I hate machine countersink ....

Post by **Spike** » Fri Jan 07, 2005 5:47 pm

No, didnt have the heart, besides, Id rather continue to whine

captain_john · Post by **captain_john** » Fri Jan 07, 2005 5:58 pm

So did you measure the thickness? Is it .040" or better?

BTW, just to muddy the waters for ya... another fix is to back it up with a sliver of aluminum 3/8" square and it'll be fine.

CJ

Post by **Spike** » Fri Jan 07, 2005 6:59 pm

Captain_John wrote:So did you measure the thickness? Is it .040" or better?

BTW, just to muddy the waters for ya... another fix is to back it up with a sliver of aluminum 3/8" square and it'll be fine.

CJ

No I didnt measure it but I believe it to be bigger than .040.

And your not muddying the waters cause it was too messed up to use aluminum to back it up. The trench was just about into the webbing in on area. I dont think we could back it up.

-- John

Bob Barrett · Post by **Bob Barrett** » Fri Jan 07, 2005 9:58 pm

Welcome to RV Building! I screwed up the rear spar of the horizontal stablizor on my RV-6A and had to buy new parts for $27.00 you got a bargin. Van's in 1999 figured the average builder would spend between $300 and $400 on replacement parts. I am getting close to halfway there!
Keep the old material I still use my firs Horzontal Spar material to test drill holes, set the depth on my countersink tool etc. In reality it was $27 well spent. With pre-punched kits it should take less in replacement materials! Good luck!

Post by **Spike** » Sat Jan 08, 2005 3:43 pm

Thanx for the info Bob. The closure to this issue is that everyone agreed that ordering a new spar was the correct road to go.

For you dimpling types out there I got around to measuring the spar last night. Sit down for this. The 9's HS spars are a whopping .062" thick. No dimpling there.

Poeboy came over last night for a few hours for the express purpose of turning my junk spar into swiss cheese. He hasnt had to do any countersinking in a while so we figured it would be good practice for the both of us. The end result was that placing some scrap stock or wood behind the holes, match drilled to the holes completely eliminated any elongation issues. Couple that with a bit of beolube in the holes and they come out perfectly as chatter is eliminated, etc. I wont every countersink a hole again without doing it this way.

Ive started the countersinking on the remaining spars and so far its absolutely beautiful!! Thanx guys (especially Poeboy) for helping figure this one out. I got my mojo back

-- John

arffguy · Post by **arffguy** » Tue Jan 11, 2005 10:14 pm

dcheckoway wrote:Don't machine countersink that stuff. Dimple it.

Dan you built a 7. The RV-9 spars are at least .040. They have to be countersunk. The RV-3, 4, 6, 7 and 8 use .032 spars which can be dimpled. I was just comparing them in a hangar yesterday as a matter of fact.

Also when countersinking it is best to have a backing piece of metal to help guide the pilot and keep it from hogging out the hole.

Also, it is interesting how Van's engineers made the forward and rear horizontal tail spars from four identical pieces and used the same two rib styles throughout in that RV-9 horizonatl stab.

Guest · Post by **Guest** » Tue Jan 18, 2005 11:51 pm

Another thing you might try...
Use a slow turning drill. I use my DeWalt cordless for countersinking.
I also do it by hand occasionally(as someone mentioned).
When you get to the tank attach nutplates on the main spar, you'll either get good at this or you'll be buying an expensive pre-fab'd main spar. I was scared for a week before I cut my first countersink. That spar sure looks expensive.

I used a slow turning drill with a plate clecoed (side-grip) on the underside to give the pilot something to hold onto. Worked out.

Dave
-8 Wings

prestwich · Post by **prestwich** » Sun May 22, 2005 10:56 am

Since I haven't even started my practice kit yet, and the tail kit hasn't arrived, I may be too much of a newbie to be offering suggestions. But, although I'm not a machinist, I do work in a company that has a machine shop and I do go in there frequently to make tooling to support my assemblers.

Countersink bits are designed to work at SLOW speeds. Even with the workpiece clamped firmly in a milling machine vice, a countersink will chatter like crazy at high RPM. Have any of you tried putting these cutters into your cordless electric screwdrivers? I'd get that speed down between 50 and 100 RPM for countersinking. If it's a blur as it turns, it's too damn fast.

prestwich · Post by **prestwich** » Sun May 22, 2005 11:04 am

Sorry "guest," I didn't see your post before responding to the others in the thread. So, I'm heartily "seconding" your idea.

gsimatos · Post by **gsimatos** » Sun Nov 26, 2006 7:50 pm

OK, i have been at this 3 weeks and I am 6 weeks behind the 8-ball on my 7 tail. Countersunk the VS doubler 808-PP to accept the VS 803-PP spar dimples. i gently counter sunk the until the mating surfaces were flush with no standoff. Then I read this thread last nite and I think I am too deep. In this case not a good thing. In the hangar today and put a rivet in to the counter sunk holes and well, they sorta just dissapear in the doubler. Move to chapter 5 in the manual and I am pretty sure I am too deep. This is a critical structure already causing one sleepless nite. You guys may have some comments but I think the real issue is "does anyone know what a new spar will cost?". I guess it is time for my first parts call the Van's in the morning. One other thing, it is snowing, Merry Xmas G

TomNativeNewYorker · Post by **TomNativeNewYorker** » Sun Nov 26, 2006 9:33 pm

Slow is the key. Slow turning speed with a light touch will always work better than a faster speed or a heavy hand.

