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  #1  
Old 04-26-2022, 04:39 PM
wirejock's Avatar
wirejock wirejock is offline
 
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Location: Estes Park, CO
Posts: 5,353
Default Mold trick

I have some down time while parts cure for the plenum inlets, so I decided to try and fab a plenum for the oil cooler air supply. How to fab a twisted and turned 4" tube?
I took a 4" closed cell foam backer rod. Basically a pool noodle. Sliced pieces off. One end is cut 30, one end 90.
Take the slices and arrange them by stacking and rotating till the mold takes shape. Draw a line on one side and two lines on the opposite side. Number them. Spray ends with 3M 77. Reassemble lining up the alignment lines. Remove, sand to shape and layup the glass. Kinda fun and might just work.
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Larry Larson
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Donated 12/01/2021, plus a little extra.
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I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #2  
Old 04-26-2022, 05:10 PM
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Default

Nice technique Larry...
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  #3  
Old 04-26-2022, 06:15 PM
David Paule David Paule is offline
 
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How do you get a smooth contour at the intersections?

Dave
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  #4  
Old 04-26-2022, 06:22 PM
Ron B. Ron B. is offline
 
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Default

Hopefully the resin doesn't eat your foam before it cures.
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  #5  
Old 04-26-2022, 06:30 PM
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wirejock wirejock is offline
 
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Default

Quote:
Originally Posted by David Paule View Post
How do you get a smooth contour at the intersections?

Dave
I plan to rough sand the exterior to smooth the joints. I will loose a little volume but the smooth interior should help. Other option would be judicious application of tape.

Quote:
Originally Posted by Ron B. View Post
Hopefully the resin doesn't eat your foam before it cures.
That's no problem. I use packing tape. Wax the tape. Layup the glass. Cure. Carve out the foam till the mold pops free. Done it many times. Fast. It's a sacrificial mold.
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wirejock at yahoo dot com
Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (3,000+ hours)
Empennage, wings, fuse, finishing kit done. Working FWF
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.

Last edited by wirejock : 04-26-2022 at 06:36 PM.
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  #6  
Old 04-27-2022, 06:48 AM
Southern Pete Southern Pete is offline
 
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Or cut the part in to 2 semi-circular parts, smooth out the internal profile and glass back together. Good thinking to use sections of stiff foam.
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  #7  
Old 04-27-2022, 08:07 AM
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wirejock wirejock is offline
 
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Default Idea

Quote:
Originally Posted by Southern Pete View Post
Or cut the part in to 2 semi-circular parts, smooth out the internal profile and glass back together. Good thinking to use sections of stiff foam.
Ding, ding, ding. We have a winner!
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Estes Park, CO
wirejock at yahoo dot com
Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (3,000+ hours)
Empennage, wings, fuse, finishing kit done. Working FWF
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #8  
Old 04-27-2022, 08:16 AM
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DanH DanH is offline
 
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Or just carve a finished mold and spend half the time for a better part.

Composites Rule #1: Time spent on quality molds and forms pays significant dividends in weight and finish.
.
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  #9  
Old 04-27-2022, 08:23 AM
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wirejock wirejock is offline
 
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Quote:
Originally Posted by DanH View Post
Or just carve a finished mold and spend half the time for a better part.

Composites Rule #1: Time spent on quality molds and forms pays significant dividends in weight and finish.
.
There's some good advise. Exactly what I did with the plenum inlets. Except, I can't carve a stick into kindling, so they still need work.
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Larry Larson
Estes Park, CO
wirejock at yahoo dot com
Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (3,000+ hours)
Empennage, wings, fuse, finishing kit done. Working FWF
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #10  
Old 04-27-2022, 08:24 AM
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DanH DanH is offline
 
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Etc.......
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