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Likely dumb question-- identifying cutters

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no such thing as a dumb question.. only stupid answers.. if it was me, I'd touch some non-edge part lightly to a grinding wheel and see what kind of sparks it gives, I guess.. or if the piece was too small to safely touch to a grinding wheel, I'd try and see if it would scratch a notch into a file (Carbide should, as far as I know? Doubt that HSS would, but I wouldn't know) Most carbide stuff would be either carbide tipped or carbide coated I would guess..
 

Timothy Allen

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fwiw, Tungsten Carbide has a density of 15.6 g/cm^3 whereas high speed steel is only about 8.2 g/cm^3 -- if the cutters you are talking about are just the tips, maybe weighing then on a sensitive scale will help you distinguish them?
 
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fwiw, Tungsten Carbide has a density of 15.6 g/cm^3 whereas high speed steel is only about 8.2 g/cm^3 -- if the cutters you are talking about are just the tips, maybe weighing then on a sensitive scale will help you distinguish them?
Hmm might work, assuming all cutters are identical volume (cm^3)...
 

Emiliano Achaval

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Not a stupid question at all Roger. I saw once a diagram of sparks to help identify different types of steels. I believe the magnet answer above might help you. But there has to be another way. This is something I suspect either @john lucas and or @robo hippy might be able to help.
 

Timothy Allen

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Hmm might work, assuming all cutters are identical volume (cm^3)...

Well, one could easily measure the volumes of each of the cutters using water displacement if you had a finely calibrated graduated cylinder or something similar. But I'm assuming the cutters are all roughly equivalent in size, and with a density difference of almost double, I would think the TC ones should reveal themselves upon weighing without one having to do too much math.

The magnet idea is a good one, too, as well as the spark test, and the hardness scratch test (TC is 9 to 9.5 on the Mohs scale, tool steels range from around 6.5 to 7.5, so the TC cutters should easily scratch your HSS tools -- or a piece of quartz).
 
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Roger Wiegand

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OK, I'm off to weigh them. Assuming I get a bimodal distribution I'll have an answer. I was hoping to avoid having to do a lot f scratching of things.

Who knows, maybe I'll get my first publication in the Journal of Irreproducible Results out of it. (Not that I haven't done a lot of work that should have ended up there!)
 

john lucas

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Well I'm away from home right now but when I get back I will test the metals and tell you. Pretty sure the spark test will.work. not sure about the magnet but you have me curious. Should have the answer by noon if I dont forget. At my age whenever I walk through a door it wipes out my memory so not making any promises.
 

Roger Wiegand

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OK, data!

I'm happy to report that there are two methods that readily distinguish the HSS from carbide, though they are most useful if you have more than one of different kinds to compare. I could only find four cutters (I'm sure I have a couple more someplace!), but the differences were striking. I weighed them and assessed magnetic attraction. With a bit more effort I could have made a quantitative assessment of the magnetic attraction, but the subjective differences were enough to make the difference obvious.


cutterweightmagnet
19.24 gweak
24.41 gstrong
39.16 gweak
49.23 gweak
I conclude that the heavy, weakly magnetic ones are carbide. This is consistent with the light, strongly magnetic one showing evidence of multiple (poor) sharpenings, while one of the carbide ones is known to be near new and has never been resharpened.


(hmm-- the forum software decided it didn't like my nicely spaced out table and crunched everything together. Still readable, I guess) (OK, 2nd edit, found the table function. See how that works.
 
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Well, first thing, which coring system? The only one with replaceable tips is the Oneway. They do have carbide tips not, and I believe Mike Hunter makes tips for them as well. The original that came with the Oneway were some type of very hard steel. They didn't say what type of metal it was. The tips from Woodcut are made from stellite. No clue as to what Kel puts on the McNaughton coring system. A super thin layer of some thing.

robo hippy
 
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I use three ways to tell the difference between carbide and HSS bits for my Oneway coring rig:
1. The carbide bits are noticeably thicker/taller than then the HSS bits, 7.3mm vs 6.5mm.
2. The HSS bits all have facets(correct term?) on top where they've been sharpened.
3. The carbide bits are the ones installed on my knives. The HSS bits are languishing in a drawer on the slim chance I will ever use them again.

I say the carbide bits are noticeably thicker, but that's only true if they are side by side. When I first got a carbide bit, I found it didn't cut well near the end of the cut (center of the bowl). I checked alignment and found that the cutter was too far above center. That's how I discovered it was thicker. The knife had probably been set higher than it should have been for the HSS too due to my experience with McNaughton blades deflecting.

Ron Campbell at AZ Carbides has the carbide bits for sale at a very attractive price. I bought a couple of the bits when they were in beta testing and have been very satisfied with them. https://azcarbide.com/1way-core-cutter/
 
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If you are going to cut a bowl blank core totally off, like with end grain or burl, you need to be at dead center for that last little bit. If you don't cut it off, you can rip through the bottom of your bowl blank. With the Oneway, with that support finger, it will stay at dead center all the way in. With the Woodcut, you can get some deflection, so may have to raise the cutter a slight bit near the end of the cut. With the McNaughton, on some of the deeper cores, because of lots of deflection and flexing during the cut, I need to be 1/2 inch or more above center by the time I get to the bottom. I can 'feel' it now, after lots of experience....

No clue as to how the Mike Hunter tips for the Oneway are in a price comparison, but Mike told me they work well. From most of what I have cored, I prefer a burr for cutting. It is supposed to be impossible to raise a burr on carbide, so don't know how they cut. Also, I haven't used one...

robo hippy
 
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