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It seems that these tips plug up too easily.
Posted by techristian
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It seems that these tips plug up too easily. November 27, 2016 09:13PM |
Registered: 7 years ago Posts: 22 |
It seems that these tips plug up too easily. For me after only 70 hours of print time 1) The first time the thermistor came out , the tip overheated and blocked. 2) The next time the heating core fell out and the tip plugged because it was too cold. 3) The 3rd time I knew that I was running out of plastic, left the printer unattended for 1 hour and the thing was still running without plastic. Somehow, when the plastic filament is an inch long, it stops being extruded and plugs up the channel. Anyway , I didn't know what happened so I bought lye crystals to clean the tip and discovered that the extruder pipe (channel) was plugged. Replacing the tip on the heater block, I overtightened it a bit and snapped it....so I need a new heater block. Luckily they are cheap enough.
Anyways , slowly but surely I'm learning the limitations of this system. This reminds my of my early days with DOT MATRIX printers. I couldn't leave them unattended either. Otherwise I would end up with torn paper or many other assorted problems. Also CD burning in the mid 90's ...also a new technology back then. I didn't consider these technology ROBUST back then...and wouldn't consider 3d printing ROBUST , at this point, either. A guy in my computer club has worked with a $100,000 3d printer and has print jobs destroyed , even on it.
Dan
Anyways , slowly but surely I'm learning the limitations of this system. This reminds my of my early days with DOT MATRIX printers. I couldn't leave them unattended either. Otherwise I would end up with torn paper or many other assorted problems. Also CD burning in the mid 90's ...also a new technology back then. I didn't consider these technology ROBUST back then...and wouldn't consider 3d printing ROBUST , at this point, either. A guy in my computer club has worked with a $100,000 3d printer and has print jobs destroyed , even on it.
Dan
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Re: It seems that these tips plug up too easily. November 27, 2016 10:15PM |
Registered: 11 years ago Posts: 5,780 |
It sounds like you have a combination of design/build problems and flawed operational technique.
If thermistors and heater cartridges are coming out, either the heater block design is poor or your assembly is poor or both. If the heater cartridge fits loosely in the block even after tightening the screw, take it out and wrap it with a couple turns of aluminum foil, then carefully slide it into its hole in the block and tighten the screw down hard. The cartridge should be firmly gripped by the heater block. Thermistor mounting is a problem with most heater blocks (one exception is the E3D blocks that use cartridge thermistors). Bending wires, then clamping them down with a screw is a disaster waiting to happen. Adding a drop of high temperature cement to the thermistor before you stick it into the hole in the heater block can help, as can controlling the wire leads so nothing is pulling on them.
When the filament runs out during a print, the last bit of filament ends up just below the drive gear in the extruder where the motor can't push it any more. In many extruder/hot-end designs, you have to remove the hot end and heat it up to remove that filament before you can feed in fresh filament. The solution to this problem is to be more careful about printing, including weighing the spool before starting the print so you know how much filament it contains. If it isn't enough to finish the print (as reported by the slicer), don't use that spool. It sounds like a PITA, but it's nothing compared to having to take things apart to clean out the hot-end.
Smoothieware has some firmware tricks that help with safety which also probably help prevent blocking the extruder due to cooking filament. One is a watchdog timer that shuts down the heaters if it takes too long to heat up (if the thermistor is out of the block this can happen). Another is if there is too great a temperature difference between the measured value and the set value (if the heater switch MOSFET fails as a short and locks the heater on it will quickly rise above the set temperature). The firmware then toggles an output pin that can be used to operate a relay to kill power to the heaters/printer.
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
If thermistors and heater cartridges are coming out, either the heater block design is poor or your assembly is poor or both. If the heater cartridge fits loosely in the block even after tightening the screw, take it out and wrap it with a couple turns of aluminum foil, then carefully slide it into its hole in the block and tighten the screw down hard. The cartridge should be firmly gripped by the heater block. Thermistor mounting is a problem with most heater blocks (one exception is the E3D blocks that use cartridge thermistors). Bending wires, then clamping them down with a screw is a disaster waiting to happen. Adding a drop of high temperature cement to the thermistor before you stick it into the hole in the heater block can help, as can controlling the wire leads so nothing is pulling on them.
When the filament runs out during a print, the last bit of filament ends up just below the drive gear in the extruder where the motor can't push it any more. In many extruder/hot-end designs, you have to remove the hot end and heat it up to remove that filament before you can feed in fresh filament. The solution to this problem is to be more careful about printing, including weighing the spool before starting the print so you know how much filament it contains. If it isn't enough to finish the print (as reported by the slicer), don't use that spool. It sounds like a PITA, but it's nothing compared to having to take things apart to clean out the hot-end.
