Re: [Emc-users] PCB engraver, spindle solenoid
On 09/21/2010 10:29 PM, Dale Grover wrote: > My inclination is to try to get this working without replacing the z > axis. I like the depth adjustment, since it eliminates a major > headache with engraving PCBs, and the current (as it were) > arrangement (two distinct drive levels) was functional at some point. > > I've started looking into what options I would have to process G-code > Z moves into various PWM or multiple signals--delving into the > integrator's manual again. > > Many thanks for the ideas and cautions. > > --Dale > A regular engraving spindle is spring loaded down with a depth adjustable nose cone. If you pull the solenoid out and replace it with a Z axis motor and screw arrangement that is hooked to the slide with a spring it seems like that may work since you have a foot to limit the depth. I have an engraving spindle on my machine, even though my safe Z height is +.25" I just use a G1Z-.75 depth when engraving. Since I have a depth limiting nosecone I have .5" of spring pressure holding the nosecone against the work. That would be more than enough pressure to drill through a fiberglass board, and if not, use G1Z-1 or more. Bill -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] PCB engraver, spindle solenoid
Andy Pugh wrote: > On 22 September 2010 02:50, Jon Elson wrote: > > >> Solenoids are not generally linear devices. As the armature is pulled >> into the >> coil, the magnetic field becomes stronger as the air gap shrinks. >> > > Doesn't this depend on the design? If it is a pure solenoid the > air-gap is constant, but the > amount of plunger inside the coil varies in a linear way, which may be > (but probably isn't) compensated by a linear spring > OK, you expressed it more accurately! Yes, the amount of plunger is the variable in that type of solenoid. Yes, with some careful design, it might be possible to set up a spring that nearly balances the change in force, and their design might do that. > This is not the case for the typical relay-style electromagnet (also > often called a solenoid) where the core is static and attracts a > moving arm. > Yes, the typical relay-style swinging armature solenoid is probably far more non-linear than the plunger style. Anyway, I'm sure this LPKF engraver will do FINE for engraving, and may be able to drill the larger holes. I hare REAL doubts that it could possibly drill .020" holes, unless there is a dashpot or something to limit the initial velocity of the stroke. I have done drilling with an air-bearing spindle and .018" drills on my Bridgeport http://pico-systems.com/wwspndl.html and it worked great with tightly controlled feedrates, but I'd hate to just slam those small bits into the board. Jon -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] PCB engraver, spindle solenoid
On 22 September 2010 02:50, Jon Elson wrote: > Solenoids are not generally linear devices. As the armature is pulled > into the > coil, the magnetic field becomes stronger as the air gap shrinks. Doesn't this depend on the design? If it is a pure solenoid the air-gap is constant, but the amount of plunger inside the coil varies in a linear way, which may be (but probably isn't) compensated by a linear spring. This is not the case for the typical relay-style electromagnet (also often called a solenoid) where the core is static and attracts a moving arm. -- atp -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] PCB engraver, spindle solenoid
My inclination is to try to get this working without replacing the z axis. I like the depth adjustment, since it eliminates a major headache with engraving PCBs, and the current (as it were) arrangement (two distinct drive levels) was functional at some point. I've started looking into what options I would have to process G-code Z moves into various PWM or multiple signals--delving into the integrator's manual again. Many thanks for the ideas and cautions. --Dale At 6:27 PM +0100 9/21/10, Andy Pugh wrote: >On 21 September 2010 16:58, Dale Grover wrote: > >> Does anyone have specific knowledge about what they intended as drive >> signals? I was tempted to replace the two circuits with just one, >> with an adjustable one-shot to drive the solenoid full, then a gated >> PWM to provide the holding current. (And replace those relays with a >> MOSFET.) But then I wondered if drilling or milling required a >> different set of timing than straight engraving? > >PWM sounds like a better way to go. >In theory you could then connect the PWM to the Z-position-cmd in HAL. >G0 Z1 would be full-power into the solenoid, G0 Z0.5 half-power, and >G1 Z0.5 F20 (or similar) would be a slowly ramping PWM suitable for >gently pushing a drill bit. >Setting Z-axis max velocity would determine how long a G0Z0 took to >complete, you could then follow each with a G0Z0.5 to apply the >holding current. > >-- >atp > >-- >Start uncovering the many advantages of virtual appliances >and start using them to simplify application deployment and >accelerate your shift to cloud computing. >http://p.sf.net/sfu/novell-sfdev2dev >___ >Emc-users mailing list >Emc-users@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/emc-users -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] PCB engraver, spindle solenoid
