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Dimple cracking caused by laser cut holes

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gotyoke

Well Known Member
Used to be all your final-sized holes were punched, you would knock off a slight burr, and be good. Now that Van's is using laser cutting, each and every hole has a notch. Eliminating the notch requires deburring to such an extent that it would oversize the hole. So instead, you just have to deburr as much as you are willing, and hope the hole doesn't crack when dimpled.

Well, here's what hoping will get you

D1FF390F-1468-4179-AB50-31A3F0448626.jpeg

Come on, man!
 
If the notch exceeds the .125 dimension, I would request an RMA and replacement. If quality work, you can anticipate a 30+ yr lifespan granting you a decent ROI.

I'd question that service-life estimate if a notch is present.
 
Agree, I’ve replaced at least one laser cut part, and still had some light file work to do after reaming and dimpling. It the ones I couldn’t see that worry me as well.
 
I have one, this is as received, even has burn marks. Had to ream and even then, had to pull the reamer to the notch side to clean up the nick. Watch your laser cut parts carefully!

IMG_4600.jpg
 
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I’m also seeing holes that contain the little notch depicted in the picture above. I guess I haven’t really thought about how much notch is unacceptable? I understand a cracked dimple is grounds for replacement, but what about the ones that don’t crack initially? What are the odds we are going to be seeing an influx of crack repairs coming from the Mothership in the next 5-15 years?
 
Tlrguy said:
I’m also seeing holes that contain the little notch depicted in the picture above. I guess I haven’t really thought about how much notch is unacceptable? I understand a cracked dimple is grounds for replacement, but what about the ones that don’t crack initially? What are the odds we are going to be seeing an influx of crack repairs coming from the Mothership in the next 5-15 years?
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I admit that I am worried about this. I'm not 100% festidious about addressing the little notches, as you can see in the original picture, because it would be literally every hole. I deburr, but nearly always a small notch remains. Final drilled was supposed to mean hole prep work was minimal. Addressing these laser cut holes may turn out to be nearly as bad as having to match-drill everything.
 
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gotyoke said:
I admit that I am worried about this. I'm not 100% festidious about addressing the little notches, as you can see in the original picture, because it would be literally every hole. I deburr, but nearly always a small notch remains. Final drilled was supposed to mean hole prep work was minimal. Addressing these laser cut holes may turn out to be nearly as bad as having to match-drill everything.
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I share your same concern. My current -10 build is my first RV and I am starting to think these laser cut parts are going to be problematic in the future. It is completely unrealistic to dress the notch out of every single rivet hole. Most of my laser cut holes are pretty clean but they all possess a little”pool” of what appears to be once molten metal.

I sure hope these airplanes started in the 2022ish timeframe don’t end up being known as “Covid Era” builds with airframes riddled in stop drilled holes and ultimately undesirable on the resale market.
 
They are using a bad strategy with the cutting. They should start close to the hole center and then spiral outward, that would not give a notch. Someone is saving a fraction of a second in cycle time by starting at the major diameter and then creating notches on every hole. A strong message needs to be sent to management.
 
gotyoke said:
I admit that I am worried about this. I'm not 100% festidious about addressing the little notches, as you can see in the original picture, because it would be literally every hole. I deburr, but nearly always a small notch remains. Final drilled was supposed to mean hole prep work was minimal. Addressing these laser cut holes may turn out to be nearly as bad as having to match-drill everything.
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Have you reached out to Van's? There was another thread where I think Van's had agreed to replace parts with this issue.
 
I reached out and was told to use a small file or a drill bit wrapped in sandpaper to fix each hole. That's what I have been doing. You can remove the notch but then the hole is no longer perfectly round. None on mine have been as bad as the ones pictured. It's definitely more work than the usual deburring. Fortunately there is minimal dimpling on the RV-12, so the holes aren't stressed in that way.
 
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That's some seriously poor manufacturing. There's no excuse for creating holes with defects like that using *any* modern tooling. The response to just file it away is BS, too.

They need to revise their cutting technique (or direct their supplier to do so).

Pretty surprising, actually...
 
I am also seeing a TON of this. All on substructure as the skins are punched I believe. Almost every hole. Some parts are much worse than others. Even after deburring there is often a noticeable notch but no crack. I do check for cracks after dimpling and have not found any yet.

I talked with Van's they said to "soften" the notch with a file. This would mean almost every hole would be oversize and oblong. So I have taken the stance of address the worst ones with a file as they suggest and otherwise check for cracking.
 
