The Murphy Builders Site

I took a look thru the archives and couldn't find anything on optimimum
sizes for bits for drilling out blind rivits. It seems to me that if one
built an airplane one would probably quickly discover the best way to do
so but its not obvious if one has not built yet.

My first guess would be a drill bit the same size as the hole the rivit
was set in. On the other hand that might leave some meat as the bit
might not center exactly. Others might try significantly larger bits
based on other arguments. Hopefully I don't start some sort of religious
argument with this novice query.
--
Garry Wright
R-068 C-FOKM Amphib
403 931 1573
wrightdg@davincibb.net

Garry,
I've only drilled out a few (knock on wood). I like to use the same size
drill (#30). I find practically no tendency for it to wander off center till
it readches the mandrel, which is a good place to stop drilling! At that
point I use a snap punch to pop the mandrel out the bottem -- it is just the
right amount of small force applied suddenly to do the trick. Hole is left
pretty as ever.

BTW Gerry, C-FISH looks awesome. Way to go!
-Ben

I took a look thru the archives and couldn't find anything on optimimum
sizes for bits for drilling out blind rivits. It seems to me that if one
built an airplane one would probably quickly discover the best way to do
so but its not obvious if one has not built yet.

My first guess would be a drill bit the same size as the hole the rivit
was set in. On the other hand that might leave some meat as the bit
might not center exactly. Others might try significantly larger bits
based on other arguments. Hopefully I don't start some sort of religious
argument with this novice query.
--
Garry Wright
R-068 C-FOKM Amphib
403 931 1573
wrightdg@davincibb.net

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I took a look thru the archives and couldn't find anything on optimimum
sizes for bits for drilling out blind rivits. It seems to me that if one
built an airplane one would probably quickly discover the best way to do
so but its not obvious if one has not built yet.

My first guess would be a drill bit the same size as the hole the rivit
was set in. On the other hand that might leave some meat as the bit
might not center exactly. Others might try significantly larger bits
based on other arguments. Hopefully I don't start some sort of religious
argument with this novice query.
--
Garry Wright
R-068 C-FOKM Amphib
403 931 1573
wrightdg@davincibb.net




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Hi Garry I've drilled out more than a few rivets and what I have found is
that if you drill too deep so that the drill bit touches the mandrel the
bit will wander and leave you with an oversized hole. To get around that I
used to punch out the mandrel before drilling the rivet but what I find
works best now is to just drill the head part way then use a hammer and a
wood chisel to knock the head off flush with the metal. after that it's
relatively easy to punch out the rivet bodies or if the back side is
accesable I grab the rivet bodies with a pair of side cutting pliers and
just pull them out. Are you planning to repair your plane yourself?

At 09:44 PM 8/14/2005 -0600, you wrote:

I took a look thru the archives and couldn't find anything on optimimum
sizes for bits for drilling out blind rivits. It seems to me that if one
built an airplane one would probably quickly discover the best way to do
so but its not obvious if one has not built yet.

My first guess would be a drill bit the same size as the hole the rivit
was set in. On the other hand that might leave some meat as the bit
might not center exactly. Others might try significantly larger bits
based on other arguments. Hopefully I don't start some sort of religious
argument with this novice query.
--
Garry Wright
R-068 C-FOKM Amphib
403 931 1573
wrightdg@davincibb.net




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Drew





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Garry,

What I learned from this list 5+ years ago when I started R687 was to use a
pin punch to punch out the mandrel, then use a 1/8" drill bit to drill off
the head, then a pin punch to pop out the rivet barrel.

The 1/8" drill bit is slightly smaller than the original rivet hole (talking
#30 rivet hole) and if you go slow when drilling the rivet head, the head
will usually just twist off before the 1/8" drill bit enters the original
hole. If it doesn't spin off and it looks like the bit is about to enter the
original hole I will stop and use a soft faced punch and tap the edge of the
rivet head. I've also used a small block of wood instead of the soft faced
punch.

This procedure has worked for me and the drill never enters the original
rivet hole.

Hope this helps.

Roger Hoffman 687R
Eugene, OR USA!



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Garry,
I've only drilled out a few (knock on wood). I like to use the same size
drill (#30). I find practically no tendency for it to wander off center till
it readches the mandrel, which is a good place to stop drilling! At that
point I use a snap punch to pop the mandrel out the bottem -- it is just the
right amount of small force applied suddenly to do the trick. Hole is left
pretty as ever.

BTW Gerry, C-FISH looks awesome. Way to go!
-Ben

I took a look thru the archives and couldn't find anything on optimimum
sizes for bits for drilling out blind rivits. It seems to me that if one
built an airplane one would probably quickly discover the best way to do
so but its not obvious if one has not built yet.

My first guess would be a drill bit the same size as the hole the rivit
was set in. On the other hand that might leave some meat as the bit
might not center exactly. Others might try significantly larger bits
based on other arguments. Hopefully I don't start some sort of religious
argument with this novice query.
--
Garry Wright
R-068 C-FOKM Amphib
403 931 1573
wrightdg@davincibb.net

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Thanks Roger. I'll try that too.

On Mon, 2005-15-08 at 10:51 -0800, rognal@dcsol.com wrote:

Garry,

What I learned from this list 5+ years ago when I started R687 was to use
a
pin punch to punch out the mandrel, then use a 1/8" drill bit to drill
off
the head, then a pin punch to pop out the rivet barrel.

