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Emco F3 conversion - electronics and controller
This is a supplementary thread to the others detailing the conversion of my Emco F3 mill, in which I will detail the changes to the electronics and some considerations for selecting a controller.
The original electronics are switch gear that are typical of the period: good quality equipment but very 1980's in execution. The power supply is 3 phase 400V AC, and interesting has no neutral wire, read on. Power to the main motor is controlled via a two speed dahlander switch which allows the motor windings to be connected as delta or star to vary the speed.
Supply to the existing X Axis power feed (the only one originally fitted) is via a transformer and the variable speed is handled by some crusty looking electronics on a board in the control box.
The coolant pump is a 3 phase motor and has a simple 3 pole switch.
The DRO is an obscure brand (Aurki) and requires 230VAC. This is supplied by one phase and connecting the DRO's neutral wire to the mill's protective earth - thus relying on the tie between the neutral and earth at the building's electrical installation to carry the return current. IMO, this is not a particularly safe way of doing it but I'll be ditching the DRO once I have the CNC conversion completed so it stays at this point in time.
The manual controls are placed on a sloped panel facing the operator - this panel sits atop the control box which is a fabricated steel cabinet bolted to the rear of the machine column. Dimensions are roughly 500H x 250W x 190 D, with the control panel protruding another 195mm.
Attachment 474500
The slightly later F3B model changed the shape of the control box - it does not slope back under the operator panel - and I think a design similar to this could provide additional internal capacity for the gear that needs to be installed.
Attachment 474502
There is sufficient room to make the box 50mm wider (although I'd like to reuse the door), or make it deeper.
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Re: Emco F3 conversion - electronics and controller
I'm also keen to retain some elements of a manual mill, i.e. be able to switch the spindle on at slow or high speed, and move the X/Y/Z axis manually in a variable spped jog mode (including rapid).
I've mocked up a layout of a replacement front panel in CAD, here's the first iteration. I've made this so it is the same dimensions as the existing operator panel.
Attachment 474504
The Ready and Fault are indicators only (not switches)
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Re: Emco F3 conversion - electronics and controller
I'm leaning towards a Eding CNC 720 board. The vendor has been responsive to my questions and it comes complete with decent software, connects via Ethernet, mounts onto a DIN rail, is 24V compatible, supports E Stop inputs, 2 coolant outputs etc etc.
I already have CL86T closed loop drivers from OMC Steppers online. These will be mounted to a hinged backplane.
The other items are the power supply for the motors (3 phase 400VAC to 48VDC, 960W), power supply for the controls, spindle motor switching contactors and protection, a disconnect relay for the E Stop button, relays for the flood/mist/light main supply breaker etc.
All in all quite a bit to fit into the box. I'll need to do some layouts to check it fits within the existing enclosure, or I can get a sheet metal fabricator to fold up the parts for a larger unit that will fit in a similar place to the original Emco item.
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Re: Emco F3 conversion - electronics and controller
OK, have done a little planning for the equipment that needs to be accommodated in the control box:
1 x 3 phase MCB
1 x 3 phase 400VAC coil (main contactor)
48V 960W 3 phase PSU (for stepper motors)
24V 240W 3 phase PSU (for general controls)
1x contactor for stepper motor PSU and spindle (E stop)
3 x contactors for spindle (dahlander control)
1x contactor for pump
1x contactor for mist
4x stepper drivers
1 x DIN rail mount EdingCNC 720 controller board with BoB
1 x DIN rail mount Eding UIO-10 auxillary board
various switchgear for manual/CNC controls
2x fans for coolimg
I've done a rough layout and will design a control box 100mm deeper than the existing.
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Re: Emco F3 conversion - electronics and controller
I've drawn up a prelim design for the control box. This follows the shape and form of the existing one, however it is 50mm wider, 100 deeper and 30m shorter.
The additional depth was required to fit the components and allow some room for a future fourth axis. I made it 30mm less tall so I can use the two M8 threaded holes in the back of the column to attach the reconfigured Y axis motor mounting plate. As this meant the existing door could not be used I made the enclosure 50mm wider to provided better airflow for cooling.
