Yes a PSU switch will do this, but you need to make sure that the switch you use is capable. Most of the cheaper E-Stop switches are not really designed for either high current DC or mains AC. You really want to kill the DC side of the PSU (completely disconnect it), as the PSU will take a small time to shut down if you disconnect the AC side. If you're using RAMPS, you at least could put it onby Cefiar - RAMPS Electronics
When you slice the object, are you starting slic3r yourself, or from within Pronterface? Pronterface might be specifying a different config file that has different values.by Cefiar - Slic3r
Where did you buy them from? If an eBay seller, please link to them? I ask because there has been a few clones that don't quite work properly. A post that might prove useful is this one (the last post):by Cefiar - Controllers
Most likely it's a diode or fuse on the USB +5V line on the RUMBA (or possibly even a track). I'm not particularly familiar with the Rumba schematic, but that is what I'd be looking at.by Cefiar - Controllers
You want to change the max speed and acceleration values in your firmware. This might slow it down appropriately.by Cefiar - Controllers
What sort of end stops, how have you got them hooked up, and how is it configured in the firmware?by Cefiar - RAMPS Electronics
Assuming no other losses, and that as it gets hotter that the bed doesn't somehow short out, that should only be about 7.5A. Beware of shorts from parts of the heated bed PCB if you're using an aluminium bed. If it heats up and bends slightly (as compared to when cold), things could short out which would cause issues. Also tends to be a right pain to figure out, being intermittent or only when hby Cefiar - RAMPS Electronics
FWIW: RAMPS-FD (which isn't quite yet ready) DOES support proper Emergency Stop, and it does this by disabling the motors AND all the heaters too. Note: Those using RAMPS with external stepper drivers are doing so they don't have to make up the heater mosfet circuits or the thermistor stuff (which apart from housing the stepper drivers, is pretty much all RAMPS does).by Cefiar - RAMPS Electronics
7.5 Deg stepper motors should work fine ASSUMING they're 4 wire stepper motors, and not 5 wire. I don't know (off the top of my head) any RepRap electronics that will drive 5 wire stepper motors. Note that you can't just ignore the 5th wire and treat them as 4 wire motors - they're wired completely differently inside. You may find that some 7.5 deg motors don't like certain types of microsteppiby Cefiar - Controllers
The options you have for RAMPS are: 1. Wire up the reset button. This will stop things but the Arduino will reboot. If whatever is talking to it keeps sending data AFTER you reboot, it might move/do stuff again. It's not really a proper Emergency stop, but it suffices for basic things. 2. Any software-based Emergency Stop will be slower than a hardware-based Emergency Stop, as you're waiting onby Cefiar - RAMPS Electronics
It's quite possible but 2 things of note: 1. RAMPS does not have Emergency Stop support. You will need to disconnect power to do the equivalent, unless there is some sort of override on the stepper drivers you can put an emergency stop circuit in (eg: could be done with the stepper enable line for example). 2. Your firmware needs to hold the step/dir signals for a set length, otherwise the drivby Cefiar - RAMPS Electronics
There is no hardware emergency stop support in RAMPS. That's one of the things we've added in RAMPS-FD, but it's not quite ready for end users.by Cefiar - RAMPS Electronics
Note: Those SparkFun converters you linked are uni-directional, so you may find that of the 4 channels, you only 2. For each stepper you'll need 3 signals (Step, Dir, Enable), and the signals all originate from the electronics (eg: RAMPS-FD) to the steppers (so they all need to be 3.3V in, 5V out). There are bi-directional ones where you can use each signal in either direction, which will definiby Cefiar - Controllers
Usually it's the problem, as you get a loop caused between: Mains ground on Printer Supply to Mains ground on PC. Mains Ground on PC to DC ground on PC's USB. USB cable from PC to USB cable on RUMBA (or any USB based electronics) DC ground on RUMBA to Mains ground on Printer Supply. This forms a loop. If instead of these all being the same voltage level, there is instead a voltage differencby Cefiar - Controllers
QuoteGordie Do you think it's possible? The step/dir/enable lines on RAMPS-FD are all 3.3V. You driver requires 5V. You will need to provide level translation to get your signals levels up to 5V. The A498x and DRV8825 drivers both support 3.3V operation for the control side, so they work as-is. QuoteGordie What are your suggestions on raching 1/64th with the RAMPS-FD? Level shifting the signaby Cefiar - Controllers
Ground loop. How are you wiring up the AC side of the dedicated PSU? A pic speaks a thousand words here. A lot of people connect AC Ground to DC -VE (or DC Gnd - in this case same thing). If DC ground on the PC is a fixed voltage different from the DC ground on the PSU, you get current flowing. This can either cause the USB to shut down, or in some cases cause the USB cable to get hot, as the cby Cefiar - Controllers
