# How to drill a straight hole?



## dat2zip (Feb 25, 2004)

OK, that sounds lame, but, I'm not mechanically inclined. Must of flunked one of those classes many years ago.

"When God handed out brains, I though he said train and took the next one."

Anyway, I was drilling a fixture last night. Last steps in my module fixture. Had to drill some small holes. Yeah, I know, vice it first, drill slow and don't try to flex the drill by drilling too fast.

Still, maybe, because I held the small vice by hand and had to repeatidly raise/lower the bit to clear the chips that the hole got larger than the diameter of the drill.

Any advice. Advice in general beyond this that you could share.

Thanks in advance,

Klutzo!


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## tvodrd (Feb 25, 2004)

Klutzo /ubbthreads/images/graemlins/grin.gif ,

Start with a _center drill_. they're short and very ridgid. That will get the process started on you're center punch mark. (You did center punch where you wanted your hole center?) After center drilling, use a smaller drill than the final size you want, and work your way up to final size. If your holes are relatively shallow with respect to their diameter, use the shortest length drill available- stub or "screw machine" length. If you've really got the bucks, use tungsten carbide drills- they're stiffer, and last far longer between resharpening.

Larry


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## Chief_Wiggum (Feb 25, 2004)

Larry = THE MAN

What he just told you in 5 sentances took me months to learn and many ruined parts. Got any more pearls, Larry /ubbthreads/images/graemlins/grin.gif


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## Atomic6 (Feb 26, 2004)

It's like Larry has been around doing this sort of thing for a while /ubbthreads/images/graemlins/grin.gif

I Love my LSN-Thanks again Larry


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## dat2zip (Feb 26, 2004)

Thanks, I guess I'm in too much of a hurry and I drill a pilot hole but migrate to the final drill right away thinking the pilot hole would be good enough.

Thanks Larry, I really feel like a bozo now.

Wayne


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## Patrick Hayes (Feb 26, 2004)

Clamp your vice down /ubbthreads/images/graemlins/smile.gif


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## MicroE (Feb 26, 2004)

Did you use lubrication?

Lube will help to:
1.) Clear the chips
2.) Reduce chatter
3.) Keep the drill bit cool.
4.) Keep the workpiece cool.
5.) Keep the drill bit on center.

Heat kills tools and workpieces.---Marc


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## Phil_B (Feb 26, 2004)

Did you sharpen up your own drills? An off centre cutting edge will give you a larger hole too. 
I have actually used this technique (deliberately!) to produce a required size when no drill bit is available (a tapping size).
If you can,when using some new material and you don't know the result of drilling fast/slow/with oil/kerosine,simply get some scrap and do a test.Don't be shy.
I'm a machinist and I play this way all the time. The other way is to listen up to folk like Larry!
Did you use a drill press? A free hand drill? These are all factors.
HTH,Phil.


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## dat2zip (Feb 26, 2004)

I have a mini drill press that has the motor in the back and a couple of pulleys across the top. This is more mechanically stable than having the chuck attached to the motor directly or so I was told. The chuck portion is on a bearing shaft assembly and I have found that it still has a few thous lateral jitter which kinda pisses me off that I bought it for it's mechanical stability and accuracy. I should spend some time in rigging a clamp assembly for it or buy one.

On the little parts I am making, I usually drill a pilot hole with a PCB carbide drill. I just wish my drill press would run at a higher rpm. It's too slow for carbides. The Dremel drill press has too much slop laterally that it's not accurate enough.

I'm in the market for a good mini drill press or one that I can mount the dremel into.

Good thing I'm working with Aluminum. The fixture I made last night came out fine. Carbide pilot holes and two drills to get to the final finished hole. 

I actually know most of this, just don't apply it on regular basis. Some good practice and hints are always good and I was hoping this would bring some nice tips out.

Drilling may sound like duck soup, but, getting a good accurate hole requires some skill if you want the hole straight, on target and the right size.

Thanks everyone for sharing your tips. Keep em coming.

I was able to get the holes one target by printing a 1:1 image on the laserjet and cutting the image out and dropping that into the hole where I needed to drill. From there, I drilled through the paper targets to get the holes where I needed them to be. With carbide bits, you don't need a center punch.

I'll post a pic of my little module fixture when I get a chance.