I have sent the drawings out for a quote from a local sheet metal fab shop. The box will be TIG tacked on the joints and then silver soldered along the seams.
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Re: Emco F3 conversion - electronics and controller
I've had one reply back for punching and folding the sheet metal, waiting for the other one. In the interim I've started drawing the circuit schematics using DIPTrace which is a useful way of documenting the parts I need and exporting the BOM.
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Re: Emco F3 conversion - electronics and controller
Ok, so another back. Double the price and a 5 week lead time. I think that helps me to decide :)
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Re: Emco F3 conversion - electronics and controller
While I'm waiting for the controller box to be cut and folded, I've gone back to doing the schematics for the controller.
Here's a post I've done elsewhere to figure out how to connect the driver alarm outputs to the controller.
https://www.cnczone.com/forums/stepp...-software.html
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Re: Emco F3 conversion - electronics and controller
I'm giving the front control panel some initial thought. The existing one is 2mm thick aluminium, painted black with screen printed graphics.
The replacement needs to be durable and affordable. A self adhesive vinyl over a blank alloy sheet would be affordable, but may not be that durable. A screen printed overlay onto a alloy panel will be durable but not that affordable. Another option would be some type of transfer on the underside of a transparent panel, polycarbonate is durable.
Time to talk to the experts. Somebody like this
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Re: Emco F3 conversion - electronics and controller
So the controller arrived today. Yay. Just waiting for the tinware to be processed so I can start the controller box build.
Attachment 475208
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Re: Emco F3 conversion - electronics and controller
I've largely completed the schematics for the electronics. I'll put up a few posts over the following days to document the design.
First off is the main power circuitry of the machine. The mains supply is 3 phase 400VAC, which is controlled via a contactor and two momentary switches on the main control panel: the first energises the coil of the main contactor and the second de-energies the coil to give a zero volt release mechanism. A NC switch is included so opening the door of the control box will cut power.
Power for control circuitry is provided by 24VDC SMPS. This is always available if the machine is powered up. A DC DC converter supplies 5VDC.
Power for the spindle and steppers is supplied via a secondary contactor, where the supply to the coil is broken by the EStop button being activated or the limit switches being triggered. This ensures in the case of a fault (or the EStop button being activated) the spindle and steppers will stop (the controls will still be active). A fault feedback LED on the operator panel will light if the contactor resets.
Power for the steppers is supplied by a 3 phase SMPS which delivers 960W at 48VDC.
Attachment 475262
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Re: Emco F3 conversion - electronics and controller
When/if I ever get around to sorting out my limit switches I was debating whether to link to the e-stop.
Now I'm thinking not, because my home position will be a back-off setting from a limit switch.
Could potentially cause me a headache.
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Re: Emco F3 conversion - electronics and controller
Quote:
Originally Posted by
dazp1976
When/if I ever get around to sorting out my limit switches I was debating whether to link to the e-stop.
Now I'm thinking not, because my home position will be a back-off setting from a limit switch.
Could potentially cause me a headache.
Surely the home switch should be physically between the limit switches. see this post.
https://support.edingcnc.com/support...d-home-switch-
Attachment 475270
If the limit switch is tripped, we want the steppers and spindle to be cut off to prevent damage. Although maybe a momentary manual override to allow jogging to back within the work envelope ?
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Re: Emco F3 conversion - electronics and controller
So the revised diagram with the Limits override switch to allow manual jogging to get the tool back within the work envelope. Hat tip to dazp1976 for getting me to think the idea through :)
Attachment 475272
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Re: Emco F3 conversion - electronics and controller
One other question I have is the indicator LED module, shown as LED1 on the circuit. Ideally I'd rather this was not being fed from the 400VAC, as it is a 230VAC part so requires extra voltage dropping which introduces thermal issues. The alternative is to use a 24VDC LED module connected to the output of the SMPS: this simplifies the circuit driving the indicator but places the 400VAC switch and 24VDC indicator next to each other on the back of the illuminated power switch (Eaton M22-DL-G). Although the parts are rated at 500V, this would require some physical separation to safeguard against the 24V coming into contact with the high voltage.
