Prop Cupping

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Ken Gibson

Active Member
Joined
Jun 21, 2010
Messages
42
OK, I'll kick this one off. Though I've been in boating off and on for a number of years, I'm a real neophyte to the customization of props. Can you enlighten me?

  1. What is meant by "cupping"?
  2. Is the whole prop blade cupped?
  3. How is it measured?
  4. How is it accomplished?
  5. How do you assure equal cup on all blades?
  6. When is cupping indicated? ie: When would cuppng help? When would it not help?

Thanks for any help you can give. I'm sure I'll have more questions. :huh:

Ken
 
Ken Gibson said:
OK, I'll kick this one off. Though I've been in boating off and on for a number of years, I'm a real neophyte to the customization of props. Can you enlighten me?

  1. What is meant by "cupping"?
  2. Is the whole prop blade cupped?
  3. How is it measured?
  4. How is it accomplished?
  5. How do you assure equal cup on all blades?
  6. When is cupping indicated? ie: When would cuppng help? When would it not help?

Thanks for any help you can give. I'm sure I'll have more questions. :huh:

Ken
Click to expand...
Hi Ken...

check this attachment and let's get this discussion rolling :)
 
Lennard Cuenco said:
[

Hi Ken...

check this attachment and let's get this discussion rolling :)
Click to expand...
Lennard,

Thanks for that article. Even though it relates to full-size (real :D ) boats, it certainly answered a few of my questions. I wish they had been more specific about how to form a proper cup. "Heat and Beat", indeed.

Do you do your own prop work? How do you get a cup on your props?

Thanks,

Ken
 
Last edited by a moderator:
Ken,

You just need a pair of propeller pitch pliers and bend at .7 radi on the

trailing edge. You should buy a Steve Wood pitch gauge so you can measure

it accurately though. Call me if you need more help. Missing? yeah plenty

of differences when you cup wrong or too much. Just remember cupping reduces

lift and also kills RPM from your engine set up.

Hope This Helps You,

Mark Sholund

231.590.3023
 
Last edited by a moderator:
shoboat said:
Ken,

You just need a pair of propeller pitch pliers and bend at .7 radi on the

trailing edge. You should buy a Steve Wood pitch gauge so you can measure

it accurately though. Call me if you need more help.

Hope This Helps You,

Mark Sholund

231.590.3023
Click to expand...

Thanks Mark,

That does help. So, can I assume that the purpose of cupping is to increase the pitch slightly? Or is there something else that I am missing?

Ken
 
As well as me, I know there are lot of people interested in learning more about propellor performance, propellor measurement and the effects of the different modifications that are suggested e.g. cupping, back cuts, tongue reduction and the basics of sharpening and balancing.

I think it would be good to try and store all the info that is currently available in one spot and include some diagrams to help with getting some consistency in the terms used. I think the post started by Marty Davis in the "General" section in relation to pitch progression and prop measurement was a good starting point and it would be good if it could be included here.

Here is my attempt at getting some of the good articles in one spot:

http://www.modelgasboats.com/Resources/Propeller_Related/Knowing_Your_Prop/

http://www.geocities.com/jwohlt5362/Propguide1.html

http://www.geocities.com/jwohlt5362/Propguide3.html

http://rcboat.com/prop.htm

http://www.modelgasboats.com/Magazine_Content/How-to_Articles/Modify_a_Prop/

http://www.modelgasboats.com/Resources/Propeller_Related/Improving_Your_Prop/

http://www.rcprops.com/TechNotes/rcprop_tech_info.htm

http://www.modelgasboats.com/Magazine_Content/Miscellaneous/Voodoo_Cupping_Tool/

http://www.modelgasboats.com/Resources/Propeller_Related/Prop_Chart/

http://www.modelpowerboat.com/content.php?137-improving-your-prop

http://www.modelgasboats.com/Resources/Propeller_Related/Heat_Treating/

I will have a lot of questions :eek: once we get this info in the one spot and get some good discussion going.

Regards,

James

prop_diagram.jpg
 
another good source of basic rc boat prop info is a sticky at the top of the boat forums on RCU.
 
mike hughes makes the cupping pliers in batches. get in touch with him & get your name on the list. when he has enough demand/names, he will do another batch. he is on here by that name.
 
Got it.

If I decide to try making one would I have a ball shape on one side and a cup of larger diameter on the other? Or a ball on each side?
 
Terry,

We just took a set of pliers and ground a crescent shape into

one side and matched the other side with the crescent shape.

They work very well.

Thanks,

Mark Sholund
 
Lennard Cuenco said:
Ken Gibson said:
OK, I'll kick this one off. Though I've been in boating off and on for a number of years, I'm a real neophyte to the customization of props. Can you enlighten me?

  1. What is meant by "cupping"?
  2. Is the whole prop blade cupped?
  3. How is it measured?
  4. How is it accomplished?
  5. How do you assure equal cup on all blades?
  6. When is cupping indicated? ie: When would cuppng help? When would it not help?

Thanks for any help you can give. I'm sure I'll have more questions. :huh:

Ken
Click to expand...
Hi Ken...

check this attachment and let's get this discussion rolling :)
Click to expand...
 
Lennard Cuenco said:
Ken Gibson said:
OK, I'll kick this one off. Though I've been in boating off and on for a number of years, I'm a real neophyte to the customization of props. Can you enlighten me?

  1. What is meant by "cupping"?
  2. Is the whole prop blade cupped?
  3. How is it measured?
  4. How is it accomplished?
  5. How do you assure equal cup on all blades?
  6. When is cupping indicated? ie: When would cuppng help? When would it not help?

Thanks for any help you can give. I'm sure I'll have more questions. :huh:

Ken
Click to expand...
Hi Ken...

check this attachment and let's get this discussion rolling :)
Click to expand...
 
Lennard Cuenco said:
Ken Gibson said:
OK, I'll kick this one off. Though I've been in boating off and on for a number of years, I'm a real neophyte to the customization of props. Can you enlighten me?

  1. What is meant by "cupping"?
  2. Is the whole prop blade cupped?
  3. How is it measured?
  4. How is it accomplished?
  5. How do you assure equal cup on all blades?
  6. When is cupping indicated? ie: When would cuppng help? When would it not help?

Thanks for any help you can give. I'm sure I'll have more questions. :huh:

Ken
Click to expand...
Hi Ken...

check this attachment and let's get this discussion rolling :)
Click to expand...
 
DSC05594.jpg

I use a small crescent with the jaws polished and a piece of aluminum or leather against the prop face to keep from putting dings in it. The aluminum strip in the picture is a 5/8" wide strip of soda can bottom folded one time, works well.
 
Guys,

I would concentrate on getting the pitch in the center of the blade right.

Cupping just kills the RPM out of these little motors. You can always grind

some of the cup out of the blades trailing edge. We have made strides in

handling and speed this year by watching the cup and adding more pitch

into the blade face. I like a pair of pliers with a rounded jaw on one side

and a matching crescent shaped jaw on the other side. You can coat them

with liquid handle grip if you like. This is the best way that I have found to

adjust the face of the propeller. Hopefully when Santa brings my Ipad 2

I will learn to do some pictures this next year. :)

Mike,

A cupping ball and brass hammer work much better trying to tip cup a propeller

than the crescent wrench does. Been their and done that. Mike Hughes sells

a nice set up for tip cupping.

Happy Holidays Fellas,

Mark Sholund
 
Last edited by a moderator:

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