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## robk (Feb 26, 2004)

I've had two of these throughout the past 20 years. The one I have now is at least 18 years old, had to replace the chuck once. Still tight bearings, very accurate, nice to use. I think I paid about $300 for it, well worth it. I can't believe they still offer the same model (slightly updated). I have drilled hundreds of thousands of holes in glass-filled circuit boards using cobalt bits, and before that it was used in my lab for drilling plastic rimless lenses. Take a look:
Cameron Drill Press 

Rob


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## Phil_B (Feb 26, 2004)

To be honest Wayne,you would be as well to take Larrys' (and my) advice to punch a centre pop before you start,you can still use the paper to locate the punch. Drill pillars with "head ache" will allow the drill,under pressure,to wander off centre. The pop just locates till it gets to its full dia.
Incedentally you can drag a hole,until it reaches the full diameter. You must only aply enough pressure to keep the tip of the drill firmly in the hole but NOT cutting downwards,then the pressure is applied GENTLY and sideways,at 90 degrees to where you want to drift the hole (the correction).
ie,to drift towards 12 o' clock on a clockwise rotating drill,pressure is applied from the 3 o' clock direction (moving the vice.Practice practice etc,and ALWAYS wear your goggles.Drills shatter and this is drill abuse!
That said,it's better than getting the last hole wrong.
Take care,and keep all your tools sharp.nothing MORE dangerous than a blunt cutting tool.
Phil.


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## tvodrd (Feb 26, 2004)

From Wayne' initial post, I responded _in general_. I did neglect to mention cutting fluid- thanks MicroE and Phil_B. For circuit board work, final size is fine with carbide "circuit board" drills and center punching/center drilling generally isn't necessary if the set-up is rigid. Phil's suggestion to center punch through the paper will be a big help. Check out a small automatic center punch like McMaster cat# 3422A5. It's adjustable for impact strength.

Larry


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## GJW (Feb 26, 2004)

Funny story..... (not really but if you're good at imagining...)
I bought a reject UBH from Dspeck that was only big enough for AA batteries.
When the TW4 was a hot topic I got the brilliant idea of using the UBH reject with the KL4 and 2xAA batteries.
Only problem was that the inner lip of the KL4 was a tad too big to fit in the UBH.
The O.D. was big enough to accomodate it -- the I.D. just needed to be enlarged.
Enter my DeWalt 18V drill and a 5/8" bit.
I actually held the UBH in my bare hands while my coworker held the drill.
We tried vise-griping it to a table but it just twisted out.
It worked pretty good too -- it only seized up about 15 times.
It took maybe 1/2 an hour but I was finally able to drill to the depth I needed.
It's not the prettiest hole I ever drilled but it worked.


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## KC2IXE (Feb 26, 2004)

Well, all the answers are good for "normal" holes - eventally, you get to DEEP holes, which If I remember right are defined as more than 4x drill diameter. They can get "interesting" - and can get REALLY interesting whne you get 10x + diameters deep - it's a whole (hole - pun intended) specialty in itself - usually called "gun drilling"


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## dat2zip (Mar 1, 2004)

Here's the fixture I made.

Simple as it may be, it saves me a ton of time and helps keep the modules spaced correctly and helps keep them parallel.


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## Darell (Mar 16, 2004)

Gread idea for a Module-helper Wayne! I can't add anything here to what's been said. My initial response was "clamp the vice and use a drill press" but we've gone WAY beyond that now. /ubbthreads/images/graemlins/smile.gif


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## ABTOMAT (Mar 17, 2004)

Dat2zip, is your DP one of those Asian 5-speed models, or a real mini drill press like a Cameron or a precision Servo Micro ($~600)?

Three things have to do with the accuracy of a drill press. First is how much slop the quill has in the head casting. Second is the machining of the spindle and/or arbor taper. Third is the TIR of the chuck itself. The stock chucks on general-use DPs up to the midrange Deltas and Jets have pretty lousy chucks.

Bolting the vise to the table and using a center or other short bit is a good way to start.

If you really need to drill really tight, tiny holes, you need either a pricise mini drill press or something massive like a vertical mill with a collet chuck.


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## dat2zip (Mar 17, 2004)

ABTOMAT,

Thanks for the info. I'm getting more confident I can drill the right size hole in the right location. /ubbthreads/images/graemlins/smile.gif


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