If you drill the holes using a #30 drill bit, you need to use a #30 piloted countersink, not a 1/8" pilot. the smaller 1/8" pilot gives you .0035" of slop to help you mess up in a New York minute.

Best thing to do is practice your countersink setup on a piece of the same type of material and thickness before trashing a good part.

captain_john · Post by **captain_john** » Sun Nov 26, 2006 9:33 pm

Well, you DO want the c-sinks in the doubler to be a shade deeper for the skin to nest properly.

You MAY NOT require a new dubblah!

How about posting some pics so we can see them?

A doubler isn't going to run you much loot. Look it up on "the list".

Post us a pic!!!

CJ

gsimatos · Post by **gsimatos** » Sun Nov 26, 2006 9:49 pm

Captain J and Co. Thanks for your reply. Anybody can wreck RV parts. It takes a real bonehead to not be able to post pics. I have a mac and I haven't been able to post anyy phtos so far. Our colleague from Australia had some suggestions a few weeks ago but so far no success. Back to the doubler, I had the counter sink set up nice But my brain told me there should be no conflict between the dimple and the countersunk hole. i figures this would make the rivet high or proud as they say. So i kept removing material til they nestled nicely but with compression of the material I think the rivet will still be below the surface and not fully cinch if ya see what I mean. i am going to get my kid to help me with the picture posting. Finally how can I access this 'list' ? I don't see it on the van's sight. Did the wright brother's have these problems?? Thanks you guys, I am bound to get smarter, aren't I??G

Anonymous · Post by **Anonymous** » Sun Nov 26, 2006 9:58 pm

here is a link to 'the list' http://www.vansaircraft.com/public/parts.txt

captain_john · Post by **captain_john** » Sun Nov 26, 2006 10:22 pm

I thought Macs were supposed to be easier to use?

Hmmmm, guess not?

Send them to me in an email and I will post 'em.

CJ

Post by **Spike** » Mon Nov 27, 2006 10:41 am

I paid under $30US for my new spar. I made swiss cheese out of the old one to practice my technique. Countersinking no longer bothers me. Practice it!

- John

captain_john · Post by **captain_john** » Mon Nov 27, 2006 4:44 pm

gsimatos wrote:OK, i have been at this 3 weeks and I am 6 weeks behind the 8-ball on my 7 tail. Countersunk the VS doubler 808-PP to accept the VS 803-PP spar dimples. i gently counter sunk the until the mating surfaces were flush with no standoff. Then I read this thread last nite and I think I am too deep. In this case not a good thing. In the hangar today and put a rivet in to the counter sunk holes and well, they sorta just dissapear in the doubler. Move to chapter 5 in the manual and I am pretty sure I am too deep. This is a critical structure already causing one sleepless nite. You guys may have some comments but I think the real issue is "does anyone know what a new spar will cost?". I guess it is time for my first parts call the Van's in the morning. One other thing, it is snowing, Merry Xmas G

Gary's pic:

CJ

Wicked Stick · Post by **Wicked Stick** » Mon Nov 27, 2006 6:53 pm

Spike,

The reason it walks as bad as it did, is that the depth of the material has nothing left to hold the bit steady on.

Whenever I'm countersinking thin stuff, I ALWAYS back it up with a piece of compressed board or plywood. Compressed board is best.

Drill and cleco the part your going to countersink to a piece of board.
Then you can simply countersink with a cordless or air drill (Sioux in my case) and the bit will never walk cause it will stay steady in the board hole.

Here's a link to a picture I took and put on the RV-8 Yahoo group I belong to.

http://us.a2.yahoofs.com/groups/g_hr_12 ... FBDIdzpbbS
http://ph.groups.yahoo.com/group/RV-8/p ... 20&m=f&o=0

On the second link, you can see from this angle that I placed an equaly thick piece of aluminum sheet up against the piece I was countersinking to help keep it level on narrow parts.

Post by **Spike** » Mon Nov 27, 2006 7:27 pm

Ya David, I fixed that problem a year ago

Gary brought this thread back up because he was having problems with countersinking too deeply.

As for the picture Gary, I say replace the spar. Put a rivet in and look on the backside and compare the size of the hole to the size of rivet shank.

-- Spike

Wicked Stick · Post by **Wicked Stick** » Tue Nov 28, 2006 12:46 am

Doh !,

I gotta start reading the date's on these things...LOL.

RivetBangers.com

I hate machine countersink ....

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