CNC vs octura?

[mtbenjamin77]

the 3/16 version is 139. I don't mind paying for a good product especially when it comes to props. But untested it's too much risk. I'll stick to sharpening and balancing my own octuras Only problem is octura does not make a prop this size in L&R

[Megabiker98]

the 3/16 version is 139. I don't mind paying for a good product especially when it comes to props. But untested it's too much risk. I'll stick to sharpening and balancing my own octuras Only problem is octura does not make a prop this size in L&R

ya I Definently agree with that first quote!!! Is this gonna go on the twin blackjack? Is this last product till its running?

[mtbenjamin77]

ya I Definently agree with that first quote!!! Is this gonna go on the twin blackjack? Is this last product till its running?

I'm looing for options for the blackjack. Really I just like to have plenty of props so I don't mind trying something new out. I might pull the trigger and be the first to test the VXP's out. I've been eyeing these props for a while now, but really at that price I could just give Andy a call and have him make me up something I know will work perfect.

[Megabiker98]

Shweet!!! Can't wait to see that baby up and running!

[twissted]

I just picked these up http://www.ebay.com/itm/170915404399...84.m1439.l2649
They will go to my 42" zonda cat.
I have used and worked with both I have a sets of stainless and they are the most work. With cnc I sharpen the edge and balance. That I can say is a very fast prosses.

[mtbenjamin77]

I like the fact that they're balanced,

Have you ever put a CNC prop on a balancer? They don't balance. They're just so light it doesn't matter. There's no possible way to manufacture a balanced prop without further work. During the manufacturing process for large impellers for very large jet boats they CNC cut the impeller then have to put the impeller on a computer balancer that tells them where and how much weight to remove. There's just no substitution for balancing. watch this vid they use a computer balancing device but then remove the material by hand. These engines turn much more RPMS than our boats do

http://www.youtube.com/watch?v=Zt1L4XXfOB0&noredirect=1

[twissted]

you need a new balancer. I checked mine and it worked just fine.

[mtbenjamin77]

you need a new balancer. I checked mine and it worked just fine.

Ha. I have many different balancers. Yours is not accurate enough because your trying to balance a prop that's is too light. There's no way around it THEY DO NOT BALANCE.

[Clueless1]

Hi all,

i just bought 2 of the OSE 52mm and 59mm props and am looking forward to testing. i didn't see anywhere about detongueing CNC props on the thread and was curios as to why? All i know is to detongue props for FE. Is it not necessary?

[electric]

I detongued a 3 blade CNC prop not along ago and used it on a Q hydro in a race and it worked great! Detongue prop will increase speed of prop and lower amp draw. What's not to like. I wish the maker of these CNC props would just make a "M" version of the prop that was already detongued for you. Really easy to detongue them, just did it with my belt sander and then filed down a sharp leading edge. Todd, just realized it was you, you aren't trying to copy my Q hydro prop are you??!?! chuckle. Interested in running this weekend?

[Clueless1]

LoL...exactly what I'm doing! This weekend works for me.

[fox88gt]

After reading this thread the other night, I decided to weigh my propellers just to see how much weight difference there is. I used my cheapy kitchen/hobby scale for these that only reads to 1 gram increments.

OSE CNC 43x60 = 2 grams
Octura X642 = 7 grams
Grim 42 x 55 = 11 grams

[jonjon00]

cool.. now go read the thread about the guy who thought he ran over a weed and bent his prop...

[Peter A]

I was just thinking about bent ali props and how hard they are to straighten without breaking. This lead me to remember something I learnt as an apprentice (over 20 years ago!). In order to bend aluminium plate to 90* without it cracking it needed to be heated, the way to get the right temperature (to much heat and it melts!), you 'soot' the surface with a sooty acetylene flame and then heat gently the area to be bent until the soot dissappears, bend while warm. I've used this method a number of times to do this, one of the 'tricks of the trade'. Now this may be a way to straighten bent cnc props. To soot it I would suggest using a candle, and then a small butane torch to heat. I don't have one to try but someone may want to give it a go and let us know.

[NativePaul]

I was asked by another member of the GB team to if I thought it was worth sharpening a Tenshock CNC prop, I was quite surprised at how bad it was considering the reputation that they have here.

On the plus side it was perfectly in balance and very sharp compared to a stock cast prop, but not knife sharp like a worked prop should be, so I immediately told him that it could use some work, on further inspection I noticed that it was "sharpened" in a very noobish manner with the blade having constant thickness for about 3/4 of the blade length, then bevelled off sharply from there (why it is like this is beyond me as its a curved surface anyway so it would not require more passes to have a nicely tapered blade thickness), while on the subject of mill passes it was obviously made with minimal cutter passes in mind, you could see and feel the groves from the fairly widely spaced passes clearly on both sides of the blades, and to avoid changing tools to a very small ball cutter the area where the leading edge meets the hub was left totally blunt.

While I was attacking it with my big file I was immediately impressed with the hardness of the material I would guess it is 7075T6 definitely up there with the hardest alloys I have had the displeasure to file, it felt just as hard as Octura BeCu props and a complete contrast to the Octura alloy props that seem to melt away under my big file.

Although it was usable out of the box in the way a cast prop isn't in order to get it right I ended up doing as much work to it as I would an Octura, the thinning was the same, I was just removing more material from the hub-blade intersection instead of the tips, the blade face needed a fair bit more sanding work than an Octura. On the other hand when I cut myself with it, it didn't hurt nearly as much.

Due to the combination of forged material and the CNC process making the blades exactly the same shape it needed no balancing straight from the packet, but once you start working on it, it IS very possible to put one badly out of balance, even if you are just tickling the edges to get the bevel knife sharp, if your balancer will not detect the imbalance then you need a new balancer or to polish the magnets and shaft tips on the one you have and set it up so it has a minimal gap between the free shaft tip and magnet.

It was worth doing the work, I was told it was faster, had more runtime and less torque roll.

[driftah]

are any big name racers or saw guys running cnc props? curious...

[NativePaul]

Yes, I would say the majority of surface drive racers at the world championships were on CNC props of one sort or another. I would doubt many serious SAWs guys run them, though you can heat treat alloy up to BeCu hardness, heat treated BeCu is going to be a step up again letting you put more power into the prop, maybe the smaller classes like M2 etc. Most SAWs guys here use them but we are not serious about SAWs, it is more about seeing how fast our race boats are going, than building boats to go fast in a straight line.