I'm left with the impression that "filing out the notch" still leaves you with a stress concentration, albeit a "smooth one". :(
 
Strange but I have not noticed this issue on my parts that have been laser cut. Some random burn marks but those come right off during my prep for priming.

Will pay closer attention to the next batch of parts in the wings and fuse.
 
Brantel said:
Strange but I have not noticed this issue on my parts that have been laser cut. Some random burn marks but those come right off during my prep for priming.

Will pay closer attention to the next batch of parts in the wings and fuse.
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Any idea on the production timeframe of your kits that aren’t having the laser cut parts issue?
 
As a (probably useless) point of reference, I got my -14 fuse kit near the end of last year. I'm in the middle of Chapter 25: Fwd Mid Fuse Bulkheads, the bulkheads themselves and side channels/angles seemed to have punched holes and look great. The cover ribs and mid fuse brace were laser cut holes and had notches.

Just now filed the laser cut ones with a few quick swipes of a narrow, fine, round file. Perhaps not strictly needed for the thicker material of the mid fuse brace, but it was the dimples in the cover ribs where it was clearly needed.

All those holes are now slightly oblong, though still in spec. :(
 
Tlrguy said:
Any idea on the production timeframe of your kits that aren’t having the laser cut parts issue?
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Late 22 or early 23. Kit was shipped March 7, 2023.

My kit has a mixture of punched and laser cut parts. I did not notice this issue while building it.
 
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If I got parts like that and was advised to file them I would send the entire kit back and buy another brand of aircraft. This is absolutely unacceptable.
 
Oval holes

Tommy123 said:
If I got parts like that and was advised to file them I would send the entire kit back and buy another brand of aircraft. This is absolutely unacceptable.
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All this time I've been carefully reaming 32,000 holes.
What did mom always say?
Do as I say, don't do as I do.
Kinda makes you wonder about the QB kits now. :D
Sorry. My sardonic sense of humor.
 
rv9builder said:
Assuming all the holes look OK, how do you tell punched parts from laser-cut parts?

Thanks,
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There are a few ways. Laser cut parts will not have the blue vinyl. Most laser cut parts have small areas of what appears to be burn marks and slag. And finally, the laser cut parts appear to be wiped clean with some sort of solution which leaves a milky residue behind.
 
Tommy123 said:
If I got parts like that and was advised to file them I would send the entire kit back and buy another brand of aircraft. This is absolutely unacceptable.
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I fully agree with you Tommy. Reality is, we have all been waiting a very long time for our kits and have long ago decided that Vans Aircraft was going to be the kit of choice.

I started my build not even being aware of these laser cut part issues and like others, I am now far too deep into the project for a return to be a sensible option.

I would really like to hear what the thoughts are from someone like Greg. I don’t believe we were ever given the video explaining the process of laser cutting and what Vans has done to confirm the process adequate for our airplane kits. There is no doubt the laser cutting process has been used in aircraft parts manufacture, I just question the CNC programs used to insure these laser cut holes are usable and will provide a quality product for many decades to come.
 
With 30 yrs of engineering in aerospace production, I'm amazed kits continue to be shipped with this known defect, and this issue remains basically unaddressed by Vans.
 
For a short while I was a inspector at Voight that was building B-747 fuselages. I have rejected stuff that was way better than these holes.
 
I ran a cnc laser for about 3 years, that looks like they are peircing the material on the cut line. The initial pierce will have a bigger kerf then the actual cut. They should be piercing inside the hole and moving to the actual cut line, even a 90 degree turn from the lead in to the actual cut will be unnoticeable. Holes are the most inefficient thing a laser can cut, time wise. They need to program a lead in from somewhere in the middle of the hole to the outside cut, at least as long as the notch they are currently leaving in the part.
 
To (have to) drill or not to (have to) drill....that is the question..

For a time there I was envious of the pre-punched kits. Imagine: having all the holes already "drilled" and all one has to do is line them up and cleco them together. No jigs. Huh. Still have to deburr, countersink and rivet, however.

I'm old enough to remember when I had to drill every stinking hole in every single part. 13,000 driven rivets meaning 26,000 holes into parts I had to line up correctly, drill, deburr, countersink and rivet. THOSE were the Good Old Days.... And people ask why it took me six years to build a "kit"..... Not rubbing it in; just fondly remembering....:p MY sardonic sense of humor.....:eek:
 
Tommy123 said:
For a short while I was a inspector at Voight that was building B-747 fuselages. I have rejected stuff that was way better than these holes.
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Quick question for anyone in the know: How often and at what rate are stress risers known to start a crack? I have to imagine these “notches” in the laser cut holes are textbook stress risers. I’m also curious about the hard slag I see embedded in the material within the hole itself?
 
