I suggest looking at a hydraulic approach. It eliminates all of the drive lash problems with the rigidity problems that follow. Ingersoll Rand built a prototype mill similiar to what you are describing, you may find getting in touch with them to be useful. However it goes, I see this adventure of yours to be an important step in pushing the technology window. Have at it.
----- Original Message ----- From: emc-users-requ...@lists.sourceforge.net To: emc-users@lists.sourceforge.net Sent: Sunday, November 8, 2015 6:55:04 AM Subject: Emc-users Digest, Vol 115, Issue 27 Send Emc-users mailing list submissions to emc-users@lists.sourceforge.net To subscribe or unsubscribe via the World Wide Web, visit https://lists.sourceforge.net/lists/listinfo/emc-users or, via email, send a message with subject or body 'help' to emc-users-requ...@lists.sourceforge.net You can reach the person managing the list at emc-users-ow...@lists.sourceforge.net When replying, please edit your Subject line so it is more specific than "Re: Contents of Emc-users digest..." Today's Topics: 1. Re: could Linux cnc control of unconventional mill design like this and general thoughts and comments. (Kyle Kerr) 2. Re: could Linux cnc control of unconventional mill design like this and general thoughts and comments. (linden) 3. Error with tripod sim can't find package Linuxcnc (linden) 4. Re: could Linux cnc control of unconventional mill design like this and general thoughts and comments. (andy pugh) 5. Re: could Linux cnc control of unconventional mill design like this and general thoughts and comments. (linden) ---------------------------------------------------------------------- Message: 1 Date: Sun, 08 Nov 2015 02:10:08 +0000 From: Kyle Kerr <ker...@gmail.com> Subject: Re: [Emc-users] could Linux cnc control of unconventional mill design like this and general thoughts and comments. To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> Message-ID: <CAK=kwweifqwcs81-z99c_kvzw1x2rbqr3ma_tsj4+qutvcz...@mail.gmail.com> Content-Type: text/plain; charset=UTF-8 Re: homing. Delta printers usually home at the top of their travel. When I asked my CNC instructor about a delta mill he said the lack of rigidity would kill accuracy. On Sat, Nov 7, 2015, 7:38 PM linden <l...@island.net> wrote: > Thanks for taking the time to look at the pictures and read through my > chicken scratch notes. Now I know that Linuxcnc should be able to > control something like this and we have a potential solution for > homing. I will keep going. I really need a real Internet connection or > some card board to start pushing shapes around simulating to see how > they interact with each other. One dimension is not to bad but trying to > picture things in my head in 3 dimensions and 6 dof freedom is a bit > much for my little brain sometimes. lol > > I am having second thoughts about using the lower set of trucks and > additional links associated with them. The original idea and thought be > hide this approach was it would give me a larger translational working > area relative to overall tool hight and may help with rigidity. looking > at the videos suggested earlier about rigidity and with the abb picker I > am having second thought. I have also seen a Russian you tube model that > has given me some ideas. once I have modled and thought a bit more I > would like to pick your collective brains again. > > all the best, > > Linden > > On 15-11-07 06:30 PM, Philipp Burch wrote: > > Hi Linden! > > > > On 07.11.2015 00:55, linden wrote: > >> Hello All, > >> > >> I have progressed a little with the design and modeling of the machine I > >> asked for help simulating. It has evolved a little over the last few > >> weeks. have a look at the pdf attached for pictures Another month and I > >> will be back to the world of fast Internet and I should be able to try > >> some of the previous suggestions for simulation. > > Looks nice :) > > Since you have 6 actuators, your design will definitely be > > overconstrained if you only want 5 degrees of freedom. But I have the > > feeling that you could actually get 6 DOF by having the nominal angle in > > C about 60? (or even 90?) rotated in respect to the picture you > > attached. Since you can control the distance between all the joints on > > the center plate to their slides, this will allow you to rotate the tool > > plate as well. > > Even if you don't need rotation around C, I'd suggest to implement this > > angular offset, as it will most probably make the system more robust > > against torsional forces. Similar to how hexapods are done. > > > >> The big question is: > >> > >> Could linuxCNC something control this? or do I have 2 many variables > >> with no fixed base position? > > When you get the kinematics right (which I'd expect to be about midways > > between the complexity of a delta kins and a hexapod), this should be no > > problem. > > > >> A few other questions and thoughts I would like to pick your collective > >> brains on. > >> > >> How would you home something like this? > > As with a hexapod, forward kins are complicated and may have many > > (practically) invalid joint positions. I'd suggest to have the following > > homing switches: > > > > 1. One for every pole at the top end, which gets