Barrel pin holes wandering off

[flehto]

Have always used a center drill only in a Bridgeport or radial drill press when the work piece is clamped. I've found that using it in a drill press can  put the hole off location. I use a 1/16" drill and it will flex if the "dimple" and drill aren't both exactly  on the same center. When the 1/16 drill is 1/16 or a little more deep, then the hole and drill are lined up by eye......Fred 

[Bob Roller]

Have always used a center drill only in a Bridgeport or radial drill press when the work piece is clamped. I've found that using it in a drill press can  put the hole off location. I use a 1/16" drill and it will flex if the "dimple" and drill aren't both exactly  on the same center. When the 1/16 drill is 1/16 or a little more deep, then the hole and drill are lined up by eye......Fred 

THIS one makes no sense to me.I use center drills every day and have no problems with inaccurate holes.

Bob Roller

[flehto]

Using a center drill on metal is ok because it'll center on the prick punch, but on wood which is much softer, the center drill can "go it's own way" because it doesn't flex like a small drill. The hole location will be "off".

When I worked as a tool and diemaker. a center drill was only used on a milling machine, radial drill press or a lathe....the workpiece is clamped  in these machines and outside of the radial drill press, a centerpunch isn't used.

People can do what they will, but it seems an awful lot of builders have trouble drilling the bbl lug and RR pipe holes and have to resort to jigs and fixtures....such a simple operation and judging from the many posts, drilling these holes becomes very complicated. Also...starting a drilled hole accurately in wood is much different than in metal which is much easier.

 Not telling anyone how to accurately drill a simple hole in wood, just relating how I do it.....Fred

 




   

[Dphariss]

Center drills are specifically designed to NOT wander, to NOT run off. They do not flex. Center drills are designed to start a hole with NO NEED for a punch mark. If people are having problems with a center drill running off there is some other problem.
Either the setup or the equipment being used has a "problem". The Center Drill will put the hole at the place its centered over. If the center drill is set to start at the wrong place the hole will be in the wrong place.

If it does not look like this its not a center drill

Dan

[flehto]

W/ a stock/bbl assembly and a prick punch in the wood , a center drill because it doesn't flex, would start cutting even if the prick punch isn't centered....the weight of the bbl/stock  assembly would resist the center drill  and result in a mislocated hole. Wood is a lot softer than steel and more difficult to drill a hole where intended.  There's  been a lot of inquiries about drilling bbl lug and RR pipe holes because it's not easy to start drilling into wood accurately.....Fred

[Jim Kibler]

I've had very good luck using a 1/16" flat bottom end mill or router bit with a 1/8" shank to start holes on an already shaped stock.  If everything is clamped in place and located properly this works extremely well to start the hole on a curved surface.

[flehto]

On a shaped forestock, I chisel a flat at each pin location so the drill doesn't "skate"  downhill. The flat  later on disappears when further shaping is done.

 I've drilled many 1/16 dia. bbl lug/RR pipe holes in one swoop and a precise layout is necessary to locate the hole into lugs that are meant for very  thin webs.....3/32"-5/32". A depth mike is used for the vertical layout......Fred   

[Dphariss]

W/ a stock/bbl assembly and a prick punch in the wood , a center drill because it doesn't flex, would start cutting even if the prick punch isn't centered....the weight of the bbl/stock  assembly would resist the center drill  and result in a mislocated hole. Wood is a lot softer than steel and more difficult to drill a hole where intended.  There's  been a lot of inquiries about drilling bbl lug and RR pipe holes because it's not easy to start drilling into wood accurately.....Fred

This would be really interesting, if I did not know better.  I have been drilling holes using center drills in wood, steel, brass, aluminum and stainless for decades now so I have some modicum of experience. When I set up a stock, precarved or otherwise, to drill a hole its FIXED in place and will not crawl away from the cutting tool.  This includes odd shaped and hard to clamp pieces. There are ways.


