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Drill Bit Durability

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dvanlanen

Joined: 25 Jul 2006
Posts: 122
Location: Madison, WI

Posted: Fri Feb 02, 2007 6:58 pm Post subject: Drill Bit Durability

Can anyone who has finished their aircraft give me a ballpark idea of how many holes I should typically be able to get out of a hi-moly drill bit (#30 and #20)?  

Thanks,  

Dave      [quote][b]

p.mulwitz(at)worldnet.att
Guest

Posted: Fri Feb 02, 2007 10:07 pm Post subject: Drill Bit Durability

Hi Dave,



 I use the threaded drill bits meant for aircraft use.  I don't think they are particularly hard alloys, but they work really well and don't have problems slipping in your drill chuck as you finish each hole.



 I start each hole with a #40 drill.  I then use #30 and optionally #20 to enlarge the holes.  This means I virtually never need to sharpen or replace anything but the #40 drills.  I sharpen the #40s using a bench grinder - maybe once a month - when they get dull.  I am more likely to break one than to sharpen it too many times.  I keep a supply of 2 or 3 spares and order more once a year or so.  I am still on my first #30 and #20.



 I highly recommend you consider buying the right angle drill gizmo from Aircraft Spruce that comes with adapters and a few screw mount drill bits.  I think the ones threaded 1/4 x 28 are the best choice.  Take a look:  http://www.aircraftspruce.com/catalog/topages/tightfittoolkit.php

 

 Good luck,



 Paul

 XL fuselage



 

 At 06:57 PM 2/2/2007, you wrote:



  	  Quote: 	
		  Can anyone who has finished their aircraft give me a ballpark idea of how many holes I should typically be able to get out of a hi-moly drill bit (#30 and #20)?

 

 Thanks,

 

 Dave

 	
 

 ---------------------------------------------

 Paul Mulwitz

 32013 NE Dial Road

 Camas, WA 98607

 ---------------------------------------------

     [quote][b]

dredmoody(at)cox.net
Guest

Posted: Sat Feb 03, 2007 8:23 am Post subject: Drill Bit Durability

And don't spin them as fast as an airdrill or a  high speed electric drill can. The heat of too high a speed shortens the cutting  life. Before you ask what rpm is best, I just learned from my dad saying "slow  it dow.... where's the fire?"  so it's become a listen and feel thing for  me but I'd guess you're safe around 650 -800 rpm.

  

 Dred

 [quote]   ---

agustafson(at)chartermi.n
Guest

Posted: Sat Feb 03, 2007 10:45 am Post subject: Drill Bit Durability

---

Jaybannist(at)cs.com
Guest

Posted: Sat Feb 03, 2007 11:05 am Post subject: Drill Bit Durability

To answer the original question:



I don't tolerate dull bits very well and I don't sharpen them.



I have probably used 5 or 6 each of #30 & #40 bits, and 3 or 4 #20.  Again, I used fewer #20s because they were always used in pre-drilled holes.



Jay in Dallas

Do not archive

 	  Quote:

naumuk(at)alltel.net
Guest

Posted: Sat Feb 03, 2007 12:44 pm Post subject: Drill Bit Durability

Aaron-

     You must live in a temperate  region! I didn't have any temperature when I got up this morning.

                                  do  not archive

 Bill Naumuk

HDS Fuselage

Townville,  Pa

 [quote]   ---

cookwithgas(at)HOTMAIL.CO
Guest

Posted: Sat Feb 03, 2007 2:57 pm Post subject: Drill Bit Durability

Dave:



I built both wings and half my fuselage with one drill bit of each size.  

When I lost one, I ordered two more and finished the plane.  Buy three or 

four of each and don't lose them and you will be good to go.



Scott Laughlin

CH601XL

Omaha, Nebraska

www.cooknwithgas.com

Still Polishing

Time: 06:58:40 PM PST US

From: "Dave VanLanen" <davevanlanen(at)sbcglobal.net>

Subject: Drill Bit Durability



Can anyone who has finished their aircraft give me a ballpark idea of how

many holes I should typically be able to get out of a hi-moly drill bit (#30

and #20)?



Thanks,

Dave



_________________________________________________________________

FREE online classifieds from Windows Live Expo – buy and sell with people 

you know

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Sun Feb 04, 2007 5:49 am Post subject: Drill Bit Durability

When drilling aluminium I tend to use a high speed.... As fast as possible

and just let the bit drill the hole.  I too sharpen my bits on a bench

grinder and if I have time I take out the bit sharpener which is actually

nothing more than a fancy bit guide for sharpening.  I've even reformed

heads on broken bits to get a hole drilled.



I never use any pressure on the drill at all.  Steel is another matter.  As

slow as possible, fair pressure and a good supply of cutting oil.



Certainly you should always have a reasonable supply of  #s 40,30 and 20

because the only time you will need another one is when the tool shop is

closed.