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Re: Emco F3 conversion - electronics and controller
Quote:
Originally Posted by
fastbike
Surely the home switch should be physically between the limit switches. see this post.
https://support.edingcnc.com/support...d-home-switch-
Attachment 475270
If the limit switch is tripped, we want the steppers and spindle to be cut off to prevent damage. Although maybe a momentary manual override to allow jogging to back within the work envelope ?
It is quite common to use the Limit Switch as a Home switch, so saves a switch and wiring, what an axis normally does when Homing is hits the switch and then backs off the switch by a number you choose to set in the Homing Parameters, Once Home is set, soft limits then protect your machine, and should never be able to ever hit a Limit Switch, if everything it setup correctly.
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Re: Emco F3 conversion - electronics and controller
Quote:
Originally Posted by
mactec54
It is quite common to use the Limit Switch as a Home switch, so saves a switch and wiring, what an axis normally does when Homing is hits the switch and then backs off the switch by a number you choose to set in the Homing Parameters, Once Home is set, soft limits then protect your machine, and should never be able to ever hit a Limit Switch, if everything it setup correctly.
I can see how that would work, and the EdingCNC manual mentions a similar homing sequence: traversing until the Home switch is triggered, and then reversing until it resets.
I like your expression " if everything is setup correctly". I have too much real life experience to rely on that so for the cost of 3 extra switches (I already have the required wires) I'm going for the "belt and braces" approach :)
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Re: Emco F3 conversion - electronics and controller
Which segues nicely into the Limits circuit.
This comprises 3 sets of two NC switches feeding into a quad opto isolator, and the Darlington outputs from those connected in series to control a low power relay. The relay is a SPNO configuration. The operating state is that normally all limit switches are closed so each of the opt isolator inputs are conducting, so the relay is active and is closed.
If any limit switch activates (goes open) then the associated opto will stop conducting and the relay will deactivate and and remove power from the motor contactor. An (active low) signal is also sent to the controller's external error input which will shut down some of the outputs (steppers, spindle, coolant etc)
Recovery from the fault condition is via the override switch (shown above in the power circuit diagram) and jogging the appropriate axis back into the work envelope. I thought about restricting the jogging speed if a limit error has occurred but ruled it out on the basis that this is an exceptional situation and is covered by a printed recovery sheet.
Attachment 475318
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Re: Emco F3 conversion - electronics and controller
Quote:
Originally Posted by
fastbike
I can see how that would work, and the EdingCNC manual mentions a similar homing sequence: traversing until the Home switch is triggered, and then reversing until it resets.
I like your expression " if everything is setup correctly". I have too much real life experience to rely on that so for the cost of 3 extra switches (I already have the required wires) I'm going for the "belt and braces" approach :)
Most CNC Manufacturers today only use (1) Proximity switch per Axis works very well, saves wiring and easier to trouble shoot when there is a problem, I'm the same as you, but with a quality control like the Eding less can be better. On a machine like you are doing it won't matter how many switches you use, just remember wherever your Home switch is this will be your work envelope unless you set up the soft limits outside of the Home switch position your max travel will be restricted by where you put the Home switch, which becomes a problem when you want that extra 5mm of travel
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Re: Emco F3 conversion - electronics and controller
Quote:
Originally Posted by
mactec54
... the Home switch, which becomes a problem when you want that extra 5mm of travel
I'll bear that in mind when I finalise the position of the home switches. I have slightly increased the X and Y travel by changing the mounting of the ballscrews cf the original acme screws so happy to give up a few mm.
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Re: Emco F3 conversion - electronics and controller
The next section of the schematic covers the control panel. This will follow the sketch in post #2 above with the following changes:
- an additional warning light to indicate if the stepper driver ALM output has been triggered. The drivers are CL86T from OMC StepperOnline which monitor the motors vis integrated encoders. The ALM triggers if the max current or voltage is exceeded, or the encoder determines that the motor did not move as instructed. The (previous) fault indicator is triggered by the limit switches and spindle overload.
