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Author Topic: Cutting down a prop...  (Read 659 times)

Offline JohnPrator

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Cutting down a prop...
« on: March 10, 2011, 07:21:43 AM »
Could someone point me towards some info on how you guys are "cutting down a prop"? What is the best way to do this accurately, I don't want to screw it up and end up with some lopsided prop. Thank you!

John
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Offline John Cralley

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Re: Cutting down a prop...
« Reply #1 on: March 10, 2011, 08:42:52 AM »
John,

I made a jig for my band saw with holes drilled at 1/2" intervals (other appropriate intervals could be used). I clamp the jig on the saw and I place a screw through the prop hub and into the appropriate hole. Then it is just a matter of carefully rotating the prop around the screw and thus the tip through the running saw blade.

Works for me.  ;D

John
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John Cralley
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Offline JohnPrator

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Re: Cutting down a prop...
« Reply #2 on: March 11, 2011, 06:55:55 AM »
Hi John,

Well shoot, all I've got is a Sawzall(sp?), a circular saw and little hobby hand saws. I'm wondering if I can cut it by hand with one of the little hobby saws and get it accurate enough?  ???
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A Veteran - whether active duty, retired, national guard or reserve - is someone who, at one point in their life, signed a blank check made payable to "The United States of America", for an amount of "up to and including my life." That is Honor, and there are way too many people in this country who no longer understand it. -- Author Unknown

Offline John Rist

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Re: Cutting down a prop...
« Reply #3 on: March 11, 2011, 07:43:54 AM »
The trick is to get the two blades the same length.  I have used a board with a peg that fits the center hole of the hub. I then rotate the prop and scribe a line on each end.  The scribe is a sharpened finishing nail that sticks through the board.  I then cut on the scribe marks with a hobby hand saw - finish sand to the line - and balance.  If you are always cutting the same length of prop - once you get it set up you should be good to go. However you can add finishing nails at different points on the board for different props. To make the peg I sanded a oak dial rod - by chucking it in drill machine (drill press)- to the right diameter.  I then superglue it into a hole I drilled in the board.  Any round stock would work.  You could even use an electric motor prop adaptor shaft if you have a spare.
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Offline Allan Perret

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Re: Cutting down a prop...
« Reply #4 on: March 11, 2011, 07:46:34 AM »
Quote from: JohnPrator on March 11, 2011, 06:55:55 AM
Hi John,

Well shoot, all I've got is a Sawzall(sp?), a circular saw and little hobby hand saws. I'm wondering if I can cut it by hand with one of the little hobby saws and get it accurate enough?  ???
You could do it accurate with a handsaw if you set up a simple jig to hold the prop and guide the sawblade blade while cutting.  Glue 2 sticks on to a base board to form a trough for the prop.  Drill hole in base board to index prop at the length you want to cut blades, you can use the same drill bit or wood dowel to index prop.  Make a kerf cut in the 2 sticks down to the base board first before cutting prop blades.  The kerf will guide the saw so you get same length on both blades.  
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Offline John Cralley

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Re: Cutting down a prop...
« Reply #5 on: March 11, 2011, 08:50:47 AM »
Quote from: JohnPrator on March 11, 2011, 06:55:55 AM
Hi John,

Well shoot, all I've got is a Sawzall(sp?), a circular saw and little hobby hand saws. I'm wondering if I can cut it by hand with one of the little hobby saws and get it accurate enough?  ???

John,  Sure you can! Just a jig such as Allan suggests. This is similar to the old fashioned miter jigs (boxes) used by carpenters since day one. Should work fine with your "hobby" saws.

John
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John Cralley
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Offline JohnPrator

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Re: Cutting down a prop...
« Reply #6 on: March 11, 2011, 11:31:02 AM »
Cool, thanks so much for the info Gentlemen!! My hopes were to cut down a 12x6 to 11" as it appears from what I've read here and there that this is a popular "mod". I'm going to give it a try and see how bad well I do. 
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Offline Dennis Toth

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Re: Cutting down a prop...
« Reply #7 on: March 12, 2011, 06:40:45 AM »
John,
Cutting the APC-E props is easy to do with metal working shears. Just mark the blade with a sharpie across the width at the point you are going to cut and snipe it off. The APC-E blades are very thin at the tips and the shears make a nice clean cut. I use to use a cutoff wheel on a dremal also did the saw but they took longer and were not any better then the metal shears.

Best,           DennisT
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Offline JohnPrator

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Re: Cutting down a prop...
« Reply #8 on: March 17, 2011, 11:07:19 AM »
Oops, missed your reply! Thanks for the tip, hope to cut a 12 x 6 down and maybe fly again this weekend!
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A Veteran - whether active duty, retired, national guard or reserve - is someone who, at one point in their life, signed a blank check made payable to "The United States of America", for an amount of "up to and including my life." That is Honor, and there are way too many people in this country who no longer understand it. -- Author Unknown

Offline Dennis Toth

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Re: Cutting down a prop...
« Reply #9 on: March 21, 2011, 01:11:01 PM »
John,
One thing to be carefull about this the tip shape after you clip it. You need to smoothly sand about the last 1/8 - 3/64" of the tip top into the bottom. On the props I have clipped the square tip shape gives a little more line tension. I have tried to angle them and reduce the tip drag and it doesn't seem to be as effective as you might think it should be. Shaping the top to the bottom seems to be effective and reduces tip drag.

Best,              DennisT
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