Drilling 1/4"

[waubm]

Got some 5.5"x12" chunks of 1/4" and a dewalt kobalt 5/8"s drill bite and a delta drill press, wondering if anyine had some tips on drilling this. What type of cutting oil will keep my bit like new? is there a better for your money bit than the dewalt? What speed should i keep this on? really slow? Seeing how this bit was near $20 i would like to clear this up before i screw up.

[brokexj]

I just drilled some 1/2" holes in 1/4" with the same bits. I started with 1/8, 3/16, 1/4, 3/8, 1/2. I used 3-1 oil, used slow speed, steady pressure and let the bit cut.My bits still cut, though.

[ECKSJAY]

Yup, let the bit cut for you and use plenty of oil. :)

Our bits in the shop last a LONG time with this stuff.

http://www.relton.com/images/nrtx.gif

[CanMan]

And if they go dull, buy one of these. Its saved me tons of money on buying new bits.

http://www.coastaltool.com/a/ab/drill-doctor/images/drill-doctor_500.jpg

[BrettM]

drill doctors are GREAT. go SLOW, probably as slow as your drill press will go. lots of pressure, let it cut. clamp the piece real tight. motor oil is a good coolant/lube that everyone has lying around.

[FarmerMatt]

Rapid Tap is good stuff. I don't believe the "Drill Doctor" will sharpen 5/8" bits, but it's not hard to do it by hand on a grinding wheel.

[tompatjr]

I have a question, how do you know when you have enough pressure? Will you get ribbons or what?

[waubm]

I have a question, how do you know when you have enough pressure? Will you get ribbons or what?


yea wat he said

[Static-XJ]

Rapid Tap is good stuff. I don't believe the "Drill Doctor" will sharpen 5/8" bits, but it's not hard to do it by hand on a grinding wheel.
The 750 models will do up to 3/4", the 500 models will if you buy the larger chuck for it.

[bigwhitey]

I had a drill doctor and it took too long to sharpen my bits. I just went back to using my bench grinder.

[QckSlvr]

You want to have a slow rpm and just enough pressure to make one continuous curl and use plenty of cutting fluid...
and as FarmerMatt said with a little practice your bench grinder is the perfect drill doctor.

[tealcherokee]

the formula for rpm is

RPM = ((4 * CS) / D) * .75

for fully flooded (continous lubrication)

and

RPM = ((4 * CS) / D) * .66

for normal lubrication

the cutting speed of mild steel is about 36

D is the diameter of the drill bit

so for your application

RPM = ((4 * 36) / .625) * .66
RPM = (144 / .625) * .66
RPM = 230.4 * .66
RPM = 152.064

so around 150 RPM, as far as pressure, keep the bit cutting, with out binding up the drill press

[JAS]

x1000

And if they go dull, buy one of these. Its saved me tons of money on buying new bits.

http://www.coastaltool.com/a/ab/drill-doctor/images/drill-doctor_500.jpg

[tealcherokee]

good job on the 2 month old post to repeat what was said........

[BrettM]

good job on the 2 day old post to say nothing.........

[CanMan]

Way to go guys. Way to say nothing about what has already been said.

[Mr.OverKill]

Way to go guys. Way to say nothing about what has already been said.what he said!

[BrettM]

I'll second the motion.

[Jump This]

I'll second the motion.
All in favor of bumping this thread...say 'yep'

[Jump This]

Wait a moment....it already was on the top....
What a dead forum!

[waubm]

I drilled five 7/16ths hole with a Dewalt Cobalt and lubracated 3 times a hole with used motor oil at 620 RPM. Bit still seems as sharp as new.


Thanks!

[GermanXJ]

A good rule of thumb the Airforce showed me is to watch your shavings. If the shavings are small chips go slower and apply more pressure. If the shavings are long than you are good. On steel slow speed heavy feed, soft metal high speed low feed.
Good drillin

[GermanXJ]

Oh yea try Beeswax as a lube for your bits. Works for me.

[toolmantim]

I'll revive old thread....:eyes:

a Drill doctor is awesome for the single reason that it cuts a splitpoint in the drill. (if desired)

Since most don't know wtf that means...

this is a standard drill bit

http://www.mmsonline.com/mag_images/068901b.gif

The flat chisel point cuts nothing. It spins in a itty bitty circle and chews things up.

this is a split point

http://www.mmsonline.com/mag_images/068901e.jpg

This is a great for drilling. Especially by hand.


You can eliminate the web of the drill by hand (bench grinder) if you know what to do. It's easy when it's a 1 1/2 drill bit, not so easy on .250 and under.

Btw I have drilled thousands of holes in alot of different steel for 10+years.

When grinding a bit by hand make sure the grey area (in splitpoint pic) is on a gradual decline. Too much rake (decline) makes bit weak.
The easiest way to achive this is to ALWAYS rock bit in a upward motion.

[csr_011]

http://www.wwch.org/TechData/DrillBitSpds.htm

[caglezxj]

All of this over drilling some 1/4 plate!

So does it matter what brand drill you use?

[rehab]

All of this over drilling some 1/4 plate!

So does it matter what brand drill you use?
yes

[88rockxj]

when ever im drilling through 1/4" or cutting it with the sawzaw i keep a cup of water next to me and dip the blade/bit in the cup every 15 seconds or so, since ive started doing that my blades and bits last around 3 times longer then they used to. keeping them from over heating works awesome for me, and drilling real small pilot holes then slowly stepping up bit by bit keeps my exspensive large sized bits from ever getting real dull. hope that helps somone

[JAS]

And if they go dull, buy one of these. Its saved me tons of money on buying new bits.

http://www.coastaltool.com/a/ab/drill-doctor/images/drill-doctor_500.jpg


x100000

Plus all of the time spent dropping your project and driving to the store just to get a new bit. I can not count the time that I have saved me a 25 minute 1 way trip to the store...Then 25 minutes back.