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Old 09-03-2018, 01:05 PM
BTromblay BTromblay is offline
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Default Getting all the dents out?

Hi,

I have a question. In the last three weeks, I had to fix two separate airplane crash parts, no one was hurt in either accident. In both accidents, the airplanes thin aluminum (3003 x .040"), looked like you drove over it with a truck. I forgot to take pictures of the second part, due to the timeline to get the job done.

1.jpg
2.jpg
3.jpg

With skill sets that I learned from Peter Tommasini, Dan Pate and Kent White, I was able to knock out the dents in short order with hand tools, and my pneumatic planishing hammer. I had a buck, to confirm my finished shape. I will be welding up the extra holes from the earlier repair patches. The surface looks and feels much flatter, than the photos are showing, the discoloration of the stripped paint is creating an optical elution.

4.jpg
5.jpg
6.jpg

My Question,

What I need more help with understanding is, metal finishing the finished surface. I have a window behind my P-hammer and the natural light helps a bunch, as it washes over the panel during the repair. I will also make the panel wet, and/or use gloves and I can feel the highs and lows. If it looks good with light and you can't feel any thing, do you need to go any further? When I watch a autobody guy, prepare a surface for paint, they seem to find stuff, that I cant see or feel and I don't know "how they do it".

Both of my repair parts, will be painted again and it is up to the painter guy, to fix if need be. But if I had to repair a part on a polished aluminum airplane, is my process, good enough for a polished surface, (I don't think so)? Jim Hery, took some time with me down at Will's, this past spring. We used a body file and fixed highs and lows. Do you always need to file or sand a surface, for it to be flat?

How do you metal finish?

Thanks Bill
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Last edited by BTromblay; 09-03-2018 at 01:08 PM.
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  #2  
Old 09-03-2018, 03:13 PM
dwmh dwmh is offline
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Yes Bill that part was quite a mess. You did well. I'm not really qualified to answer your question as I'm no expert. But on .040" material for an aircraft I don't think you want to file it. I would put marking blue on it as a guide coat and use 1000 wet and dry on a sanding block. We need someone like Kent to chime in on this.
I have done plenty of paint refinishing over the years and guide coats do pick out the highs and lows.
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  #3  
Old 09-03-2018, 03:16 PM
crystallographic crystallographic is offline
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Quote:
Originally Posted by BTromblay View Post
Hi,

I have a question. In the last three weeks, I had to fix two separate airplane crash parts, no one was hurt in either accident. In both accidents, the airplanes thin aluminum (3003 x .040"), looked like you drove over it with a truck. I forgot to take pictures of the second part, due to the timeline to get the job done.

Attachment 48630
Attachment 48631
Attachment 48632

With skill sets that I learned from Peter Tommasini, Dan Pate and Kent White, I was able to knock out the dents in short order with hand tools, and my pneumatic planishing hammer. I had a buck, to confirm my finished shape. I will be welding up the extra holes from the earlier repair patches. The surface looks and feels much flatter, than the photos are showing, the discoloration of the stripped paint is creating an optical elution.

Attachment 48633
Attachment 48634
Attachment 48635

My Question,

What I need more help with understanding is, metal finishing the finished surface. I have a window behind my P-hammer and the natural light helps a bunch, as it washes over the panel during the repair. I will also make the panel wet, and/or use gloves and I can feel the highs and lows. If it looks good with light and you can't feel any thing, do you need to go any further? When I watch a autobody guy, prepare a surface for paint, they seem to find stuff, that I cant see or feel and I don't know "how they do it".

Both of my repair parts, will be painted again and it is up to the painter guy, to fix if need be. But if I had to repair a part on a polished aluminum airplane, is my process, good enough for a polished surface, (I don't think so)? Jim Hery, took some time with me down at Will's, this past spring. We used a body file and fixed highs and lows. Do you always need to file or sand a surface, for it to be flat?

How do you metal finish?

Thanks Bill

Quick Check highlighting spray.jpg
Bodyshop guys use slow reducer to highlight the surface before primer.
Or this stuff.
Once you make the surface smooth enough that you cannot work it smoother, then you change to metal finishing, and go smoother with that process.
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Old 09-03-2018, 05:59 PM
John Buchtenkirch John Buchtenkirch is offline
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Guys who didn’t come up thru the auto body trade may not agree with this but after you block out plastic (Bondo) on auto body panels for a year or two you end up with a fairly advanced understanding of panel flow and how to feel (with your hand) for surface irregularities that the general population just doesn’t have. Some collision shop workers become very good at it while others fall to the wayside or end up working on taxi cabs, they just don’t have a very good feel for it.