Andy Pugh wrote: > PWM sounds like a better way to go. > In theory you could then connect the PWM to the Z-position-cmd in HAL. > G0 Z1 would be full-power into the solenoid, G0 Z0.5 half-power, and > G1 Z0.5 F20 (or similar) would be a slowly ramping PWM suitable for > gently pushing a drill bit. > Solenoids are not generally linear devices. As the armature is pulled into the coil, the magnetic field becomes stronger as the air gap shrinks. So, enough current to start it moving from the fully-up position might still make it slam hard at the end of the stroke. Jon -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] PCB engraver, spindle solenoid
That looks very inventive on IBC's part. I would have to agree with Jon, however, in gutting the electronics because it looks like a linear actuator might take the place of the solenoid. The type like a hollow stepper motor with a moving leadscrew (http://www.haydonkerk.com) could be your new Z-axis with one more Geckodrive. Just a thought. jim -Original Message- From: Dale Grover [mailto:dgro...@redcedar.com] Sent: Tuesday, September 21, 2010 1:42 PM To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] PCB engraver, spindle solenoid Here's a picture of the front: http://www.redcedar.com/misc/IBC_BM.jpg The brass cylindrical object is the solenoid; it pushes down right where that green button is. To the right is the spindle motor. Just to the right of the cutter is the foot with a wear button on the bottom; this depth is adjusted via the knurled nut. The cutter is secured in the collet with a set screw (1/8" dia cutters). The spindle motor, foot, and cutter all move up and down on two 1/2" or so steel rods with linear bearings. In this photo, the top surface of the machine has been removed, so you can see the 5/8" ball screw below. --dg At 12:23 PM -0500 9/21/10, James Louis wrote: >Dale, > >Do you have any pictures of the solenoid available? I'm curious >about how this can be used for a Z-axis. It sounds interesting. > >Jim > >-Original Message- >From: Dale Grover [mailto:dgro...@redcedar.com] >Sent: Tuesday, September 21, 2010 10:58 AM >To: EMC User List >Subject: [Emc-users] PCB engraver, spindle solenoid > >I'm fixing up an IBC BoardMaker , a 22" x 22" PCB engraver. So >far I've replaced the Y axis with a McMaster-Carr 5/8" ball screw & >nut, which had been a proprietary-threaded rod with self-adjusting >anti-backlash (plastic) nut that self-destructed, and replaced the >stepper drivers with Gecko G251's. > >The machine uses a solenoid to move the spindle down until a >wear-button hits the PCB, thus establishing the cutter height. >Spring return. > >My question is about the solenoid drive. There are two identical >circuits--both are logic-level in (from a db-25 parallel port) >driving a relay that supplies +45V to the solenoid (i.e., they are in >parallel), though one has a 5W 40 ohm resistor in series. (The >solenoid is not identified, but has 70 ohm resistance.) > >This sounds to me like a way of driving the solenoid hard to move the >spindle down, then holding it with reduced current. This is often >done with a (big) cap across the current-limiting resistor. The >solenoid doesn't move all the way down with just the "hold" current. > >I don't have the original control software, so don't know what the >original software control signals look like. (IBC seems long gone, >but may have had connections in the past with LPKF.) > >Does anyone have specific knowledge about what they intended as drive >signals? I was tempted to replace the two circuits with just one, >with an adjustable one-shot to drive the solenoid full, then a gated >PWM to provide the holding current. (And replace those relays with a >MOSFET.) But then I wondered if drilling or milling required a >different set of timing than straight engraving? (In particular, I >was imagining breaking a lot of 0.020" drill bits by driving full >speed into the board.) Any ideas? > >Thanks. > >--Dale > >-- >Start uncovering the many advantages of virtual appliances >and start using them to simplify application deployment and >accelerate your shift to cloud computing. >http://p.sf.net/sfu/novell-sfdev2dev >___ >Emc-users mailing list >Emc-users@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/emc-users > >This communication is for the use of the intended recipient only. It >may contain information that is privileged and confidential. If you >are not the intended recipient of this communication, the >disclosure, copying, distribution or use hereof is prohibited. If >you have received this communication in error, please advise me by >return e-mail or by telephone and then delete it immediately. > >-- >Start uncovering the many advantages of virtual appliances >and start using them to simplify application deployment and >accelerate your shift to cloud computing. >http://p.sf.net/sfu/novell-sfdev2dev >___ >Emc-users mailing list >Emc-users@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/emc-users ---
Re: [Emc-users] PCB engraver, spindle solenoid