activated when the > > upper slide reaches the top limit. > > > > 2. One between every two slides on a pole which is closed when the > > slides are closer than the nominal position (shown in your PDF) and open > > otherwise. This must NOT be limit switches, as movement in both > > directions over the activation point must be possible. > > > > Additionally, it will help to have an approximation of the distance > > between every two slides on a pole. This could be done rather easily by > > using a linear potentiometer. > > > > You could then implement the homing about as follows, using coordinated > > movements in the XYZABC space (not on a joint basis): > > > > 1. When the system gets turned on, all you know is that it must be in > > some mechanically feasible position. So start by a linear move towards > > Z+, meaning that all slides run synchronously upwards. Stop as soon as > > one upper slide reaches the top homing switch. > > > > 2. Use the feedback from the pots as an initial guess of the slide > > distances for the kinematics. Using those, perform a move in the XY > > plane perpendicularly away from the joint which has it's top slide > > homed, i.e. moving approximately towards the center position. Stop as > > soon as the second upper slide hits the top homing switch. Since this > > movement will also adjust the distance of the slides on a pole, you may > > also detect one or the other homing switch edge of those. Use this > > information to correct the joint position guesses. > > > > 3. Do the same as in step 2, but this time with a movement perpendicular > > to the connecting line of the two homed poles. So you should eventually > > also reach the top homing switch of the third pole, meaning that all > > upper slides know their positions and the tool is roughly centered. > > > > 4. Move all slides down by a few millimeters to get some "working range" > > for the last step (i.e. coordinated move towards Z-). > > > > 5. Perform a movement to X0Y0A0B0C0, i.e. to the approximate nominal > > position with an aligned tool base. This is possible using the > > information form the pots. > > > > 6. Perform moves from C-30 to C30 (or less, depending on the accuracy of > > your potentiometer feedbacks), so that all homing switches of the lower > > slides see at least one edge. As soon as this happens, all joints are > homed. > > > > All this will require that the tool can rotate around a C axis (which in > > my terminology is perpendicular to the machine table, NOT aligned to the > > tool axis). This means that it will be required to have this angular > > offset of the tool base plate as described above. > > > >> I stile haven't simulated the movement digitally yet or built a complete > >> cardboard and drinking straw model, but i think i have finally settled > >> on approximate geometry any questions or comments are gladly welcome. > >> Has any one seen any thing like this before I am sure I am not the > >> first? Is there any grate big flaw with this logic that I have missed? > > At least from my feeling, I think that this should work with the > > mentioned adaptation. I'm not very familiar with complex machine > > kinematics, however. > > > > I find it a cool construction :) No idea if someone else already built > that. > > > > Good luck! > > > > Regards, > > Philipp > > > > > > > > > ------------------------------------------------------------------------------ > > > > > > > _______________________________________________ > > 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 > ------------------------------ Message: 2 Date: Sun, 8 Nov 2015 19:13:27 +0800 From: linden <l...@island.net> Subject: Re: [Emc-users] could Linux cnc control of unconventional mill design like this and general thoughts and comments. To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> Message-ID: <563f2e57.7070...@island.net> Content-Type: text/plain; charset=utf-8; format=flowed yes this is a big issue rigidity and vibration damning have traditionally been done by increasing the mass and by using cast iron that has a natural tendency to absorb and dissipate vibration. You can build very rigid light wait structures but most of these have harmonics like a tuning fork. These vibrations would not be good for your surface finish and on the other hand if you built every thing out of cast iron with a mass of several thousand kg your speed and acceleration are limited. The trick is to build a rigid machine with light moving parts that absorbs vibration. Every thing is a compromise trying to find a compromise that will accomplish what you need is where the fun is. linden On 15-11-08 10:10 AM, Kyle Kerr wrote: > Re: homing. Delta printers usually home at the top of their travel. When I > asked my CNC instructor about a delta mill he said the lack of rigidity > would kill accuracy. > > On Sat, Nov 7, 2015, 7:38 PM linden <l...