Breaking the Edge...Help...

I'm up to the point of the tailcone construction on my RV-12 and the instructions call for "breaking" the edge of the sheets. I've experimented with both the modified vice grips and the round plastic thing with rollers. Both make a wavy mess in thin material like the .020 of the tailcone.

How has everyone done this with good success? I'd hate to ruin this part of the kit after everything else fits like a glove.

Thanks in advance,

Mitch Garner
RV-4 flying
PL-4 flying
RV-12 under construction

Breaking the Edge

Not being familiar with construction plans on the 12, to me "breaking the edge" says to use an edge tool to take the sharp burr left from the cutting process? Could be wrong.

Cleaveland Tool

The Cleaveland Tool worked worked for me. The trick to using it is not to clamp down very hard. If it is hard to pull along the edge, then it is too tight. It is better to make several passes with light pressure.
Joe

I like the modifier vise grips for this type work. I have not tried them on material as thin as .020 but would suggest not putting as much squeeze into the process. It doesn't take much bend for the edge to remain tight after the rivets are installed.

The 'round thing' is what I use and it works well with a bit of practice. The trick is to use light pressure, spend more effort keeping the tool on the sheet and less trying to twist it to make a bend. Most illustrations of using the tool make it look like you have to make a multi-degree bend all in one go. Instead, aim for a barely visible bend in three or four passes. I think the pliers version would work better for curved edges but I've never had anything like that which needed to have the slight bend put in.

I say throw them tools out and don't turn the edges.

When I did my sheetmetal work, the areas where I did turn the edges are way more visable than the areas where I stopped doing it. I never have had a properly fit skin raise up after riveting so I think this step is just asking for problems.

Cleveland

A second vote for the Cleveland tool. I used it on my 12 and they came out perfect.

Brantel said:

I say throw them tools out and don't turn the edges.

When I did my sheetmetal work, the areas where I did turn the edges are way more visable than the areas where I stopped doing it. I never have had a properly fit skin raise up after riveting so I think this step is just asking for problems.

Click to expand...

Maybe this worked for a -7 but the F-1278 upper tailcone skin on the -12 needs it.

I have both the avery and cleveland tool. The cleveland tool works best on long skins. Multiple passes for the best result. The avery worked well for the wing walk doubler.

Good luck!

WHOA!

The original poster asked about "breaking edges". This requires a file or edge deburring tool, NOT a rolling tool like the photos posted here or discussed. That is an entirely DIFFERENT operation! "Breaking" an edge just removes any sharp corners from the part. See
http://www.eng-tips.com/viewthread.cfm?qid=238675&page=5

The rolling tools depicted in this thread are for putting a slight bend in the edge of a piece of sheet metal so that when it is riveted to an adjacent sheet, there is a slight preload between the two which tends to eliminate any gaps. Nothing to do with breaking the edge...

Garmin737 has it right, the Cleveland tool is right for most of the work, I did use the Avery tool for the area on the two tail cone skins that we are told to use more break on. The key to the Avery tool is to make one pass at a time at a constant speed as any stop will likely leave a mark.

Best regards,
Vern

Noah said:

The original poster asked about "breaking edges". This requires a file or edge deburring tool, NOT a rolling tool like the photos posted here or discussed. That is an entirely DIFFERENT operation! "Breaking" an edge just removes any sharp corners from the part. See
http://www.eng-tips.com/viewthread.cfm?qid=238675&page=5

The rolling tools depicted in this thread are for putting a slight bend in the edge of a piece of sheet metal so that when it is riveted to an adjacent sheet, there is a slight preload between the two which tends to eliminate any gaps. Nothing to do with breaking the edge...

Click to expand...

If you read section 5 of your construction manual you will find that this is the nomenclature used by vans for this process.

There also are a lot of things that builders of other RV models (even very experienced builders) can not correlate to the RV-12 without having built one.
Breaking the edges is one of those things.
I fully agree with Brantel...it is something that is commonly over done on RV's. The intent is to only do just enough and only when it is really needed. The challenge is determining (particularly for a novice) when it is really needed.
The RV-12 is different. There are a few places that it has been predetermined from shop experience that breaking the edge is required. The great thing about the RV-12 is that those places are specified in the construction manual (which is the reason for the O.P. starting this thread).

more than one meaning

Many words in the English language have more than one meaning. The words brake and break have several. Definition 4 below is the meaning that pertains to the tail skins on the RV-12. Some of the tail skins are curved to such an extent that a noticeable gap would be present without braking the edge. It a builder skips this step, then he has not followed the plans and might not be able to register his RV-12 as an E-LSA (if the inspector wants to be picky). Do a Google search on "sheet metal brake". Make sure to include the quotes.
Joe

brake (br?k) noun
1. A toothed device for crushing and beating flax or hemp.
2. A heavy harrow for breaking clods of earth.
3. An apparatus for kneading large amounts of dough.
4. A machine for bending and folding sheet metal.

