What did I do wrong drilling these holes?

[5030]

I'm going to switch back to HyGard before cold weather.

The primary reason why I don't use Kubota SUDT in my winter use tractors. The clod flow ability of SUDT causes pump cavitation so I use Chervron All Weather THC synthetic instead. Also why I use 5-40 Rotella T5 in the crankcase.

 

[rScotty]

The primary reason why I don't use Kubota SUDT in my winter use tractors. The clod flow ability of SUDT causes pump cavitation so I use Chervron All Weather THC synthetic instead. Also why I use 5-40 Rotella T5 in the crankcase.

There's several points there. Engine oil chemistry is a known subject with lots of standards and testing. Anyone can study and compare engine oils and engine oil testing.
But hydraulic oil doesn't have any standards. It is proprietary to the manufacturer. So each manufacturer of a trans/hydraulic oil makes their own. The amazing thing is how compatible that they seem to be.

Ignorance being bliss, I run run SUDT in our M59 because it has that HST+ transmission and apparently the SUDT was developed for HST+. Lubricating that wobble plate in the HST has always struck me as the weak point in any HST tranny, and so I use their own SUDT with hopefully all the right additives for their own wobble plate HSTs. It's basically a "cross my fingers and hope" type of thing.

Now for transmissions other than HST - like in the M series Kubotas and in our commercial JD with it's torque converter and power shift there should be less demands and so there are other choices. Kubota, Chevron, JD HyGard, & New Holland Multi-G are ones I've tried. So far the only difference I've noted is that Multi-G seems quieter... but then my ears don't work like they used to & that may be the reason.

In the crankcase... I'm not worried about engine oils anymore because the standard tests have improved them.
Way back when multiweight engine oils were new on the market, the knock against multiweight ENGINE oils was that increasing the temperate span also decreased the lubricity.

The problem seemed insurmountable because it had to do with how and why oil viscosity changes with temperature in the first place. But now we see multiweight engine oils that test good for both an expanded temperature range AND increased lubricity. The standard tests show they work.
rScotty

 

[SmallChange]

This has been a great and inspiring thread. I wanted to share the notes I made about it and also some answers.

I was drilling "low carbon, also known as mild steel" bars I just bought from McMaster-Carr, whom I've never found selling something different than what they claim, not in 40 years of shopping there. They describe it like this:

Yield Strength: 54,000 psi
Hardness: Rockwell B70 (Medium)
Heat Treatable: Yes
Max. Hardness After Heat Treatment: Rockwell C60
Specifications Met: ASTM A108

I was applying 3-in-1 oil from a small can. I found a number of web references saying this is dumb, and a couple saying this is smart.

My drill bits, well, shame on me. I should have figured this was asking for trouble. I was using a "Do it" brand 21 piece titanium coated set. They were made in China. I probably bought this set 25 years ago. It cost $16. I'll buy a better set and am researching the question now, but thinking cobalt, maybe with titanium nitride coating (note "cobalt" and "titanium" are two different questions and you can get bits that are one or the other or both or neither). Maybe split point.

I'm reading such a wide range of statements about Drill Doctor sharpeners; apparently if you go to a machinist forum, everybody will point and laugh at you if you say they're any good, and the only good sharpeners are very very expensive and no longer made.

Here are my notes summarizing (and sometimes paraphrasing) the specific things I took special notice of in this thread:

big difference in quality of tools bits
Home owner -> tradesman -> manufacturing
use the cutting oil
use one of these rigid oilers
use a drill doctor
135° better on steel
First drill most likely went dull then work hardened the hole
slower on the RPMs
recommended drill bit speeds were designed for production work
getting hot, smoking, or not drilling at the rate it was in the last hole, it's time to stop and investigate
use good quality cobalt bits
haven't bought anything but cobalt bits for the last 20 years
NEVER use petroleum lubricating oil
pilot hole about the size of the web of the final drill
When drilling steel, MAINTAIN THE CHIP! that is, keep the cutting lips cutting, don't RUB.
perfectly fine to go slower or even a lot slower
chatter also related to too high RPM, indicator that things weren't going well
on those size drills, I wouldn't even bother with pilot holes
Feed rate is just as important as speed
mistake #1 was drilling a pilot hole for such a small final size anyway
only need to pilot larger bits that aren't split point
read the chips, feed it too light for the speed = chips turn blue, too hot
don't let the chips turn colors more than a light straw on HSS
doubt work hardening was an issue with mild steel
proper cutting is removing heat
TapMagic and pressure for a good chip curl works for my cheap drill bits
AnchorLube for a lubricant
only use a pilot hole in mild steel for 1/2" diameter holes and larger
smoking and/or hot, stop and let it cool off
Blue chips are bad unless using carbide cutting tools
Apply light pressure for about 5 seconds then wipe the bit with the brush with my off hand while pulling it out
clears the chip, cools the bit, and allows some coolant into the hole
don't want to ever see long, stringy chips
disagree about never wanting a long stringy chip, indicates good and consistent feed pressure
Rule of Thumb, spindle speed = 4 X SFM / Dia, HS tooling = 100 SFM, Carbide tooling = 300 SFM

My parts for this project are finished except for one weld I need to find a welder to do for me. It's an assembly that clamps onto my FEL mounting frame, and holds a vertical exhaust mod in place so I'm not driving over my own exhaust all the time. I have the mod prototyped, hanging from a pipe attached to my canopy, and what it does for exhaust is perfect; now I just want it sturdy and not hanging from the canopy.

