Match drilling necessity???

[RNB]

I am VERY new on my RV10 kit.

As I go through the first few days I am surprised at the number of times the directions have me Cleco parts and final size drill, especially when the drill bit seems to easily go through without removing metal. For example, Page 6-3,step 4 tells me to final drill #40 all the holes common to the skin and skeleton. This really seems pointless and extra.

I recall that the RV10 is supposed to be final match drilled.

Where is it ok to ignore the point by point directions and just know that things are already matched?

 

[rocketman1988]

I am VERY new on my RV10 kit.

As I go through the first few days I am surprised at the number of times the directions have me Cleco parts and final size drill, especially when the drill bit seems to easily go through without removing metal. For example, Page 6-3,step 4 tells me to final drill #40 all the holes common to the skin and skeleton. This really seems pointless and extra.

I recall that the RV10 is supposed to be final match drilled.

Where is it ok to ignore the point by point directions and just know that things are already matched?

If it say to do something specifically, there is a reason for it.

 

[kirkbauer]

Yes you can ignore most of the match drilling in the instructions. The instructions were not updated based on the final drilled holes. But sometimes you still do need to final drill. Most of the time this is only on steel components. It's fairly easy to just check and see if they are already drilled large enough.

But sometimes you can skip whole portions of assembling because they say to assemble, final drill, disassemble, then deburr. Unless there are other steps in there you may be able to carefully skip all of it.

 

[RNB]

If it say to do something specifically, there is a reason for it.

Van's Announces Plan to Move to Final-Size Holes on RV-10 Kits - Van's Aircraft Total Performance RV Kit Planes

Van’s Aircraft has initiated the process of phasing in the production of final-size, matched-hole RV-10 parts. Until now, all parts for the RV-10 have been produced with slightly undersized holes, which the builder must up-size with a drill and then debur prior to assembly. We will be...

www.vansaircraft.com

 

[RNB]

So, is there a good way to determine when required?
Be careful if steel?
Assume skin and ribs are final sized?
If the called for drill size fits thru easily assume it is good?

 

[Ironflight]

Van's Announces Plan to Move to Final-Size Holes on RV-10 Kits - Van's Aircraft Total Performance RV Kit Planes

Van’s Aircraft has initiated the process of phasing in the production of final-size, matched-hole RV-10 parts. Until now, all parts for the RV-10 have been produced with slightly undersized holes, which the builder must up-size with a drill and then debur prior to assembly. We will be...

www.vansaircraft.com

So it says in the 2020 press release that you quoted that parts will be labeled as final size when they are done that way….
What you really need to do is send your question to VAN’s, not a bunch of random people here on the internet. They can tell you if your kit (or parts) is(are) final drilled or not - no way I (or really anyone else here) can.

 

[wirejock]

Insert the pin from your dimple die. If it won't go in, you need to match drill.

 

[Dr_Dave_MT]

Insert the pin from your dimple die. If it won't go in, you need to match drill.

I took a piece of wooden dowel about 1.5”
Glued a -3 rivet on one side, -4 on other.
I can use that to quickly verify these newer parts are CNC punched to final size.
My empennage kit was a mix and Vans had put orange stickers or sharpie marks on part numbers to notify if they were not the new CNC final size. (Circa 2020)

 

[climberrn]

I met a -7 builder once that just dimpled parts right out of the box. Said the dimples die went through the holes easily. We ended up getting in an argument over it because he was told by a popular build center that’s the way it’s done and didn’t want to hear differently. Ended up just walking out.

His kit has since been sold. As Paul said, reach out to Vans with questions like this, or be darn sure the parts are final size before proceeding. FYI: I can attest my dimple dies can go right through sheet metal without pilot holes with minimal effort. Ask me how I know.

Insert the pin from your dimple die. If it won't go in, you need to match drill.

 

[Dr_Dave_MT]

I met a -7 builder once that just dimpled parts right out of the box. Said the dimples die went through the holes easily. We ended up getting in an argument over it because he was told by a popular build center that’s the way it’s done and didn’t want to hear differently. Ended up just walking out.

