Prop Tech 101/ a group effort.....

[Slideblues]

OK, I will start off with this from Paul G.

Basic terms, Explained,

OK, somebody else chime in and lets all learn something from this, Newbe's and Pro's

Basic and advanced mods, balancing, polishing, etc.....

Gene ;D

 

[MikeP]

Lets start out with some easy stuff.

I would like to reduce the diameter of a 1667. The way I understand it is I measure the widest point take equal amounts off of each blade as well as the same amount along the leading edge. Is this correct?

-MikeP

 

[Ian Inverarity]

Mike,

It depends. On my gas boats I would reduce the diameter of my X470/3 blade props by scribing a line on the blade at the diameter I wanted and trimming it to that. This allowed it to rev a bit more but otherwise didn't change the way the prop worked.

But making the whole blade smaller is an approach that seems to work well on hydro props from what I have seen.

Ian.

 

[topfuel443]

OK, Gene , and others I have always thought the "X" prop was a lifting prop, but not acording to the passage, can someone elaborate ?

~ James

 

[shoboat]

James,

The Octura X-series props have always been a no-lift prop.

The 1400 series props are the lifting props and also the

1600,1700,1800,1900,20 and 21 series propellers.The 18

to the 21 are really more for SAW boats.

Boaters,

Some of the problem you have with doing prop work is the

equipment that you use.It takes some really trick 3M Scotch-

Brite wheels to do some nice metal removal.I have found this

out after a lot of searching for the right tools.Once you have the

right wheels,buffing wheels,jewelers rouge,etc. then it is not

that difficult.

As far as cupping,pitching,spooning,etc. you need the right

pitch gauge to do this.I have been in boating for over 15 years

and I can tell you there is nothing like the pitch gauge that

Grimracer sells at Power Surge Racing Products.I know $206.00

is a lot of money but that is THE pitch gauge that most of the

prop wizards are using.I have just bought one recently

and it has made pitching props crystal clear.

For Now,

Mark Sholund

PROPS-2-U

 

[Ron Olson]

OK, I've pretty much have gotten the Octura and Prather props figured out for what I need. Now, what about the others such as ABC and Prop Shop? How can I figure out which ones I would need?

Polishing. I have a buffing wheel on my bench grinder and have tried a few different rouges and have gotten good but not great results. What rouges can I use for the best shine and where can I get them?

 

[shoboat]

Ron,

For ABC props all you need to know is the MM of the props

that you are using and pick the right dimension.Octura,and

Prather are also measured in MM you just need a good prop

chart Ron.The best Rouge is the ones that a jewelry store

uses,they will tell you if you ask them.Our prop tools are

very much like what the jewelers use everyday.

Thanks,

Mark

 

[topfuel443]

Hey Ron I used to do alot of metal polishing in the customizing business. The rouge I would recommend are as follows

for taking material off (works great for thinning blades) ~ Black

for secondary polish use the brown (slightly rougher, prepares metal for final polish)

for the final polish use the white rouge ( this is the jewelers rouge)

the white is to fine to do it start to finish, using the others as mentioned will speed the process greatly.

I get my polishing supplies from " Tarheel Parts" in north carolina. you can call them and get them to ship what ever you need. the staff is VERY knowledgeable and helpful. just tell them what metal type you are trying to polish and they will set you up with the correct supplies without selling you something you dont need.

sorry dont have the number but they should be easy to find (internet, 411)

Hope this helps ;D ~ James

oops.... just found there website www.tarheelparts.com

you will need part # 1010, 1020, and 1030 for what I mentioned

 

[Slideblues]

Diagram for blade shaping:

From Marty's Listbot, full series at

http://www.rcboat.com/prop.htm

Gene ;D

 

[Slideblues]

And one of my fav's Texas Cut:

This one works great with like with a prop the next size larger than you would normally use, reduce the dia. by rounding off the tips, texas cut, and recup.

Gene ;D

One thing else I might throw in here is out of the bag work, like on casting flaws, grainy texture, etc.

I rate the manufactures as follows,

1) ABC: These are real close right outta the bag on texture and balance, exception on the larger H series, 48-50, but I think Jim retooled the mold's to fix this now.

2) Prather: Few flaws next to hub and overall good texture.

3) Octura: Last bunch I got required a lot of cleanup on casting flaws, and generally rough on texture, requires a little more work to get smooth than other's.

Again just my opnion, exception's in all cases I am sure.

 

[Atious]

Odd question perhaps, What about using glass props to determine final prop size. I ask because I picked up a box of props on ebay last year as it contained a couple BC props I wanted. I have what must amount to several manufacturers complete line of sizes in glass. Are the performance characteristics too differant? I'd think I could save some money with trail and error and whatever glass prop worked best, I could then get it in BC or SS. To take that a step further, being glass these props can be shaped. Could a modified glass prop acurately reflect the benifits if applied to a BC or SS prop?

BTW, I know I couldnt change the pitch or cup on the glass props, just the basic shape of the blade.

 

[Slideblues]

A example of polishing from Don Betz:

 

[Slideblues]

A example from Chris Hicks:

 

[Slideblues]

Barr Backcut on left from Paul G.

OK somebody else's turn, my keyboard just caught fire!!!

Ha,Ha,

Gene ;D

 

[_laxmasta2039]

Gene,

thanks for the pics/explanations- it's starting to be hammered into my skull....

i've got a Prather 215 on a modified 3.5cc KB outboard that has been balanced/sharpened by TunnelBill- are there any general modifications that should be done to this prop combined with this engine to increase performance?

Joe

 

[Slideblues]

Joe,

Bill's work is first rate all the way, the 215 is the prop that I run all my base lines with first when I start mods. My advice is to get with Grim for one of his mod 1440's they kick major boot- tae!!!! with a mod K@B.

Gene ;D

 

[Ian Inverarity]

I once asked about prop finish on the rcboat.com listbot many years ago. Apparently Andy Brown recommends finishing props with about 400 grit sandpaper. Since for props, he da man, I haven't polished a prop since. 8)

Gene,

I would rate the out of the packet finish of the Prop Shop's even higher than ABC.

Ian.

 

[Ian Inverarity]

This is probably the best bit of technical info I have seen on props and understanding the flow around them. From rcboat.com:

http://rcboat.com/527_3.pdf

It is a pity that Brian Callahan doesn't write much on the listbot anymore, he had some interesting things to say....

Nitrocrazed racing: How about a prop dyno.....

 

[_laxmasta2039]

thanks Gene,

i'll talk to Grim about a 1440 when i've got enough spare $$ or i hit a turtle, log, etc. and break the P215 [which ever comes first!]

Joe

 

[Slideblues]

Ian,

I have never tried the Prop Shop brand, I have heard very good comment's about them.

Paul G. and myself had a great post on the old forum about blade surface and polishing vs. satin and polishing front side only and satin back side. We both did testing on the different combos and the results were only a few tenth's more MPH in the very top end of the speed range. Kinda a SAW gets polished and Oval got satin if I remember right. And your right Andy does em satin so the jury was still out last time I checked.

Gene ;D

Here is the link to Paul G's site, lotsa good stuff there!!!!

Click the Stryker Cat ta enter,

http://rcprops.com

Somebody want to talk about balancer's and method's?