I will, however, get my drilling resolved better, so the next project does not hit any problems.

Thank you all very much, it's been a great education!

 

[5030]

Like I said in a previous post, Darex makes precision drill sharpeners but you really cannot afford one. They make the box store 'Drill Doctor as well. Bought mine used at a machinery auction and it was almost 2 grand used. Your 3rd line 'heat treatable' says it all. You heat treated the steel with a dull drill inadvertently.

 

[LD1]

This has been a great and inspiring thread. I wanted to share the notes I made about it and also some answers.

I was drilling "low carbon, also known as mild steel" bars I just bought from McMaster-Carr, whom I've never found selling something different than what they claim, not in 40 years of shopping there. They describe it like this:

Yield Strength: 54,000 psi
Hardness: Rockwell B70 (Medium)
Heat Treatable: Yes
Max. Hardness After Heat Treatment: Rockwell C60
Specifications Met: ASTM A108

I think mcmaster's description is a bit misleading....

Mild steel (AKA 1018) isnt cant be hardened by heat/quench....AKA work hardening in your case.

Yet they claim it can reach a max hardness of C60......which is about the hardness of a good file. Which is NOT something normally attainable with 1018 without adding carbon to the mix.

I suppose its possible you created the perfect storm with the 3n1 oil and heat from the bit.....maybe the oil introduced some carbon to the steel....
However I think its far more likely you just had some junk bits you toasted....and that the piece wasnt hard at all. And simply switching to a good sharp bit would have drilled right through the hole you stalled in.

Good bits or junk bits....dry or cutting lube....pilot or no pilot......the SINGLE biggest thing is read the chips period. Adjust speed and feed(pressure) and try not to let the chips change color. IF you are peeling out blue chips....it dont matter how good the quality of the bit is...if its HSS you wont be drilling very many holes

 

[rScotty]

I think mcmaster's description is a bit misleading....

Mild steel (AKA 1018) isnt cant be hardened by heat/quench....AKA work hardening in your case.

Yet they claim it can reach a max hardness of C60......which is about the hardness of a good file. Which is NOT something normally attainable with 1018 without adding carbon to the mix.

I suppose its possible you created the perfect storm with the 3n1 oil and heat from the bit.....maybe the oil introduced some carbon to the steel....
However I think its far more likely you just had some junk bits you toasted....and that the piece wasnt hard at all. And simply switching to a good sharp bit would have drilled right through the hole you stalled in.

Good bits or junk bits....dry or cutting lube....pilot or no pilot......the SINGLE biggest thing is read the chips period. Adjust speed and feed(pressure) and try not to let the chips change color. IF you are peeling out blue chips....it dont matter how good the quality of the bit is...if its HSS you wont be drilling very many holes

Hmmm.... just as an aside, it's interesting to see that several people agree about the hardenability of that mild steel. I'd be surprised if it could be accidently hardened to any real amount. Still....

Wanted to say that the real value I am getting from this thread is a reminder that it's time to replace at least one of my drill bit sets in the shop with nice new ones. Been meaning to do so for a couple of years now... So it's time to ask for recommendations.

My "go to" drill index needs updating anyway. The old one is the standard steel drill index box for a 115 piece set with fractional to 1/2", number, and letter size bits. Bought about 1988 for $175.
The nominal 118 degree drills are all labeled with the size, PTD, HS, and USA on the shank - very decent set.
Actually when I measure the drills, they seem to be about 122 degrees - but that's just eyeball measure.

Next time I may try a set of 135 degree split points just for the difference. I do prefer 135 for metal - but with a good centerpunch the 118 degree with the fat web tip is completely serviceable.

Any recommendations as to brand? I would much prefer to buy made in USA.

rScotty

 

[5030]

Cleveland Twist or Chicago Latrobe.

 

[Smokeydog]

Cleveland Twist or Chicago Latrobe.

Some of the best and durable. Especially large drills.

Drill Hog says they are made in USA?? Interesting information on some of their alloys. Have a left hand set and cobalt set that’s worked for me.

Like you working from many sets over the collected over decades. Have drilled feet thru steel on chinesium drill bits in a drill press with TapMagic. Can snap them pretty quick in a hand drill. Had to supplement on some sizes like #7.

Grew up with neighbor with one eye lost from breaking a drill bit. That’s always influenced my buying quality and watch feed pressure.

Lots of high tech manufacturers in our area a see selections of new drills from CNC? , mostly cobalt for sale at flea market about a buck apiece. Have some spilt point 6mm cobalt I use a lot that I can’t kill and cut steel or SS like butter. I probably couldn’t afford a set like that.

 

[LD1]

CLeveland, C-L, and PTD are all good drills.

Alot of the smaller drills (like the index's with 1/2" and smaller bits) have no name.....and honestly dont know what brand most are. But anything places like MSC or grainger or fastenal are stocking the local factories with are probably more than good enough for a home shop.

Thunderbit's (made by triumph) are pretty darn good bits too IMO

 

[5030]

Triumph makes a very good (expensive) S&D drills with Tin coated flutes (only). I have a set myself with reduced shanks. Made right here in America. They even come with relieved heels which are necessary on large diameter drills anyway.