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I have a paper submitted to the NAWCC about Mobil 1 products. I use 0W-20 (smaller pivots) and 5W-30 (larger pivots) in my cars as well. Not expensive when compared to $30/ 4 oz containers for two brands sold for clocks. And heck, its good for 20,000 milesI am thinking of synthetic oil like Modil 1. It is more expensive but I keep a quart of so on hand for my lawnmower and snow blower. I know a very good clock maker who uses it to lub most of the pivots in the clocks he does and I use a lighter grade on watches. These horological applications use the stuff by the droplet so I always have some on hand, It is very stable non flammable and keeps forever in partially sealed containers.
Linseed oil is a fire hazard because it's a "drying oil", which means it hardens (polymerizes) on exposure to air; this reaction gives off heat, which can cause a spontaneous fire. It's the oil they're talking about when warning of the danger of "oily rags". Most oils, like mineral oils, do not have this property.Boiled Linseed it is then. Most seem to think it stinks, but oddly I like the way it smells.
Mobile 1 is an engine oil and the advantage I'm aware of is its so easy to find. There are a few real disadvantages. First, it may have some EP additives that will over time (pun intended) eat away at bronze/brass alloys causing premature failure of bearings. Secondly, the detergents keep any dirt in suspension. That's quite important for a machine gear box (you don't want contaminants in suspension), perhaps less so for a clock or total loss lathe oil system, however its still sub-optimal.I have a paper submitted to the NAWCC about Mobil 1 products. I use 0W-20 (smaller pivots) and 5W-30 (larger pivots) in my cars as well. Not expensive when compared to $30/ 4 oz containers for two brands sold for clocks. And heck, its good for 20,000 miles
From air to oil to water the tool steel gets a bit cheaper so it makes some sense to use W1 when you can - and less mess. A difference between the two is that things will more readily crack in a water quench than oil. That will depend on the shape of the part, but becasue of that I keep O1 in stock as the standardW1 means no oil mess, and there's not enough difference in performance characteristics between O1 and W1 to cause me to change.
Glen,One big thing to keep in mind in all these discussions is the size of the things we're talking about. Quenching a 2-inch (50mm) piece of 2mm diameter rod stock is very, very different from quenching a 5mm thick, 50mm wide, 300mm long knife blade.
The following discussion is ONLY about heat treating things that are the size of clock and watch parts, things that are made from very small stock. If you're looking here for heat treating instructions to heat treat a scythe blade or anything else bigger than a pencil, you're in the wrong place. Use common sense. Do your research on heat treating big things.
A coffee can full (say a quart/liter?) of pick-your-oil will 1) provide a huge amount of quenchant for the job and 2) be plenty big enough to where flash point and all the other technical blah-blah is rendered irrelevant. Any oil will do. Lots of people use peanut oil because it smells good. Plunge the piece quickly and deeply (and as vertically as possible to minimize/avoid warping) into the quenchant and swirl it non-stop for fifteen seconds or so. Don't dip it and remove it to watch the fascinating flare-up, don't yo-yo it in and out of the quenchant, don't ease its delicate little toes in and give it time to adjust. Shove it in deeply and leave it completely immersed and move it around. Figure eight, circles, fancy curlicues, whatever - the swirling pattern doesn't matter. Superheated steel cools surprisingly quickly in a quenchant. For 2mm stock fifteen seconds will take the piece to about room temperature. You avoid the threat of fire by the "plunge...quickly" step. You move the piece through the vapor barrier quickly enough that it doesn't have time to flash, you cool the piece very quickly, and you isolate the piece from oxygen. That doesn't mean you don't need to have a fire extinguisher handy just in case - use common sense. The only time you need to heat the quenchant or any of that stuff is when you're dealing with pieces that are several hundred times the size of clock or watch parts. As we've discussed in other threads, tempering doesn't have to be a long process at these sizes. Once an area turns your target color, you're through unless you're intentionally shooting for a measured hardness. You don't need to carefully calculate soak times or any of that folderol. Heat the piece, dunk it, swish it, clean it off, temper it, move on.
I use W1 tool steel and quench 4-inch long (100mm) pieces of 5mm diameter rod stock in a coffee can full of cold-water-tap water. Quenching that big a piece in that much water does a great job of warming the water to a really nice temperature for washing your hands. W1 means no oil mess, and there's not enough difference in performance characteristics between O1 and W1 to cause me to change.
Hope this helps.