Tlrguy said:
Quick question for anyone in the know: How often and at what rate are stress risers known to start a crack? I have to imagine these “notches” in the laser cut holes are textbook stress risers. I’m also curious about the hard slag I see embedded in the material within the hole itself?
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Exactly, a crack will form from these areas.
 
Lots of factors.

Off the top of my head (dinner bell is ringing)

Alloy,
Temper
How concentrated
Stress the assembly is subjected to, direction, rate of imposition of stress.

Look up the subject of strength of materials and gain an understanding of stress, yield, failure. It's valuable information.
 
I have been unimpressed with Vans. I know everyone raves about the company, but my personal experience hasn't lined up. I think they have a fantastic design, but made some very poor choices during Covid.

Personally I'd even rather have undersized holes. These "final size" with defects are more work than just running a reamer to final size the hole and remove the nicks and cracks caused by lazy laser programming.

If I could send back all these laser cut parts, I would exchange them in a heart beat. Unfortunately support wants to address each and every one on a case by case basis. And the story is always the same, file it out, build on.
 
I want to educate myself. I agree with everyone that the quality of these new parts seems to be lacking. My inventory is in the same condition. That said it is how it is and I am building on addressing the worst of the notches. As everyone pointed out its nearly impossible to address every one and it's easy to miss some. I cannot imagine having to replace every part with Van's its simple not feasible. Sometimes I consider stopping the build due to this exact issue and the concern that I will see many issues in the form of cracks done the road.... Then I do some searching on this forum and the whole of the internet. It would seem to me that if this was a major issue you would see all kinds of reports of flying 14s and 10s that had final size holes with cracks appearing. I just haven't seen these reports. Now, that could be that the fleet is so new. That does make some sense. OR could it be that most of this internal structure is not loaded in a way where these notches matter? It would seem that the loading path on these holes may not be significant enough to produce a crack. The rivet, the skin compression against the structure and the multitude of holes spreading the force might be enough to make each notch/hole imperfection enough to make any difference. Now I'm not a materials guy but I am a mechanical engineer and do understand stress concentrations and the notch concerns.

I have to imagine that Van's has considered this issue and is watching all of these posts on this forum. I would hope they would address the problem if it was that much of an issue. They are mostly unconcerned it would seem. I gather this from my own calls with them, this forum, and their lack of addressing the problem. Also I assume the factory built 10s and 14s have the same parts as we do and that they would also see these issues as a safety concern if they were. If this isn't the case then I would highly consider abandoning this build. As it calls into question even the engineering of the design and their safety outlook and procedures.

Lastly, I understand that in a perfect world, the holes would not have these defects. I also understand that some on here are building perfect planes and this is unexceptable for them, but is it a real safety concern or is it just a perfectionist/idealistic view? Like the primer debate, I can't imagine every cessna out there had perfectly polished edges and holes...

I could be way of base. Looking forward to everyone's comments.
 
JoeRuscito said:
I want to educate myself. I agree with everyone that the quality of these new parts seems to be lacking. My inventory is in the same condition. That said it is how it is and I am building on addressing the worst of the notches. As everyone pointed out its nearly impossible to address every one and it's easy to miss some. I cannot imagine having to replace every part with Van's its simple not feasible. Sometimes I consider stopping the build due to this exact issue and the concern that I will see many issues in the form of cracks done the road.... Then I do some searching on this forum and the whole of the internet. It would seem to me that if this was a major issue you would see all kinds of reports of flying 14s and 10s that had final size holes with cracks appearing. I just haven't seen these reports. Now, that could be that the fleet is so new. That does make some sense. OR could it be that most of this internal structure is not loaded in a way where these notches matter? It would seem that the loading path on these holes may not be significant enough to produce a crack. The rivet, the skin compression against the structure and the multitude of holes spreading the force might be enough to make each notch/hole imperfection enough to make any difference. Now I'm not a materials guy but I am a mechanical engineer and do understand stress concentrations and the notch concerns.

I have to imagine that Van's has considered this issue and is watching all of these posts on this forum. I would hope they would address the problem if it was that much of an issue. They are mostly unconcerned it would seem. I gather this from my own calls with them, this forum, and their lack of addressing the problem. Also I assume the factory built 10s and 14s have the same parts as we do and that they would also see these issues as a safety concern if they were. If this isn't the case then I would highly consider abandoning this build. As it calls into question even the engineering of the design and their safety outlook and procedures.