Some hints. When you run your hand over a panel you want to focus on irregularities passing under the flat of your hand, not on the texture of the metal on your fingertips. Because of that some guys prefer a thin rag under their hand, I just keep very light pressure on my fingertips but sometimes regret not mastering the rag trick when I occasionally cut my hand. If you feel a problem area you are not sure of run your hand over it in different directions. As crazy as this sounds sometimes it helps to close your eyes so you are focusing only on your feel. I dust coat panels with quick drying Krylon primmer and then sand or file them very lightly to highlight highs & lows…….. you really only want to remove the primer, not the metal. I prefer a somewhat dull Vixen file for this work, a sharp one will tend to hook & cut off metal especially with aluminum. That’s all I can think of at the moment……….. gotta go cook for mom . ~ John Buchtenkirch
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Old 09-03-2018, 06:20 PM
Charlie Myres Charlie Myres is offline
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I do the same as John, but I use a piece of very thin leather instead of a rag; but you probably know that already Bill, seeing that you have done such a good job already.

Once you have the metal as smooth as you can, the finishing involves finer and finer grades of wet-and-dry paper and then polishing, either with a buffing wheel or by hand, to get a shiny metal finish. There is a very good aluminium polish available in the USA, which someone posted here once,

Cheers Charlie
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Old 09-03-2018, 06:50 PM
Sprint Relic Sprint Relic is offline
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This is something I have been wondering about, how good is good? I have mostly only seen other peoples metal work in pictures, and they look great. In pictures of my own stuff it looks good, but when I actually look and feel of it in real life it would be good enough for paint but I would not think it would be good enough to polish. I like working with aluminum and my racecar past almost always make me choose to use light (.040) which makes me ask, can you use to thin of metal for a part with lots of shape because lack of thickness for filing versus trying bring every low and high into compliance? Couple of pics visual confusions for me.
First picture before "finishing"
VideoCapture_20180903-171521.jpg
After
VideoCapture_20180811-133845.jpg
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Old 09-03-2018, 08:34 PM
Mike Rouse Mike Rouse is offline
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I us the reflection of the Florsent light tubes to find he highs and lows. Rotate the part to examine the surface.
Mike
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  #8  
Old 09-04-2018, 04:39 AM
Peter Tommasini Peter Tommasini is offline
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[Quote]

Both of my repair parts, will be painted again and it is up to the painter guy, to fix if need be.

Bill first of all, let me tell you that you have done extremely well to get that panel to that stage............. I am impressed!
If you need... or like to go further with the finish, this is what I personally would do. Clean the panel from any grease or oil, then wipe or paint some engineering blue on it, use a soft block (not too soft but not hard either) that will allowed you to wrap your hands around the shape, use 120 grit sand paper (DRY)+spread and use soap on the panel , sand the panel down a few square inches at the time, look out, or feel for high spots FIRST! then ..try to elevate the low spots with a polished flipper (not a hammer) by tapping any highs spots down, once that is done simply feel the panel with some masking paper on you hands, that will allow you to feel the most difficult irregularity which are hard to see or otherwise feel. once that is done all over the panel there should be very little blue left on the lows, after this paint the surface again with blue, and do the same thing BUT.... this time use a higher grit paper for example ...240 grit. (It's up to you to decide when to stop) but the same procedure can be done again over and over with higher grit paper till the ally start to shine. By the pics you have the panel in pretty good shape, there is no need to use a file at any time
IF any panel like that was to be polished (not painted) I would strongly suggest to make a new one, simply because of the time factor to repair it to that standard, plus you need to keep in mind the thickness of the metal, the unwanted holes you would need to fix, corrosion etc ...In another words it be quicker to make a new one, and by keeping your top wheel and lower anvils clean at all time with acetone, by the time the panel is finished it will be 90% polished
Peter
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  #9  
Old 09-04-2018, 09:49 AM
John Buchtenkirch John Buchtenkirch is offline
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Quote:
Originally Posted by Sprint Relic View Post
This is something I have been wondering about, how good is good? I have mostly only seen other peoples metal work in pictures, and they look great. In pictures of my own stuff it looks good, but when I actually look and feel of it in real life it would be good enough for paint but I would not think it would be good enough to polish. I like working with aluminum and my racecar past almost always make me choose to use light (.040) which makes me ask, can you use to thin of metal for a part with lots of shape because lack of thickness for filing versus trying bring every low and high into compliance? Couple of pics visual confusions for me.
First picture before "finishing"
Attachment 48660
After
Attachment 48661
Parts prepared to the degree of perfection required for polishing or chroming always require extra hours of tedious work compared to painted parts. I’d say it’s sage advice to start out with one or two gauges thicker material on parts to be polished…….. once a professional polisher hits it with his polishing belt there is going to be material removed, it’s just part of the process. I prep some parts for a local chrome shop and if it wasn’t for the fact that the owner is a ski buddy I’d pass on that work, it’s just too tedious . ~ John Buchtenkirch
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Old 09-04-2018, 10:35 AM
billfunk29 billfunk29 is offline
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Default powder coat

I am curious where powder coating fits in the finishing spectrum? I assume you can't use filler because of the heat. And like wise the heat may produce warpage. I would think it is more forgiving than a polished part though.
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