My First Mistake.

Jeff Moreau · Post by **Jeff Moreau** » Mon Dec 06, 2004 2:39 pm

Unfortunately I had to order two HS-405 replacement ribs for my RV8 this morning.

Here is how it happened. I was progressing nicely with drilling my horizontal stab. It came time to mate the front flange of the HS-405 to the HS-702 and HS-810-1 and HS-814-1.
This is to be done using the holes previously pilot drilled to #40 in the forward flange of HS-405 as a drill guide.
The instructions say that it is best to use an angle drill for this step.
No problem I thought. I'll use the angle drill set that came in my Avery's RV builders tool kit. It looks like a wonderful tool but beware! ! !
When I started to drill the hole the bit started to wander in the hole and acted more like a small router than a drill bit. Now mind you, this is the first time that I have attempted to use this angle drill on an actual aircraft part, but the way it chewed the hole up I can say that I would recommend it or use it in the future. If you are getting ready to drill these holes anytime soon all that I can offer as advice is BE CAREFUL!
I hope this helps someone avoid the mistake that I made.
And P.S. Yes I ruined both HS 405 ribs attempting to drill the holes.
I am now looking for a new solution to drill the holes.
Any advice will be greatly appreciated.

Post by **Spike** » Mon Dec 06, 2004 3:34 pm

Hmm, are you saying that you think its the drill's fault or your fault? Im a bit unclear on that. If its the drill's then I'd be interested in knowing why. I will have to get one in the future and want to know what I should stay away from

-- John

Jeff Moreau · Post by **Jeff Moreau** » Mon Dec 06, 2004 4:20 pm

spike wrote:Hmm, are you saying that you think its the drill's fault or your fault? Im a bit unclear on that. If its the drill's then I'd be interested in knowing why. I will have to get one in the future and want to know what I should stay away from

-- John

I believe the drill is the culprit. The head of the drill is a bit too large to fit in the area that is required. It has to rest against the 405 and this places a bit of side stress against the bit and causes it to wander.
Believe me, I was extremely careful (considering that I had already damaged one rib) and it happened again a second time.

Post by **Spike** » Mon Dec 06, 2004 4:50 pm

Ok got it. Sounds like its not so much a tool quality issue as much as it possibly being the wrong tool, or at least not a good variant for that particular job. Thanx for the info

-- John

arffguy · Post by **arffguy** » Mon Dec 06, 2004 8:55 pm

I am not sure with your pre-punch parts but with my empennage I used those foot long number 40 and 30 drill bits. You have to bend it slightly then guide it with your other hand but it works. (I personally prefer to drill the holes smaller, cleco them together with a silver cleco then enlarge later when separated. Replace with copper cleco if needed. However if you listen to the tool purists the best way to enlarge a hole is with a reamer.)

captain_john · Post by **captain_john** » Mon Dec 06, 2004 9:37 pm

arffguy wrote:I am not sure with your pre-punch parts but with my empennage I used those foot long number 40 and 30 drill bits. You have to bend it slightly then guide it with your other hand but it works. (I personally prefer to drill the holes smaller, cleco them together with a silver cleco then enlarge later when separated. Replace with copper cleco if needed. However if you listen to the tool purists the best way to enlarge a hole is with a reamer.)

Ditto on the 12" drill bit. Negatory on the reamer. I haven't used a reamer before, but the side cutting action scares the bejesus out of me. I am afraid of accidentally elongating the hole.

CJ

Guest · Post by **Guest** » Tue Jan 18, 2005 11:30 pm

Here's another thing to watch out for.....
When I drilled these holes the first time, I used an angle drill with a short bit. I had to slightly angle the "angle drill" and as it started to cut through the material, the chuck pushed-up against the rib and made the hole oval.
The second time I did this, I used the angle drill attachment but with a long (12 inch, or so) bit.

Dave