Hi folks, Velleman K8200 user here, got a short question.

3D Printing
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1

Hi folks, Velleman K8200 user here, got a short question.

I’ve gone through a short calibration process by printing a thin walled part, measuring its thickness and adjusting the filament output accordingly. I’m now at 80% output (which to me appears pretty low). With this setting the wall thickness matches its virtual counterpart, 1mm in the CAD program is pretty much exactly 1mm (+/- one tenth of a mm which is acceptable) in real life after printing.

However, the quality of the surface and the infill of the printed object degrades a lot from going down with the filament output. When I go up with the output I gain surface quality at cost of dimensional accuracy.

Any idea on what settings might be wrong, might be causing this?

Cheers!

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2

That looks like an accurate, but gooey mess. What temperature are you running?

Also, if you have to reduce your output that much, something’s not right. Have you calibrated your extrusion rate too?

3

±0.1 mm per mm is still a 10% error. You can tune that better printing solid blocks and seeing if the part is overstuffed or has gaps. How did you calibrate your extruder steps per mm?

Is that ABS? It looks like it’s extruding very hot.

Also, I see some missed steps in both X and Y. Either too little current on the stepper driver for your acceleration, or temporary thermal shutdown due to too much current.

4

I’m so sorry you bought that printer. An x-y build platform is absolutely outdated and poorly engineered.
But I’m sure you can get it running. To me, it looks like your extrusion temperature is way too hot. Start by bringing it down at least 10 degrees.
80% is definitely too low. You need to check your extrusion feed by extruding 100mm and measuring it to see if it actually moved 100mm. Next, get a good micrometer. Calipers dont do as well
Measure multiple points along the filament and average them, use that in your slicing software. Then you do the single wall calibration.

5

Hey, easy on the noob! The machine looks perfectly capable, other than the inherent speed limitations of the moving platform.

6

Alright, it’s the temperature. The thermistor of the hotend isn’t where it’s supposed to be. It’s next to the hole, not inside, and so I’ve got an offset of about 30°C between actual and measured temperature. I mean, when I set the temp to 190°C I actually print with 220°C which is… well… too high.

I’ll try to move the thermistor into the hole again and hope that it won’t break… fingers crossed.

Thanks for the advice! Wouldn’t have thought that… and hence haven’t paid attention to this tiny little b…

7

Okay, first test-print looks much better.

To answer your questions: filament is PLA, I print at 190°C which is default for the K8200 (which, considering its price, is awesome, just needs some tuning). The lost steps are likely caused by too high acceleration and/or too low motor current. I’ll see if I can tune it up a little bit.

I see the K8200 as a hobby. If I just wanted to print I could have waited a little longer and put some more money aside to buy a Replicator or something. But I wanted to go through all this hassle because of the experience that comes with it. I don’t regret buying the K8200 so far.

Maybe, who knows, I’ll buy a ready made printer like a Replicator or an Ultimaker in the future… I probably will. But until then I’m satisfied with what the K8200 is able to do and what I learn from tinkering around with it.

8

Heh. Once You know your way around a printer, you may not be satisfied with a ready made one. Anyhow, Makerbot is not well loved around here. Their printers aren’t liked much either. I don’t have any experience with them, just ask around if the time ever comes.

9

Yeah, maybe. It’s just, we’ve got a Mojo at the university. I’ve had the privilege to use it for my bachelor thesis and I’m really surprised of what quality a middle class FFF printer can achieve. But that thing costs about as much as a small car and a kilogram of filament for it is about ten to twenty times as expensive as that for my K8200. Still, I’m hoping to achieve a quality that is at least close to that of a Mojo. Or at least one of those ready made printers.

So, while, like you said, Makerbot isn’t liked much around here, how about Ultimaker? Same story?

10

Ultimaker is well liked, both the printers and the business practices.

Any of these printers can match the print quality of expensive commercial printers, with the exception of the quality of slicing software. However, what’s available in the community is rapidly approaching the proprietary slicers, especially as regards things like peelable support. In some cases, the quality of commercial machines has been surpassed. Mainly that was accomplished by the amount of control we have over the machines.

11

So, I’m sure that you can calibrate the printer for good prints, but speed and acceleration will be limited due to the high mass of the platform. The good news is that you’re printer is made of materials that likely won’t break. From there, you can build or design a new 3d printer, by printing out your own parts.

12

Yeah, I’ve been thinking of converting it into a printer with a z-axis print bed and x-y-axis extruder. Should be possible.

13

Have you been following the Ingentis Builders Community here on G+?

14

Umh, no… not yet. What’s it about? … //edit… ah the Ingentis printer. I see. Thanks for the advice! I’ll have a look at it.

15

Awesome! Looks definitely like an alternative to my Velleman. Now that I have a printer at hand, building another one shouldn’t be that difficult. Well, that is aside from some unprintable parts that I still would have to buy… still, awesome!

16

Ingentis FTW :wink:

I have a mendel, bed is Y, printhead is X-Z…

THIS model of printer REALLY highlights the bed problem… for instance, if I infill at 0 / 90 degrees, you can turn the X infill up, like 200% speed of the Y infill, because the Y moves the bed in one direction and then has to reverse the direction of that large mass, which has much more inertia than the x carriage! Even when there is no lost steps / slipping belt, high speeds are only ‘attainable’ at the cost of quality, the frame is not super-sturdy and moving the bed quick will cause vibrations and reduce the surface quality of the part.

I’m glad I bought a “poorly engineered” printer myself, it highlights what you should look for in your next printer, and gives you inspiration to take your time, study systems and choose wisely! (but at the same time you’re still able to print!

My hot end is also a ‘bit iffy’… and I find I extrude PLA between 160-200(MAX) or it is far too hot… Every time I read tips I see ‘start at 205, go up or down if necessary’, never works if I try it.

Don’t be discouraged, be encouraged, as you say, you now have to be even more careful with your choice of settings and finding a ‘sweet spot’ of feedrate, temperature etc. You will have much more understanding if you eventually move to a ‘better engineered’ printer and should be able to tune it beyond average because you have the knowledge from your previous printer :wink:

Should follow the Ingentis builders community if a new printer is of interest… The thing is already excellent, borrows from some of the best engineered designs in open source, is cheap, large, fast and fairly simple. As advanced as it is, it is also very young! With many innovations and new designs being made almost daily.

17

I’ll probably build an ingentis or clone akin to what @ThantiK is attempting, with the switch to belts.