If you let the work MOVE you have a POOR SETUP and will reap what you sow. Proper setup and work holding will eliminate this.  What WILL happen with a center drill on a contour is that it will, naturally, cut deeper on one side than the other, so one MAY have to use a center cutting end mill in some cases. On a STEEL surface with a steep angle strange things can occur due to the much harder material so use an end mill. On wood YES its possible to cut a flat for the drill.

IF the punch mark is not EXACTLY under the center line of the drill the typical drill will FLEX to align with the punch mark, This bending of the drill will cause run out on the other side. Since most drill chucks will have some run out one has to be very careful with where the center of the drill really is. So if you set up a RIDGED drill like a center drill and the intended location for the hole is not under the center due to being set up without taking runout  into consideration. Runout will also increase the size of the hole created by the center drill.

Dan

[Turtle]

 pardon my ignorance. Do they make center drills I 1/16"?

[louieparker]

To start my holes I use a round shank sewing machine needle, Sharp pointed . In the drill press it goes in very straight without wondering and the speed of the drill press and a very light pressure it goes down and contacts the tab. Then the 1/16 drill bit will follow that hole.. Round or flat stock...LP

[flehto]

Dan...after the 1/16 drill flexes slightly and goes to a depth of approx. 1/16", then the drill is centered and the hole drilled through. Have done 100s of holes like this and surprisingly, they all came out "right on the button". I don't clamp the bbl/stock assembly to the drill press table...just manually hold it. There's a zillion ways to do things and whatever way works, that's the route to go

Evidently many builders have trouble drilling these holes and probably haven't found what works for them......Fred.



 

[Dphariss]

pardon my ignorance. Do they make center drills I 1/16"?

They come in many sizes.
http://drillsandcutters.com/0-regular-hss-combined-drill-bit-and-countersink-qualtech/?gclid=CjwKEAiA4_WjBRCNgf7A_KeE9jwSJADtegYdq_LM-5zZ_jPOEZB3EoGB-4Q_bL3eFzPBr7L76Mb4zxoCZP_w_wcB

Dan

[Dphariss]

Dan...after the 1/16 drill flexes slightly and goes to a depth of approx. 1/16", then the drill is centered and the hole drilled through. Have done 100s of holes like this and surprisingly, they all came out "right on the button". I don't clamp the bbl/stock assembly to the drill press table...just manually hold it. There's a zillion ways to do things and whatever way works, that's the route to go

Evidently many builders have trouble drilling these holes and probably haven't found what works for them......Fred.



 

Whatever.

Dan

[Captchee]

Like some of the others , I drill from both sides  . I also us 1/16th  finish nails for pins . I cut them down and then round an polish the ends
 I would also agree that there is no substitute for  quality drill bits .
 However  I have found that in a pinch those cheep bits will work . You just cant push them to hard .
  Many years back I made a center  jig from an old cheep  2 inch C clamp .
  Now days you can purchase much the same thing  but they for the most part take a long drill bit which can be hard to find at times ..
  As I recall there also is a  tutorial on making  such a jig  down in our tools forum ..
The one I made is a little different but does the same thing  in that it aligns the bit  so you drill , point to point ..
 No real need for a drill press , mill ends  or center drills .
 However if your  trying to drill  after the stock is shaped or into molding , then center drills can work nice . So do small end mills .
 But if you don’t have either , I have found that a small bit  will start the hole , without flexing , as long as you don’t have it to  far out of the chuck  IE no more the ¼ to 3/8 .
 
 For the most part though I just  lay up my marks , use a pin drill to  start the hole , align my center jig  so that  the point  is on the location  on the off side  and the  point with the drill bit slid through it aligns on the  mark on the  other side . Tighten the jig slightly . Slide the bit into the jig and drill the hole  tell it his the lug .  Flip the jig around. Drill from the other side . Then drill out the lug  with the barrel out of the stock