drill bit procurement; resharpen by self,replace, send out?

[Dale M.]

Several charts are available at "Google Images" on how to sharpen ... Search phrase "drill bit sharpening guide"... Also some manufactured and home grown tooling for sharpening...

Unfortunately for me, I have a coffee can full of funky bits and lack a decent grinder... Wonder what I could cobble together using my belt sander or chainsaw "tooth" sharpener...


Dale

[Leatherneck]

I imagine the Drill Doctor manual has better guidance.

Whatever angle you use will be wrong for the material you are drilling next.

Manual, HA!!! That is what you are for, second statement, yes pretty much.

[theKbStockpiler]

Are all cobination drill/countersinks bits also center drills? I can't find hardly anything listed as 'center drill bits'. http://www.mscdirect.com/browse/tn/Hole ... 4287923764

[Ol'fogasaurus]

Countersinks are an odd thing, as I remember they come in four standard sizes: 82°, 90°, 100° and 120°. 82° seems to be pretty common and 120° is just the opposite. A big diameter head for spread out loading; you need to have enough meat to get the head mounted flush. I prefer to use a separate CSK rather than a combo drill bit; I want to be sure the hole is drilled perpendicular and I then can more easily control the dia. of the head/depth of the CSK to make the fastener fully flush.

One of my first turning brake mounts came with provisions for a 100° CSK bolt. One of the better known hotrod shops around here had never heard of anything that large. I got real lucky and found a pair of 100° Allen head bolts on a miss-order of fasteners by someone else.

[SCOTTRODS]

Are all cobination drill/countersinks bits also center drills? I can't find hardly anything listed as 'center drill bits'. http://www.mscdirect.com/browse/tn/Hole ... 4287923764

Don't know if I'd call all of them capable, but the rigidity of the short double ended bits will be a solid factor in putting the hole exactly where you want, countersink be damned... The most common use I have for the Countersink centering bits, is drilling centers in broken bolts and studs to finish drilling out the threads. Better than any drill bit I have ever seen. The page you listed has some mighty proud pricing on some of those sets...

[GS guy]

I've found drill bits I've "poorly re-sharpened" by hand on a bench grinder still cut better than a dull one! I've re-sharpened a few bits, especially if I'm using them mostly to enlarge holes where I've already drilled a pilot hole, and also especially in steel where it can dull the bit pretty quickly. I usually buy all my cutting tools from McMaster, can't go wrong and cheap bits are pretty much worthless. Small bits I just replace, but will sometimes re-sharpen the mid size ones (say up to ~5/16" or so). I take a lot of care with the larger bits, cut slowly with lots of cutting fluid - they're expensive to replace too often! I really like the step-drills in sheet materials, much easier to work with in thinner materials. A good cutting fluid is key and not letting the bit get too hot, really helps with tool life and leaves a cleaner hole.
Jeff

[Leatherneck]

I use these guys for the centering situation... You can use these (Generally I use one that is a 1/4" shank) to center all critical holes. Mostly in thin stock, but as you can see, the stock thickness can vary quite a bit without too much issue as well... 1/4" plate is my thickest stuff normally, but I still go thicker at times.

Use these in a regular hand drill?

[SCOTTRODS]

All the time... Not using to drill deep holes, just using them to center my bit for extracting screws mostly.

[Piledriver]

You will probably want a carbide ball mill and a good set of cobalt drills for drilling out busted bolts.

I did discover I had a great tool for pulling stripped out CV bolts, picked up a set of Craftsman extractors on sale ages ago, that look sorta like sockets (OD type) finally had a chance to try them...
Hammered on one that fit over a couple stripped CV bolts and nailed it with an impact... May just use that in future for all CV bolt removals, came off with absolutely zero drama.

[Dale M.]

All this and not a really decent way to sharpen bits ... Not one suggested fixture... I finally have really decent grinder and still have coffee can full of bits needing attention...

Dale

[Ol'fogasaurus]

I have a drill doctor and am not always happy with the job it does. If you talk to tool makers or machinists most of them still do it by hand and using jigs... a learned process based on my talkng to them.

Also remember that there are different angles for different jobs. I seem to remember 132 - 135 degrees is pretty much a catch all angle but it a compromise drill angle that works ok to most materials being "holed" and the intent of the job. Wood is one thing, ferris metal is an other, SS (CRES) vs. AL, as I remember require different angles. If you ever got the chance to read some of the Process Specs on material removal (fr instance0 you would be overwhelmed by the information in them. There are embedded process specs inside them and those also have them "... and so it goes on and on, ad infititum" (at one time that was part of my job when making "data packages" for contracts).

Lee

[Dale M.]

Basically I want to to keep it simple, just want to refresh angle already on bits... I want to drill holes, not get a phd in drill bit science...

Dale

[Ol'fogasaurus]

As usual I was trying to help not irk you. What i said was true but I recommend you get a Drill Doctor and live with it... as I do.

Yesterday I was making some stuff out of scrap metal that had work/weather hardened un-evenly. I broke 3 or 4 new TIN drill bits as they would start out making chips then hit hardened areas and stopped cutting the pilot holes, dull up immeaditly then fracture. I had to change drill bit sizes just to get the pilot holes formed to the final hole size. Trying to get clean holes: I started my final hole from the back, got a start of the final size hole (shiney straight bore sides) then turned the piece over and went in from the other side to finish the non-burred the hole.

When working on the one hole that was giving me the most trouble all of a sudden I hit a soft spot and the drill bit was through the piece before I could let up on the trigger. That is what happens when you are dealing with drilling and not knowing what you are working with vs. what you have to work with.

The scourge!

[SCOTTRODS]

Basically I want to to keep it simple, just want to refresh angle already on bits... I want to drill holes, not get a phd in drill bit science...

Dale

Toss out the can of metal dullness, and buy a cheap set of bits then... You will be hours ahead, and we all know time is money...

[Piledriver]

Like many things, practice is the only real remedy for lack of drill-bit sharpening proficiency.