His kit has since been sold. As Paul said, reach out to Vans with questions like this, or be darn sure the parts are final size before proceeding. FYI: I can attest my dimple dies can go right through sheet metal without pilot holes with minimal effort. Ask me how I know.

Well, the physical act of dimpling the metal does indeed enlarge the diameter of the opening. I think Scott M once posted a comment about that effect. Vans support has never given me any grief on even my most “novice” questions. Just takes a little time to review and comment back. I take advantage of that free service as you can always move to another step I.e. deburring countless ribs as you await a response.

 

[wirejock]

I met a -7 builder once that just dimpled parts right out of the box. Said the dimples die went through the holes easily. We ended up getting in an argument over it because he was told by a popular build center that’s the way it’s done and didn’t want to hear differently. Ended up just walking out.

His kit has since been sold. As Paul said, reach out to Vans with questions like this, or be darn sure the parts are final size before proceeding. FYI: I can attest my dimple dies can go right through sheet metal without pilot holes with minimal effort. Ask me how I know.

I know that's been done. Some say the non-match drilled then dimpled hole yields a tighter final rivet hole. Good Maybe ok, but if the hole wasn't deburred and was undersized, the hole can crack from the dimple force. Might get away with it. Might not. At the very least, debur the holes.
Best ask Vans first.

 

[gkochers]

As the builder of an RV-10 that I started n 2021, it was a bit confusing during the transition to final holes. I initially interpreted that the final sized parts would be marked with a high lyes parts tag. The. When I started realizing my in,armed parts were final sized, I reread the addendum that came in the kit. Non-final sized holes were marked with highlighter. Starting from my empennage in 2021 and continuing through fuselage in 2023, I found that all holes in skins and ribs were final sized from Van’s. Yes, there may be a few substructure parts that you should double check. I suggest checking your parts with a -3 rivet, not with the dimple die. Larger holes should definitely be double checked.

As far as the assembly sequence, you will get more comfortable interpreting the instructions as you go. It is still good to do a dry run of the assembly to understand how it all goes together before priming (if you choose to) and dimpling everything. As you get more comfortable you will be able to skip some of the initial assembly steps and go straight to deburring and priming. Pay attention to the instructions for the words “match drill” vs “final drill” and make sure you understand the intent before skipping steps. There are many times that holes between parts are match drilled to each other at a smaller size and then final drilled to the correct size.

If in doubt just continue to follow the instructions and run a #40 reamer through the final size holes until you’re comfortable that you understand when it is not necessary. I final drilled almost every hole in my empennage before I figured out that I didn’t need to.

 

[280FX]

I know that's been done. Some say the non-match drilled then dimpled hole yields a tighter final rivet hole. Good Maybe ok, but if the hole wasn't deburred and was undersized, the hole can crack from the dimple force. Might get away with it. Might not. At the very least, debur the holes.
Best ask Vans first.

From my neighbor -

I thought that cracks in dimpled holes from the laser (mis)cut parts testing showed no issues, so why would cracks from an oversized dimple pilot be any different? To be clear, the build assist center that went straight to dimpling of undersized punched holes used special dimple dies to do so. The holes were deburred. Additionally, a well known former Van’s engineer did thorough testing of this process and showed no loss of strength. Use of these special dimple dies did not cause cracking of the dimpled holes - unlike dimpling of laser (mis)cut parts. I know this as I built two airplanes at this build assist center and asked a lot of questions when a former Van’s employee said here on VAF that the process wasn’t approved. It was tested and approved.

 

[RNB]

From my neighbor -

I thought that cracks in dimpled holes from the laser (mis)cut parts testing showed no issues, so why would cracks from an oversized dimple pilot be any different? To be clear, the build assist center that went straight to dimpling of undersized punched holes used special dimple dies to do so. The holes were deburred. Additionally, a well known former Van’s engineer did thorough testing of this process and showed no loss of strength. Use of these special dimple dies did not cause cracking of the dimpled holes - unlike dimpling of laser (mis)cut parts. I know this as I built two airplanes at this build assist center and asked a lot of questions when a former Van’s employee said here on VAF that the process wasn’t approved. It was tested and approved.

Thanks for all the going between you and your neighbor...especially for explaining the special dimple dies.

