, oxygen, inhalers, meds),
It has been reported that it does cause cancer,
If your like me: working on the props you eventually will get a few cuts in your fingers. Well ya know what? even if you wet/oil sand and not cover up you little cuts it will get into your blood stream and end up in your lungs. So be careful about those little cuts.

Still plan on being a spectator at the FE nationals though

John

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Originally Posted by Johnc

Ok guys first hand experience here, listen up,
Just got out of the hospital (12 days, 6 in ICU) for guess what? beryllium copper poisoning. Stupid me: got a little itty bitty belt sander just to work on the props, decided to try and see if it would work, started the sander up and touched the prop to it a couple of times. Couldn't have touched the prop more than 10 maybe 15 seconds total in different positions. Next day was calling 911 because I couldn't breath. On oxygen 24 hrs a day, 9 different meds, going to take 10 t0 12 weeks before wheezing starts to go away.

Here's a few items about that stuff:

You can build up a tolerance (but depends on your body) but not worth trying that one,
You never, never get rid of it and will get worse over time, doctors can only help you to be able to breath (steroids, oxygen, inhalers, meds),
It has been reported that it does cause cancer,
If your like me: working on the props you eventually will get a few cuts in your fingers. Well ya know what? even if you wet/oil sand and not cover up you little cuts it will get into your blood stream and end up in your lungs. So be careful about those little cuts.

Still plan on being a spectator at the FE nationals though

John

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Sorry to hear that John. But, I'm sure I'm not the only one that is glad you are okay. I've always used a mask when I work on my props but I didn't know that getting cut is the same thing. . .still gets in your system. I've been cut so many times because I really like very sharp blades. Now, with the information you have provided, I'll start wearing gloves from now on. Thank you for the info and glad you're ok.

That’s horrible to hear. Were you working on octura props? I talked to Jim Schaefer the owner of abc and he said his props don’t contain enough beryllium to be toxic but octura does. I always wear a mask and try and keep things wet. 99% of the props I do are abc.

Screw octura - do they really need that toxic crap in their props? ABC is fine without it, why can't octura do the same?

It's amazing how people don't seem to take this seriously. Imagine how many naive beginners are messing up themselves ... and not knowing any better.

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Originally Posted by dmitry100

Screw octura - do they really need that toxic crap in their props? ABC is fine without it, why can't octura do the same?

It's amazing how people don't seem to take this seriously. Imagine how many naive beginners are messing up themselves ... and not knowing any better.

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I dunno but when I first starting doing octura props I wasn’t wearing a mask. I’m probably messed up too and not aware of it. I haven’t had any issues that I know of. I have been scanned several times and been operated on and numerous tests been run on me since then and nothing has showed up. Maybe I was just lucky. Knock on wood lol

Sorry to hear that John. Glad you are doing better. I think you should copy that post into a new thread and it should be made a sticky.

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Originally Posted by kfxguy

I dunno but when I first starting doing octura props I wasn’t wearing a mask. I’m probably messed up too and not aware of it. I haven’t had any issues that I know of. I have been scanned several times and been operated on and numerous tests been run on me since then and nothing has showed up. Maybe I was just lucky. Knock on wood lol

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Same here, when I first started doing my own props I never wore a mask and did my props DRY. . .no wet sanding or anything until I got educated and most of my props at that time were mostly Octura. OMG, I wonder if my shortness of breath and the inability to do any running or just something strenuous, even for a short moment, could be related to beryllium copper poisoning. I think I'm going to have to have some tests done.