Thread: Making a plane blade 1

Originally Posted by doug3030

.....There are also claims that motor oil is carcinogenic, is harder to put out if you have a fire and smells worse.....

Doug, I don't know how carcinogenic sump oil is, but prudence induces me to avoid too much skin contact or inhalation of fumes. Back in the bad old days of leaded petrol, it was a common cause of poisoning in cattle. For reasons only known to the bovine mind, they relish the stuff, but there was enough lead in it to kill them.

The sump oil did catch fire when I first dunked my hot blades in, but I was prepared for that with a metal cover. However, the flames died out almost immediately, before I could drop the cover on it. The canola didn't throw a single flame.

I can confirm the odor assertion. My shed does smell like a fish'n'chip shop tonight, but that's a little more appetizing than the stench of hot sump oil...
Cheers,.

Originally Posted by IanW

Well, blow me down, once again the instructions were worth reading. I finally got around to buying a couple of litres of cheap canola oil today, cooked up another blade, swirled it in the oil and bingo! A good 35mm of the business end is now hard enough to cause a sharp file to skate.

I'd still like to know what the difference is - I've used old sump oil for quenching O1 gauge plate steel quite a few times in the past and it came out hard. I wonder if it has to do with the slightly lower C content of 1080? Mr. Gargle tells me that O1 gauge plate is typically 0.95% carbon, so maybe I've been getting the O1 only partly hardened, but because it's got more C, it still appears to be plenty hard by my crude file test.

And a cautionary note: The brine solution I used sure as heck got the blade I quenched in it nice & hard, but I mustn't have cleaned it off very well, 'cos when I looked at it a couple of weeks later, it was covered in a luxuriant bloom of rust! Fortunately, the rust was still pretty superficial and cleaned off with little evident pitting. I haven't flattened it properly yet, and there's more lapping to go on it before it goes into service, so it'll be shiny bright again before I finish - no real damage has been done.

I must have gotten the old pair of pliers I was using as tongs liberally sprayed too, when I was dunking the blade They were also covered with rust, and the hinge partly seized the next time I picked them up. I think I'll quietly ditch brine quenching as a bad idea - most of my gear is a bit too close to the action in my small shed!

Now, all I need is a quiet morning at home alone to sneak the hard blades into the oven for a couple of hours.....

Cheers,

canola oil flows better and probably bubbles less. Whatever it does, it creates a faster temperature transition, which you'll need with 1080 vs. O1. Some sites (metal makers or sellers) are full of data, and others don't have as much, but somewhere, you'll be able to find the minimum transition temperature. That won't be of that much use directly, because we can't really measure that, but if you see that V11 needs 50 degrees F *per minute*, you pretty much know if you heat it, you won't be able to stop it from getting hard.

If you see that 1080 needs to transition 20% faster than O1, then that'll let you know why one hardens and the other doesn't. Generally with plain steels, the lower the carbon, the faster the transition needs to occur (at least in the tool steels that we use). Much is manipulated with alloying, but I"ve never really followed that because most of us aren't doing industrial production where it will make a difference (e.g., on an assembly line where chisels are quickly heated with a coil and then splashed without ever leaving their holder).

Originally Posted by IanW

Doug, I don't know how carcinogenic sump oil is, but prudence induces me to avoid too much skin contact or inhalation of fumes. Back in the bad old days of leaded petrol, it was a common cause of poisoning in cattle. For reasons only known to the bovine mind, they relish the stuff, but there was enough lead in it to kill them.

The sump oil did catch fire when I first dunked my hot blades in, but I was prepared for that with a metal cover. However, the flames died out almost immediately, before I could drop the cover on it. The canola didn't throw a single flame.

I can confirm the odor assertion. My shed does smell like a fish'n'chip shop tonight, but that's a little more appetizing than the stench of hot sump oil...
Cheers,.

I don't think it's "that carcinogenic", but it is a little when it's used. It's probably one of those things for a home user where the stink is a bigger deal. Use canola or soy or anything you have there that flows well with a high smoke temp and you can put it in the oven and the mrs. will just look at you funny.

I think cows like the sweet taste of lead. That might sounds stupid, but they're the same animals that would lick the mirrors and windows on my car when I'd go fishing with a friend and park in a pasture. All fun and games until you realize that you can't see anything on the mirrors and the slobber is dry.

Oven thermometer for you guys - if you're using a kitchen oven, you'll want something like this. It'll change faster than the steel does, so you can see what range you're working with and pair it with the metal while tempering if you'd like.

