> On Apr 10, 2024, at 12:47 PM, gene heskett <ghesk...@shentel.net> wrote: > > On 4/10/24 13:03, John Dammeyer wrote: >> Hi Gene, >> Just like I can't get my head around Fusion360 or similar CAD.
I find that many people’s problem is that they are still thinking that CAD is used to “draw” a part and that somehow the final product is a “‘drawing”. This is completely contrary to how it works. What you do is make the part, just like you would in the shop. There is no “drawing”. In the shop you might start with an extrusion then cut it and mill a pocket and then make some holes and then what ever until it was the right shape. With CAD now, the first step is usually drawing the profile for a custom extrusion. If you try and hand code gcode or use OpenSCAD you are limited to very simple shapes and can never exploit the full capability of the milling machine. Just TRY and hand code a typical hand-held power tool or even a triangular pocket on the side of the sphere in hand-written gcode. So, if you want to model a part in CAD, just think how you would make it in a very well equipped shop. >> AlibreCAD has gone downhill since they trashed their relationship with >> MecSoft which correspondingly trashed AlibreCAM. >> I'll take a closer look at your approach later today. > > My approaches subroutine will take a loop as the primary slicer because each > piece of the scroll will need to start at the root of that slice but the > curved pie slice is wider at the outside. A spiral is a continuous curve, already we jhave assen the curve’s equation. You just marchthrough the point the equation producse and it is literally “perfect”, no approximation. The only problems left are 1) The method is “too perfect” and will generate to make points and be slow 2) doing it all in one pass is a poor machining technique. > The target is to carve each slice from its apex point but widen the rim so > that your 3mm wide fin is all that's left, then advance to the apex of the > next pie slice. So the subroutine will start at 6 common points around the > central axis, and you wind up with 6 3mm wide fins in the scroll shape. > > That won't be the most efficient shape but will get you started. To improve > the efficiency, that central subroutine will need to be converted to use G4 > nurbs to describe the spiral path. But that's for next week. And I expect > Andy might have some better ideas on the nurbs points. I have a good idea > what they can do but zip about the math involved. Flow thru a venturi etc > type math. > >> Thanks >> John >>> -----Original Message----- >>> From: gene heskett [mailto:ghesk...@shentel.net] >>> Sent: April 10, 2024 3:42 AM >>> To: emc-users@lists.sourceforge.net >>> Subject: Re: [Emc-users] Carving a spiral >>> >>> On 4/10/24 03:37, John Dammeyer wrote: >>>> Hi Marcus, >>>> >>>> Here's the problem. >>>> >>>> My Alibre CAD/Cam can produce a spiral slot in a disk using X and Y >> motion. >>> >>> I looked at alibre, could not get my Iowa farm kid head around it. Far >>> easier for me to write my own gcode. >>> >>> In linuxcnc, you can trade the axis names around to fit your hdwe. >>> >>> How far can you tilt your Z? Mine can do a full 90, aka lay the spindle >>> horizontal. Either way IIRC. I can then use X as X, A as A, and a >>> single straight line move to carve the spiral using Z while A is turning >>> N degrees to carve the spiral. So the gcode then becomes a subroutine to >>> do that, and a 2nd loop routine to handle the start of the spiral and >>> possibly a master outer loop to do any incremental cuts to get to the >>> depth needed. Maybe 80 LOC total. >>> >>> If your head cannot tilt that far, then you''l have to cobble up a C, >>> facing up which I CAN do but its a 90/1 drive and will restrict the >>> speed as It can't turn fast enough. Also has a std stepper motor, push >>> its speed and it stalls. Someday I'll put a good motor on it. >>> >>> A Warning though, most of the combo gizmos they sell for $300 or so on >>> ebay are belt drive and no-where near strong enough for this. I did use >>> my 90/1 as A when making my tap hats. Used it to drill & tap the 4 grub >>> screw holes. I setup workstations on the length of the go704's table, >>> put a piece of brass rod in the spindle, drilled the hole for the