The 1/8" drill bit is slightly smaller than the original rivet hole
(talking
#30 rivet hole) and if you go slow when drilling the rivet head, the head
will usually just twist off before the 1/8" drill bit enters the original
hole. If it doesn't spin off and it looks like the bit is about to enter
the
original hole I will stop and use a soft faced punch and tap the edge of
the
rivet head. I've also used a small block of wood instead of the soft
faced
punch.

This procedure has worked for me and the drill never enters the original
rivet hole.

Hope this helps.

Roger Hoffman 687R
Eugene, OR USA!



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I took a look thru the archives and couldn't find anything on optimimum
sizes for bits for drilling out blind rivits. It seems to me that if one
built an airplane one would probably quickly discover the best way to do
so but its not obvious if one has not built yet.

My first guess would be a drill bit the same size as the hole the rivit
was set in. On the other hand that might leave some meat as the bit
might not center exactly. Others might try significantly larger bits
based on other arguments. Hopefully I don't start some sort of religious
argument with this novice query.

Hi Drew,

I will be doing as much as I can under the tutelage of an AME. I'm
hoping to develop at least some of the skills one gets in building the
airplane. Your method with the wood chisel will work well if the chisel
doesn't damage anything you want to retain. There will be more queries
of a similar nature as I go along. Thanks for the response.

Garry

On Mon, 2005-15-08 at 08:40 -0400, Drew Dalgleish wrote:

Hi Garry I've drilled out more than a few rivets and what I have found is
that if you drill too deep so that the drill bit touches the mandrel the
bit will wander and leave you with an oversized hole. To get around that I
used to punch out the mandrel before drilling the rivet but what I find
works best now is to just drill the head part way then use a hammer and a
wood chisel to knock the head off flush with the metal. after that it's
relatively easy to punch out the rivet bodies or if the back side is
accesable I grab the rivet bodies with a pair of side cutting pliers and
just pull them out. Are you planning to repair your plane yourself?

At 09:44 PM 8/14/2005 -0600, you wrote:

I took a look thru the archives and couldn't find anything on optimimum
sizes for bits for drilling out blind rivits. It seems to me that if one
built an airplane one would probably quickly discover the best way to do
so but its not obvious if one has not built yet.

My first guess would be a drill bit the same size as the hole the rivit
was set in. On the other hand that might leave some meat as the bit
might not center exactly. Others might try significantly larger bits
based on other arguments. Hopefully I don't start some sort of religious
argument with this novice query.
--
Garry Wright
R-068 C-FOKM Amphib
403 931 1573
wrightdg@davincibb.net




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Drew





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Good to hear you're doing the work Garry I'm sure you'll enjoy the process.
I forgot to mention that you should slightly round off the corners of your
wood chisel to keep them from scratching.

At 12:06 PM 8/15/2005 -0600, you wrote:

Hi Drew,

I will be doing as much as I can under the tutelage of an AME. I'm
hoping to develop at least some of the skills one gets in building the
airplane. Your method with the wood chisel will work well if the chisel
doesn't damage anything you want to retain. There will be more queries
of a similar nature as I go along. Thanks for the response.

Garry

On Mon, 2005-15-08 at 08:40 -0400, Drew Dalgleish wrote:

Hi Garry I've drilled out more than a few rivets and what I have found is
that if you drill too deep so that the drill bit touches the mandrel the
bit will wander and leave you with an oversized hole. To get around that I
used to punch out the mandrel before drilling the rivet but what I find
works best now is to just drill the head part way then use a hammer and a
wood chisel to knock the head off flush with the metal. after that it's
relatively easy to punch out the rivet bodies or if the back side is
accesable I grab the rivet bodies with a pair of side cutting pliers and
just pull them out. Are you planning to repair your plane yourself?

At 09:44 PM 8/14/2005 -0600, you wrote: Drew





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Drew





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FWIW I use 7/64th or 1/64 less than 1/8. I then break the head off by
inserting the back end of another 7/64 bit into the rivet head. Some
rivets require driving the mandrel back a bit with an automatic punch or
squeezing the back of the rivet with side cutters or end nippers to do
the same. End nippers work best if you have the room. That lets you
drill deep enough to break the head off. I have removed about 4000 of
the little devils in this manner without enlarging the holes.

For stainless drill at slow speed and I use a 1/8 cobalt bit. If not
using cobalt, a drop of oil helps keep the bit from overheating and dulling.

Ken

wrightdg wrote:

I took a look thru the archives and couldn't find anything on optimimum
sizes for bits for drilling out blind rivits. It seems to me that if one
built an airplane one would probably quickly discover the best way to do
so but its not obvious if one has not built yet.

My first guess would be a drill bit the same size as the hole the rivit
was set in. On the other hand that might leave some meat as the bit
might not center exactly. Others might try significantly larger bits
based on other arguments. Hopefully I don't start some sort of religious
argument with this novice query.

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I took a look thru the archives and couldn't find anything on optimimum
sizes for bits for drilling out blind rivits. It seems to me that if one
built an airplane one would probably quickly discover the best way to do
so but its not obvious if one has not built yet.

My first guess would be a drill bit the same size as the hole the rivit
was set in. On the other hand that might leave some meat as the bit
might not center exactly. Others might try significantly larger bits
based on other arguments. Hopefully I don't start some sort of religious
argument with this novice query.
--
Garry Wright
R-068 C-FOKM Amphib
403 931 1573
wrightdg@davincibb.net




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