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| How do I grind sharp accurate tools - cutter grinder upgrade |
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| raynerd:
I'm about to cut an escape wheel for a clock and the plans show for a fly cutter with a very specific profile. Some kind chap building this clock last year sent me the cutter he used. It has been in my draw for over 12 months and I have yet to touch it until today. It is beautifully cut, crisp and sharp edges, super straight grinds. Sadly, when it comes to measure it up, I find it is t quite right!! I get the end tip width as 0.062" rather than the 0.075" stated and the 24deg angle is more like 27deg. I've got a feeling that actually it'll be ok - it'll just need a deeper cut but it must work as the chap has used it. What scared me most is that if I wanted to recut it or make similar in future, I could no way get as sharp grinds as he has done. My grinding setup is a cheapo nu-tool bt150 grinder with a simple bent steel bracket rest. There is little chance I could safely hold such a small piece of steel, never mind cut such sharp grinds. Two questions in one -how are such sharp cuts made or, what equipment do I need to upgrade to to achieve quality tool steel grinding. I presume a full tool cutter grinder would be a step too far or is something as high quality as that needed?? Chris |
| vtsteam:
Well I'm sure there will be many suggestions for wonderful tools. Here's a bit of a more err uhhh scrap heap approach that actually works quite well! http://madmodder.net/index.php/topic,9051.0.html |
| sbwhart:
You could use my home brew cutter grinder with the a few add ons, http://madmodder.net/index.php/topic,9270.msg102867.html#msg102867 Or Harold Halls book:- Tool and Cutter Sharpening shows a bit of kit that you could make/use Stew |
| Fergus OMore:
My take is if you are stuck with a 6" Chinese or whatever double ended grinder is to immediately chuck the abrasive wheels away and get replacements in white aloxite in grades like 60 and 80 grit. I think that that I did write and say possibly Cromwell Tools is one firm which comes to mind. #My next move would be to scrap the flimsy rests and if push came to shove, use wooden ones. I used best B and Q 50mm square timber ones on a crap Clarkson- to see the wheels go round :wack: In your case, I would make up rests to repeat the existing angles on your cutter. It may be unorthodox- but that is me. Probably the cheapest- and simplest book is still Ian Bradley's Shaping Machine and Lathe Tools. Mine is 1976 but none the worse for that. Probably it is only a few quid on E-Bay. He wrote a bigger book- but I digress. A worthwhile digression is to have a look on the net for Conrad Hoffman's web site where he describes honing tools using something similar to the Goniostat in Charles Holzapffel's books on turning. If you think that this is a bit odd, you have to find a quarter of a million quid to buy the lathe that goes with it. If my aged memory is holding out, the Society of Ornamental Turners produced a simpler design to the Goniostat. I use diamond grit but the old watchmakers used various cheaper pastes. As some one else remarked, there are lots of ideas but mine work, have stood the test of time and are inexpensive. |
| vtsteam:
This is a separate topic from the jig used to guide or hold the tool to be ground, but I really appreciate the fact that I, almost accidentally, decided to use the old circular sander as the grinding means. There are many reasons: 1.)I don't have to worry about wheels shattering, I can just turn it on without standing back from it. I am also not in line with the periphery. It is quieter and more pleasant to work with. 2.)I am grinding on a flat surface rather than a curved one. It doesn't impart a hollow to the face being ground. This is important. A conventional grinder's disk shaped stone shouldn't be used on the flat side face (or that's what is generally decreed). So if used properly it grinds hollow. True, special conical stones allow flat grinding. But they are expensive ( many times more than my entire tag sale sander) and they tie up your grinder -- they limit what you can grind besides machine tools. I often need to sharpen axes etc. , or grind down raw stock, and that would certainly abuse a special conical stone. I have a conventional grinder with conventional stones for these things. Also it accepts special purpose wheels like a green wheel or even a buffing wheel. Not disparaging a conventional grinder, but for sharpening lathe tools now, I greatly prefer the sander. 3.) The sander doesn't require dressing to keep it sharp, or true. Just pop on a new sanding disk. You could buy a lot of sanding disks for the price of a conical stone. And you can change grits in a minute. 4.) I can use the sander for many other purposes that would be unsuitable for a grinding stone -- wood in pattern making, soft alloys, etc. 5.) It is compact, and fits nicely where I need it. I'd love a Quorn or any of the other wonderful cutter grinders out there, no question, and if one dropped out of the sky to alight on my workbench, that's where tools would get sharpened. But failing that, my precision tool sharpening has moved from the grinder to the sander with no regrets. |
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