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Thank you! 1 A... The panel went from .040" at the center to .057" at the edge. The sample piece, that was metal spun, went from .040" at the center to .029" at the edge. I always like thicker than thinner 2 A... An surprising and quiet interesting issue popped up in my last few projects with the use of 3003-H14 material and my power hammer. I use plastic thumbnail dies in the Pettingell and plastic planish hammer dies in my CP for shaping. I'm getting an awesome tool mark free surface finish, with no visible cracking and very effective shaping as far as time involved with making the part. My problem, instead of the part work hardening and getting harder, it is getting softer. I have confirmed this with the use of my personal Rockwell hardness tester in heavily shrink parts. The hardness drops and there for the yield strength also drops, this is why I had to stop annealing the material. The only way that I can get the hardness back up to baseline hardness is to use steel on steel dies and hammer the surface. My hypothesis is as follows, 1, The process is very efficient in creating dislocation and making an airworthy part. The steel on steel dies are need to close or lock the dislocation and to regain the strength of the material. -or- 2, The process is very inefficient and is causing micro cracking of the material. My fear would be steel on steel dies are closing the micro cracks, masking the issue. Snap_002.jpg I took this photo with my micro scope and I see no issue, but I lack the obvious power needed to determine this any further. The two spots in the photo are center punch marks for reference when taking the photo. I have a friend who is finishing up his PHD in metallurgy at UW Madison. I have sent this issue onto him to see what his conclusion might be out of curiosity. Because the metal shaping process has been excepted by the Aerospace industry, I assume I have not uncovered anything new, just new to me. 3A... The 1946 Fairchild is Ranger engine powered. I have another set of brake covers to make that will on on a 1937 Fairchild 24 with a Warner radial engine. Thank you Bill
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Bill Tromblay "A sign of a good machinist, is one who can fix his F$@& Ups" My mentor and friend, Gil Zietz Micro Metric Machine. |
#22
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I've also noticed "work softening" with the various die materials I use with my Air Hammer ... after some long years of working various alloys and seeing consistent results, I contacted the authors of the "slip plane" theory and presented my findings years ago. Of course I was laughed at and immediately disregarded. But that was then, and of course successful trends continue - and the news spreads between craftsmen. At some point the mechanics of this "work softening" will become more understood at the slip-plane level, although I do persistently count on this phenomenon for success while not knowing "why" exactly. I have always preferred thicker to thinner.....Hence - You may at some point also discover the relative fatigue rates associated with shrinking aluminum, using all the various methods to accomplish "thicker." Yeehaw, the metal awaits,
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Kent http://www.tinmantech.com "All it takes is a little practical experience to blow the he!! out of a perfectly good theory." --- Lloyd Rosenquist, charter member AWS, 1919. |
#23
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Making progress
Ok I got 4 1/2” depth with a 5 inch radius on one piece, tried to make the mirror of and overstretched a slight amount.
I believe when I was annealing it, I overheated a spot. It turned very granular and wrinkly. I believe I am using the right descriptions for the effect. I may not be. Is there a way to re anneal the piece at that point of did I just make an expensive recycling part? Appreciate all your folxs help. Jaroslav I think I under stand your hockey puck idea, is a press or arbor press needed? Does the die need to be the same radius as you are seeking? 9FD417B7-11EB-43D8-8B15-135B69142905.jpg 92CDBC2C-B363-41E0-9463-5A52192949EA.jpg C620C1E4-3259-4357-AAF3-CB75B4CA659F.jpg F7C2EF34-0480-4A4C-B003-6425885C7D42.jpg 82E16784-7E77-4D03-8738-0FF25C8A9500.jpg D817AEA6-C97B-420E-BDF0-F82A7DA26B79.jpg
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Paloma Making magic at times Last edited by galooph; 06-04-2022 at 03:12 AM. |
#24
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Paloma. Of course, start at the county. I don't know annealing. It could work without annealing.
Use a half ball out of the bottle cap, for example, if you have no other idea. Try, try, but you remember wrong steps. Just think about what's going on. Keep asking yourself why and why. It's a mental issue. You can do it differently after each. Nothing is a definitive method. Watch out for one "American tooth", this is a method that is very effective for to look at .... But? But? Where is the final product that you originally wanted with this method.
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Jaroslav |
#25
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Paloma you've done a great job, well done. From what you describe of annealing, yes you have overheated it and I don't think you can undo the damage, other than cut the area out and weld a patch in.
I use BIC felt tip marker pens and put lines over the area to be annealed, As different makes fade at different temperatures I check with a tempilstik marker on a test piece of scrap to check the amount of fade out of the lines at the required temperature.
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David Hamer |
#26
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Hi,
Congratulations on getting the part made. The damage from over heating can only be repaired by cutting it out and welding in a patch. B
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Bill Tromblay "A sign of a good machinist, is one who can fix his F$@& Ups" My mentor and friend, Gil Zietz Micro Metric Machine. |
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