@island.net> wrote: > >> Thanks for taking the time to look at the pictures and read through my >> chicken scratch notes. Now I know that Linuxcnc should be able to >> control something like this and we have a potential solution for >> homing. I will keep going. I really need a real Internet connection or >> some card board to start pushing shapes around simulating to see how >> they interact with each other. One dimension is not to bad but trying to >> picture things in my head in 3 dimensions and 6 dof freedom is a bit >> much for my little brain sometimes. lol >> >> I am having second thoughts about using the lower set of trucks and >> additional links associated with them. The original idea and thought be >> hide this approach was it would give me a larger translational working >> area relative to overall tool hight and may help with rigidity. looking >> at the videos suggested earlier about rigidity and with the abb picker I >> am having second thought. I have also seen a Russian you tube model that >> has given me some ideas. once I have modled and thought a bit more I >> would like to pick your collective brains again. >> >> all the best, >> >> Linden >> >> On 15-11-07 06:30 PM, Philipp Burch wrote: >>> Hi Linden! >>> >>> On 07.11.2015 00:55, linden wrote: >>>> Hello All, >>>> >>>> I have progressed a little with the design and modeling of the machine I >>>> asked for help simulating. It has evolved a little over the last few >>>> weeks. have a look at the pdf attached for pictures Another month and I >>>> will be back to the world of fast Internet and I should be able to try >>>> some of the previous suggestions for simulation. >>> Looks nice :) >>> Since you have 6 actuators, your design will definitely be >>> overconstrained if you only want 5 degrees of freedom. But I have the >>> feeling that you could actually get 6 DOF by having the nominal angle in >>> C about 60? (or even 90?) rotated in respect to the picture you >>> attached. Since you can control the distance between all the joints on >>> the center plate to their slides, this will allow you to rotate the tool >>> plate as well. >>> Even if you don't need rotation around C, I'd suggest to implement this >>> angular offset, as it will most probably make the system more robust >>> against torsional forces. Similar to how hexapods are done. >>> >>>> The big question is: >>>> >>>> Could linuxCNC something control this? or do I have 2 many variables >>>> with no fixed base position? >>> When you get the kinematics right (which I'd expect to be about midways >>> between the complexity of a delta kins and a hexapod), this should be no >>> problem. >>> >>>> A few other questions and thoughts I would like to pick your collective >>>> brains on. >>>> >>>> How would you home something like this? >>> As with a hexapod, forward kins are complicated and may have many >>> (practically) invalid joint positions. I'd suggest to have the following >>> homing switches: >>> >>> 1. One for every pole at the top end, which gets activated when the >>> upper slide reaches the top limit. >>> >>> 2. One between every two slides on a pole which is closed when the >>> slides are closer than the nominal position (shown in your PDF) and open >>> otherwise. This must NOT be limit switches, as movement in both >>> directions over the activation point must be possible. >>> >>> Additionally, it will help to have an approximation of the distance >>> between every two slides on a pole. This could be done rather easily by >>> using a linear potentiometer. >>> >>> You could then implement the homing about as follows, using coordinated >>> movements in the XYZABC space (not on a joint basis): >>> >>> 1. When the system gets turned on, all you know is that it must be in >>> some mechanically feasible position. So start by a linear move towards >>> Z+, meaning that all slides run synchronously upwards. Stop as soon as >>> one upper slide reaches the top homing switch. >>> >>> 2. Use the feedback from the pots as an initial guess of the slide >>> distances for the kinematics. Using those, perform a move in the XY >>> plane perpendicularly away from the joint which has it's top slide >>> homed, i.e. moving approximately towards the center position. Stop as >>> soon as the second upper slide hits the top homing switch. Since this >>> movement will also adjust the distance of the slides on a pole, you may >>> also detect one or the other homing switch edge of those. Use this >>> information to correct the joint position guesses. >>> >>> 3. Do the same as in step 2, but this time with a movement perpendicular >>> to the connecting line of the two homed poles. So you should eventually >>> also reach the top homing switch of the third pole, meaning that all >>> upper slides know their positions and the tool is roughly centered. >>> >>> 4. Move all slides down by a few millimeters to get some "working range" >>> for the last step (i.e. coordinated move towards Z-). >>> >>> 5. Perform a movement to X0Y0A0B0C0, i.e. to the approximate nominal >>> position with an aligned tool base. This is possible using the >>> information form the pots. >>> >>> 6. Perform moves from C-30 to C30 (or less, depending on the accuracy of >>> your potentiometer feedbacks), so that all homing switches of the lower >>> slides see at least one edge. As soon as this happens, all joints are >> homed. >>> All this will require that the tool can rotate around a C axis (which in >>> my terminology is perpendicular to the machine table, NOT aligned to the >>> tool axis). This means that it will be required to have this angular >>> offset of the tool base plate as