how to you measure a prop to determine it's diameter

[Boomer]

What is the correct way to measure the diameter of a propeller? I took a picture showing how I am measuring a propeller, but even with a digital micrometer, the props I measure don't seem to match the advertised diameter.

Please share the proper points to use to get the correct diameter measurement.

Thank you
Boomer

[Steven Vaccaro]

You have it right.

Lots of the Octura props wont measure what they are listed at. It seems they use different molds or experience shrinking on some more than others.

[teach]

Also as you sharpen and balance a prop, some of the tip usually will get taken off lowering the total diameter. Same for rounding the tips.

[martin]

All casting shrink when material is solidified after casting so patterns must be made larger to allow for shrinkage. I suspect some manufacturers copy other propellers & simply take their mould from some one elses finished props. Saves a fortune to take an allready good prop & just copy but you end up with an undersize prop casting because the copied original was proper finished size. By the time a mould is taken the mould ends up finished size & them when the props are cast in this mould you get the relevent shrinkage. Aluminim shrinks around 6% & copper based materials around 4%. This is why some copper based castings with no filling just flash removal should be a 40mm prop but are 38mm +. Thanks Martin.

[Boomer]

Thank you for each reply! Thought it was me. Usually is, so it is nice to know I was doing something the right way for a change!
Boomer

[Doug Smock]

Kevin Sheren made these cool tools for checking diameter while making sure both blades are the same. 3/16 and 1/4" mandrels
When I got mine I was suprised how much some of my props were off.

Doug

[westbeach]

Hey Doug, do you have a close up on one of these handy calipers? Thx

[Doug Smock]

Hey Doug, do you have a close up on one of these handy calipers? Thx

I'll post one tomorrow.
Doug

[Doug Smock]

Here you go.
If I remember right Kevin was letting these go for $65.00 shipped . You can contact him here if you are interested. Gas_dir@yahoo.com
If you get one of these be prepared to spend a bit of time with your prop box. Like I said, I was suprised how many props I had that were off. This tool is well worth the money.

Doug

[Steven Vaccaro]

Here you go.
If I remember right Kevin was letting these go for $65.00 shipped . You can contact him here if you are interested. Gas_dir@yahoo.com
If you get one of these be prepared to spend a bit of time with your prop box. Like I said, I was surprised how many props I had that were off. This tool is well worth the mo

Doug

Very cool. I have to buy or make myself one of those!!!! Probably buy one for that great price.

[egneg]

Doug is the pin on center with the jaw for the different pin sizes?

[Doug Smock]

Doug is the pin on center with the jaw for the different pin sizes?

Yes sir.
D.

[egneg]

Yes sir.
D.

Thank you, it would be good to do a quick check. This is what I use to make sure all the blades match. I can also use it to check pitch with a gizmo I made.

[dasboata]

Thank you, it would be good to do a quick check. This is what I use to make sure all the blades match. I can also use it to check pitch with a gizmo I made.

You can check pitch with that I would like to know how as pitch is checked on the face of the prop

[egneg]

You can check pitch with that I would like to know how as pitch is checked on the face of the prop

The indicator is turned 90* and a wiggler is attached.

[dasboata]

The indicator is turned 90* and a wiggler is attached.

Whats a wiggler ? can I see some pics of it turned 90 * with the wiggler ? yhanks Chris

[egneg]

Whats a wiggler ? can I see some pics of it turned 90 * with the wiggler ? yhanks Chris

Sure ... I will take some pictures tomorrow.

[dasboata]

And I will show you mine !!!! LOL

[egneg]

And I will show you mine !!!! LOL

We might end up in jail !

[Doug Smock]

We might end up in jail !

Oh Noooooooooo!!

[egneg]

Whats a wiggler ? can I see some pics of it turned 90 * with the wiggler ? yhanks Chris

This isn't the exact setup as I did this so you could see what a wiggler is.

[dasboata]

yea ok so how do you measure degrees of travel Its impossible to measure pitch with that angle and set up this is what you need

[egneg]

I have the Hughey pitch gauge. to measure with. In the previous posts I said "check" blades to see if all things are equal. And the picture was not the setup but to show what a wiggler is.

Thanks for showing yours!

[dasboata]

Thank you, it would be good to do a quick check. This is what I use to make sure all the blades match. I can also use it to check pitch with a gizmo I made.

OK thanks Chris

[properchopper]

Kevin Sheren made these cool tools for checking diameter while making sure both blades are the same. 3/16 and 1/4" mandrels
When I got mine I was suprised how much some of my props were off.

Doug

It took me A WHILE to figure out that to get the correct/accurate reading of a prop's diameter using this tool that you have to add half the diamater of the prop holding shaft ( 1/2 4.76250mm = 2.381 mm) to the caliper reading, then double that number. Until I realized that, I thought that all my props were much smaller in diameter than claimed

[dasboata]

It took me A WHILE to figure out that to get the correct/accurate reading of a prop's diameter using this tool that you have to add half the diamater of the prop holding shaft ( 1/2 4.76250mm = 2.381 mm) to the caliper reading, then double that number. Until I realized that, I thought that all my props were much smaller in diameter than claimed

I have one from Kevin also,, the problem with them is that once in a wlile, you hit one of the buttons, by mistake, and it resets on you ,,then you have to take the alum block off to reset the thing !! other then that it is a good idea chris