Smoothieware has some firmware tricks that help with safety which also probably help prevent blocking the extruder due to cooking filament. One is a watchdog timer that shuts down the heaters if it takes too long to heat up (if the thermistor is out of the block this can happen). Another is if there is too great a temperature difference between the measured value and the set value (if the heater switch MOSFET fails as a short and locks the heater on it will quickly rise above the set temperature). The firmware then toggles an output pin that can be used to operate a relay to kill power to the heaters/printer.
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
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Re: It seems that these tips plug up too easily. November 28, 2016 12:27AM |
Registered: 7 years ago Posts: 22 |
Quote
the_digital_dentist
When the filament runs out during a print, the last bit of filament ends up just below the drive gear in the extruder where the motor can't push it any more. In many extruder/hot-end designs, you have to remove the hot end and heat it up to remove that filament before you can feed in fresh filament. The solution to this problem is to be more careful about printing, including weighing the spool before starting the print so you know how much filament it contains. If it isn't enough to finish the print (as reported by the slicer), don't use that spool. It sounds like a PITA, but it's nothing compared to having to take things apart to clean out the hot-end.
I JUST BOUGHT A <5KG SCALE TODAY...MOSTLY FOR POSTAGE FOR EBAY...BUT I WILL CHECK THIS OUT . THANKS !!
How do you calculate the weight? I'm using 1.75 PLA and Repetier says that it requires 13,538 mm for my next print..
Dan
Edited 2 time(s). Last edit at 11/28/2016 12:34AM by techristian.
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Re: It seems that these tips plug up too easily. November 28, 2016 07:27AM |
Registered: 11 years ago Posts: 5,780 |
Calculate the number of cubic cm in that length of filament and multiply by the density of PLA. PLA density is about 1.2-1.4 g/cm^3. Use the 1.4 value to get a conservative result. Filament approximates a cylinder. The formula for volume of a cylinder is pi*(d/2)^2*l You're using mm for d and l, so you're going to get mm^3. There are 1000 mm^3 in 1 cm^3, so divide your mm^3 value by 1000 to get cm^3.
Two things to do with every spool of filament:
1) Every time you open a new spool of filament, remove all the packaging and desiccant and weigh it. Subtract the weight of the filament. That's the empty spool weight. Mark the empty spool weight on the spool. If you bought a 1 kg spool of PLA and it weighs 1270 g, it's a safe bet that the empty spool weighs 270 g. Alternatively, and even better if you use the same filament supplier a lot and they use one type of spool, weigh one of your empty spools. You don't have to weigh the spool every time you print, just when it starts to get questionable. If you've got half a spool of filament and you're going to print a tugboat, don't bother weighing it. But before you start a 10 or 20 hour print, if there's any doubt about how much filament is on the spool, weigh it.
2) Measure the filament diameter in 20-30 places using a caliper that can read down to 0.01 mm and calculate the average value. Mark that average diameter on the spool and use it every time you slice for or print with that spool. If your extruder is properly calibrated, using the average filament diameter every time you print will yield consistently high quality prints. In 3 years of doing this I have had only one spool of filament that actually averaged out to 1.75 mm. A few hundredths of a mm difference in the diameter will make a visible difference in the appearance of your prints. If after printing with a spool for a while you notice a reduction in quality that looks like over or under extrusion, measure the filament again. Some manufacturers are better than others at maintaining a consistent diameter over the length of a spool.
This sort of thing is one of many reasons why 3D printing isn't a consumer thing (and may never be).
Edited 1 time(s). Last edit at 11/28/2016 09:18AM by the_digital_dentist.
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Two things to do with every spool of filament:
1) Every time you open a new spool of filament, remove all the packaging and desiccant and weigh it. Subtract the weight of the filament. That's the empty spool weight. Mark the empty spool weight on the spool. If you bought a 1 kg spool of PLA and it weighs 1270 g, it's a safe bet that the empty spool weighs 270 g. Alternatively, and even better if you use the same filament supplier a lot and they use one type of spool, weigh one of your empty spools. You don't have to weigh the spool every time you print, just when it starts to get questionable. If you've got half a spool of filament and you're going to print a tugboat, don't bother weighing it. But before you start a 10 or 20 hour print, if there's any doubt about how much filament is on the spool, weigh it.
2) Measure the filament diameter in 20-30 places using a caliper that can read down to 0.01 mm and calculate the average value. Mark that average diameter on the spool and use it every time you slice for or print with that spool. If your extruder is properly calibrated, using the average filament diameter every time you print will yield consistently high quality prints. In 3 years of doing this I have had only one spool of filament that actually averaged out to 1.75 mm. A few hundredths of a mm difference in the diameter will make a visible difference in the appearance of your prints. If after printing with a spool for a while you notice a reduction in quality that looks like over or under extrusion, measure the filament again. Some manufacturers are better than others at maintaining a consistent diameter over the length of a spool.
This sort of thing is one of many reasons why 3D printing isn't a consumer thing (and may never be).
Edited 1 time(s). Last edit at 11/28/2016 09:18AM by the_digital_dentist.
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
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