IMO the zener is there to limit the gate voltage to 15V. The only way I could see that happening is getting drain to gate leakage on the FET that is being driven. No idea how likely that is in this setup. Might be worth looking at one of those integrated driver chips that were discussed in the RAMPS-FD thread. Probably cheaper, definitely less component count, and simpler to integrate.by Cefiar - Controllers
I saw your design on G+ and commented there (Re: good choice on connectors), but just thought of something else to ask. Do you have any thermistor input protection (over-voltage)? I don't know how many people have fried the analog inputs of their electronics due to accidentally shorting the hot end +Volts to the thermistor input, but it's a lot. If you haven't, take a look at RAMBo and also atby Cefiar - Controllers
QuoteCefiar FWIW: I didn't get an order in for any boards yet, and Chinese New Year has basically put a halt on any new boards out of the place I order from. They won't be shipping anything out till after Feb 7th (more likely later, since I haven't ordered yet), so I won't be getting boards till after that time. Sorry for the people who asked if they could get them from me. Note: To the peopleby Cefiar - Controllers
FWIW: I didn't get an order in for any boards yet, and Chinese New Year has basically put a halt on any new boards out of the place I order from. They won't be shipping anything out till after Feb 7th (more likely later, since I haven't ordered yet), so I won't be getting boards till after that time. Sorry for the people who asked if they could get them from me. Note: To the people who sent meby Cefiar - Controllers
With a multimeter, measure the resistance of the heated bed. It's possible that it's too low or there is a short. That said, I hate those PTC fuses because they fail in odd ways (including catching fire). I prefer real standard fuses, like automotive blade fuses.You can't mount them on the RAMPS board, but they definitely are an improvement.by Cefiar - RAMPS Electronics
Well, there is no reason we can't create a base board (especially if at the time we can somehow address the USB ground loop issue that it seems almost all Arduino variants seem to suffer from with an external PS in use), and then later look at turning it into an "all in one" design as a "next generation" thing.by Cefiar - Controllers
The standard MOSFETs on a RAMPS board aren't really good at high currents. If you're staying under 30V (which is 99.99% of people) then I suggest something like the IRLB8743. Handles higher current, has a lower Rds(on) (= more volts to your heated bed), etc. It's used on RAMPS-FD and on other electronics like Gen7. BTW: The IRLU8743 is almost identical to the IRLB8743. Both devices are pin-by Cefiar - RAMPS Electronics
Q: Are you looking at an 'all-in-one' board version of RAMP-FD -basically adding the CPU on the board itself? If so, I'm interested in this as well. In fact, that was sort of my reason of getting involved with your RAMPS-FD project in the first place.by Cefiar - Controllers
I haven't had a chance to look at the board due to the Melbourne heatwave. Was 31 Deg C on Monday, 41+ Deg C days since then (Today is supposed to be 44), and most nights not getting below 25 Deg C. Temp is supposed to drop tomorrow, so I'll have a look at it then. So I thought what the heck I'd look at it now. Only thing that I can see is a non-issue as long as we document it: The two Due mouby Cefiar - Controllers
Depends on your PSU. If it's well constructed and you don't have any part of the ground that can come into contact with live wires, then it's not likely to be a problem. The issue tends to be either people not connecting wires securely (which come loose), or the insulation comes off leaving them exposed. When I terminate wires, I tend to cover all the existing wires with heatshrink, thereby giby Cefiar - Controllers
There's a list of suppliers here: Make sure you go stainless (normal or marine grade) or hardened chrome (such as clarky sells). Hardened chrome is of course better, but at least if it's stainless, it shouldn't rust (which is about the worst thing that you could want to happen - as it really stuffs your bearings too).by Cefiar - Australia, Melbourne RUG
Measure the voltage either side of the big PTC fuse (the yellow blade shaped things). My guess is that the current draw for your heated bed is just high enough for it to work for about 20 seconds then it trips as it's over the current limit of the PTC fuse. Also: Make sure that they're not actually touching each other. They work by heat and will trip once the internal temp gets to a set value.by Cefiar - RAMPS Electronics
I'll be getting some boards fabbed as well (well, 10 boards), which will be delivered to me in Aus. If anyone in Aus wants one, I'll probably have ~7 I can pass on (1 is already taken, 2 are for me).by Cefiar - Controllers
When someone got the same problem with the RAMPS-FD board (meaning, the Due which has the ground reference has the issue), they suggested 1kohm. I think you don't need to go that high. Even as low as 100 ohms may be enough to stop the problem. Really though, the issue is the ground on the Melzi (and any board that has its own USB connector) is that the USB shield tends to be wired directly to tby Cefiar - Controllers