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

[theKbStockpiler]

I'm at the point where I need to stop fooling around trying to drill straight holes. The best luck I have is using Pilot Points after drilling a center hole. Some of them have a lot of runout and I have to return them to the store for another one. I drill a small center hole first ,then widen it to just enough depth that the Pilot Point 'pilot fits well and then finish the hole with the Pilot Point for the finished size I need. This process is usually acurate with a hand drill to about + or minus 1/64" which is usually good enough. I'm refering to the location of the center of the hole and not the actual hole size. I have a guide that a hand drill can be attached to but as is well known then the other issue is getting the work piece at the correct angle and the second chuck has a lot of play to it as well.

Are machinist bits better than a Pilot Point ? Does the 'DrillDoctor' work? Should I send bits out to a service to have them sharpened?

Thanks for your expertise!

[Ol'fogasaurus]

I had to look up "Pilot Points" to make sure if I was on the same page as you with this term... I was.

Very basic information for everyone:

http://www.engineersedge.com/class_i.htm

Technically, Class I and Class II holes are "ream to fit". They are tight fit holes that are drilled undersize then reamed to fit for a close tolerance fit. Class I is a tighter fit than a Class II.

A Class III hole is a hand drilled hole "using a sharp drill". Personally, I do not use Pilot Point bits as I have had problems with them in the past by doing all kinds of nasty things on me like walking after the hole is started. I use standard "metal working" twist bits.

I start out by marking the hole(s) with a snap marker (one of those kinds where you put the point on the location you want then push on the handle. I then come back and using a point set and hammer and deepen the mark so the bit has a less tendency to walk (which doesn't mean it can't but if you are holding the drill at 90° to the material it is less likely to.

I then drill a pilot hole followed by progressively larger bits assuming the hole is going to be larger than say an 1/8th of an inch. It is not always a recommended thing to do but it is the way I like to do it. Another trick when drilling in thicker materials and you have piloted the hole is start drilling from one side then, when you pull the drill out you see the edge of the hole a short ways is to flip the piece over then drill back the other way. This way you should get a burr less hole.

If you are drilling Class IV holes then stop and look at what you are doing wrong.

One of the other keys here is drill speed! Too fast and you get too much heat which, if it is too much you can harden the material. Too slow and the flutes can grab on you. You want so see spiral material come out or at the least chips and they should not be blackened when they come out.

http://store.curiousinventor.com/guides/drill_speed

I have a couple of Drill Doctors and most of the time they give good sharp drill bits. But like anything else, you have to be careful and pay attention to what you are doing. If not the end can be off center to one side or the cut may not be on the twist correctly or you can put too much heat into the bit and ruin it.

http://www.drilldoctor.com/?source=bing ... Sharpeners

[SCOTTRODS]

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.

[theKbStockpiler]

Those 'above' bits fit a mill correct?

[Ol'fogasaurus]

http://www.diydata.com/tool/drillbits/drillbits.php

https://en.wikipedia.org/wiki/Drill_bit

HSS Titanium coated, as I remember, cannot be sharpened due to the material the are made from. They are high speed drill bits and lake anything else have their place in the metal working world.

http://www.carbideprocessors.com/pages/ ... -bits.html

Do a search as there is a lot more information on this out there; it is worth it!

theKbStockpiler Good subject... thanks

[Dale M.]

Those 'above' bits fit a mill correct?

The are usually use in lathe work where you have to have a accurate dead center point to support work in tail stock ...

I use them in drill press to start the hole I intend to drill, I find even with accurate lay out and center punching long skinny pilot bits tends to wander when I APPLY TO MUCH PRESSURE when starting drill operation in drill press..... Always preferred to standard drill bits with standard points... I generally get HHS bit as black oxide and titanium coating and the other "hype stuff" to be off little significance ... IF one has good center punch marks problem probably lies with poor quality (not sharp) drill bit or operator error... Proper drill speed (RPM) is always a factor in boring holes...

Dale

[Ol'fogasaurus]

Very good reply Dale; especially your adding the part about "too much pressure".

When I was talking about speed and the chips/cuttings being blue or black the subject of pressure should have been there. Also keeping the drill bit sharper longer is/can be a result of proper pressure. The concept of "riding on the drill" (not just hand drilling either but can go into the drill press also) might be fun but it is tiring and can cause the bit to flex and break, wander before starting the hole or worse yet making the hole not straight/circular/ oval/or adding a lot of burrs much less the drilling stops as the drill dulls quickly and starts "gumming" the hole (been there, done that. Every tried to eat solid/tough foods w/o teeth ).

Like I said: this is a good subject that really needs to be brought up on a regular basis.

[5.0 Chero]

Another point nobody referenced is good lubrication...

[Ol'fogasaurus]

So true!

[Piledriver]

You can sharpen TiN coated bits just fine, they are HSS underneath unless garbage grade to begin with.
Sharpened properly, the effective cutting edge is still TiN coated.

I invested in a small set of cryo'd cobalt bits...
I say "invested" as I have abused them for about 5 years now and am still using them, and I have only had to resharpen a couple due to chipping corners, and broke/replaced some of the smaller sizes a few times.
Tough as hell and can drill holes in stainless steel all day long.

If you can only have one set of drill bits, you want the cryogenic treated cobalt bits..

Well worth the extra $ IMHO, and you should have a small set anyway as you can drill hard stuff HSS won't touch.
A carbide burr in a few sizes is handy for same reasons.

We have a Drill Doctor at work. It works ~OK.
IMHO you will be way ahead learning how to sharpen bits by hand, its typically the first thing a new machinist is taught, after how to run a broom.

[Ol'fogasaurus]

One of the sites I looked at talked about some of the HSS coated bit not being able to sharpened; it was not more specific than that but I can't find it right now.

COSTCO used to sell little compartmented cases that contained bunches of Tin coated bits of many sizes. I bought two kits but I wish they still sold them.

Do a search on sharpening bits as there are a lot of videos and write-ups on drill sharpening.

Lee

[SCOTTRODS]

Those 'above' bits fit a mill correct?

They fit anything you can turn them with... They're design is Mill/Lathe and their uses are all over. The 1/4" shank fits my drill (Milwaukee's finest 5 year old cordless) easily, and I find if accuracy is an issue, they get me closer than anything due to the short length and rigidity, I have much better control of the point. I could get a Milwaukee brand drill bit to stay where I want it one day, and worked in a place with an Aerospace machine shop (Piledriver and helowrench both know of the place), I was complaining about the walking issue and one of the machinists handed me 2 of thses little guys and said "try this". End of Story...

Just 'cause it's made for a Mill, doesn't mean you can't use it elsewhere.

Also, they may not be the best of qulaity, but you can buy a small set at Harbor Freight... They call them Center Drill Countersink Bits
http://www.harborfreight.com/center-dri ... 60381.html

[Leatherneck]

On Drill Doctor, metal working bits what is the correct point/angle to set them?


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[Piledriver]

On Drill Doctor, metal working bits what is the correct point/angle to set them?

That...Depends...
110 degree faster cut (more cutting edge, can grab/pull through hand drilling on soft materials)
80 degree cuts slower. Not always a bad thing.

I imagine the Drill Doctor manual has better guidance.

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

[Ol'fogasaurus]