Here's a picture of the front: http://www.redcedar.com/misc/IBC_BM.jpg The brass cylindrical object is the solenoid; it pushes down right where that green button is. To the right is the spindle motor. Just to the right of the cutter is the foot with a wear button on the bottom; this depth is adjusted via the knurled nut. The cutter is secured in the collet with a set screw (1/8" dia cutters). The spindle motor, foot, and cutter all move up and down on two 1/2" or so steel rods with linear bearings. In this photo, the top surface of the machine has been removed, so you can see the 5/8" ball screw below. --dg At 12:23 PM -0500 9/21/10, James Louis wrote: >Dale, > >Do you have any pictures of the solenoid available? I'm curious >about how this can be used for a Z-axis. It sounds interesting. > >Jim > >-Original Message- >From: Dale Grover [mailto:dgro...@redcedar.com] >Sent: Tuesday, September 21, 2010 10:58 AM >To: EMC User List >Subject: [Emc-users] PCB engraver, spindle solenoid > >I'm fixing up an IBC BoardMaker , a 22" x 22" PCB engraver. So >far I've replaced the Y axis with a McMaster-Carr 5/8" ball screw & >nut, which had been a proprietary-threaded rod with self-adjusting >anti-backlash (plastic) nut that self-destructed, and replaced the >stepper drivers with Gecko G251's. > >The machine uses a solenoid to move the spindle down until a >wear-button hits the PCB, thus establishing the cutter height. >Spring return. > >My question is about the solenoid drive. There are two identical >circuits--both are logic-level in (from a db-25 parallel port) >driving a relay that supplies +45V to the solenoid (i.e., they are in >parallel), though one has a 5W 40 ohm resistor in series. (The >solenoid is not identified, but has 70 ohm resistance.) > >This sounds to me like a way of driving the solenoid hard to move the >spindle down, then holding it with reduced current. This is often >done with a (big) cap across the current-limiting resistor. The >solenoid doesn't move all the way down with just the "hold" current. > >I don't have the original control software, so don't know what the >original software control signals look like. (IBC seems long gone, >but may have had connections in the past with LPKF.) > >Does anyone have specific knowledge about what they intended as drive >signals? I was tempted to replace the two circuits with just one, >with an adjustable one-shot to drive the solenoid full, then a gated >PWM to provide the holding current. (And replace those relays with a >MOSFET.) But then I wondered if drilling or milling required a >different set of timing than straight engraving? (In particular, I >was imagining breaking a lot of 0.020" drill bits by driving full >speed into the board.) Any ideas? > >Thanks. > >--Dale > >-- >Start uncovering the many advantages of virtual appliances >and start using them to simplify application deployment and >accelerate your shift to cloud computing. >http://p.sf.net/sfu/novell-sfdev2dev >___ >Emc-users mailing list >Emc-users@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/emc-users > >This communication is for the use of the intended recipient only. It >may contain information that is privileged and confidential. If you >are not the intended recipient of this communication, the >disclosure, copying, distribution or use hereof is prohibited. If >you have received this communication in error, please advise me by >return e-mail or by telephone and then delete it immediately. > >-- >Start uncovering the many advantages of virtual appliances >and start using them to simplify application deployment and >accelerate your shift to cloud computing. >http://p.sf.net/sfu/novell-sfdev2dev >___ >Emc-users mailing list >Emc-users@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/emc-users -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] PCB engraver, spindle solenoid
Dale Grover wrote: > I'm fixing up an IBC BoardMaker , a 22" x 22" PCB engraver. So > far I've replaced the Y axis with a McMaster-Carr 5/8" ball screw & > nut, which had been a proprietary-threaded rod with self-adjusting > anti-backlash (plastic) nut that self-destructed, and replaced the > stepper drivers with Gecko G251's. > > The glass-fiber dust may also destroy the ballnut unless you find a way to shield it. > The machine uses a solenoid to move the spindle down until a > wear-button hits the PCB, thus establishing the cutter height. > Spring return. > > My question is about the solenoid drive. There are two identical > circuits--both are logic-level in (from a db-25 parallel port) > driving a relay that supplies +45V to the solenoid (i.e., they are in > parallel), though one has a 5W 40 ohm resistor in series. (The > solenoid is not identified, but has 70 ohm resistance.) > > This sounds to me like a way of driving the solenoid hard to move the > spindle down, then holding it with reduced current. Yes, I'm pretty sure that is what they are doing. What a totally primitive way of doing it, though! Relays! > This is often > done with a (big) cap across the current-limiting resistor. The > solenoid doesn't move all the way down with just the "hold" current. > > I don't have the original control software, so don't know what the > original software control signals look like. (IBC seems long gone, > but may have had connections in the past with LPKF.) > > Undoubtedly, they turn both relays on at first, then turn off the direct supply relay after a short time. My personal preference would be to rip the ghastly mess out, and make up a simple circuit with 2 power MOSFETs and a 555 timer. When the single "down" command comes from the computer, both transistors are turned on, and after a short and adjustable