I only have a budget of around 2k for my next printer. Where did you get the mini if you didn't intend on using it?

Then you must be the guy who won first prize in the company category. I was the second place guy in the individual category.

Same to you... Good luck in your sale.

This post has been edited by altan: Jun 11 2015, 08:35 PM

I guess you got yourself a faulty thermistor in the J-head hotend.

I had that happen to me before and it was really funny. The hotend was working like normal for a few months and suddenly one day I sense a funny plastic smell and the next thing I realize was the heating block melting the PEEK barrel and fell off the barrel. I was lucky to have noticed it and identified the problem as faulty thermistor because the host could not reach the set point temperature and continuously heat the hotend till it fell off.

You might want to get a replacement for that.

Yes, try changing the MOSFET for the heated bed as suggested or get a SSR switch rated for 12v DC and high current (15Amps and above) as a switch for the heated bed.

The heated bed is normally difficult to be maintained at the setpoint temperature due to the high heat loss vs input power.

This post has been edited by altan: Jun 24 2015, 07:29 PM

Good question, someone has to try that out both methods but if not mistaken, it should work for both bang-bang and proportional/PWM switching. Maybe the SSR has a switching frequency limit that I am not aware of so defeats the use of PWM switching.

My printer sometimes freezes up and sometimes stops completely due to the serial port cable coming loose when the whole printer shakes during prints.

If one of the motor stops running while the rest are still running during print then its likely due to the overheated stepper driver. Only solution is to reduce the current limit on the trimpot or add an extra fan.

Either MOSFETs should work as long as the gate turn-on voltage threshold is below 5v (its 1.8v and 2.5v for the two). To keep cost low, I would recommend the IRLB8743PBF (2.5 mOhms) which is good enough for reprap use and does not necessarily require a heatsink to keep cool. The thermal power loss would be about 7 times less compared to your existing one.

You can calculate the thermal power loss of a MOSFETs by following the example at: http://reprap.org/wiki/Basics_about_switch...ds_with_MOSFETs

Obviously you can reduce thermal power loss by about 14 times with the IRLB3034PBF (1.2 mOhms) but the two MOSFETs would heat up to roughly to the same temperature and it cost 3 times more. Just my 2 cents.

Good luck!

Finally back from an event and I am surprise to see some on going activity here.

About your broken barrel (or was it melted barrel?), you can use a spanner on the j-head heating block and a large pliers on the barrel to dismantle them.



Good report on the MOSFET mods, I didn't think the MOSFET change could have an effect on the entire Ramps board.


Lelong? I always thought there were lots of dishonest sellers and scammers at Lelong.

No wonder the steppers are heating up from the result of the previous MOSFETs...

For replying to multiple quote, just click on the quote button (bottom right and can select more than one) of each post then click on add reply button at the end of the page.

Its really strange to see the extruder motor not skipping and not grinding the filament at the same time. Usually if it grinds, its means the stepper drivers are still doing its job and its likely caused by the hotend or the filament. As for skipping, this happens when the stepper driver are overheated or the pot adjustment is too low. Since it is long term, most probable answer for skipping is the stepper drivers are overheating.

Another thing I suspect for those symptoms is the extruder motor cables could have come loose during prints (on the motor end). I had a faulty extruder motor that sort of fidgets (not turn properly and doesn't cause grinding) early or halfway through the print and it was caused by the repetitive loosening of the cable on the motor side. I push and press the cable end into the stepper and it magically works and this means one of the wire in one of the four is probably damaged. I think since we normally don't tie down the motor cable end to the motor/platform and we leave it hanging free, the movement in the Y or X axis causes the cable to wear internally and causes the wires to disconnect from the stepper.

Anyway long story short, try to change your stepper motor for the extruder and also cable tie the cable to the motor. Make sure to leave some slack on the cable motor end.

My advice for you is to get an all-metal hot end and not use the PEEK barrel J-Heads which are not actually spec for ABS printing. Some all-metal have a teflon tubing inside and it will still work for ABS but you might have to buy the teflon sleeve replacements.

I suspect the J-Head PEEK barrel doesn't form a proper thermal barrier between the hotend and the filament input end and causes the whole ABS filament to soften and jam up mid barrel. Another solution to try is to add a small fan pointing towards the barrel so it will assist in dissipating the heat and forms a good heat gradient profile.

Leaking from between the heater block and the thermal break/barrel means the threads are worn or possibly damaged.

I would recommend cleaning out all the PLA in the thermal break and the thread by picking out the PLA bits with a tweezers and some heat (hot air gun or hair dryer). If the threading on the thermal break is stil there, you can save it by using some PTFE/Teflon tape (plumber white tape) on the male end (probably the heater block threads that's like a bolt) but don't use too much as it can damage the threading and make it difficult to assemble back.

Also, I think tightening it without cleaning out the leaking PLA could have damaged the thread further because the leak PLA when its cool and hard, is quite solid on its own. I would recommend warming the thermal break before opening or tightening so the PLA gets soft and pliable to work on.

What type of hotend are you using?

Try online like eBay, ali express, or from your reprap supplier?

I attached a non standard hotend to my 3D printer with a custom made 3D printed adapter. You should be able to find designs for x-carriage with other hotend profiles for kossel in Thingiverse.

UGPM

Yeah, since he is local supplier, you can bug him for problems...

Got competition already?

You can try but one of the design he sent is not an easy print.

More like floating platforms.

Is the cube a little shorter than before? I have not experience this issue before but to me it looks like your cube is a printed at a much higher temperature than before. It could also be caused by several factors like ambient heat from the hotend, the z-axis step calibration is out, or the x and y axis are wobbling.

What would happen if you print a thin wall or a thin wall cross.

Glad to know it was resolved easily. You should try printing at a lower temperature, say around 195, so you reduce your chances of clogging up your nozzle in the long run. If you know how to configure your slicer to print at different temperatures at certain time/layer height, then my recommendation is to print at high temp around 215 and bring it down slowly to 195 after the first layer. This way you get both good bed adhesion and non-melted looking prints.

Seems like a hardware issue, did your stepper motor skip a step or got stuck in that particular axis during the print?

I don't understand the part you said "lifting slightly of the ground"

I think this could be due to the hotend crashing into the print which causes the sound. I had a issue with a reprap 3d printer that kept crashing into the print and the whole layers just offsets in one axis. The crashing is caused by the flimsy frame of the printer when the printer shakes, there is a chance the frame flexes and the hotend hits a part of the print causing the crashing sound. I don't know how if this fact can be applied to your delta printer but you could try running the print at a slower speed or checking the frame for any loose joints.

Glad the print turn out ok for you. I would appreciate if you could post a comment or feedback in my lowyat sales page in my signature. Extra points for post with picture.

Do you mean you need an extra 100k NTC thermistor?

Since your concern is regarding the controller board then you should look out for the ramps 1.4 controller board since its a standard controller for most reprap out there. A lot of discussion and documentation on it. Fine printing depends on the stepper controller module, the stepper motor quality, GT2 timing belt, a good firmware, and the structural rigidity of the printer frame. Also experience in tweaking the printer for ultra fine prints is a must, you can't expect a 3D printer to work out of the box all the time.

My advice is if you want a reliable printer that can produce fine prints then I would recommend one in metal frame and not made with wood or acrylic. Also fine and sharp brass nozzle for the hotend will do well for fine prints.

You can try getting one of those makerbot clones from china. I wouldn't mind buying one if the frame is aluminium and use familiar reprap controller and firmware. Maybe you might want to replace the hotend and thermistor with a better one.