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Printing issues ...
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Re: Issues with printing larger objects - 7 years ago
I'm so done right about now. I've found the problem. So, the linchpin that's been a pain in my neck for the last few months, the constant sword of Damocles over my prints, has been isolated to number 4.1 on the shifted layers page on the reprap wiki. That refers to cheap chinese pulleys which aren't machined to a sufficient depth to properly grasp the teeth of the belt. Mine were aluminium, andby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
QuoteJamesK Interesting. A hot motor might lead us back towards binding as a possibility. One of the issues with H-bot/coreXY is that the belt tension pulls the sides together across what is conventionally the X axis, but looks like the Y axis in your build. I see you don't have a structural member bracing that axis in your build, so you are potentially vulnerable to the rods flexing and changingby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Ok, Good news, I just ran Drift King at 1mm/s, and as expected, it drifted. Practically a ridiculous 5 degree overhang to the plate, though there was indeed a bit of bearding on the bottom. I think I've isolated the problem, I marked both pulleys and belts, but when I came back and found it had drifted severely, I observed two things. One, the Y motor responsible for moving the diagonal parallelby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
QuoteMCcarman I really wish I could help you. We know one drive is out of sync with the other hence the diagonal shift. The shift is progressive in one direction. So its not just something loose or it would be variable. The shifts are less than belt pitch so its not jumping teeth. The motors have D shafts so the gears can't slip progressively round the motor. The motors are different but they haby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
QuoteJamesK Oh. Jerk sounds high. Try taking that way down, just in case (e.g. start at 1 and see what happens). What's your moving mass like? Hmm, doesn't look too bad, and doesn't explain why the problem only affects one motor. Still feels like a possible wiring problem at the moment - did you try running a second set of wires for the motors to rule that out? emf/magnetics are unlikely to affeby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Ok, I made a test object of a 200mm hollow cube with 2mm thick walls, and printed it in vase mode (so no roof or floor) with 0.32 layers. My prior failed prints were much smaller at around 80-120mm across at most. However, the thin walls continued printing fine for more than 1cm, at which point I stopped it, but the smaller, more detailed models all failed as early as 5mm up. This suggests thatby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
#crazytheorytime I'm just short of buying an Ouija board or a deck of tarot cards to attempt to communicate with the spirit possessing my printer, but I decided to wave a compass on it instead. My frame is cold rolled steel slotted L profiles, the kind used in making cheap shelving (check the images). Likely due to all the wires running all over it, as well as the presence of strong magnets insidby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
QuoteJamesK Ah, ok. If you've had it so the motors were running hot then we can probably rule out lack of current as the cause. The DRV8825 aren't that bad, at least not for cartesian printers. They are prone to creating surface artifacts because they don't handle the first few microsteps very well when there is a large difference between the supply voltage and the target voltage needed for the mby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
QuoteJamesK Everything you describe is consistent with too little drive current. Please could you describe again how you calibrated the current? Initially, I calculated the current as per pololu's website, and measured vref with a multimeter. When I started getting this layer misalignment issue, I slowly increased the current and then ran it at the max for my drivers, but the layer drift stillby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Right, so I've converted my printer from a HBOT to a CoreXY, replaced the belts, got new bearings so both axes run smoothly through their entire travel, got a new hot end mount printed, got brand new stepper motors for the X & Y axes, ensured there are no wires running parallel, re-tuned stepper currents, tried 3 different slicers and checked my horoscope. Regardless, it still has the same stby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Quotethe_digital_dentist In that case it sounds like a mechanism binding problem. Things may move smoothly and easily without the belts in place but belt tension can cause things to flex out of alignment. Can you post some pictures of the machine? That is a possibility, as my mechanism does have a bit of racking, my test cubes are slightly the shape of quadrilaterals when looked at from above.by A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Quotethe_digital_dentist In a corexy mechanism diagonal lines are produced when only one motor is turning. I don't know if h-bot works the same way. In a corexy machine that torque-slips on the 45/135 degree lines, I'd turn down the acceleration until it stops slipping. My acceleration is down to 20mm/s2 now, it's much lower than what it was, but it still drifts. H-Bot and Corexy are the same aby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
QuoteMCcarman Since the layers print OK, what happens if you reduce the move speed to the same as the print speed? That should rule out speed related issues. I don't know much about H-Bots but I assume motor synchronisation is critical. Assuming the firmware is configured correctly then differences in the drivers may have an effect. Just speculating but wire size and length differences? I'm curby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Alright, I just did two test prints, 3 cubes in a line, one print oriented to the X axis, and the other oriented towards the Y. Both prints got misaligned, and although the X drifted earlier in the print, I haven't repeated this test multiple times, so the results seem inconclusive. However, I noticed that sometimes, the print would get misaligned during the skirt itself. The initial loop would cby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Right, I realized the Y axis rods weren't perfectly aligned, so I went and got some supports lasercut out of MDF. I realigned the frame, the Y rods, and the stepper motor & idler mounts, and finally, after 2 months or trying to fix my printer by procedurally checking every possible thing short of a