difalkner Posted January 10, 2018 Report Share Posted January 10, 2018 Good observation. Yes, that cross has sharp corners but in the final version they have the same radii and fit nicely. Not sure why I cut that one 'cause it's not usable as is. It's propped up against my subwoofer in the shop. David Quote Link to comment Share on other sites More sharing options...
wdwerker Posted January 10, 2018 Report Share Posted January 10, 2018 I would build the form for a Morris chair arm out of vertical layers. 3 or 4 line up pin holes could be cut w the CNC couldn't they ? Quote Link to comment Share on other sites More sharing options...
Mick S Posted January 10, 2018 Author Report Share Posted January 10, 2018 13 minutes ago, wdwerker said: I would build the form for a Morris chair arm out of vertical layers. 3 or 4 line up pin holes could be cut w the CNC couldn't they ? Yes. It depends on how you plan to glue the layers, with clamps or with a vacuum bag. If it's with clamps where you have a male and a female form, I would draw a rectangle first, then draw my curve for the bottom surface of the arm spanning the width of the rectangle, then offset a line above that by whatever the arm thickness is, say 1". That gap would be the area the layers occupy when they're clamped. Then trim the vectors to remove the ends of the void where the arm goes, join the remaining vectors and add some clamp holes and location pin holes. Copy it as many times as needed for the width of the arm, toolpath it and cut it. If I were using a vacuum bag, just draw the bottom part of the form to correspond to the bottom of the arm. Add pin holes and cut it. You can see the vertical layers on the end of the form. 2 Quote Link to comment Share on other sites More sharing options...
Mick S Posted January 10, 2018 Author Report Share Posted January 10, 2018 9 hours ago, difalkner said: Good observation. Yes, that cross has sharp corners but in the final version they have the same radii and fit nicely. Not sure why I cut that one 'cause it's not usable as is. It's propped up against my subwoofer in the shop. David Sounds like some deep religion! Quote Link to comment Share on other sites More sharing options...
difalkner Posted January 10, 2018 Report Share Posted January 10, 2018 Haha! Not that deep, it's just an old computer subwoofer but it sure helps the sound in my shop David Quote Link to comment Share on other sites More sharing options...
Popular Post Mick S Posted January 18, 2018 Author Popular Post Report Share Posted January 18, 2018 Very dusty video, but Carl's first CNC project, a walnut cutting board. Two-sided machining, finger pulls on the bottom and drip groove on the top. 3 Quote Link to comment Share on other sites More sharing options...
Mark J Posted January 19, 2018 Report Share Posted January 19, 2018 On 1/9/2018 at 9:40 PM, Mick S said: I would draw a rectangle first, then draw my curve for the bottom surface of the arm spanning the width of the rectangle, then offset a line above that by whatever the arm thickness is, say 1". That gap would be the area the layers occupy when they're clamped. Then trim the vectors to remove the ends of the void where the arm goes, join the remaining vectors and add some clamp holes and location pin holes. Copy it as many times as needed for the width of the arm, toolpath it and cut it. I remember from high school what a vector is (although I was hoping never to see one again), and I grasped the last part, "cut it", otherwise not so much. Guess I'm not so much trying to climb the learning curve as find the begining. Here's a cutting board question. Can you program the CNC to cut the drip groove such that it gets deeper as it moves from one end of the board to the other? Quote Link to comment Share on other sites More sharing options...
kyokahn Posted January 19, 2018 Report Share Posted January 19, 2018 6 hours ago, Mark J said: Can you program the CNC to cut the drip groove such that it gets deeper as it moves from one end of the board to the other? Yes, you can, and that's a great idea! Quote Link to comment Share on other sites More sharing options...
difalkner Posted January 19, 2018 Report Share Posted January 19, 2018 Very nice cutting board! That's a pretty healthy cut he's taking, Mick, and at a fairly decent feed rate. Is that a 3/8" bit? Looks too big to be 1/4" and not quite big enough to be 1/2". Also, what is causing the 'stutter' right before it makes the turn at each corner? Is this a Fusion 360 generated toolpath? David Quote Link to comment Share on other sites More sharing options...
Mick S Posted January 20, 2018 Author Report Share Posted January 20, 2018 17 hours ago, difalkner said: Very nice cutting board! That's a pretty healthy cut he's taking, Mick, and at a fairly decent feed rate. Is that a 3/8" bit? Looks too big to be 1/4" and not quite big enough to be 1/2". Also, what is causing the 'stutter' right before it makes the turn at each corner? Is this a Fusion 360 generated toolpath? David Thanks, David. We ran it 225 ipm, 18000 rpm at .5" DOC per pass using a 3/8" compression bit, followed by a 3/8" low helix 3-flute finisher to remove the last .008" for a cleaner edge. I'm not sure what's causing the stutter. I've looked at the G-code and don't see anything, and checked that we're running in CV mode. I didn't have time to look at the specific CV setup, but I suspect I need to adjust the parameters. Programmed in VCarve Pro. Quote Link to comment Share on other sites More sharing options...
difalkner Posted January 20, 2018 Report Share Posted January 20, 2018 That's something I have yet to do - run a finishing pass to clean up the edge. I'm not sure in Fusion 360 what I need to do to accomplish that but I truly haven't looked. It probably isn't that hard, just haven't looked. I also haven't cut anywhere near that DOC and feed rate but then I primarily use a 1/4" downcut spiral for that outer profile and it's probably not wise to cut that aggressively with a 1/4" bit. Not in Walnut, anyway. Did the finishing cut also have the stutter? Just curious... David Quote Link to comment Share on other sites More sharing options...
Mick S Posted January 20, 2018 Author Report Share Posted January 20, 2018 1 hour ago, difalkner said: Did the finishing cut also have the stutter? Just curious... Yes, it did. It may be in the specific Mach3 post I'm using, but I suspect it's a CV setting issue. The parameters of the Constant Velocity mode can be adjusted from not slowing at all around corners (likely overshooting the corners) to stopping prior to cornering. It's probably set closer to the latter. Quote Link to comment Share on other sites More sharing options...
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