Amazon.com

I have a digital convection oven (the kind where they tell you "the heat is perfectly even all over"). Where the fan blows the heat out in the center of the oven, it's hotter.

These little dial thermometers are pretty accurate and will give you an idea where you want to set as your favorite spot in the oven. They're also durable. Point being for most of this is the value will probably be in finding the hot spots in case you want to go a little above where the oven says it will to temper something at some point.

Someone here told me that the non-contact thermometers aren't accurate on certain surfaces, but my dial thermometer and non-contact thermometer pretty much agree with each other. I like to shoot tempering blades once in a while just to see ...well, I guess it's OCD. They're always 25F above indicated temperature in my "pet spot" in the oven.

Originally Posted by D.W.

.......I think cows like the sweet taste of lead...

Lead sulphate was called "sugar of lead" in the days before chemistry became a little more sophisticated, and it does indeed have a sweet taste (don't rush to confirm this, just take the word of reliable textbooks!). So old car batteries are/were another common source of poisoning in cattle. Farmers insist on dumping their old tractor batteries etc., behind the shed and forgetting them. That is, until the sun & frost fracture the case. It always seemed like their "best" cow was the first to discover it & happily consume the contents. They don't remain happy for long.

No text I've read comments on the taste of the lead compounds in sump oil, but in any case, I suspect the used oil & other gunk in it would mask the flavour of the lead in this case. I think you should just assume that what cattle will lick/chew/swallow has little to do with taste. How many folks do you know that go around happily chewing on a great bolus of material they've just eructated from their stomachs some hours after their last meal??

Cheers,

All mineral oils are know to be carcinogenic and have been listed as such on the US Sept of Human Health's annual Report on Cancer since 1980. Thats why like many other hydrocarbons the raw products has a recommended max concentrations in air etc see below.

Used (sump) engine oils are worse than new oils as they contain all manner of metals and even more carcinogenic hydrocarbon fragments. Used diesel engine oil also contains diesel combustion particulates in high concentrations making them a worse than used petrol engine oils.

It doesn't matter what oil is used, a seriously large concentration of PM2.5 particles is generated during high heating of ANY oil. This happens in cooking and in the heat treatment of steels using oil. Fortunately we don't usually cook with mineral oil and for hobby level heat treatment the event is short lived although the generated particles can hang around for hours afterwards unless adequate ventilation is used.

I use about 4L of "new" engine oil heated to about 120ºC in to cook the finished parts for about 30 minutes as the final stage of the fume bluing process I am really keen on. I usually heat the oil in a stainless steel saucepan and to get the oil up to temp I start by setting the hotplate to max and then coming back later and turning it down. One time I forgot and came back about an hour later to see a thick blue haze in my "small" shed and for the first time had my sawdust particle counter running showing PM2.5 particle concentration that were off the scale (>1200 ug/m^3) - I did check the oil temp - it was ~175º. I currently use the same "new" oil in my steel heat treatment although in the past I have used canola. I usually preheat the oil to ~150º for oil quenches AND always have my shed ventilators on when doing this.

High temp frying in ordinary vegetable oils also generates large concentrations of PM2.5 particles. Several times inside the house I have seen PM2.5s around the 600 ug/m^3 mark just frying a pan of snags and onions. And that was with the dust detector was in my study 4 rooms away from the kitchen. We tend to bake our snags these days but that is not much better (~250 ug/m^3) and in all cases it takes hours to get back to normal.

Occupational Safety and Health Administration (OSHA) While this section accurately identifies OSHA’s legally enforceable PELs for this substance in 2010, specific PELs may not reflect the more current studies and may not adequately protect workers. Permissible exposure limit (PEL) = 5 mg/m3 for mineral-oil mist.

Guidelines
American Conference of Governmental Industrial Hygienists (ACGIH)
Threshold limit value – time-weighted average (TLV-TWA) = 5 mg/m3 for mineral-oil mist. Threshold limit value – short term exposure limit (TLV-STEL) = 10 mg/m3 for mineral-oil mist.
National Institute for Occupational Safety and Health (NIOSH)
Recommended exposure limit (REL) = 5 mg/m3 for mineral-oil mist.˝ˇShort-term exposure limit (STEL) = 10 mg/m3 for mineral-oil mist.˝
ˇImmediately dangerous to life and health (IDLH) limit = 2,500 mg/m3 for mineral-oil mist.