 

[wirejock]

From my neighbor -

I thought that cracks in dimpled holes from the laser (mis)cut parts testing showed no issues, so why would cracks from an oversized dimple pilot be any different? To be clear, the build assist center that went straight to dimpling of undersized punched holes used special dimple dies to do so. The holes were deburred. Additionally, a well known former Van’s engineer did thorough testing of this process and showed no loss of strength. Use of these special dimple dies did not cause cracking of the dimpled holes - unlike dimpling of laser (mis)cut parts. I know this as I built two airplanes at this build assist center and asked a lot of questions when a former Van’s employee said here on VAF that the process wasn’t approved. It was tested and approved.

I'm not an engineer.
My last sentence... Ask Vans. Maybe Scott will comment, and if I'm wrong, no harm.

 

[rvbuilder2002]

Well, the physical act of dimpling the metal does indeed enlarge the diameter of the opening. I think Scott M once posted a comment about that effect. Vans support has never given me any grief on even my most “novice” questions. Just takes a little time to review and comment back. I take advantage of that free service as you can always move to another step I.e. deburring countless ribs as you await a response.

I have commented about this in the past.
In a nutshell…

The process of dimple countersinking does enlarge the hole.
If you start with a number 40 hole diameter, the dimpling process opens up the hole to right at or just under the max recommended diameter in the mill spec.
All statically tested structures at Vans have been built with skins that were dimple countersunk after the holes were sized to number 40.
At Vans, we never endorsed dimple countersinking holes that had not been final drilled to number 40 because of the stretching that gets exerted on the edge of the hole when the dimple die pilot is forced in.
This was based on a concern for a higher likelihood of cracking on the hole perimeter.
A letter was issued to at least one of the build assistance centers many years ago that approved dimpling without final drilling if custom dimple dies with a reduced diameter pilot were used, but I am not aware that they ever implemented the use of custom dies.
I personally didn’t approve of this idea because of the knowledge of how surface finish and additional stretching because of the smaller size hole, can have an influence on the likelihood of cracks. Think of the laser cut parts fiasco.

As for what builders should do with uncertainty of whether their parts have final sized holes, or they require final drilling…
Just use a rivet as a go no go gauge
If a rivet will insert in the hole, then its diameter is the expected final diameter and it can be dimpled / riveted as is.
If a rivet will not insert, then the hole should be final drilled.

 

[rvbuilder2002]

I thought that cracks in dimpled holes from the laser (mis)cut parts testing showed no issues, so why would cracks from an oversized dimple pilot be any different?

That should be obvious…

The testing that validated the acceptance of radial cracks on skin dimples was only done recently.
It would’ve been irresponsible to approve a process that was known to cause cracking, without the knowledge of what influence it would have on the structural strength and fatigue longevity.

 

[climberrn]

I have commented about this in the past.
In a nutshell…

The process of dimple countersinking does enlarge the hole.
If you start with a number 40 hole diameter, the dimpling process opens up the hole to right at or just under the max recommended diameter in the mill spec.
All statically tested structures at Vans have been built with skins that were dimple countersunk after the holes were sized to number 40.
At Vans, we never endorsed dimple countersinking holes that had not been final drilled to number 40 because of the stretching that gets exerted on the edge of the hole when the dimple die pilot is forced in.
This was based on a concern for a higher likelihood of cracking on the hole perimeter.
A letter was issued to at least one of the build assistance centers many years ago that approved dimpling without final drilling if custom dimple dies with a reduced diameter pilot were used, but I am not aware that they ever implemented the use of custom dies.
I personally didn’t approve of this idea because of the knowledge of how surface finish and additional stretching because of the smaller size hole, can have an influence on the likelihood of cracks. Think of the laser cut parts fiasco.

As for what builders should do with uncertainty of whether their parts have final sized holes, or they require final drilling…
Just use a rivet as a go no go gauge
If a rivet will insert in the hole, then its diameter is the expected final diameter and it can be dimpled / riveted as is.
If a rivet will not insert, then the hole should be final drilled.

Thank you for clarifying. I’m sure there are several ways to fit the parts but following the plans and checking with Vans support before straying from Vans instructions should be the only right answer.