On Saturday 20 February 2016 09:46:04 Gene Heskett wrote: > On Saturday 20 February 2016 05:18:13 Marcus Bowman wrote: > > On 20 Feb 2016, at 09:29, Gene Heskett wrote: > > > On Saturday 20 February 2016 02:49:15 Marcus Bowman wrote: > > >> On 20 Feb 2016, at 02:31, Gene Heskett wrote: > > >>> Greetings all; > > >>> > > >>> I am not haveing any luck finding one smaller than 3/8 radius, > > >>> and I need one that cuts with a 1/8" radius. > > >>> > > >>> Any body know of a place I might be able to source one that > > >>> small? > > >> > > >> Not sure where might be close to you, but I have one which I got > > >> at a local wood turners' store. It is a 1/8inch gouge tool, but I > > >> made it into something more like a fingernail tool by grinding. I > > >> just copied the shape of one of my larger fingernail gouges. With > > >> a tool that small in section, it needs support close to the > > >> cutting edge, because I find mine prone to chatter unless the > > >> rest is set close in. I would be inclined to fix it in a 5/8inch > > >> sleeve machined with a tapered nose. > > >> > > >> I can also highly recommend the Drozda Finial Gouge, which takes > > >> things a stage further. Cuts beautifully when used by hand. You > > >> can buy one here: http://www.cindydrozda.com/html/Tool_Info.html > > >> > > >> but I bought the DVD which shows you how to make one (too far > > >> away for the expensive carriage on the tool to make sense). There > > >> is a youTube video around which shows much the same thing, I > > >> think. There used to be a clip on the Drozda site, as I recall. > > >> > > >> Marcus > > > > > > But Marcus, I am not doing this by hand, or even on a wood lathe, > > > this would be a router bit, chucked in my milling machine, > > > possibly making multiple passes to get the correct edge profile. > > > > Point taken; sorry. > > So could you do this using a ball-nosed end mill? Or could you > > reshape an end mill? > > No, ball is the inverse of the shape I need, see > > <http://grizzly.com/products/C1214> > > for an example but that ones 3/8" width of hollow is nominally 2x > wider than what I need. A 1/8" radius would be the bees knees for > this. > > I have some 4" wide, 1/2" thick 7075-t6 that I can make a blade holder > disk from by boring a 22mm hole to fit an arbor, then taking out a pie > slice, and fitting a 1/2" x 1/8" piece of A2, and shape the end with a > 1/4" SC mill, basically makeing the tool I need but it will take me > most of the weekend. I would rather the disk was steel as I expect > the mass would improve the quality of cut, but that alu is what I > have. And I haven't the capability of hardening the A2 when its done. > > Thanks Marcus. > > Cheers, Gene Heskett
Thinking about this, and the fact that around 2700 revs is wide open, combined with the faster the edge going by the wood, the cleaner the cut, I am tempted to use a square of that alu, and put the blade in a corner of the square. But I am also reminded that its a 3d curve, and I can't exceed the radius of the already carved face and end curves at the junction of the curves. The curves were carved with a 4" diameter blade, intended for a Porter-Cable #557 biscuit joiner, blade mounted on an arbor in the mill, and with the vise tipped up about 36.5 degrees. The blade was then swept down at that same angle, at 20 IPM, and back up to x0y0 at 2 IPM to leave a surface that 2 minutes of sanding on a 220 grit form leaves a surface ready for finish. And with a 4" blade laying horizontal and the vise tipped 36.5 degrees. So how do I calculate the radius of where the two curves meet?, because that is the maximum diameter of the cutting tool radius I can actually use. When I made the sanding form, the radius of that curve, driving a 3/4" bullnose tool, was 3.25", and while the form is wider, the workpiece is only 2.1" wide, and thats within a thou of matching what I have cut with the saw blade. So that is a pretty good guess for a starting point. But wouldn't the junctions sharp edge where those two curves meet, be effectively a smaller radius? But I've no math knowledge to use to calculate how much smaller. :( For starters the bullnose tool would have a rising cutting edge as it goes off the centerline and the highest point of that curve, which would make the radius of that curve slightly larger than the R-3.25" that was in the G3 gcode that carved it. Would it suffice to measure the chord and the depth below the chord line, can I somehow determine the maximum tolerable radius of tool by that means? I know there is some trig about this chord stuff in the Handbook #27, so I'll go see if some button pushing can arrive at a usefull number. The concern is that if I make too big a cutter I'll be cutting off the outside corners without reaching the center. If I make it a few thou too small, I can always plug in a small G3 in the gcode to expand it. I'll come back in before I've made any swarf to check and see if anyone has a shortcut for this. Thanks everybody. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