- an extra switch added for a machine light. I'll wire this to control a 24V LED device.
- an extra switch to run the Home All macro. The software manual for Eding says it is a good idea to leave the machine in a known state before switching off so this makes it easy.
- The jog speeds are now 0.001, 0.01, and 0.1mm per press, with the Rapid override running at 1mm. So the 4 position switch has been replaced with a 3 position 60 degree switch.
Jogging
There are 4 pairs of momentary switches (S11-S17) to control jogging in the X/Y/Z/A axes. Jogging speed is controlled by S6 which provides a Rapid override, and S7-S9 giving the normal speeds.
Cooling and Aux
Flood and Mist cooling are driven by S18/S19. The feedback status of these outputs is on another page of the schematic and is driven by the output relays.
The worklight is activated by S21 - no feedback LED is required.
The Home All macro is triggered by S22.
Spindle Control
The spindle speed is selected by S24 which is connected to 3 motor contactors providing a 2 speed Dahlander arrangement (I have not changed the original spindle motor and gearbox). The nets labelled SpindleSlow and SpindleFast connect to the coils of the contactors. I'll do a separate post later explaining how that works.
The spindle is (manually) activated by S22. This energises RS1 where the first set of contacts act as a latch and the second set of contacts supplies a signal path to the controller input that controls spindle activation.
The spindle is deactivated normally by pressing S23 which de-energises the coil of RS1. The second set of contacts signals the controller that the spindle state should be stopped.
There is also a zero volt release arrangement, so if the 48V supply is lost, relay RS1 will signal to the controller that the spindle state should be stopped. This is a safety provision I added after including the limit override switch, as I did not want a stopped spindle suddenly starting if the machine was jogged back into the work envelope.
CNC Mode
The CNC mode can be set to Run or Pause via switches S25/S26. The Pause state is provided by an LED in the switch, although I have to figure out how the controller outputs that state.
Attachment 475368
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Re: Emco F3 conversion - electronics and controller
The Home and Probe switches are simple NC micro switches connected via a quad opto isolator and DIN style connector plugs.
There are 4 Home inputs on the controller and a Probe input.
I have yet to work through the schematic for the Probe, so am interested to hear what other people do here.
Attachment 475370
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Re: Emco F3 conversion - electronics and controller
Some switchgear parts have arrived and I've been testing them against the controller.
I've made a small change to the control panel setup in post #21 above. The control I'm using to select the non rapid jog speeds is a 3 position latching rotary knob from Eaton in their M22 series. Part number is M22-WRK3. This has a separate mounting plate that attaches after the actuator is fastened to the front panel and the switch mechanisms (blocks) snap into the mounting plate.
I had interpreted the datasheet to think I could snap in 3 NO blocks to drive the 0.001, 0.01, and 0.1 inputs. I turns out that the actuator only switches the 2 outside positions with the middle position being a "dead/off" position where nothing is switched.
Luckily the blocks are stackable so I've added 2x NC blocks, one on the back of each of the NO block, and wired these NC blocks in series to give a 3 position output. The relevant part of the schematic is now
Attachment 475464
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Re: Emco F3 conversion - electronics and controller
Quote:
Originally Posted by
fastbike
... so I've added 2x NC blocks, one on the back of each of the NO block, and wired these NC blocks in series to give a 3 position output.
Or I could switch the STEP001 input with a couple of diodes and a Mosfet. I will be mounting the (Limit and Home) Optoisolators on some perf board so could do the same with this. The NC switch modules are approx $22 each so a $2 Mosfet makes for a good saving.
My electronics skills are a little rusty, so am interested if anybody has got a good link for a tutorial on how to design a Mosfet switch, where the input will be driven by switches S7 and S9 in parallel. These are normally open and switch to GND when active. So I want the Mosfet to switch to GND when S7 and S9 are open and be floating (high) when they close.
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Re: Emco F3 conversion - electronics and controller
Back in post #15 I was pondering how to indicate when the machine is powered up - using a green LED module to illuminate the main power switch.