If you use a deburring tool it may be a good idea to have an extra one of

those on hand too.  Generally I use a 3/8 bit in my hand to de burr....

Just remember to deburr gently or you could end up chamfering your hole.



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

tshank(at)core.com
Guest

Posted: Sun Feb 04, 2007 8:08 am Post subject: Drill Bit Durability

Dave,

 I received one #20 and #30 bit with  my rudder kit many years ago. My drill fell one day and broke off the end of the #30 bit, Thus I went to Sears Hardware and bought an extra of each, by the way I resharpened and still use the shortened bit. I still have them and use them. The trick is to either learn how to sharpen then freehand or buy a sharpener. Other than breakage or loss a single drill bit will last for the whole project. You will want to invest in the right angle and long bits to reach those places where you just can't get the drill in.

 

 Tim Shankland

 

 Dave VanLanen wrote: [quote]         Drill Bit Durability    

Can anyone who has finished their aircraft give me a ballpark idea of how many holes I should typically be able to get out of a hi-moly drill bit (#30 and #20)?   

Thanks,   

Dave    	  Quote: 	
		  

	
 [b]

Crvsecretary(at)aol.com
Guest

Posted: Sun Feb 04, 2007 9:57 am Post subject: Drill Bit Durability

Hello fellow listers:

  

 Just a comment on resharpening these small drill bits...

  

 I don't believe the typical hobbyist can accurately resharpen drill bits  except with a middle to high end sharpener, and with the capital expense  involved, why bother?  Freehand sharpening can only approximate the angles  involved (yes, I agree small drill bits do not have to involve reducing the web  and other intricate angles) and with the best of freehand sharpening,  you will only get one of the cutting edges working at a time.  Not a  good practice where the goal is nice, round holes.

  

 For amateurs like me and others who do not have the benefit of being, or  working with machinists with a LOT of gray hair earned with years of trying to  accurately resharpen drill bits, I say use 'em & pitch 'em.

  

 They are cheap enough; when they stop cutting quickly, toss 'em.  That  being said, with high cutting speeds and low feeds (light pressure on  the drill), a good quality drill bit cuts LOTS of holes.

  

  Tracy  Smith

Naugatuck, CT

601xl N458XL (reserved)

  

  

 In a message dated 2/4/2007 11:09:27 AM Eastern Standard Time,  tshank(at)core.com writes:

  	  Quote: 	
		  Dave,

I received one #20 and #30 bit with  my rudder kit many    years ago. My drill fell one day and broke off the end of the #30 bit, Thus I    went to Sears Hardware and bought an extra of each, by the way I resharpened    and still use the shortened bit. I still have them and use them. The trick is    to either learn how to sharpen then freehand or buy a sharpener. Other than    breakage or loss a single drill bit will last for the whole project. You will    want to invest in the right angle and long bits to reach those places where    you just can't get the drill in.



Tim Shankland



Dave VanLanen    wrote:     	  Quote: 	
		            

Can anyone who has      finished their aircraft give me a ballpark idea of how many holes I      should typically be able to get out of a hi-moly drill      bit (#30 and #20)?     

Thanks,     

Dave      

      

	
	


  [quote][b]

p.mulwitz(at)worldnet.att
Guest

Posted: Sun Feb 04, 2007 2:11 pm Post subject: Drill Bit Durability

Hi Tracy,



I respect your position on resharpening drill bits, as well as your 

analysis of some of the issues involved.  On the other hand, I think 

there is something to be said for the other approach 

too.  (Admittedly, I do have lots of grey hair.)



Building an all metal airplane is mostly an exercise in drilling 

holes.  For me, that means focusing on the hole drilling process is a 

good way to improve your building experience.  It is also an area 

where a little learning goes a long way.  (Remember, education is one 

of the primary reasons we are supposed to be building these contraptions.)



I decided to learn "Free hand" drill bit resharpening a couple of 

years ago -- about the same time I started work on my XL.  I found it 

relatively easy to turn a dull bit into one that drilled holes better 

than before.  OK, maybe the angles on the bit didn't end up the same 

as they started.  Does this really matter when holding a contest 

between tool steel and aluminum?  Indeed, my reading on the web told 

me a drill should have a sharper angle for drilling soft materials 

than the one provided on store-bought drills which are designed to 

drill steel parts.



My recommendation for anyone new to the drill sharpening process is 

this:   Start with new bits.  When they get dull put them aside and 

use a new one.  After a while you will have a small collection of 

dull bits.  You can try to resharpen these yourself.  You can also 

get someone who knows how to do it to show you.  Or, you can just 

throw them out.  If you try to learn how to do this yourself, the 

only possible loss is some time.  Perhaps you will renew the bits or 

perhaps you won't.



