Cheap 3D printer

Hello,

I've scavenged enough info off here in the last week I thought I should at least put a post up.

Having a background in engineering and now computers (and having been trained to use one of the early CNC's lathes 30 years ago) I decided I liked the idea of 3D printing as it might be useful and fun to play with.

So I brought the cheapest one I could find (until I know it is for me), one of these Amazon

It came nicely packaged.




Assembly was fun ,
The instructions have 'ZHUHAI CTC ELECTRONIC CO., LTD' on the top of them (that probably means more to you guys than me) and the board in it is a GT2560 (again no idea what that means but I needed to find out for the assembly below)

The instructions to cable the main board up were just wrong (searches on this forum pointed me to a diagram of the GT2560 Wiring thanks).
The bolts for the extruder bracket were too short (luckily I had a box full of random stuff with some that fit)
And the software won't install on my PC.

Anyway I got it built and found an updated version of the software it came with (cura) to get me started but I have no idea what to chose for the printer from the list so I chose Pursa first but that didn't work so well, too hot temperatures meant lots of blockages and the printed item was a lot bigger than it should have been, well the base was as that's as far as I got.
Next I chose 3D MakerStarter and managed to get the cube printed ... and it was the right size as well as being good enough quality for myself.

At this point I thought I was done bar tweaking and quite pleased with myself I decided to jump right in and try something bigger ... the Yoda head.

Not so good this time, the printer seems to go off part way through which I assume is to re-calibrate the table on the end stops. The only problem is it goes the wrong way on the x axis to the side without a stop. This causes the stepper to jump and it resumes printing in the wrong place.

Printers gone wild video ... ok just one that is a little bit off on the stepper

If anyone has any info on this model (I don't even know what it is called ,so I can't chose a printer from the programs), or has a starter guide that would be good.

I'm still trying to work out how to use it but thought a numpties write up might help someone else with one. I just tried to run up slic3r and the first question is 'pick your machine from the list below' lol. errrrrmmm ... Time for some more googling I think (so glad they don't charge for that )

Well, you have a Prusa I3 for starters. But that isnt saying much as there is so many variants of the pusa that that doesnt tell the slicer much of anything. X skipped steps could be caused and therefore solved many different ways.
1. Too high jerk/acceleration (probably not the cause, but easiest to test, just run it slower and if needed reflash the firmware)
2. Belt too loose. (self explanatory)
3. Too low voltage (increase voltage on the stepper driver by turning the pot)

Thats all that comes to mind, oh and do you know if you have microsepping enabled? A lot of build guides skip the step showing you how to do it and it improves print quality so much. What material are you printing? usually 190c to 210c for PLA and 220c ish for ABS (just noticed the roll is clearly labeled PLA).

---

If you need some help, or don't understand what I just said, feel free to send me a PM anytime

Printer: Prusa i3, 2 E3D v6 Hotends, Arduino + RAMPS 1.4 with a Bypassed 5V Regulator, 400w Insignia ATX PSU, Custom Designed Bowden Extruders

Thanks, the Prusa i3 is good to know. I guess the firmware in it is what I need to find out next (so I can select the correct printer name).

I don't think it is skipping steps. At 15 minutes into the print in the video it suddenly went full right on the machine but that side doesn't have a stop switch. This meant it run out of space and either the belt or servo skipped. When it moved back in to the center to continue it was off by 5-10 mm on the x-axis. I think I need to look at the why it did this in the first place (do prints occasionally go to the stops to check positioning?) and also to check if there is a setting saying it has a stop that side.
Until I figure it out I don't want to print again as something like that could break the belt/servo I guess, currently I'm thinking it is the printer option I selected in cura.

I will try slicer and see if I can find a printer that works with my machine

The 20mm square came out great (by great I mean it was square and the correct size, and the printer didn't do anything unexpected). I had to change the settings as at first the machine was using 250 and just jamming the extruder through the heat, once reduced it printed much better.

So, I thought you meant it gradually got closer to the X+ side, which would mean skipping steps/skipping of the belt. I have no idea why cura would suddenly go to X max most of the way through a print. But would definitely try a different slicer

---

If you need some help, or don't understand what I just said, feel free to send me a PM anytime

Printer: Prusa i3, 2 E3D v6 Hotends, Arduino + RAMPS 1.4 with a Bypassed 5V Regulator, 400w Insignia ATX PSU, Custom Designed Bowden Extruders

No problem. You can see what it is happening in the first link (I video'd what it was doing).