tap, >>> move the brass to a clamp, drilled and tapped for a locking to an r8 >>> collet screw hole, moved the brass to the A chuck and drilled and tapped >>> all 4 grub screws. All in the same gcode file with pauses and automatic >>> tlo offset corrections as the drills were different lengths. Made a >>> regular production line out of it, took longer moving the brass around >>> than the total run time for the machine. >>> >>> >>>> >>>> >>>> If I tell it to use my 4th axis it's like the video you posted. >> Designed >>>> for creating a spiral on something horizontal to say the X axis. >>>> >>>> I think I'd have to buy the 5th axis capability in order to be able to >> have >>>> the rotary table turn while the cutter moves in the X direction as the >>>> spiral is created. >>>> >>>> >>>> >>>> So if I wanted to move the rotary table N degrees while moving X a >> spiral >>>> would also be created. I guess I'm having trouble figuring out the math >> for >>>> the G-Code. >>> >>> It just one command with prelimiinary. in your case position incut at N >>> degrees >>>> >>>> John >>>> >>>> >>>> >>>> >>>> >>>>> -----Original Message----- >>>> >>>>> From: marcus.bow...@visible.eclipse.co.uk >>>> >>>>> [mailto:marcus.bow...@visible.eclipse.co.uk] >>>> >>>>> Sent: April 10, 2024 12:00 AM >>>> >>>>> To: Enhanced Machine Controller (EMC) >>>> >>>>> Subject: Re: [Emc-users] Carving a spiral >>>> >>>>> >>>> >>>>> As I recall, someone on this list posted a note or a link about how to >>>> >>>>> create a fusee for a clock (essentially a tapered spiral, running from >>>> >>>>> large diameter to smaller diameter while spiralling - rather like a >>>> >>>>> tapered woodscrew thread). Is a constant-diameter version of that what >>>> >>>>> you had in mind? >>>> >>>>> https://www.youtube.com/watch?v=KAAajypWQyw >>>> >>>>> >>>> >>>>> Sadly, I can't remember who contributed that note on this list. I do >>>> >>>>> think there may be a routine somewhere in the LinuxCNC electronic >>>> >>>>> resources. >>>> >>>>> >>>> >>>>> Marcus >>>> >>>>> >>>> >>>>> >>>> >>>>> >>>> >>>>> On 2024-04-10 06:55, John Dammeyer wrote: >>>> >>>>>> A friend and I have been discussing exactly how to write the G-Code to >>>> >>>>>> create a spiral scroll. >>>> >>>>>> >>>> >>>>>> His rotary table 90:1 reduction with a 1600 micro-step motor could be >>>> >>>>>> set up >>>> >>>>>> to move N steps for each step of the X axis to create the spiral. But >>>> >>>>>> that >>>> >>>>>> approach seems clumsy. >>>> >>>>>> >>>> >>>>>> Say I wanted to cut a scroll with a 6mm pitch using a 3mm cutter. >>>> >>>>>> >>>> >>>>>> >>>> >>>>>> >>>> >>>>>> Without using G2 or G3 it's really just a triangle isn't it? Move >>>> >>>>>> rotary >>>> >>>>>> table distance A and move X axis distance A'. Do it in small enough >>>> >>>>>> increments and you get a spiral. But I feel like I'm missing >> something >>>> >>>>>> really simple. >>>> >>>>>> >>>> >>>>>> >>>> >>>>>> >>>> >>>>>> Suggestions? >>>> >>>>>> >>>> >>>>>> Thanks >>>> >>>>>> >>>> >>>>>> John >>>> >>>>>> >>>> >>>>>> >>>> >>>>>> >>>> >>>>>> >>>> >>>>>> _______________________________________________ >>>> >>>>>> Emc-users mailing list >>>> >>>>>> Emc-users@lists.sourceforge.net >>>> >>>>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>>> >>>>> >>>> >>>>> >>>> >>>>> _______________________________________________ >>>> >>>>> Emc-users mailing list >>>> >>>>> Emc-users@lists.sourceforge.net >>>> >>>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> Emc-users mailing list >>>> Emc-users@lists.sourceforge.net >>>> https://lists.sourceforge.net/lists/listinfo/emc-users >>> >>> Cheers, Gene Heskett, CET. >>> -- >>> "There are four boxes to be used in defense of liberty: >>> soap, ballot, jury, and ammo. Please use in that order." >>> -Ed Howdershelt (Author, 1940) >>> If we desire respect for the law, we must first make the law respectable. >>> - Louis D. Brandeis >>> >>> >>> >>> _______________________________________________ >>> Emc-users mailing list >>> Emc-users@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/emc-users >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> . > > Cheers, Gene Heskett, CET. > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author, 1940) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