The American Heritage? Dictionary of the English Language, Third Edition copyright ? 1992 by Houghton Mifflin Company. Electronic version licensed from InfoSoft International, Inc. All rights reserved.

Mich48041 said:

Many words in the English language have more than one meaning. The words brake and break have several. Definition 4 below is the meaning that pertains to the tail skins on the RV-12. Some of the tail skins are curved to such an extent that a noticeable gap would be present without braking the edge. It a builder skips this step, then he has not followed the plans and might not be able to register his RV-12 as an E-LSA (if the inspector wants to be picky). Do a Google search on "sheet metal brake". Make sure to include the quotes.
Joe

brake (brâk) noun
...4. A machine for bending and folding sheet metal.
.

Click to expand...

OK, I'll buy that. I think I see the source of the confusion. The original poster (and everyone else in this thread) misspelled the word "brake". "Braking the edge" means to bend it (although I've never seen brake used as a verb before), as in a sheet metal bending brake, while "breaking the edge" means to remove sharp edges. Obviously, totally different operations. Like your 7th grade English teacher said, "Spelling counts"!

Breaking edges

Van's uses "breaking" to me putting a slight bend in edges that will overlap. I used tthe disk with rollers (my first experience with breakling edges) and it came out OK using multile passes as everyone recommends. Somme sjightr waviness after riviting (too much bend?) can be reduced by rubbing the edge with a block of wood or a wallpaper edge rolling tool.

Wayne 120241
emp kit done, only wingtips left on wings

Sorry to get everyone riled up on the lingo. I was just asking RV-12 folks for a little help...and Van's plans do use the word "break", not "brake".

Mitch

RV-4 flying
RV-12 under constuction

Breaking

Mitch, I just finished my tailcone and here's my breaking experience: I used the Avery "disc", following the instructions in the plans on which sheets to break. Everything looked good until I clecoed the top skin and it was clear more breaking was in order.

I learned the hard way on my 6A that too much break is not a good thing, so I created a more gradual break by putting washers under the rollers on the disc. This prevented the dreaded "line" from overbreaking. It worked out fine and that top skin is snugged down nice with a large radius, invisible break.

I might add that you can evaluate your breaking progress with a straight-edge and penlight. Good luck.

Breaking the edged

Van's instructions re 'breaking the edge' does not refer to deburring, it means to use the Avery vise grip rollers or the 'round' thingy to put a slight bend in the edges of those tail cone sheets, so that when you rivet them the edge lays down flat rather than curls up a bit.

I use one of those 'round thingys' on both my RV-6A and the RV-12 tail cone and it works perfectly. It isn't really 'fussy' to do at all. I just used long strokes and then went over the edges again gently and it worked out perfectly.

Throw out the tools!

All the tools supplied to me in the past to do this can result in very nasty results if you slip. The temptation is to apply too much force and you end up buckling the sheet or leaving unsightly marks in the alclad.

The method that has worked best for me is to take a piece of timber (say 2 X 2 X 6 inches) and cut a slot in it with the bandsaw near the base.

The slot needs to be about half an inch deep and at right angles to the grain. Ideally, you want the slot to be just a bit wider than the edge of your sheet so it fits snugly.

Place the sheet on a work bench and run your newly constructed tool along the edge. As you move along the edge, hold the top of the use the tool to lever and brake the edge in the direction you need. Your other hand support the base near the sheet to stop it coming out. You don't do this in one pass. Less is more. Take it slowly and make many passes till the brake is just right.

I suggest you experiment on some scrap. You will find the wider the timber (longer slot) the better the results will be. You can experiment with different grades of timber, sizes and cut angles on the slot to see what works.

Done properly, you will end up with a very smooth brake in your sheet. Remember, the intention is that the sheet sits down when you rivet it. Too much bend is unsightly, not enough and it will pucker up.

Best of all, the tool is cheap!

Richard

Noah said:

(although I've never seen brake used as a verb before), )

Click to expand...

"At the stop sign, make sure to brake to a full stop."
Brake gently on slippery road surfaces.

I tried to get the Cleveland tool and could not so had to settle for the round one. I have only completed the emp kit and found it to work well. I was worried about the wavy issue but as posted above, make a few light passes and concentrate more on the following:


Keep the tool flush against the sheet to stop it slipping off.
Keep the two rollers at a 90 degree angle. I think that the wavy finish comes from twisting the tool a bit so that the two rollers are no longer each at 90 degrees to the sheet.

cheers
Reilly