I tried printrun and played around with moving the axis. If I try to move it manually the z axis stops at 100mm and the x/y axis will go to the limits of travel without stopping. I assume this means the firmware needs some changes in it as the soft stops are set wrong.

Now I just have to figure out how to update it without wiping everything out lol. I'll need to figure out how to read the firmware off to see if I can update it.

If your using PLA a good starting point is 180c on extruder and 70c and if ABS than 230c and 110c. Cura has never been good to me so I use SLIC3R. If you use Repetier than you can reverse direction of the steppers. Also stay low on print speeds to start. 40mm/sec is slow enough for good quality but not to slow. Higher speeds come later once you know your machine. My plexiglass printer instructions had the endstops in the wrong position. Y endstop showed at front when it needed to be at the back. I just reset my stepper voltages to .68 from .55 and completely cleaned up rough and unpredictable surface bulges and ridges. My board is a Melzi and the procedure is simple. Turn off power, unplug USB cable, switch jumper position to USB, plug in USB cable, led comes on, touch meter black to (power in) ground and red lead to pot adjuster screw. Factory default seems to be .5 volts. It is suggested not to exceed .7 volts. Many lessons to come. That's the fun of a cheap printer. As you can see I've redrawn and reprinted every part on mine accept the chassis. Good luck.

Thanks, I'll try those settings and give SLIC3R a go to see how that prints.

I just tried the extrude 100mm in Repetier and got a bit pile of PLA lol. I have no idea if this is a setting in Repetier or the firmware, but given the cube I produced from cura was ok I think it must be in Repetier.

Still trying to work out which printer to select so that was probably the issue. Using prusia i3 doesn't seem to work very well for this machine even though the log shows it being a 'I3 Pro B' with 'Marlin' firmware.

10:09:59.459 : start
10:09:59.459 : echo:Marlin1.0.0
10:09:59.459 : echo: Last Updated: Jan  4 2016 19:03:56 | Author: (John, default config)
10:09:59.459 : Compiled: Jan  4 2016
10:09:59.459 : echo: Free Memory: 3795  PlannerBufferBytes: 1232
10:09:59.459 : echo:Hardcoded Default Settings Loaded
10:09:59.459 : echo: Steps per unit:
10:09:59.459 : echo:  M92 X78.74 Y78.74 Z2560.00 E105.00
10:09:59.459 : echo:Maximum feedrates (mm/s):
10:09:59.459 : echo:  M203 X400.00 Y400.00 Z2.00 E45.00
10:09:59.459 : echo:Maximum Acceleration (mm/s2):
10:09:59.459 : echo:  M201 X1400 Y1400 Z100 E80000
10:09:59.459 : echo:Acceleration: S=acceleration, T=retract acceleration
10:09:59.459 : echo:  M204 S1400.00 T5000.00
10:09:59.459 : echo:Advanced variables: S=Min feedrate (mm/s), T=Min travel feedrate (mm/s), B=minimum segment time (ms), X=maximum XY jerk (mm/s),  Z=maximum Z jerk (mm/s),  E=maximum E jerk (mm/s)
10:09:59.459 : echo:  M205 S0.00 T0.00 B20000 X13.50 Z0.30 E5.00
10:09:59.459 : echo:Home offset (mm):
10:09:59.459 : echo:  M206 X0.00 Y0.00 Z0.00
10:09:59.459 : echo: PID settings:
10:09:59.459 : echo:   M301 P19.86 I1.00 D98.93
10:10:02.586 : N1 M110 *2
10:10:02.586 : N1 M110 *2
10:10:02.586 : N2 M115 *4
10:10:02.586 : N3 M111 S6 *68
10:10:02.586 : N4 M111 S6 *67
10:10:02.606 : N5 M80 *62
10:10:02.616 : N6 M80 *61
10:10:02.616 : N7 M105 *0
10:10:02.869 : echo: SD init fail
10:10:02.919 : FIRMWARE_NAME:Marlin V1; Sprinter/grbl mashup for gen6 FIRMWARE_URL:[firmware.ultimaker.com] PROTOCOL_VERSION:1.0 MACHINE_TYPE:I3 Pro B  EXTRUDER_COUNT:1 UUID:00000000-0000-0000-0000-000000000000
10:10:02.929 : N8 M220 S100 *73
10:10:02.929 : N9 M221 S100 *73

I tried a print using slic3r . I took the yoda head and set up the best parameters I could guess for the printer.