complete stripdown, The misalignment is now at regular steps. Pretty much perfectly, there'sby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Day 40, hope is starting to dwindle, frustration building. I borrowed a RAMPS 1.4 and mega from a friend, and installed marlin RC8 onto it, and hooked it up to my printer. It started up, began printing, and got misaligned as usual. Same error again, even with another board. Now I'm really getting stumped on what's the issue. I think I'll try swapping two stepper motors and seeing if that somehowby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Quotesigxcpu Quotekentmcn Why the system would add (or subtract) to both X and Y though, seems odd. Because it is a H-bot and one motor moves at 45/135 degrees? HBots and coreXY's are a pain to troubleshoot, because if only one motor is turned, then the head moves diagonally, and if the other is turned, then it goes diagonally perpendicular to the first one. If one is turning, and the other skby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Quotekentmcn It looks like both X and Y axes are affected and at the same time--as if the Arduino was overloaded, the RAMPS board couldn't produce enough power, or the SD communication was losing packets. Why the system would add (or subtract) to both X and Y though, seems odd. Maybe try to reduce the processing load on the Arduino? Check the power that's available throughout the print? And chby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Just in case, I also updated my marlin firmware from RC6 to RC8. A little head scratching and bug stomping later, I got my printer working, but again, the issue persisted. I'll try to swap out either the arduino or ramps boards with another and see if that fixes it.by A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Alright, I removed the belt and checked the axes again, friction is still negligible. I checked the page, and crossed every item off the list. The only remaining possibility is that my controller's gotten somehow messed up, either the arduino or the ramps board. I conducted a visual inspection of both boards, and I didn't see anything burnt, poorly soldered, or otherwise damaged. Is there a chanby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
QuoteFloyd Im still going with current needs to be higher. I have to have mine REAL high and the motors burning hot otherwise ill miss steps. Missing steps creates a audible sound, so I would have noticed it. I tried tuning my drivers with vref, but that turned out to be way too low, so I tuned it until I didn't get any more torque when increasing, and only more noise. Besides, it was working eaby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
QuoteVDX ... there were similar effects with slipping gears, not enough fixed on the motor shafts ... My stepper's have standard D shafts, and the pulleys are locked on tight. They're definitely not the problem, and I've put marks on the pulley to check if there was any slipping, and it's rock solid. I thought it might be the endstops falsely triggering, but I get no messages about that, and I trby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
QuoteVDX ... still looks like loosing steps - have you tried to rise the motor current? The current's at its max, and I've used new stepper motor drivers just in case, but still the same issue. I'm microstepping at 1/16 with A4988 drivers. It also doesn't make any sounds like missed steps or impacts when the deviation shows up.by A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Quoteobewan Have you tried a print with 'avoid crossing perimeters' set or maybe with 'Z hop' set. This would remove the possibility of the nozzle snagging on the centre piece. Sorry if this is a stupid idea At this point, I'm desperate enough to try anything, this issue has been on my head for a month now. Earlier, it didn't make any sounds or movements to indicate nozzle catches, so I dismisby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Quoteo_lampe The misalignment seems to be in perfect 45° direction?! If a H-Bot has same kinematics as a CoreXY, this indicates one of the steppers competely fails. I'd check the hardware and wiring for cold solder joints or broken wires. QuoteA_Designs I'm not sure if that's the case, but I don't think I can rule it out entirely either. I've had prints fail early as the second layer, to as lateby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
Quoteo_lampe The misalignment seems to be in perfect 45° direction?! If a H-Bot has same kinematics as a CoreXY, this indicates one of the steppers competely fails. I'd check the hardware and wiring for cold solder joints or broken wires. I'm not sure if that's the case, but I don't think I can rule it out entirely either. I've had prints fail early as the second layer, to as late as 20 min in duby A_Designs - Printing
Re: Issues with printing larger objects - 7 years ago
QuoteGaou when this happens to me it is always a nozzle hitting on the print makes it lose steps...! do you watch the print from the beggining to the end ? I've carefully watched my printer, and it doesn't seem to hit anything or make any sounds to indicate jamming, impact or contact with obstruction. It just starts suddenly printing it offset from the previous layer. Quoteo_lampe The most signiby A_Designs - Printing
Issues with printing larger objects - 7 years ago
Hello, reprappers, I built a custom H-Bot, solid steel frame, 300mm x3 build volume, heated bed, bowden extruder, print cooling fan, run by Marlin-1.1.0-RC6 on RAMPS 1.4. I've been having some really strange issues with it, when I print a large volume on the XY axis, like a 40mm cube, it gets a layer misalignment problem. This doesn't happen with smaller objects, or even less of the same objectby A_Designs - Printing
Re: Mesh bed leveling - Z axis not moving during print - 7 years ago
QuoteRoxy Did you activate the Mesh Leveling? quote=obewan] Try sending M420 S1 this enables mesh leveling in marlin I hadn't tried M420 before, so I just did, but it still isn't running the Z motors. On the bright side, I got a somewhat successful print today, after manually tweaking the Z screws, but it's still a bit uneven.by A_Designs - Firmware - Marlin
Mesh bed leveling - Z axis not moving during print - 7 years ago
Greetings, So I have a 3D printer of my own design, hbot with moving Z-axis bed, running the latest version of Marlin. There are two steppers moving the bed up and down via threaded rods. I recently tried using Mesh bed leveling with a 3x3 grid (with the discount reprap LCD controller) to compensate for a mild tilt in my bed, but the Z axis motors just didn't move to compensate for the tilt duby A_Designs - Firmware - Marlin
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