A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Home Built
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

aluminum rib, aluminum spar, holes drilled but screws broken off



 
 
Thread Tools Display Modes
  #11  
Old December 14th 06, 12:29 AM posted to rec.aviation.homebuilt
jls
external usenet poster
 
Posts: 60
Default aluminum rib, aluminum spar, holes drilled but screws broken off


jls wrote:
I'm rebuilding a Super Cub wing and the flanges on the ribs and the


blahblahblah. Larry, you damn long-winded thing, you.

OK, guys, here's what the friendly engineer says. Use a 3/32 cobalt
drill bit. Drill at 28k rpm or better and use cutting oil, ie,
kerosene and lard. Hit it and back it off; hit it and back it off.

Will let you know how it works, although I bought a lot of that other
recommended stuff and a diamond burr the dentists use.

  #12  
Old January 2nd 07, 12:34 PM posted to rec.aviation.homebuilt
Charles
external usenet poster
 
Posts: 3
Default aluminum rib, aluminum spar, holes drilled but screws broken off



Lots of good advice given but there's one problem that hasn't been
addressed. That's keeping the drill bit in the broken screw and not
letting it wander off into the spar. if the screw has been broken off
under flush there's not an easy way of dressing up the surface for a
good start. To keep from really messing up the job you may want to make
a drill guide to keep the bit aligned and going straight into the
broken screw.
A piece of 1/2" square steel stock about 8" long from any hardware
store will do. Set it up in a drill ress and drill a hole the size of
the bit you want to use through one side directly through. Set the bar
on the spar and line up the hole over the broken screw and then clamp
the bar down securely to the spar flange. Now you can drill through the
bar into the broken screw with far less chance of needing one of those
special figure eight shaped screws to cover the mess you made.
Any good quality SHARP drill bit will do the job with the correct
technique. For drilling out steel screws, use a slower RPM and more
pressure than for drilling aluminum. Start with a couple of light taps
at high RPM to ensure the drill gets a good center on the broken screw
shank or use a small center punch that will fit through the guide.
Using cutting oil is a good idea.
I don't think the Craftsman extractors are small enough for a #4
screw. I would go with a left handed bit, mouse milk, and take my time.

  #13  
Old January 2nd 07, 10:24 PM posted to rec.aviation.homebuilt
Roger[_4_]
external usenet poster
 
Posts: 677
Default aluminum rib, aluminum spar, holes drilled but screws broken off

On 2 Jan 2007 03:34:14 -0800, "Charles" wrote:



Lots of good advice given but there's one problem that hasn't been
addressed. That's keeping the drill bit in the broken screw and not
letting it wander off into the spar. if the screw has been broken off
under flush there's not an easy way of dressing up the surface for a
good start. To keep from really messing up the job you may want to make
a drill guide to keep the bit aligned and going straight into the
broken screw.
A piece of 1/2" square steel stock about 8" long from any hardware
store will do. Set it up in a drill ress and drill a hole the size of
the bit you want to use through one side directly through. Set the bar
on the spar and line up the hole over the broken screw and then clamp
the bar down securely to the spar flange. Now you can drill through the


I would suggest using a "center drill" that just nicely fits the hole
in the steel plate at this point. It won't wander and will create a
nice cone shaped indentation in the screw shank.

Then switch to a drill and metal plate with a hole that fits the
drill. A good sharp drill *should*follow the screw

bar into the broken screw with far less chance of needing one of those
special figure eight shaped screws to cover the mess you made.
Any good quality SHARP drill bit will do the job with the correct
technique. For drilling out steel screws, use a slower RPM and more
pressure than for drilling aluminum. Start with a couple of light taps
at high RPM to ensure the drill gets a good center on the broken screw
shank or use a small center punch that will fit through the guide.
Using cutting oil is a good idea.
I don't think the Craftsman extractors are small enough for a #4
screw. I would go with a left handed bit, mouse milk, and take my time.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
  #14  
Old January 3rd 07, 09:06 AM posted to rec.aviation.homebuilt
[email protected]
external usenet poster
 
Posts: 111
Default aluminum rib, aluminum spar, holes drilled but screws broken off

I just looked, and the Craftsman extractors I referenced go down to a #
5 screw. It had a reference for a size smaller than #6, and I thought
it was a #4, but alas.

Bud


Charles wrote:
Lots of good advice given but there's one problem that hasn't been
addressed. That's keeping the drill bit in the broken screw and not
letting it wander off into the spar. if the screw has been broken off
under flush there's not an easy way of dressing up the surface for a
good start. To keep from really messing up the job you may want to make
a drill guide to keep the bit aligned and going straight into the
broken screw.
A piece of 1/2" square steel stock about 8" long from any hardware
store will do. Set it up in a drill ress and drill a hole the size of
the bit you want to use through one side directly through. Set the bar
on the spar and line up the hole over the broken screw and then clamp
the bar down securely to the spar flange. Now you can drill through the
bar into the broken screw with far less chance of needing one of those
special figure eight shaped screws to cover the mess you made.
Any good quality SHARP drill bit will do the job with the correct
technique. For drilling out steel screws, use a slower RPM and more
pressure than for drilling aluminum. Start with a couple of light taps
at high RPM to ensure the drill gets a good center on the broken screw
shank or use a small center punch that will fit through the guide.
Using cutting oil is a good idea.
I don't think the Craftsman extractors are small enough for a #4
screw. I would go with a left handed bit, mouse milk, and take my time.


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
misdrilled hole on on tubular aluminum spar question patrick mitchel Home Built 12 October 2nd 06 08:17 PM
Question about Alodine 1201 Andrew Sarangan Home Built 20 April 11th 06 01:31 PM
Looking for Cessna Caravan pilots [email protected] Owning 9 April 1st 04 02:54 AM


All times are GMT +1. The time now is 07:58 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AviationBanter.
The comments are property of their posters.