How do I measure a prop to detemine it's diameter?
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
Last edited by Boomer; 01-10-2011 at 12:41 PM.
Reason: typo
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.
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
MODEL BOAT RACER
IMPBA President
District 13 Director 2011- present
IMPBA National Records Director 2009-2019
IMPBA 19887L CD
NAMBA 1169
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
Last edited by Doug Smock; 01-11-2011 at 03:42 PM.
MODEL BOAT RACER
IMPBA President
District 13 Director 2011- present
IMPBA National Records Director 2009-2019
IMPBA 19887L CD
NAMBA 1169
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.
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.
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
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.
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.
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
2008 NAMBA P-Mono & P-Offshore Nat'l 2-Lap Record Holder; '15 P-Cat, P-Ltd Cat 2-Lap
2009/2010 NAMBA P-Sport Hydro Nat'l 2-Lap Record Holder, '13 SCSTA P-Ltd Cat High Points
'11 NAMBA [P-Ltd] : Mono, Offshore, OPC, Sport Hydro; '06 LSO, '12,'13,'14 P Ltd Cat /Mono
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
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