The fact that very hot oil makes lots of small particles is why I have been experimenting with a Dispersed Oil Particulate generator.
Dispersed Oil Particle generator

Bob, I'd certainly be cautious if using hot oils fairly regularly the way you describe! Frying & grilling food also generates nitrosamines, which are pretty nasty chemicals, too. Fortunately, evolution has equipped us with ways to deal with very low levels of many potentially toxic, teratogenic, or carcinogenic compounds. The emphasis is usually on LOW levels, but bas long as you keep exposures brief & infrequent, you are probably not increasing your risks significantly over the combined effects of all the other exposures we accept or can't avoid in normal everyday living.

All the fun things in life seem to be illegal, immoral or carcinogenic.

Cheers,

Most of the car dealerships around here make anyone servicing vehicles wear nitrile gloves doing any oil work.
Rgds,
Crocy.

Originally Posted by Old Croc

Most of the car dealerships around here make anyone servicing vehicles wear nitrile gloves doing any oil work.
Rgds,
Crocy.

That's pretty well standard everywhere now. I keep reminding myself I should be doing that when metal turning/milling as I tend to end up with very oily hands after just a few minutes on the job.

Bob, in a very quick search, I only found one reviewed research paper that directly addresses the question (I'm sure there must be a few more). These folks found that used oil from petrol engines was carcinogenic in the mouse skin test and the longer it had remained in the engine between services, the greater the effct. It was also mutagenic in another standard test, but neither fresh oil, nor oil from diesel engines had any carcinogenic or mutagenic effects. The latter test just shows if something is able to cause changes in bacterial DNA and is not conclusive, but a strong indication the substance should be treated with caution. I'm not going to worry about servicing my old ute once a year, but I would certainly be careful if I was exposed to used petrol oil on a daily basis. A single set of experiments neither exonerates nor damns anything for certain, but it's certainly a warning! All complex aromatic hydrocarbons should be treated with respect, but I suspect you & I are probably more likely to die from some completely different cause than cancer induced by occasional exposure to used engine oil.

Many years ago, I worked for a while at a place in England where they tested all sorts of compounds for any ill effects, and one of the substances being tested while I was there was a cutting oil. It passed it's tests comfortably, and I presume most cutting oil sold today would have been subjected to similar rigorous testing, so my occasional use of cutting oil doesn't concern me too much either.

Always a good idea to read the MSDS and observe any precautions thereon.....


Cheers,

Originally Posted by IanW

Bob, in a very quick search, I only found one reviewed research paper that directly addresses the question (I'm sure there must be a few more). These folks found that used oil from petrol engines was carcinogenic in the mouse skin test and the longer it had remained in the engine between services, the greater the effct. It was also mutagenic in another standard test, but neither fresh oil, nor oil from diesel engines had any carcinogenic or mutagenic effects. The latter test just shows if something is able to cause changes in bacterial DNA and is not conclusive, but a strong indication the substance should be treated with caution. I'm not going to worry about servicing my old ute once a year, but I would certainly be careful if I was exposed to used petrol oil on a daily basis. A single set of experiments neither exonerates nor damns anything for certain, but it's certainly a warning! All complex aromatic hydrocarbons should be treated with respect, but I suspect you & I are probably more likely to die from some completely different cause than cancer induced by occasional exposure to used engine oil.

Many years ago, I worked for a while at a place in England where they tested all sorts of compounds for any ill effects, and one of the substances being tested while I was there was a cutting oil. It passed it's tests comfortably, and I presume most cutting oil sold today would have been subjected to similar rigorous testing, so my occasional use of cutting oil doesn't concern me too much either.

Always a good idea to read the MSDS and observe any precautions thereon.....


Cheers,

Ian

We live in a litigious society and manufacturers, if they think there is even the remotest possibility their product could be carcinogenic, classify as such so down the track they can deny liability. Consequently the MSDS for diesel fuel says it is carcinogenic. A good proportion of the population today has exposure to this product far more than diesel oil. I think that in the extremely small levels of exposure for us it is not a concern:

Different if we go into business hardening plane blades.

Regards
Paul

Originally Posted by Bushmiller

.....Different if we go into business hardening plane blades......

Just speaking for myself, that's not bleedin' likely!

Originally Posted by IanW

Just speaking for myself, that's not bleedin' likely!

Me too! Oh, is that the wrong group?



Regards
Paul