On Wednesday 10 February 2016 08:41:41 Todd Zuercher wrote: > Not sure if I'm getting your description of your piece that you are > trying to shape. If I'm picturing it right, I'd start with a thicker > block of wood, shape it with a round-over on a router-table then slice > off the finished piece with the table-saw. > But its shaped like a piece of stretched leather, with the outside edges curled up, and the "curl" continues as it "folds" over the top of the baseboard. The back is cut away so its like a 1/8" piece of leather, fitting over the face and top of the baseboard. So the top end, where it folds over the top of the baseboard, also has this same "stretched leather" contour to the end. The cut leather effect is spoilt a bit by rounding over the outside edges with a 1/8" radius roundover, but the sharp edges would be the first thing damaged by an errant shoe walking up to it. And that would really spoil the effect.
I can do it by hand on a combo disk/belt sander, but the finest grit belt is a 120, which leaves huge crossgrain scratches it takes forever to sand out if you do the curves over the end roller. On end grain in particular, the finish soaks into the unsmooth surface and turns it darned near black. So there, the final sanding grit needs to a wet-r-dry 2000, and that means dipped in a 4 lb cut of shellac to seal it well enough to use the sandpaper wet. Using it dry=instantly clogged sandpaper. That also keeps the final finish, possibly teak oil, from soaking in and blackening the end grain. Unless I sand away too much of the shellac, opening up the shellac sealed end grain. :( Since I cannot rotate a co-ordinate map about the Y axis, (could this be a feature request?) it looks like I'll have to do it in at least 3 setups because the upper front corner roundover is going to need the vice set at 45 degrees to do the corner with a roundover running in an YZ axis circle with the head also tilted that same 45 degrees to keep the sharp pointed roundover's point from scaring the work. Or find the right sized bullnose cutter and lay the head horizontal. Better yet, turn the work downward 45 degrees and leave the head trammed. Can you spell a pain in the ass? And in order to assure uniformity, do the back face cutaway first so I've a face to locate the outside, visible work to. 4 setups, gah! I'd better cut me some white pine scraps to fine tune this with... This would be days simpler to do if I could just rotate a co-ordinate plane to any arbitrary angle instead of being locked to the z axis. So I'll explore making a bullnose cutter, and a vise tilt of 45 degrees which will rotate that end edges cut to the horizontal plane. The tilting vise is a $60 snears & takeitback but its been a pretty rigid vise for a decade+ now. The tilt scale seems to be accurate enough, but workholding must obviously be by the edges. Shoe-shining that roundover with crocus cloth is almost looking to be faster. :( > ----- Original Message ----- > From: "Gene Heskett" <ghesk...@wdtv.com> > To: "Enhanced Machine Controller (EMC)" > <emc-users@lists.sourceforge.net> Sent: Wednesday, February 10, 2016 > 4:02:56 AM > Subject: [Emc-users] Another curve problem, in 3d this time > > Greetings all; > > This is something I've not attempted before. I need to, using either a > 1/2" cove router tool, or a 1/4" ball nose, do some cleanup work on > around 32 little decorator pieces for the base of these cabinets I am > making. The intention is to add what looks like a leather strap under > tension that starts at the floor, come up the height of the baseboard, > and meets the straight face just below the roundover cut, of a strip > of solid mahogany biscuit jointed to the edge of a 3/4" mahogany > veneered botton panel whose outer face is about 3/8" from covering the > top edge of the basebaord > > They are approximately 3.4" long, and 2.0625" wide, starting with > 15/16" thick stock mahogany. The front or outer face already has a > shallow depression of about 1/8" deep centered on that 2.0625 width by > passing it over a 10" blade at about a 30 degree angle on the table > saw. With the final pass made once each way so that any un-evenness in > the groove is visually centered, so there could be a slight high spot > in the center. NBD if so. > > Doing that in gcode is fairly easy, but when it reaches the top end, > this curve needs to make a 90 degree turn, with about a 1/8" radius > made by combining the curve as it rotates, such that the curves visual > radii is carried on over and carved into the end of the piece. > > With the right size of drum sander, its something that could be done > almost by hand, but it would take a drum sander about 8" or 9" > diameter, and I don't hardly have some more of those. Not to mention > that the sandpaper would be running cross-grain, leaving quite visible > sanding marks. Hence the thought of using the 1/2" cemented carbide > tool I have, which has already been re-sharpened and left a finish > ready surface on a gunstock I made for one of my BP rifles 3 years > back. > > But I cannot grasp how this can be done unless an xz co-ord rotation > is done at the corner point, effectively turning the curve being > carved in the YZ axis over so it effectively becomes a YX curve while > leaving a 1/8" radius as it "turns the corner". > > Is this an idea that combined with the radius of the 1/2" ball nosed > tool, can be made to work, getting a finish ready surface by use of a > X stepover of just a few thou per Y pass? > > If I can do this as three moves in the X domain, a 3+" run across the > length of the top, a 90 degree arc at the corner, with the corner axis > being rotated to do the same curve across the end, stepping the repeat > in the Y domain so that any machine marks left run with the grain, I > would consider it a workable idea. But to make sure the curves > matched, face and one end, it seems I'll need to rotate the > co-ordinate along the Y axis, but the rotation point will also need to > be adjusted according to the curve. > > I'll play around in the simulator with that idea, but if anyone has a > better idea, head me off at the pass, please. > > But, the first problem is a showstopper, checking on a "G10 L2 > Rdegrees" I find it can only rotate around the Z axis, and for this I > need to rotate around the Y axis. So that idea is dead in the water. > > Work-arounds? Hopefully not a math nightmare I'd never understand... > > Thanks everybody. > > Cheers, Gene Heskett 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