Lastly, I understand that in a perfect world, the holes would not have these defects. I also understand that some on here are building perfect planes and this is unexceptable for them, but is it a real safety concern or is it just a perfectionist/idealistic view? Like the primer debate, I can't imagine every cessna out there had perfectly polished edges and holes...

I could be way of base. Looking forward to everyone's comments.
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I dont think there are enough flying planes with laser cut parts.

These only surfaced maybe a year to a year and a half ago. They outsourced a lot of parts because of order demand that they couldn't fulfill internally. Future kits will go back to being fully punched I believe.
 
I think the next point of interest would be what specifications did Vans provide the outside source in making the parts.
 
JoeRuscito said:
I want to educate myself. I agree with everyone that the quality of these new parts seems to be lacking. My inventory is in the same condition. That said it is how it is and I am building on addressing the worst of the notches. As everyone pointed out its nearly impossible to address every one and it's easy to miss some. I cannot imagine having to replace every part with Van's its simple not feasible. Sometimes I consider stopping the build due to this exact issue and the concern that I will see many issues in the form of cracks done the road.... Then I do some searching on this forum and the whole of the internet. It would seem to me that if this was a major issue you would see all kinds of reports of flying 14s and 10s that had final size holes with cracks appearing. I just haven't seen these reports. Now, that could be that the fleet is so new. That does make some sense. OR could it be that most of this internal structure is not loaded in a way where these notches matter? It would seem that the loading path on these holes may not be significant enough to produce a crack. The rivet, the skin compression against the structure and the multitude of holes spreading the force might be enough to make each notch/hole imperfection enough to make any difference. Now I'm not a materials guy but I am a mechanical engineer and do understand stress concentrations and the notch concerns.

I have to imagine that Van's has considered this issue and is watching all of these posts on this forum. I would hope they would address the problem if it was that much of an issue. They are mostly unconcerned it would seem. I gather this from my own calls with them, this forum, and their lack of addressing the problem. Also I assume the factory built 10s and 14s have the same parts as we do and that they would also see these issues as a safety concern if they were. If this isn't the case then I would highly consider abandoning this build. As it calls into question even the engineering of the design and their safety outlook and procedures.

Lastly, I understand that in a perfect world, the holes would not have these defects. I also understand that some on here are building perfect planes and this is unexceptable for them, but is it a real safety concern or is it just a perfectionist/idealistic view? Like the primer debate, I can't imagine every cessna out there had perfectly polished edges and holes...

I could be way of base. Looking forward to everyone's comments.
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OR, as noted, this is a NEW problem with parts that only started showing up recently with laser-cut components.

This post sounds a whole lot like rationalizing a decision rather than making an informed one.
 
unimpressed with Vans. I know everyone raves about the company, but my personal experience hasn't lined up
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Yep, agree.
And makes one wonder that the company hasn't taken any position in a thread that has been running for a few days now... or did I miss something?
 
Looking back at the QB corrosion issues during covid this seems to be the same response. As in no response until they knew the issues and had a solution. Unfortunately in my opinion this is the wrong way to fix the situation. Clear open communication would build trust way more than silence.
 
Hoping someone "official" weighs in soon!

HAL Pilot said:
Clear open communication would build trust way more than silence.
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This is definitely a true statement in my case. As a soon-to-be RV-14A builder (wing kit "Assigned to Crating"), this thread is making me very nervous!
 
Consider sending the factory a "Request for Further Assurances" seeking assurance that the kit shipped to you be inspected prior to shipping to insure no "notches" are present.

It might delay delivery, but receipt of a kit without defects is what you bargained for and will reduce the complications if a compromised kit is delivered.
 
Here are two threads from 2022 where Greg H. mentions the advent of their laser cut parts:

1/17/2022:


From Post #15 of the above thread:

Q: "I do hope we get more info on laser cut parts. I’ve always heard that the heat makes it prone to cracking. I’m fully confident Vans has investigated and determined it’s safe, but I would love for them to put my wandering mind at ease! Haha"

A: (from Greg Hughes - Van's Aircraft): "We'll have a video dedicated to the materials and fatigue testing topic soon, and will discuss this in that context. The short version is, extensive testing was conducted and specific criteria and tolerances have to be met. We've invested in some new specialized machinery and made key hires in this area over the last couple of years."​


2/17/22:



Sounds like an update is in order.
 
