It's interesting to note that the previously much maligned carbide that wouldn't take an edge and those disc shaped turning tools that came to cut, but could only scrape have suddenly become highly recommended for proper hollowing. Just takes the right experts to endorse and use them (at least in their demos).
They are touted to 'eliminate' tearout, catches and even will make sharpening a thing of the past. I don't know about all that, but I do know they cost your hat & ass and buying a set will 'eeeliminate' any bulge in your wallet and make it smooth and thin walled.
There's no profit in it so it's unlikely that my suggestion will be endorsed by anybody, but some of you might might want to try making disc shaped cutting tools from discarded engine valves (usually free from lawnmower and auto repair shops). Get a few different sizes, insert the stems into wooden handles, hone the edges and keep the seating bevels or grind to the angles of your choice. Ride the bevel or raise a burr if you want a scraper.
Do Not, repeat Do Not, grind or cut the stems, some are filled with sodium.
Old engine valves probably need a better endorser than me to convince you, so if you try it you probably won't like it. Carbide is now fashionable ...Who would have thought it? :)
I was fairly satisfied with the carbide cutters I got from the machinist up the way a number of years back. The best were those with the trough around the edge to curl the waste like the Hunter tools. Of course the round-disk HSS Sorby would shear fine, and I could sharpen him by myself. The carbides are in the drawer, victims of a fickle public who wouldn't buy "hollow forms" save ornaments, and since the Termite outdid them on endgrain ... well, maybe someday again.
"Arch" wrote: (clip) Get a few different sizes, insert the stems into wooden handles, (clip) Do Not, repeat Do Not, grind or cut the stems, some are filled with
^^^^^^^^^^^^^^^^^^^^^ What a great idea! I think your concern about sodium may scare some people.
1.) I believe you are unlikely to find sodium in any but high performance engines. 2.) Sodium is solid at room temperature, so it's not going to jump out at you. If you do happen to cut into a valve with sodium in the stem, it will start to react with the humidity in the air, forming sodium hydroxide (lye), which is not nice stuff. After that reaction is finished, you could drop the valve into vinegar and get socium acetate, or into Clorox, and get salt. DISCLAIMER: I have not done this.
Sodium and water produce a vigorous, fiery reaction, so don't throw the valve into vinegar or Clorox before the sodium is through reacting with the humidity.
The reason I think this is worth discussing is that I think a valve with the stem coming out at right angles to the head would prove awkward to hold properly to the wood. Arch, if you have done this and know I am wrong, please tell me.
A tip for those that make their own tools. Those round carbide cutters are common in the metalworking industry. They can be had from machine shop suppliers for about $2.00 each. Drill and tap a hole in a suitable bar, put a handle on it and, for about $10.00, you have a tool that you could have bought for about $95.00 (and the replacement cutters for the commercial tools run about $20.00).
Leo, good discussion. The ones that have worked for me have the head & stem in line with the handle. I may not have understood your question because I've not found you to be wrong before.
I probably did post an overabundance of caution. Blame it on my having once dumped some metallic sodium into the soapstone vat at the end of the bench in chemistry lab. I was allowed to stay in school, but it was iffy! :)
BTW, some here might not know that valve stems make useful burnishers for putting burrs on their scrapers. One or two passes across the scrapers edge will raise a nice even burr. The valve can be hand held or for a more elegant device fixed in a hole in a 2X4 plus a nail to force the tool against.
Lobby, I know I'm missing something, but I think I see the concern. Actually, I have used the valves in line with the handle (edge perpendicular) on external convex surfaces not on concave as in hollowing. Maybe I should forget the sodium, cut the stems short and insert them at an angle to the handle?
I've been a heavy proponent of the carbide tipped cutting tools produced by Mike Hunter,Jack McDaniels, and Vermec in Austalia. These tools use a new type of carbide cutter that actually is sharp enough to cut wood well. I went to a machinist tool supplier to see if I could purchase these cutters. None of the cutters they could come up with were as sharp as those used by these woodturners.
I was first introduced to them when I met Mike Hunter at the Desert Woodturning Roundup in 2006. I purchased a 3/8" cutter with handle from Mike for Mildred, my wife. When I returned home, I tried it out and discovered that it worked as good as Mike Hunter had said it would. I called Mike to get more information on the tool for a story. He sent me an unhandled 1/2 tool (the cutter was 1/2" in diameter) to try in a stabalized boring bar. I used both tools in the test. Although they are really excellent for endgrain hollowing, I found that they can be used to completely turn a dry bowl and can even do spindle work. They don't cut "V" grooves very well on spindles. Also, they do not seem to work as well in wet wood.
When Jack McDaniels came out with the Eliminator tool, I had to try it also. Guess what, it works extremely well and for new turners it works exceptionally well because it has two flats on the shaft to help apply the cutter at the proper angle by simply laying one of the flats on the tool rest as you cut. One flat is for inboard cutting and one is for outboard cutting. I have two different sizes of Jack's tool. The one with a 1/4" cutter. This is a real honey for fine work inside a box. The other has a 3/8" cutter which works for most other things. Jack has also came out with a model having a 1/2" cutter with a one inch shank that is excellent for reaching further over the tool rest when hollowing.
