Random, but drill bit sharpening???

[pookie]

Is there a cheap way to sharpen a drill bit? I am mounting rock rails on my Jeep and to do so you have to drill into the frame. After drilling all 8 for the passenger side my bit is pretty worn down so it is taking forever to drill the ones for the drivers side. I thought I would run down and pick up a drill bit sharpener (never used one just knew they existed) from the home d-pot and those things are $99 bones. I didn't pay that much for the stupid rock rails. So how can I sharpen my bit enough to drill the last 7 holes I need to drill? I've got files and all that but I'm not quite sure of sharpen the bit. Is it just a matter of filing it down at an angle to get rid of the warn section? The reason I ask is that will be quite a steep angle. With all that said its not drilling through the metal well at all anymore, but it drilled through the pool ball I made into a gear shifter just fine. Also for reference it is a Hibachi metal/wood/pvc bit and came with others in a little green and black case. Drill's being used are a Black and Decker 9.3 volt and a Black and Decker 14.6 volt or.7, cordless drill. Bit in question is 5/16.

Any thoughts? Yes I could just buy a new bit and probably will, but this is more out of how to curiosity for future reference then it is to fix this exact bit. I just see sharpening the bit and ending up with this dramatic point and the bit not being effective.

Slow day at work what can I say?

[Andy Clements]

Buy a new bit....get a cobalt....use it only for metal drilling at the slowest speed you can and use a cutting oil. If the bit gets overly warm...stop immediately and let it cool back down before continuing.

Good luck.

[pookie]

So I should use oil when driling through the metal? I didn't know if that would work or hinder my process. And it should be used on slow speed? Huh well I did both of those wrong then. I was thinking about it after I posted and I don't ever remember having to drill holes in thick metal before. What type of cutting oil should I use?

[Trak Ratt]

Plenty of sharpening detail available from Google. And yes slow through metal, with oil. Once you build enough heat to turn the drill “blue” it’s done. Metal bits are cheep

[Vicegrip]

Oil helps the bit cut and helps keep the bit cool. High speed will make the bit tips and base metal get too hot and the bit tips will deform. Once this happens it is all down hill as the deformed cutting edges now make even more heat and de-temper the bit metal. A good rule of thumb is to look for nice thin curls of metal one from each of the flutes as you sink through the metal. Too fast and you will get little chips and then little flakes as the bit starts to fail. Oil the bit a little, get it started and run at a good speed until the bit sinks in to the width of the bit. Now slow down and watch the curls as you go. Reduce pressure as you come through the back to keep from binding the bit and chipping the tips or snapping the bit off. Clamp a backer block of hard wood to the back of the metal being drilled if you can. This will keep the bit from moving foward too fast at the end of the hole and binding up in the hole.
The oil also helps the bit clear the cut metal. Think of it like when you cut a block of semi soft cheese. It is easy to push the knife through at the start but the cheese grips to the sides of the blade and soon you have to push real hard to get the knife to keep moving. Oil the blade and the edge still cuts but the materal just slides off the sides of the blade rather than sticking and it takes much less power to make the cut.

Drill in a little, wet the bit tip wit oil drill some and re wet when you start to see any little tendrels of smoke. Bigger the bit the slower you go. 1/2 inch in hard metal would be 120 rpm tops. Funny thing, the hole will still get done in about the same time but the bit will feed at the rate it wants to and work less hard. A well kept good bit can last for 100s of holes in hard metal. I have also smoked them in the first one. For real machining there is cutting fluid that flows over the cutter and materal all the time to cool, lube and carry the cut materal away.

In a pinch you can resharpen using a grinder, a Dremmel or even a belt sander. Belt sanders work very well when you use fine grit paper. A file will not work well on metal cutting bits. Follow the existing pattern as best as you can. I have been able to get some extra life by back cutting the bit tip down with a grinder or better yet a belt sander until the flute edges look sharp. The surface of the drill bit is the hard part and resharpened bits loose this harder surface so the get dull faster. The gold color Ti coated bits loose the coating fast if used dry or are reground. Colbalt will fail fast too. Colbalt is good for real hard to drill materals like Stainless steel. Oil is a must for any bit when drilling stainless or other hard to machine metals.

Drill bits, saws, lathe cutters, mill heads and chisels all work in the same way for the most part. Each tooth on a saw or flute on a drill acts like a single chisel and shaves away a strip of the materal. The drill bit only moves in a circle rather than a line. It turns and shaves a strip of metal or wood as it moves. The lube makes the cut materal slide away from the cutter with less friction.

[wludavid]

Bigger the bit the slower you go. 1/2 inch in hard metal would be 120 rpm tops.
Sounds like you would need a lot of torque to drill that big a hole that slowly.

[Vicegrip]

You can run down the hill and drill one hole or walk down the hill and drill them all...

[pookie]

Thanks Kurt.

So this is one of those, slow and steady wins the race eh? I will give it a go tonight. Back to the oil will any oil work like 3 in 1 or does it have to be specific cutting oil.

[KevinOyler]

There are specific cutting oils, but for the job you describe, 3-in-one will suffice.

[Andy Clements]

Think of it like when you cut a block of semi soft cheese.

Kurt, you have such a way with words....I don't know why I didn't think to tell him that! :)
drilling steel = semi soft cheese :) :)

Drill in a little, wet the bit tip wit oil drill some and re wet when you start to see any little tendrels of smoke. Bigger the bit the slower you go.

...and I'm not even going to touch that.... :)

this thread officially de-railed

[Trak Ratt]

Sounds like you would need a lot of torque to drill that big a hole that slowly.
Electric motors and steam engines produce maximum torque at zero RPM. 1/3- ½ HP works very well, though it helps to start small.

[pookie]

New drill bit, slower rpms, 3 and 1 oil and frequent cleanings of the bit, I drilled the last 8 holes like "butta baby". Got the rock rails mounted and I am ready to go.

Thanks for the tips

[Vicegrip]

Our work is done..;)