delay, the direct MOSFET is shut off by the 555. Slight problem is the 555 output will go high when the timer is triggered, so the output is opposite of what you want. You might be able to rig the other side of a 556 as an inverter. > Does anyone have specific knowledge about what they intended as drive > signals? I was tempted to replace the two circuits with just one, > with an adjustable one-shot to drive the solenoid full, then a gated > PWM to provide the holding current. (And replace those relays with a > MOSFET.) Yes, this is an even more elegant solution. Best would be to have a current sense resistor and a comparator, and have the PWM controlled by solenoid current. It might need a little RC circuit to boost the controlled current for an instant at turn-on to pull in the solenoid. > But then I wondered if drilling or milling required a > different set of timing than straight engraving? (In particular, I > was imagining breaking a lot of 0.020" drill bits by driving full > speed into the board.) Umm, yeah, I think if you want to do drilling, too, then you should toss the solenoid and install a Z axis motor. You can plunge pretty fast with a .020" drill at 50,000+ RPM, but you'd still a dashpot or something to control the plunge rate. It is possible the solenoid has a copper sleeve that acts as a single massive shorted turn to control the plunge rate, a magnetic dashpot. Anyway, you use different plunge rates for different drill sizes. I actually had a calculation in a program that converted Excellon drill files to G-code. Here's the line from that Pascal program (that kind of dates it, doesn't it?) ToolFeed := (ToolDiam/15.0) * RPM; So, for a .020" drill and 24000 RPM, that would be (.02 / 15) * 24000 = 32 IPM. Jon -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] PCB engraver, spindle solenoid
On 21 September 2010 16:58, Dale Grover wrote: > Does anyone have specific knowledge about what they intended as drive > signals? I was tempted to replace the two circuits with just one, > with an adjustable one-shot to drive the solenoid full, then a gated > PWM to provide the holding current. (And replace those relays with a > MOSFET.) But then I wondered if drilling or milling required a > different set of timing than straight engraving? PWM sounds like a better way to go. In theory you could then connect the PWM to the Z-position-cmd in HAL. G0 Z1 would be full-power into the solenoid, G0 Z0.5 half-power, and G1 Z0.5 F20 (or similar) would be a slowly ramping PWM suitable for gently pushing a drill bit. Setting Z-axis max velocity would determine how long a G0Z0 took to complete, you could then follow each with a G0Z0.5 to apply the holding current. -- atp -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] PCB engraver, spindle solenoid
Dale, Do you have any pictures of the solenoid available? I'm curious about how this can be used for a Z-axis. It sounds interesting. Jim -Original Message- From: Dale Grover [mailto:dgro...@redcedar.com] Sent: Tuesday, September 21, 2010 10:58 AM To: EMC User List Subject: [Emc-users] PCB engraver, spindle solenoid I'm fixing up an IBC BoardMaker , a 22" x 22" PCB engraver. So far I've replaced the Y axis with a McMaster-Carr 5/8" ball screw & nut, which had been a proprietary-threaded rod with self-adjusting anti-backlash (plastic) nut that self-destructed, and replaced the stepper drivers with Gecko G251's. The machine uses a solenoid to move the spindle down until a wear-button hits the PCB, thus establishing the cutter height. Spring return. My question is about the solenoid drive. There are two identical circuits--both are logic-level in (from a db-25 parallel port) driving a relay that supplies +45V to the solenoid (i.e., they are in parallel), though one has a 5W 40 ohm resistor in series. (The solenoid is not identified, but has 70 ohm resistance.) This sounds to me like a way of driving the solenoid hard to move the spindle down, then holding it with reduced current. This is often done with a (big) cap across the current-limiting resistor. The solenoid doesn't move all the way down with just the "hold" current. I don't have the original control software, so don't know what the original software control signals look like. (IBC seems long gone, but may have had connections in the past with LPKF.) Does anyone have specific knowledge about what they intended as drive signals? I was tempted to replace the two circuits with just one, with an adjustable one-shot to drive the solenoid full, then a gated PWM to provide the holding current. (And replace those relays with a MOSFET.) But then I wondered if drilling or milling required a different set of timing than straight engraving? (In particular, I was imagining breaking a lot of 0.020" drill bits by driving full speed into the board.) Any ideas? Thanks. --Dale -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users This communication is for the use of the intended recipient only. It may contain information that is privileged and confidential. If you are not the intended recipient of this communication, the disclosure, copying, distribution or use hereof is prohibited. If you have received this communication in error, please advise me by return e-mail or by telephone and then delete it immediately. -- Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