While printing from SD card I had the log running and once again saw the bed run off to the edge. The log shows some weird stuff so I think something isn't right somewhere.

The first error (84 E24.78460) I found in the gcode in only one place and that looks good.

So it seems the gcode is ok and these errors are coming from somewhere else, Interferance or loose connection maybe. This might take a while to figure out

Gcode

G1 X79.401 Y83.204 E24.53371
G1 X80.400 Y81.954 E24.72376
G1 X80.755 Y81.584 E24.78460
G1 X81.019 Y81.349 E24.82659
G1 X81.266 Y81.188 E24.86160
G1 X81.766 Y80.945 E24.92768

Log

10:43:04.779 : echo:enqueing "M23 yoda~1.gco"
10:43:04.789 : echo:enqueing "M24"
10:43:04.789 : echo:Now fresh file: yoda~1.gco
10:43:04.789 : File opened: yoda~1.gco Size: 13449303
10:43:04.789 : File selected
10:43:07.011 : N659 M105 *13
10:43:10.080 : N660 M105 *7
10:43:13.125 : N661 M105 *6
10:43:16.191 : N662 M105 *5
10:43:19.255 : N663 M105 *4
10:43:22.319 : N664 M105 *3
10:43:25.371 : N665 M105 *2
10:43:28.423 : N666 M105 *1
10:43:31.469 : N667 M105 *0
10:44:58.783 : N668 M105 *15
10:45:00.155 : N669 M105 *14
10:45:03.210 : N670 M105 *6
10:45:06.270 : N671 M105 *7
10:45:09.323 : N672 M105 *4
10:45:12.382 : N673 M105 *5
10:45:15.443 : N674 M105 *2
10:45:18.496 : N675 M105 *3
10:47:01.746 : N676 M105 *0
10:47:02.447 : N677 M105 *1
10:47:05.504 : N678 M105 *14
10:47:08.569 : N679 M105 *15
10:47:11.621 : N680 M105 *9
10:47:14.680 : N681 M105 *8
10:47:17.751 : N682 M105 *11
10:47:20.793 : N683 M105 *10
10:47:23.861 : N684 M105 *13
10:47:26.914 : N685 M105 *12
10:47:29.967 : N686 M105 *15
10:47:33.023 : N687 M105 *14
10:47:36.082 : N688 M105 *1
10:47:39.136 : N689 M105 *0
10:47:42.195 : N690 M105 *8
10:47:45.265 : N691 M105 *9
10:47:48.312 : N692 M105 *10
10:47:51.368 : N693 M105 *11
10:47:54.441 : N694 M105 *12
10:47:57.489 : N695 M105 *13
10:48:00.546 : N696 M105 *14
10:48:03.598 : N697 M105 *15
10:48:06.659 : N698 M105 *0
10:48:09.719 : N699 M105 *1
10:48:12.777 : N700 M105 *0
10:48:15.831 : N701 M105 *1
10:48:18.889 : N702 M105 *2
10:48:21.942 : N703 M105 *3
10:48:25.000 : N704 M105 *4
10:48:27.620 : echo:Unknown command: "84 E24.78460"
10:48:28.060 : N705 M105 *5
10:48:31.119 : N706 M105 *6
10:48:34.180 : N707 M105 *7
10:48:37.230 : N708 M105 *8
10:48:40.290 : N709 M105 *9
10:48:43.350 : N710 M105 *1
10:48:46.405 : N711 M105 *0
10:48:49.460 : N712 M105 *3
10:48:52.521 : N713 M105 *2
10:48:55.583 : N714 M105 *5
10:48:56.113 : echo:Unknown command: "???????????????????????????????????????????????????????????????????????????????????????????????"
10:48:56.113 : echo:Unknown command: "???????????????????????????????????????????????????????????????????????????????????????????????"
10:48:56.113 : echo:Unknown command: "???????????????????????????????????????????????????????????????????????????????????????????????"
10:48:56.113 : echo:Unknown command: "???????????????????????6.646 E51.69563"
10:48:58.634 : N715 M105 *4
10:49:01.707 : N716 M105 *7
10:49:04.767 : N717 M105 *6
10:49:07.821 : N718 M105 *9
10:49:10.884 : N719 M105 *8
10:49:13.927 : N720 M105 *2
10:49:16.996 : N721 M105 *3
10:49:20.049 : N722 M105 *0
10:49:23.102 : N723 M105 *1
10:49:26.158 : N724 M105 *6
10:49:29.210 : N725 M105 *7
10:49:32.273 : N726 M105 *4
10:49:35.326 : N727 M105 *5
10:49:38.407 : N728 M105 *10
10:49:38.790 : echo:Unknown command: " Y111.164 E65.17906"
10:49:41.447 : N729 M105 *11
10:49:44.060 : echo:enqueing "M84 X Y Z E"
10:49:44.500 : N730 M105 *3
10:49:47.556 : N731 M105 *2
10:49:50.628 : N732 M105 *1
10:49:53.674 : N733 M105 *0
10:49:56.729 : N734 M105 *7
10:49:59.792 : N735 M105 *6
10:50:02.848 : N736 M105 *5
10:50:05.906 : N737 M105 *4
10:50:08.966 : N738 M105 *11
10:50:12.018 : N739 M105 *10
10:50:15.076 : N740 M105 *4
10:50:18.147 : N741 M105 *5
10:50:21.196 : N742 M105 *6
10:50:24.253 : N743 M105 *7
10:50:27.306 : N744 M105 *0
10:50:30.367 : N745 M105 *1
10:50:33.426 : N746 M105 *2
10:50:36.478 : N747 M105 *3
10:50:39.536 : N748 M105 *12

