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General control line discussion => Open Forum => Topic started by: Claudio Chacon on May 17, 2022, 12:05:41 PM
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Hello guys!
I have a Brian Eather 3b CF prop, 12,5" x 4" and need to go up to 5" or 5,5"...
Need advice on the propper procedure to achieve this.
Thanks in advance for your help.
Claudio.
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Set up your pitch gauge then hold the blade under hot running tap water (140f) until it softens then give it a twist, dry it with a towel and check it. Hold the prop at the hub and about 2/3 out on the blade. Try to twist a big section, if you try twisting little sections, it can be done but, you're in for allot of headaches. When you get it where you want it, dip the blade in cold water. If you twist it too much, hold it in the hot water a little and it will spring back then chill it again.
Some props you can't twist. I don't know about Brian Eather props but, some props I got from HobbyKing (China) and the props I make, you can't twist them after they're fully cured. So, if it doesn't want to move with reasonable heat and pressure don't burn the resin or break the fibers trying too hard.
Motorman 8)
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I use boiling water and gloves. This controls the peak temperature.
The time in the water is a function of the blade thickness at the station being twisted.
Good lighting to accurately read the pitch gage is helpful.
I use a white or silver paint pen to label the stations and pitch.
It takes practice and time to develop a technique that works for you.
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Hello guys!
I have a Brian Eather 3b CF prop, 12,5" x 4" and need to go up to 5" or 5,5"...
Need advice on the propper procedure to achieve this.
In addition to Jim's excellent advice, if you have a target pitch, set the pitch on the scale, and then use a spring clamp to hold the pitch gauge blade at the right setting. Then adjust it successively until it matches. This way you can be sure you are setting the target the same on all three blades. Work from the center to the edge - do all three prop blades at station 5, reset the guage, then move to 7, out to the tip. I usually skip every other station until I get to the tip, the last inch or so, I do each one.
They do generally need boiling water, not just hot - an Eather prop will not budge unless it is nearly at full boiling water temperature. Bollys can take a lot less, and also have a tendency to tweak themselves in a hot car. Mark each station with a pencil as you are doing it, then only dip the prop into the water far enough to hit your current station, and leave the previous station out of the water, so you have less tendency to change earlier settings after you have done them.
Brett
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Motorman, Jim and Brett...
Thank you very much for taking the time to answer to my questions!
See you around...take care,
Claudio.