described above. >>> >>>> I stile haven't simulated the movement digitally yet or built a complete >>>> cardboard and drinking straw model, but i think i have finally settled >>>> on approximate geometry any questions or comments are gladly welcome. >>>> Has any one seen any thing like this before I am sure I am not the >>>> first? Is there any grate big flaw with this logic that I have missed? >>> At least from my feeling, I think that this should work with the >>> mentioned adaptation. I'm not very familiar with complex machine >>> kinematics, however. >>> >>> I find it a cool construction :) No idea if someone else already built >> that. >>> Good luck! >>> >>> Regards, >>> Philipp >>> >>> >>> >>> >> ------------------------------------------------------------------------------ >> >>> >>> _______________________________________________ >>> 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 ------------------------------ Message: 3 Date: Sun, 8 Nov 2015 22:28:24 +0800 From: linden <l...@island.net> Subject: [Emc-users] Error with tripod sim can't find package Linuxcnc To: emc-users@lists.sourceforge.net Message-ID: <563f5c08.7030...@island.net> Content-Type: text/plain; charset=utf-8; format=flowed Hello all, At a loss cant figer out what is going on here I am trying to load the tripod sim in tklinux drop down list with no luck. See error below i get the same error with all 3 configurations in the tklinux drop down list. All the Axis sim choices work and some of the other ones as well. Is there any other options or recommendations for experimenting with no trivial kins in a simulated environment. Where would I find Non trivial kins examples I would like to start playing and work toward building and simulating the kins for my unconventional machine thanks again linden draft@X200CA-draft ~/Linuxcnc_Sim/linuxcnc/scripts $ ./linuxcnc LINUXCNC - 2.8.0~pre1 Machine configuration directory is '/home/draft/Linuxcnc_Sim/linuxcnc/configs/sim/tklinuxcnc' Machine configuration file is 'tripod.ini' Starting LinuxCNC... Found file(lib): /home/draft/Linuxcnc_Sim/linuxcnc/lib/hallib/tripodsim.hal Note: Using POSIX non-realtime Error in startup script: can't find package Linuxcnc while executing "package require Linuxcnc" (file "/home/draft/Linuxcnc_Sim/linuxcnc/tcl/tklinuxcnc.tcl" line 21) Shutting down and cleaning up LinuxCNC... task: 257 cycles, min=0.000016, max=0.008605, avg=0.001036, 0 latency excursions (> 10x expected cycle time of 0.001000s) Note: Using POSIX non-realtime LinuxCNC terminated with an error. You can find more information in the log: /home/draft/linuxcnc_debug.txt and /home/draft/linuxcnc_print.txt as well as in the output of the shell command 'dmesg' and in the terminal draft@X200CA-draft ~/Linuxcnc_Sim/linuxcnc/scripts $ ------------------------------ Message: 4 Date: Sun, 8 Nov 2015 14:35:09 +0000 From: andy pugh <bodge...@gmail.com> Subject: Re: [Emc-users] could Linux cnc control of unconventional mill design like this and general thoughts and comments. To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> Message-ID: <can1+yzvdfhftqtnobe4c3dfvtafo7o4kz9dcgkwob3acuey...@mail.gmail.com> Content-Type: text/plain; charset=UTF-8 On 8 November 2015 at 02:10, Kyle Kerr <ker...@gmail.com> wrote: > Re: homing. Delta printers usually home at the top of their travel. When I > asked my CNC instructor about a delta mill he said the lack of rigidity > would kill accuracy. It can be done, in fact one of the very first applications of EMC when it was still EMC and with NIST was a large milling machine based on a hexapod https://www.nitrd.gov/NGI/apps/nist/hex.aspx -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------ Message: 5 Date: Sun, 8 Nov 2015 22:54:51 +0800 From: linden <l...@island.net> Subject: Re: [Emc-users] could Linux cnc control of unconventional mill design like this and general thoughts and comments. To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> Message-ID: <563f623b.7000...@island.net> Content-Type: text/plain; charset=windows-1252; format=flowed This is cool with the six legs of a start platform the forces should be balanced as you have one leg in tension and the corresponding one in compression. I could see motor tuning could be fun with multiple pid loops all fighting each other. We will see if I get that far at least I know some one else has been up these mountains with the same tools. Just much earlier versions so it should be easer now ;-) On 15-11-08 10:35 PM, andy pugh wrote: > On 8 November 2015 at 02:10, Kyle Kerr <ker...@gmail.com> wrote: >> Re: homing. Delta printers usually home at the top of their travel. When I >> asked my CNC instructor about a delta mill he said the lack of rigidity >> would kill accuracy. > It can be done, in fact one of the very first applications of EMC when > it was still EMC and with NIST was a large milling machine based on a > hexapod > https://www.nitrd.gov/NGI/apps/nist/hex.aspx > > ------------------------------ ------------------------------------------------------------------------------ ------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users End of Emc-users Digest, Vol 115, Issue 27 ****************************************** ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