Looks like serial interference, causing communication disruption

Use high quality short usb cables preferably shielded ones.

Also maybe lower the baud rate if your using 250000 (some computer really don’t like that baud rate)

I thought that as well, until I realised the printer did unusual things at the same time (kind of rules out printer to serial connection issues)

I can try downgrading the speed to see but I'm not completely sure how to do that, does that need flashing of the firmware?

Just a quick update to say that printing direct from Repetier for a couple of hours now (9 hours estimate for yoda head, I think I may have to look at the settings or is that about right :O) and so far no random movements.

So it looks like it doesn't like printing from the SD card.

On another note I am gradually turning down the nozzle and bed temps during the print. It seems that 190 was a bit high (print seemed to be extending upwards into nozzle). I reduced it down 5 deg every few layers until at 170 it showed signs of being too low (incomplete extrusion) so i will leave it at 180 for the rest of the print. Just hope the couple of bad layers don't otherwise ruin it.

I notice this cheap printer has 2 Z motors fully supported threaded rods(constrained) and a timing belt between them, I'm wondering if some of the issues are with that arrangement?

ooops thats the pic from what elwood posted...

Edited 2 time(s). Last edit at 09/25/2016 07:32PM by MechaBits.

Interesting observation, I noticed that difference as well. Later on (once I'm past the get it working smoothly stage) I was going to ask if that was a better setup and a possibly improvement (less change of going out of balance I'm guessing

I did notice an interesting thing happen. I turned on the desk lamp to check how the print was going (one of those halogen thingies) and the printing stopped and wouldn't start again

Luckily I could see where it got to so I modified the gcode file to start where it left off. Took a few attempts (one which sent the print head down into the print) and I seem to have recovered it. Learning something all the time .

Have a look at his UK Youtuber who has one of these CTC printers (his vidoes are called "ebay printer"), you may get some tips on improvements. StevenQ-NE-UK Videos

I found one of his videos already but going through the rest now.

There are quite a few on there on this type of model, I guess the seller of these watches them as the firmware he upgraded to in the video appears to be the same as in mine (as it came).
I like the bed mods he did (I will probably do them on mine eventually as well).

So far I have managed a few parts (when I've had time to play with it). I'm now waiting to see if the random movements are cured by not using my desk lamp

Still got random offset issues. I tried printing the fan duct for the third time. The first one is a bit small, the second one had a blockage part way though and missed a few layers and then this one had the random feed issue.

Part way though the bed moved to full forward (away from the stop switch) and back again once it detected issues with the steppers jumping. This left it offset so the rest of the print was out of line.
Bad thing is this time I didn't have the lamp on so it looks like that isn't causing the issue
I managed to cut off the right hand part and glue it back on so it is usable but not ideally what I was looking for.

Any other ideas what could cause this, it isn't always in the same direction. When it goes x or y to the stops it handles it as it doesn't end up offset. Occasionally it seems to pause in place as well. The Z axis hasn't randomly moved yet.

Looking at the errors they are all incomplete instructions.
I can't offer help but perhaps someone who knows more on the communication side can help.
Whether this is interference in the comms, a buffer size mismatch, comms speed (SD card speed) issue.
If its loosing part of the commands you may get one where it misses a decimal and you end up with a travel over 10 times larger than required.