I think there are three "Secrets"  to drill bit sharpening.  The 

first is to have a grinding wheel with a really flat surface and 

sharp corners at the edges.  The second is to start holding the bit 

at the same angle as you do each side of the point.  The third is to 

"Scrape" the bit upward as you finish the point to get the rake angle 

needed to make the drill actually remove metal.  The last part (not a 

secret at all) is to inspect the point - if it comes out with the 

point in the middle of the bit then both sides are the same.  If you 

try twisting the bit into a piece of wood it should dig in.  In this 

case you have a nice new bit to make more holes in your airplane.



Of course anyone can say this is too hard to learn or not worth the 

effort.  Still, if you do you will feel good about learning a new 

skill and also find yourself a little better off when it comes to 

having the tool you need when you need it.



Best regards,



Paul

XL fuselage





 	  Quote: 	
		  For amateurs like me and others who do not have the benefit of 

being, or working with machinists with a LOT of gray hair earned 

with years of trying to accurately resharpen drill bits, I say use 

'em & pitch 'em.

n963wb(at)frontiernet.net
Guest

Posted: Sun Feb 04, 2007 2:52 pm Post subject: Drill Bit Durability

I have found one of the easiest and most accurate means of "touching up" a 

drill bit is a cut off wheel in my hand held Dremel.  The side of the cut 

off wheel makes for an ultra smooth surface to work on, and because it is 

hand held, I can walk over to my magnifier light (have gray hair too) and 

steady my hands on my chest.  I have pretty good results with this method. 

I have a couple of long drills, which I made using a quarter inch steel rod 

that I drilled holes in the end then brazed a smaller bit in the end.  I 

don't want to go through the hassle of reattaching drills to these 

extensions so a brief touch on the cut off wheel brings them back to life. 

Granted using the side of the fragile cut off wheels might not be how they 

were intended to be used but so far I have not broken a single wheel 

sharpening a bit.



Dick Neitzel

Sayner, WI

701 Jab 2200

N963WB

JohnDRead(at)aol.com
Guest

Posted: Sun Feb 04, 2007 8:31 pm Post subject: Drill Bit Durability

Hello List:

                 Drills  will last longer if a small amount of lubricant is used during drilling. I use  Boelube from The Yard in Wichita. Burrs after drilling are also smaller with the  use of lubricant.

  

 Regards, John

 Building CH701 in Colorado

  

 Do not archive

  [quote][b]

planecrazydld(at)yahoo.co
Guest

Posted: Mon Feb 05, 2007 4:42 am Post subject: Drill Bit Durability

we used beeswax at Cessna in Wichita. warm the bit and push it into the block or spin the bit on teh side of the block.

   

  do not archive



JohnDRead(at)aol.com wrote:

  [quote]    Hello List:

                  Drills will last longer if a small amount of lubricant is used during drilling. I use Boelube from The Yard in Wichita. Burrs after drilling are also smaller with the use of lubricant.

   

  Regards, John

  Building CH701 in Colorado

   

  Do not archive

[quote][b]     TV dinner still cooling?

[url=http://us.rd.yahoo.com/evt=49979/*http://tv.yahoo.com/]Check out "Tonight's Picks"[/url] on Yahoo! TV. [quote][b]

BobTezyk

Joined: 10 Jan 2006
Posts: 38
Location: Midlothian, TX

Posted: Mon Feb 05, 2007 9:20 am Post subject: Drill Bit Durability

One thing I have not seen mentioned in this thread has been  the Drill Doctor.  The Drill Doctor will sharpen a drill bit to a perfect  point in under a minute.  You will be surprised what a difference it makes  to always have a sharp bit.  In addition to getting better holes, there is  a time savings in drilling every hole with a sharp bit.  It is designed to  make a perfect point and removes a minimum of metal doing it.  I have had  one for years and have all but stopped buying drill bits.  I drill a  lot of steel,  so drill wear is a constant issue for me.

  

 They make several different versions starting at under  $100.  I got the cheap one but in retrospect, I should have opted for the  lowest price one that has a replacable diamond wheel.  I can tell that I am  getting near the point of replacing it due to the wheel wearing out.   

  

 Regards,

  

 Bob Tezyk

Midlothian, TX 

601XL / 3300  S/N  6-6777

Rudder Complete, Took delivery of the QB kit.

bob(at)eaglesnestestates.org (bob(at)eaglesnestestates.org)

http://neo.datamatrix.com/eaglesnestestates/index.php?option=com_rsgallery2&Itemid=28&catid=23

   [quote][b]

pacificpainting(at)comcas
Guest

Posted: Mon Feb 05, 2007 2:02 pm Post subject: Drill Bit Durability

I'm glad someone brought up the "Drill Doctor".  I've thought about getting one for years and never did. I haven't always  had the best of luck with what seems like it may be some kind of gimmick devise.  I don't know about other people, but I have a lot more drill bits than the ones  I use on aluminum. Larger bits are a little more expensive to throw away when  they get dull.

  

  

 [quote]   ---

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