prop cupping pliers

[suckmywake]

“Necessity if the mother of invention”

I made these prop cupping pliers. I am using a ¼ acorn nut as the cupper and some plastic as the foot. The acorn nut has a dia about 10mm or .4”. This seems to be right for props in 45mm + dia range. I put screw stop on so I can control how far it will squeeze the blade so all blades will be cupped the same. Prop in pic is a x450/3. I have not tried them yet but looks like it will work well. Anyone has any comment or suggestion let the fly.

[dana]

seems like a great idea to me. the only thing i would have done different is use vise grips instead. it would just make it a little easier on the hands, but i like it. the early guitar makers used hammers to hit frets into place, much like people using a hammer to cup props. nowadays they make presses and something called "jaws" that is basically a handheld press using vise grips. much more accurate than hammers. you're on the right track

[Fluid]

You may find the plastic too soft to get repeatable bends. Pros use steel tools for a reason, but OTOH yours may work fine.


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[monojeff]

Here is a picture of some that T-Mod Mike makes & sells over on JRCBD.
People have said good things about them.
He as been making them & using them for quit some time as far as I know.
contact email: t-modracing@comcast.net

[suckmywake]

I looked at vise grips but they have too much side play in jaws for any repeatable accurate cupping. With vise grips they are riveted together and I needed pliers that could be taken apart to mod. The plastic is pretty tuff stuff. It is the same matl. used in plastic cutting boards. I though of using oak wood and might give it a try instead of plastic. My first thought was just grinding out a cup on one of the jaw of pliers but I was trying to come up with something that would not scratch up or mar a polished prop. I think this tool will be at its best for just tweaking an already mod prop at the water edge between runs. I have seen that picture of those plieres and this is my take on his idea.

[suckmywake]

link to Jaws on you tube.

http://www.youtube.com/watch?v=Tm7kTtZ9inU

[wiskers]

I think you've come up with a great 'do-it-yourself' tool. I like it. I'm sure the plastic foot will work fine, (you're not mass producing custom props you're tweeking what you you have for yourself). You get thumbs up from me.:thumbup1:

[dana]

I looked at vise grips but they have too much side play in jaws for any repeatable accurate cupping. With vise grips they are riveted together and I needed pliers that could be taken apart to mod. The plastic is pretty tuff stuff. It is the same matl. used in plastic cutting boards. I though of using oak wood and might give it a try instead of plastic. My first thought was just grinding out a cup on one of the jaw of pliers but I was trying to come up with something that would not scratch up or mar a polished prop. I think this tool will be at its best for just tweaking an already mod prop at the water edge between runs. I have seen that picture of those plieres and this is my take on his idea.

i would stay away from oak wood, even though it is a very hardwood, it is in fact brittle at the same time,, and splits easy. if youre looking for a superstrong hardwood i would go with Ebony. have you tested your pliers yet?

[m4a1usr]

Those look pretty dang good Bob. If there is a stud or something similar to change out the upper accorn nut for the radius change those could serve many different prop sizes. The bottom plastic piece should be something different but there is no reason this couldnt be a piece of machined copper or aluminum. All it needs to be is a piece of dimpled softer metal. Something akin to the radius of the accorn nut. I like it! Great job.

John

[suckmywake]

I made some alterations to the pliers after I played with an old x642 prop in them. I change out the cupper for a larger dia. This larger cupper ball is 0.7” dia. I also make the indent in the foot a little larger. This was easy to do. I just heated up larger ball with heat gun and squeezed it into the plastic foot and then cut off the material that squeezed out.The smaller ball formed very aggressive cup. The plastic works great as a foot. I put some reference lines on to help locate prop blade in pliers. I figured I was going to mess up the first prop I try any way and had no use for this x642. I put many cup in this prop and hammered them back out again over and over until I got a technique down. The blade will kind of roll or squeeze out toward the tip as you cup it. So far the best results are to set the tip of the prop just passed the center of cupping ball. I set the screw stop so it is bottomed out with pliers closed with no prop in it. The cup is very smooth and consistent. It is not hard to reproduce an identical cup on the other blade. It does not take a lot of strength in hands to add a cup to a blade of a prop. I have an x645 that I don’t like. I will put this x645 on my cyber storm the next time I run.I will do a gps run with prop as is and bring the boat in and cup prop and do another gps run with same batts just a few minutes later. I will also watch and see if I notice if the boats running attitude has changed. The cupping ball is changable the plieres are drilled and taped for a 1/4-20 threads.

[suckmywake]

On the pliers foot I was thinking about laminating thin layer of oak with the gain at 90 deg. I do have some copper from large electrical fuses that is about ¼ thick that I might try to dimple. The plastic as the foot is working out very well so far.

[suckmywake]

I had a chance to test my cupping pliers today. I put a bs x645 on my boat and did a gps run (gps 56mph). I was taking off the prop to cup and noticed that the rear bearing in my strut was gone. I can’t explain it. This was a Jeff Wolht’s ceramic bearing strut with about 5 runs on it. We switched gears and put the uncupped x645 prop on Johnson’s new DF 35 Pirate with 1717 1580kv 6s. This was the second run ever on this boat. We ran 1 set of batteries thru Johnson’s boat before we ran mine. The ghs showed I think 45.1mph. We open up the boat to reset gps and I cupped prop. It takes me about 30sec for me to cup a prop. We taped back up boat and did another gps run with same batts. I think it went 46.3mph. I am not 100% pos I remembered these speed correct but know it was 1.2 mph faster and boat looked faster and run better. We then put fresh batts in and put on his x548 uncupped prop and did a couple gph passes brought boat in and cupped prop and did a couple more gps passes and it pick up over 5mph. Again boat appeared to be faster and ran better with prop be cupped. Both of these props are star or pointed ear props and nothing else was done to them or change boat set up in any way. We all no gps is not a 100% but both times you could tell boat was faster. I don’t think that batt temp went up because of discharging after first run because batts were heat slightly before first run and the air temp were in high 30 with snow on ground so if anything batt temp went down. Both of these test were in an over powered mono that had a motor that could easily spin the mod prop and was not over propped. I call this a success. Johnson has vid and I asked him to post it. The prop in pic is the x645. cupped.:beerchug:

[LarrysDrifter]

Sorry to hear of your bearing failure Bob. Very unfortunate.

[m4a1usr]

Right on Bob! You just got edmujucated on prop tweaking. Subtle things do have effects. About the bearing, well.........who knows. By mod'n a prop you should always go back and balance it. Maybe with the cupping the prop became off balanced and shattered the bearing? You cant bend each side perfectly, and match them. What I will say is a step forward in performance gets you further no matter how you effect it. Learn and stay focused.

John

[suckmywake]

The bearing went out on prop before anything was done to it. The prop was ballanced. I dont think the bearing going out had anything to do with prop. I have seen and got a few props from others who have said were ballanced. I would say their idea of ballanced and mine are two different things. I still bet the prop is ballanced but good point I will check.

[monojeff]

The bearing went out on prop before anything was done to it. The prop was ballanced. I dont think the bearing going out had anything to do with prop. I have seen and got a few props from others who have said were ballanced. I would say their idea of ballanced and mine are two different things. I still bet the prop is ballanced but good point I will check.

I hear that I just got a prop from someone the other day that said it was S/B and it did have some work on it but was not sharp & far from balanced! I am no expert but if I would have ran the prop as it is and took their word for it. :sinking-guy: