bottom layer looks terrible

kissfan4 · 2015-12-07T00:43:44.000Z

How do I get the bottom layer to print like the top? The bottom layer makes my parts look like crap.

1449448989252-2017397811.jpg2988×5312 4.11 MB

1449448939515839061182.jpg2988×5312 4.56 MB

MB3D · 2015-12-07T04:05:30.000Z

It looks like your printbed is way too far away from the nozzle when printing the first layer, try to adjust it! Also don’t use a raft, just a brim if needed at all. You can also play around with the extrusion multiplier for the first layer. Play around with those variables to find the best settings for your printer. Cheers, Marius Breuer

kissfan4 · 2015-12-07T13:02:42.000Z

thats what doesnt make sense, i adjust my printbed with a sheet of paper like i always have, i print a test cube of either 5mm-10mm, and it is either dead on, or very close, say 4.95mm cubed. This was printed without a raft, and just using a brim with 0 distance from the object. How do i adjust the setting for just the 1st layer? I am using slic3r.

JMBishop · 2015-12-08T01:12:59.000Z

I had a similar problem with slic3r, my solution was to use a older version of Cura.

kissfan4 · 2015-12-08T14:40:15.000Z

ok, so after playing around with layer height, and extrusion settings, i got it to look much better, but now i have shifted layers, these shift gradually to the rear of the printer on the y axis, for a few layers, then begins printing in the correct fashion.

layer shift.jpeg1440×2560 341 KB

Christian_Habib · 2015-12-10T19:55:08.000Z

Hello, I think the distance between the extruder and the plate is too big for your first layer.

Check the documentation of your printer to adjust the 0 level of the Z Axis.

cH4rF1r3 · 2015-12-12T02:37:39.000Z

Shifted layers, means a few things,

1. Either your belt tension is too tight/too slack, hence causing the y axis to skip steps.

2. Your rods are not sufficiently greased.

3. Your y axis stepper motor has overheated, or your stepper drive chip has overheated, you have to ventilate it.

4. Your filament feeding is being hindered, has too much tension hence pulling the print head backwards along the y axis, or your spool was hindered momentarily by some avoidable circumstances.

To be honest, you have to check which direction it shifted in before you take off the print from the bed, and then analyze what could have cause the layer shift. I have had quite a bit of troubleshooting to do when I encountered layer shiftings.

kissfan4 · 2015-12-14T04:08:17.000Z

The layer shift is occurring on the y axis, I have lubed the rods, ensured the filament was not binding, I marked the belt and pulley to see if the belt is jumping teeth on the pulley, and it is not. The only other thing is a flakey connection at the motor, but not sure how to diagnose that one. Any suggestions?

cH4rF1r3 · 2015-12-14T12:41:51.000Z

Yes, there is a flakey connection, but wait, it’s not your motor, but your limit switch, the y axis limit switch. I have experienced that when limit switches cables are flexed too much during printing, eventually the copper wires within the cables will break bit by bit, and it will get to the point where your y axis limit switch will give false signals to the printer, OR it is caused by the rubbing when the wire touches another surface repeatedly, OR the inner pin connector from the connector head has lost it proper seating or the wire has desoldered from the pin connector due to the repeated flexing/movement/strain.

The best way to check for this is to connect your computer using Repetier Host, and then use manual control to move the bed y axis from one end to the other end, first to see whether it is working properly.

You can next, try to forcefully replicate the false signal, by using your hand to move the cables which are near the connection of your y axis limit switch. When you have successfully caused a false signal, you will get this in Repetier’s log, “echo:endstops hit: Y” or something. If you see this in the log, good news, you found the problem, bad news you have to either change the whole limit switch, OR you have to desolder and resolder a new set of cables for the y-axis limit switch, OR you have to check which pin connector is the culprit and change it yourself, with crimping tools and such.

After the repairs, do look to how you can prevent this from happening in the future, like keeping the wiring out of the way, or do something to prevent much flexing to the limit switch cables.

Ok summary, It is either your limit switch that is faulty, or the connector is faulty, or the wire is semi-broken. I would assume that it is the connector that is faulty, the pin, that has lost proper seating/contact with the cable head. It could be just one of them, if you can get your hands on some pin connectors, you could replace all 3 pin connectors that go into the connector head that goes into your limit switch end stop board connector header.

If your sure that it is the pin connector that is improperly seated, you can use a small flat head screwdriver to push it back in, and then find some way to tape the cable to something, so that the pin connector does not get pull out accidently again*

kissfan4 · 2015-12-14T13:09:31.000Z

i am pretty sure you are correct, because starting last night, when i would home all axis, occasionally the y axis would go to the home position, but would not stop, i used my ohm meter to check the limit switch and it was working, but now i know to focus more on this switch. thank you

cH4rF1r3 · 2015-12-14T13:23:33.000Z

No problemo =) Glad I could help, although you were pretty much there already =d

kissfan4 · 2015-12-16T02:43:40.000Z

So I replaced the limit switch, it was bad. When I put the new one in I routed the wire in a way to limit the strain on it, but the first print I tried had shifted layers again. I am at a loss, guess my next step is get a pair of snap ring pliers, and pull the y axis linear bearing and try greasing them up. I might order some new ones, since these are the cheap Chinese ones that came with this kit. Other than that I don’t know what to do.

Kestrel038 · 2016-02-01T08:50:47.000Z

Check your retract settings. If there is a slight curling at the edges of your print (more prominent when printing overhangs without support), then your nozzle may be catching on a cooled lip whilst travelling across to print a new area. I found that increasing the z travel on retractions to around 0.5 mm rather than 0.2, this stopped happening. (This is assuming you didn’t change your acceleration or travel feed rates of course).

When your bottom layers were freeflow, your wouldn’t have had any tiny areas of over extrusion etc. so there would have been less to catch the nozzle on.