Quote:
Originally Posted by
fastbike
... Ideally I'd rather this was not being fed from the 400VAC, as it is a 230VAC part so requires extra voltage dropping which introduces thermal issues.
I've dug around on the manufacturers website, and they show an extra module M22-XLED230-T which is designed for my use case, so I will go that way.
Attachment 475474
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Re: Emco F3 conversion - electronics and controller
Quote:
Originally Posted by
fastbike
I had interpreted the datasheet to think I could snap in 3 NO blocks to drive the 0.001, 0.01, and 0.1 inputs. I turns out that the actuator only switches the 2 outside positions with the middle position being a "dead/off" position where nothing is switched.
Attachment 475464
I've found an accessory part on the manufacturer website M22-XW. From what I can see these snap into the actuator plungers and enable operation of a switch block in the centre position. I will order on to see how it works, if it does what I think the centre "0.01" step setting will only need a single NC switch.
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Re: Emco F3 conversion - electronics and controller
Sheet metal supplier is running a little slow, so I've down the layouts for the internals of the control enclosure. I have not modelled it in 3D, but essentially there are 4 planes with components:
- operator control panel, which has switches and status indicator lights
- power supply and main contactors, all DIN rail mounted. This is located on the front of the enclosure underneath the angled operator panel.
- floor, which has the DIN rail mounted controller and auxiliary IO board from EdingCNC
- hinged backplane (sits inside the rear access door), which has the main MCB, Dahlander spindle contactors, pump contactor, stepper drivers, and miscellaneous IO relays.
It all fits in :) with a little room to spare. More importantly I can now see where to run the trunking and where the 400VAC needs to be run to avoid the control cables.
And Emco came back to me with the red colour they use on their machinery: RAL3020, so time to order some paint.
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Re: Emco F3 conversion - electronics and controller
The control panel has evolved a little since post #2.
I've added a button to control the work light, a Home All button, and a warning light for the fault alarm from the stepper driver.
The jog speed reflects the 3 slower speeds (0.001, 0.01, 0.1 mm per press) and the rapid button advances at 1mm.
I'll print this out and mock up a panel before doing the final artwork.
Attachment 475614
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Re: Emco F3 conversion - electronics and controller
Another possible change to the control panel is to emulate the behaviour of the Emco FB3 power feeds in X and Y axes:
- when the spindle is off the X+/X-/Y+/Y- buttons are only active when pressed
- when the spindle is on the X+/X-/Y+/Y- buttons latch when pressed (this requires an extra feed stop button)
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Re: Emco F3 conversion - electronics and controller
I collected the sheet metal for the enclosure yesterday. The folding is very good apart from a folded tab at the front base which is preventing the front panel from fitting flush. I'll cut it off with a grinder rather than taking it back for alteration.
Attachment 475842
Attachment 475844
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Re: Emco F3 conversion - electronics and controller
And here it is welded up. Well technically not welded as I TIG brazed it with silicon bronze.
And I've done the cutout for the control panel plate, which was done after welding to ensure the box did not distort. The beauty of TIG brazing is very little heat is needed so distortion is minimal. Also a wipe down with acetone is all that is needed on the zincalume plate - no need to remove the zinc plating in the weld area. Tomorrow is hinging the rear door, and the hinged backplate. After that tack welding in the mounting plate for DIN rails etc.
Attachment 475858
Attachment 475860
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Re: Emco F3 conversion - electronics and controller
Quote:
Originally Posted by
fastbike
I've found an accessory part on the manufacturer website
M22-XW. From what I can see these snap into the actuator plungers and enable operation of a switch block in the centre position. I will order on to see how it works, if it does what I think the centre "0.01" step setting will only need a single NC switch.
The parts arrived and easily snap into the 3 position rotary switch. I've fitted a NO switch block at each end, and a NC in the centre. This gives me the 3 settings for STEP0001, STEP001 and STEP01.
The Eaton M22 controls are very well designed and flexible in how they can be configured. A little spendy but that reflects the quality.
