On Wednesday 10 February 2016 12:15:34 Chris Albertson wrote: > On Wed, Feb 10, 2016 at 7:51 AM, andy pugh <bodge...@gmail.com> wrote: > > The lazy way would be to build a 3D model of what you want and then > > let a CAM package do the work. > > Lazy? no. It's the most accurate way to go. When the shape is (as > it is here) so complex that you can not explain it using words and > can't draw a pencil sketch then it is time to use 3D modeling. This > shape of a leather strap is more like a sculpture then a machine part. > If you try and model it mathematically you might end up with a rather > sterile looking part lacking the organic properties of real leather.
The exact situation that existed on the first of these chests, which because I was out of storage room, and my oldest stepson came down for the weekend, I've already given it to him. I was proud of everything on that chest except those decorators. This time I am determined that they will be a better resemblence to the leather strap effect than those were. I had 2 pieces left over from that one, so I've rigged a clamp up in that vise, but with the back facing up so that I will have a fixed distance/thickness to the long leg of the L shape. So first, I plowed the inside corner groove with a 1/4" ball nose, then cleaned off the back to that depth with a 3/4 cylinders tools end tips. Looked great. Then I sat down to compose the hollowed out top end, using Johns new arcgenm18.py, finding and adjusting the G10 P2 offsets to put the G3 R zero point back in the middle of the post, which is ok as it will never attempt to move there, its just an anchor point for the G3 X Y R format. The X offset put into G55 places 0.0000 dead in the center of the boards width. Then find a Y point that is not quite touching the wood. The G3 to the opposite sign of X with a radii of about 8.5". A test cut from mdi just toughing it looked great, so I added a loop that would take the BN tool about 30 thou deeper per pass. But in the preamble, I was being a good guy and had coded a G53 G0 X0 Y0 z0, then reset G54 and G55 to that default zero so that in placing all the touch offs, it was genuinely starting from the home switchs. Then I added the offsets to the G55 mapping to put the machine where it needed to be with the first active move in the loop. But I left the tool at final depth, so when it exec'd the G53 G0 xyz=0.00, it came up at an angle and broke off the back edge of the test piece. Ooops. So its glued back in place, and once set I will finish the carving and recheck that fit. Then I'll figure out how to do a lifelike roundover on the upper outside corner. The short leg of that L should reach across the edge of the baseboard to come in close contact with the non-contoured lower edge on the boxes bottom surround, biscuited to the box bottom panel. A piece of coarse sandpaper held against that trim serves as the abrasive to achieve a "gas tight" fit on a per piece basis. When it fits, glue it up quick before it changes its mind. Its wood, it will. :) As its grain is crossways to the baseboard, and it all moves with the seasons, a glue with some flexability seems to be in order, so I am tempted to use something like goop in place of Elmers good stuff. Lateral and seasonal forces it should take, although a determined pry in the joint will part it. Sold by loctite as GO-2 these days, its good stuff where a teeny bit of flexability is needed. > The trouble with using 3D modeling is the CAM software will create a > tool path that is just a grid pattern and the finish might not be > perfect. But that is why they make fine grit sand paper. Modeling > this using something like Blender is far for being lazy, It is a lot > of work. Work I'd rather do with geany, directly on the gcode. I can get to a first pass that may need some fine tuning in about an hour. Write once, run many times. Change tools to the next one, wash, rinse, & repeat. This curve pon the end? if too shallow, reduce the R and it will cut a wee bit deeper in the middle on the next run. Next subject: My 45 degree dovetail tools arrived today, so once this phase of this project is done, I'll take a break and make the camera mount next. Those are HSS, so can I assume they should be running knee deep in Buttercutt when carving 1065 steel? I have some I may as well use. 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