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RV8JD said:
Here are two threads from 2022 where Greg H. mentions the advent of their laser cut parts:

1/17/2022:


From Post #15 of the above thread:

Q: "I do hope we get more info on laser cut parts. I’ve always heard that the heat makes it prone to cracking. I’m fully confident Vans has investigated and determined it’s safe, but I would love for them to put my wandering mind at ease! Haha"

A: (from Greg Hughes - Van's Aircraft): "We'll have a video dedicated to the materials and fatigue testing topic soon, and will discuss this in that context. The short version is, extensive testing was conducted and specific criteria and tolerances have to be met. We've invested in some new specialized machinery and made key hires in this area over the last couple of years."​


2/17/22:



Sounds like an update is in order.
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Yes! That was my post. I emailed Greg a few times. He responded first and said the video and information should be released soon, just need to finish editing.

A second email a few months later didn't get a response.

I still hope to get more information here. My first worry is safety, which I think is probably OK, but second worry is who is going to deal with all the cracking and painting that might occur in ~5 years of use.

Who knows, maybe I am overthinking it as I am just a homebuilder. But, Section 5 is quite specific on edge finish.
 
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Apologies for the slowness in replying here. I don't check VAF every day (unfortunately) but I'll provide a quick reply now, and we'll communicate again on this soon.

We will replace parts as needed when a non-solvable problem is observed and reported to our support team. Note that KAI Chapter 5 includes guidance on this subject and what is acceptable or not, as well.

We're aware of a small number of parts fabricated by one of our laser-cutting partner companies, where we identified that the method of cutting (along the lines of what Jslow2 mentioned in this thread previously) may have been incorrect for a period of time, which sometimes resulted in the type of hole-edge issues depicted in the photos in this thread. That issue has been remediated with the vendor and we are inspecting the quality of all laser-cut parts when they are received from each vendor that provides that service to Van's.

As always, if find you have a part with cracks or another issue that cannot be remedied let our builder support team know and we will review. We will, of course, replace a part when a customer has a problem with a kit part that cannot be addressed otherwise.
 
Where in Chapter 5

Thanks for the insight Greg. I have been looking through Chapter 5 and not finding anything about this subject. Can you point us to where it talks about this?

Maybe I'm looking at an out of date version?
 
txnbuilder said:
Thanks for the insight Greg. I have been looking through Chapter 5 and not finding anything about this subject. Can you point us to where it talks about this?

Maybe I'm looking at an out of date version?
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Latest version of Section 5:



He may have been referring to Section 5.2, "EDGE FINISHING, HOLE DEBURRING & SCRATCH REMOVAL", and also Section 5.5, "COUNTERSINKING AND DIMPLING". It doesn't refer to laser cut parts per se, but the idea is the same.

From Section 5.5:

"Occasionally, a hole will crack when dimpled. This does not necessarily mean that the part must be scrapped. The criteria below provide guidance on how to evaluate cracks in dimple. Cracks exceeding the criteria stated below not only present a safety risk from a structural standpoint, but also could crack further in the future:

• A crack in a dimple countersink may not extend more than 1/3 the height of the dimple measured from the bottom edge of the dimple.

• For cracks in dimples for 3/32 rivets, 1/8 rivets and #6 screws: Remove the crack with a rounded file.

• For cracks in dimples for a #8 screw: File out the cracks if short or, if cracks are the full 1/3 length, stop drill with a 1/16 drill bit. The edge of the stop drill holes shall not extend more than 1/2 the height of the dimple measured from the bottom edge of the dimple. The stop drill hole will not be visible with the screw in place."​
 
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Thanks, Carl - you beat me to it.

And yes, that is what I was referring to in the updated Section/Chapter 5 that Carl linked to.
 
Greg, I have seen that guidance as it relates to cracks, but would you address the issue of notches that exceed the max OD of the hole but do not crack when dimpled? I have not seen any cracks do to notch left in the hole.

I have called support on this subject a few times already and their guidance was not to replace the part but to file it smooth and oblong the hole. I mentioned this was almost every hole on some parts. There are without doubt some that I have missed and some that I decided not to file. This is omni present on my kit and I would have to replace nearly every laser cut part if replacing it was the correct path. I could be the odd man out here but suddenly I am considering abandoning my build as there is just too much uncertainty that a notch will cause me headaches down the road. How can we be sure that the outsourced QB kits do not have the same issues and are hidden behind the already placed rivets?
 
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