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Re: Emco F3 conversion - electronics and controller
Got some cabinet hinges yesterday. I've bolted one leaf to the flange at the back of the cabinet and cut the other leaf to fit the door and tacked into place (whoops - a bit much current on these thin parts).
I'll finish this off tomorrow, mount the latch and then look at fabricating a bracket for the door microswitch and the channels for the EPDM door seals.
Then I can get onto mounting the hinged backplate, and the DIN rail mounting tabs.
Photos to follow.
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Re: Emco F3 conversion - electronics and controller
So, I mounted the latch and the door microswitch this morning, then life got in the way. Hopefully tomorrow will see the backplate installed (and some more photos)
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Re: Emco F3 conversion - electronics and controller
More progress on the enclosure. Way back 3 years ago when I started this conversion a comment was made that the mechanical parts would be the hardest, with the electronics being straight forward. Hmmm, this enclosure and the electronics have taken a lot of nutting out to get the machine characteristics that I want, and to make things fit.
Anyway, here's a progress report. I mounted the enclosure door and the hinged backplane. This shows the backplane up in the normal position.
Attachment 476218
I have drilled holes for the stepper drives (room for 4 axes) and DIN rails. I've snapped on a few of the contactors, relays and the main MCB. Two views, this one with the backplane hinged down for access to the box.
Attachment 476220
And this, an internal view, from the aperture for the control panel showing the backplane in its normal position.
Attachment 476222
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Re: Emco F3 conversion - electronics and controller
Quote:
Originally Posted by
fastbike
This gives me the 3 settings for STEP0001, STEP001 and STEP01.
I hooked these switches up on the test bench to the EdingCNC UIO-10 accessory board to check how the switching works with the software.
I encountered two problems: the first is that the input for stepping 0.001mm per pulse is actually mapped to 0.01mm. Eding are looking into this and I expect a new version of the firmware will be forth coming.
The second was a bit harder to diagnose; the switch inputs were randomly being triggered. I tried a variety of wiring configurations, none of which made a difference. I have access to an oscilloscope so hooked that up to the switch wire and saw a very dirty wave form with periodic pulses. Disconnecting the power supply from the laptop running the software cleaned up the scope trace. However the laptop can only run so long on battery so I'll need to figure out a better solution, maybe some filtering or ferrites ?
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Re: Emco F3 conversion - electronics and controller
Quote:
Originally Posted by
fastbike
The second was a bit harder to diagnose; the switch inputs were randomly being triggered. I tried a variety of wiring configurations, none of which made a difference. I have access to an oscilloscope so hooked that up to the switch wire and saw a very dirty wave form with periodic pulses. Disconnecting the power supply from the laptop running the software cleaned up the scope trace. However the laptop can only run so long on battery so I'll need to figure out a better solution, maybe some filtering or ferrites ?
Eding have come back to me, so we're going to try a few configurations. In the interim I have spray primed the enclosure and door. I'm using a two pack urethane acrylic top coat in RAL3020, over an etch primer.
The backplane has been painted with a rattle can.
More photos when the painting is finished.
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Re: Emco F3 conversion - electronics and controller
I got a first coat of the red paint onto the enclosure and door this morning. This cannot be over-coated for 12 hours so I'll try to get the second coat done tomorrow - weather dependent as I don't have an indoor spray booth and need a reasonably windless day to paint.
Meanwhile I've started work on wiring up the backplane. I've done most of the Dahlander circuit for the main spindle, and have started the stepper drivers and auxiliary relays.
Here's a photo of the partially wired backplane.
Attachment 476620
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Re: Emco F3 conversion - electronics and controller
And here's the enclosure painted, actual colour has more orange in the colour than is showing on my monitor. Almost time to start installing the components inside but I'll give it a day or so to harden up a bit.
Attachment 476664
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Re: Emco F3 conversion - electronics and controller
I'm about half way through wiring up the control box. It's really quite time consuming, although I'm work slowly and methodically as I do not want any mistakes. I've almost finished the power supply and spindle control section (all the 400V AC stuff), so will move onto the controllers and drivers next. Here's a progress photo (taken through the aperture where the control panel will be attached.
Attachment 476946