Finally, when we were in Australia in 2006, I met Enzo Verrecchia of Vermec at a craft show that the IWCS was attending to promote memberships (I was with the IWCS group). (Incidentally, IWCS is short for the International Wood Collector's Society) Enzo had some tools that were pretty impressive. They also used these carbide cutters. We later visited their business, which is near Vicmarc, and purchased one of Enzo's sphere cutting jigs. It is one of the best that I've used. Later when a friend of Enzo was in the United States demonstrating using Enzo's tools, he sent them to me to try and buy if I chose. One was a stabalized boring bar that I had seen at the craft show and was impressed with and the other was a set of tools with part of them using the carbide cutters. I purchased those tools also and saved shipping from Australia.
I still use my bowl gouges, my spindle gouges, and my skew chisel, for bowls and most spindle work, but when it comes to hollowing end grain I use these carbide tools. They really do work and they are worth every penny one pays for them.
The old carbide tools using cutters to cut steel were never sharp enough to cut wood well. These new cutters are exceptionally sharp and they last a long time if you don't drop the the tool in the floor or bang them on the lathe bed. They do chip quite readily, but they cut wood very well for a long, long time. Incidentally, I tried to sharpen a dull one with chips in it and found it not worth the time.
I know all of the other posts have pretty much bashed the carbide cutter, but I doubt that any of the posters have used the new carbide tools I've just described.
"Arch" wrote: (clip)Actually, I have used the valves in line with the handle (edge
^^^^^^^^^^^^^^^^^ You have found the source of my confusion. I was trying to picture a valve head mounted mushroom-wise on a handle being used on the inside of a vessel.
While we're on the subject, Arch: consider heating the stem to a cherry red just below the head, and bending it about 75 degrees. Then you could use it inside the vessel, and control the angle of attack by rotating the handle.
I don't believe the lower-octane gasoline in use presently demands the cooling that the sodium provided, but precautions and research would certainly be in order.
Hi Fred, A reasoned and courteous rebuttal of my flippant post from your actual experience. Is the composition of the 'new carbide' different or are the bits sharpened better? If I wrote anything for "More Woodturning" you would spend half your time editing, correcting and deleting. Hi Leo, You are seldom wrong! Good idea for you to use your welding gear on, but just my luck for the valve I tried to bend to be the one in ten thousand that's sodium filled.
Hi George, I'm way over my head, but I wonder if higher octane retards burning and prevents explosion so that lower octane would make the valve stems run hotter. Probably not since sodium filled stems are for high performance engines.
Hi Everyone. Instead of starting this thread, I shudda stood in bed! :)
From what I remember the high octane reduces 'pinking' pre-ignition (hence unleaded fuels having normally a lower rating have their ignition retarded). If the valves are not fully closed at the time the fuel ignites, some will bun into the exhaust port, which will raise the temperature in the port and hence around the valve stem. In addition to loss of power.
I am not sure about the materials used in valves but assume that sodium is a relatively new addition. Maybe a valve from a vintage engine might be a good start, though the steel its made from may not be as hard as that used in modern engines? I have a nice big box of pre 1960's motorcycle valves here , maybe one day I will have a play at converting one or two for wood turning.
OK, first things first. Intake valves are cooled by the fuel, so they're solid stems. High-performance engines used sodium-filled exhaust valves for cooling. Aircraft (air-cooled) were seldom without them. Vehicles designed to operate under heavy loads also had them. Preignition has nothing to do with it. That just raps the valve prematurely on the seat (pinging), destroying it. It seems from this that the new four-valve versions of common engines are moving to sodium-filled valve stems, if you believe this article, but they were not common in normal engines heretofore.
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For more of what causes valve failure and an insight into sodium-filled valves try:
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I earned extra money in college installing "export" valves in VWs, which were first shipped here with valves made for 87 octane. They suffered mightily from the then 105-115 octane leaded fuel we used. Neat job doing a bug, actually, you didn't raise the engine, you raised the vehicle and dropped the engine!
I don't know what the composition of the carbide is in the cutters, but they are sharper than any carbide cutters I've seed before these became available. I haven't pushed any of the guys using these cutters to make their tools to find out where they get them or what name they may have attached to them, because I do not feel it is right to give away secrets that would allow other people to start making tools like these guys, and maybe at a lower price than they can produce them in their limited production shops.
In case someone should find the source and can locate one of the little carbide cutters in the 1/8 inch diameter size, I would certainly like to know the source. I think they would make a great Chinese Ball cutting tool at that size.
"Arch" wrote: (clip) Hi Leo, You are seldom wrong! Good idea for you to use your welding
^^^^^^^^^^^^^^^^^^^ Cut it out, Arch! Are you getting ready to ask me for a big favor or something? Use the info provided by George: intake valves would never have sodium in them, since they don't run as hot as exhaust valves. I'm curious to know what would happen if you used a torch on a sodium-filled valve. I think: nothing.
[Extreme care is required in handling elemental/metallic sodium. Sodium is potentially explosive in water (depending on quantity) and is a caustic poison, since it is rapidly converted to sodium hydroxide on contact with moisture. The powdered form may combust spontaneously in air or oxygen. Sodium must be stored either in an inert (oxygen and moisture free) atmosphere (such as nitrogen or argon), or under a liquid hydrocarbon such as mineral oil or kerosene.]
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