As its the same with SD and Repetier I guess its at the printer end. Or do you print from SD with a computer attached?
Some of the boards have jumpers to define if you run on the 12v power or from the USB port power. The recommendation is to set this to 12v or anything that drops the USB voltage can cause issues. That includes sleep mode on the PC or could be other peripherals using USB on the PC.

Thanks for the reply, some good things to consider there (I never new about the 12v jumper).

I've moved some cables etc round as I think interference might be the issue.

The instructions don't show routing information for the cables so I routed them as neat as possible (ignoring bleed over).

The power and LCD cables were routed together (as well as some other cables in other areas). I have moved as many of the cables away from each other (looks a bit of a mess but functional for now) and have completed two prints without any random movements.

I've been printing from the SD card in the LCD display for now to reduce the number of items to debug in one go.

I also moved the LCD cable away from a stepper motor as that could also have been an issue.

So far so good. If I get a third print with no issues I will rerun the wires properly (aka neatly) and hopefully can start to look at improving the print quality (lots of settings to work out what they are and then tweak).

The second print (after moving cables) came out with no random movements (plenty to work with in tuning). There does seem to be a bulge in the top part which could be down to printing at 200Deg on the extruder, a lower temp may also improve surface finish.
It is a rivet pusher (a nice simple design for the learning the printing process), it goes over rivet head to make it easier to push into if it is a tight fit. The first one worked well until I tried tapping it in with a hammer lol. rivet 1, pusher 0.




Mods so far.
New top mounts removing threaded rod hole
Extruder fan duct

Edited 1 time(s). Last edit at 10/03/2016 05:06PM by plastic_splodge.

Though I should add an update (for anyone else getting one of these).

Moving the cables seems to have fixed the random movement issues so it looks like it was bleedover between the cables (or a lose cable that is now fixed by moving it).

I have managed several prints without an issue.

I have replaced the z-axis threaded rods as the originals were bent and binding half way up (meaning only half height prints could be attempted). The new rods and couplers are better but I need to spend some time to get them fully lined up but at least I can do fully height printing.

I do have another issue now though. It seems as soon as I put even the slightest tension on the x axis belt I get a grinding noise. It looks like the belt is fouling/rubbing on the carriage. If I leave the belt lose I get better surface finish but corners show artefacts, if I tighten them I get ridges on the surface, lots of noise but squarer corners.

I still have to figure out how to fix this. Maybe time to upgrade the x-carriage (it has a little play in the slider/rod connection so these will be replaced at some point anyway). Just need to find a replacement carriage model to print (not found it yet on www.thingiverse.com or change to a new layout )

The binding point is shown below.


If anyone knows where I can get the stl file for that carriage I'd be very grateful, if a CAD file is available that would be better (so I can change it to get more clearance rather than try to modify a printed part). The files that come with the printer don't seem to match what is fitted.

Quote
plastic_splodge
Still got random offset issues. I tried printing the fan duct for the third time. The first one is a bit small, the second one had a blockage part way though and missed a few layers and then this one had the random feed issue.

ss_zpswpfurgsm.jpg

Part way though the bed moved to full forward (away from the stop switch) and back again once it detected issues with the steppers jumping. This left it offset so the rest of the print was out of line.
Bad thing is this time I didn't have the lamp on so it looks like that isn't causing the issue
I managed to cut off the right hand part and glue it back on so it is usable but not ideally what I was looking for.

Any other ideas what could cause this, it isn't always in the same direction. When it goes x or y to the stops it handles it as it doesn't end up offset. Occasionally it seems to pause in place as well. The Z axis hasn't randomly moved yet.

The stepper motor drivers have a little current limiter adjuster so that they don't send too much current to your stepper motors.

If they are set too low, you will skip steps.

Quite a good how to here on adjusting them... but first google your stepper motor model number and "specification", to find out how many amps it can take.

[matterhackers.dozuki.com]

As for the STL file, no, can't help. There are scads of i3 compatible print carriage STLs out there... I honestly don't know which ones work best. Plus, the one you are looking for might have been tweaked in China and was never released as open source.

I figured out what the skipping was (it wasn't really skipping just running to the end of the axis occasionally and then jumping the belt), It looks like it was lose connection or crossover between cables as after moving them apart I haven't had the issue again.

I suspect you might be right with the carriage being a modified part. I guess I will need to look for different one to print out if I can find something that looks right.