Meausuring pitch

[Brian Blazer]

I think it is about time for me to learn how to measure pitch using a pitch guage (I have a hughey). I usually just bend, but now I want to get a better idea what the boats like so I can match it.

Can someone post step by step directions on how to measure a prop with pictures preferably.

thanks so much!!!

Brian

 

[nitrotoys]

I Tooo have a hughey gauge and dont know really how to use it.

I would like to know more about pitching props, Like WHERE TO do a Pitch adjustment, I do the tips some, I have seen people repitch in the middle of the blade.

Any input would be great.

Tom

 

[Terry Keeley]

I used the Hughey gauge for years with a lot of success, mine didn't come with instructions either!

The first thing you have to do is measure the depth of the little step gauges and mark them.

You should figure a station (position) on the prop you want to measure at and probably stick with that number for all your props. I use 75% or 3/4 out on the blade from the centre of the hub. Now you have to position the little pointer that touches the blade to that position, so....

Measure the diameter of the prop with a set of verniers (I use mm), divide it in half and multiply by 0.75. Measure the diameter of the prop shaft on the unit (3/16 I believe) and the pointer, add the two and divide in half. Now add those two numbers and that will give you a mesurement for the outside of the two shafts. Set your verniers to that number and move the pointer until the two just fit your vernier mesurement.

Now to measure the pitch (at 75%). Put the prop on the shaft and tighten the nut. Position the pointer as close to the TE of the prop as possible, move the prop to position the degree pointer at zero. I first measure the average pitch from TE to LE so move the pointer along the prop to the LE and using the step gauges put the biggest one you can in the space between the base and the bottom of the prop. Let the prop rest on this gauge and note the number of degrees the prop has moved to go this distance.

You should have charts that give inches of pitch for each step gauge and certain degrees. If you don't have the chart it's not too hard to calculate it.

As mentioned I first measure the average pitch LE to TE then I measure cup as the last 15 degrees of the blade (I use an ART gauge that sets the degrees and measures the distance with a dial gauge). You could use one of your smaller step gauges to mesure the last little part of the blade where you can have some big pitch.

You've definately got the right idea working with a pitch gauge, many props are nowhere near what they're supposed to be and often the blades are not equal.

You can make all the horsepower in the world but if you can't get it to the track you'll smoke the tires every time...

 

[Wally Marsh]

Brian,

Terry's notes above are right on the money. You can also get a wealth of information regarding this (and much more) at rcboat.com, look up Past Tech Notes and there will be a very helpful article written by Marty Davis on prop pitch measurement and how to make various modifications for tuning your props. The best way to learn is experiment and see what happens, then document what you've learned, good or bad.

Wally Marsh

 

[Brian Blazer]

Thanks Terry, that is exactly what I am after.

Brian

 

[gil sonsino]

For years I 've used hughey gauge but once bought Grimracer's one I must confess that now I'm saving lot of time with much more accurate mods to my props.

Terry is in the ball park but think to try this new one!

Gill

p.s Hi Marsh has been long since I've received your last mail Keep in touch!Regards

 

[Terry Keeley]

Hey Gil:

Meant to reply to your post about your records, nice job. How fast was your best pass in mph? What props are you using?

 

[gil sonsino]

Hi Terry

Best pass up to 112mph turning 2170 cup 7.1 and 7.4.Next weekend will try other props and will post the results.

Thanks

 

[Terry Keeley]

Hi TerryBest pass up to 112mph turning 2170 cup 7.1 and 7.4.Next weekend will try other props and will post the results.

Thanks

Kewl!

 

[nitrotoys]

Was that a Moded 2170?

Cut down in size? tips rounded?

Tom

 

[gil sonsino]

correct!

 

[nitrotoys]

LOL Thanks Gil, Dont want you to give out your prop secrets or anything.

My rigger likes the mod 2170 as well.

But all around good prop is the 967/3 blade. pitched up and spooned tips, with some lift taken out of it.

Tom

 

[gil sonsino]

Hi Tom

Sorry I'm not secretive at all. My 2170's are diam at 67 -68mm and barrcut plus backcut. Our best performance even trying the V967/3 is with two blade prop.

Regards

Gill