Help! My bottoms are melting

3D Fabrication
1

I’ve been coming to DMS for several months on Saturday. I am having a persistent problem with the bottom spreading as if it were melting. I showed Max the problem, he thought I might have the brim enabled. I don’t. I took a picture not sure how well it will show in the image, but her goes…

20191207_111500
20191207_1115001932×2576 1.49 MB

I used this filament…

https://www.amazon.com/gp/product/B00J0H8EWA/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

My cureent thought is maybe I can tweak the tool temperature and stop the melting. I may be wrong, but I am listening. Help?

2

The Z-axis is probably very squished on the first layer. This is called “elephant footing”. I think the Z-height needs adjustment on some of the printers.

2 Likes
3

I have seen that from too hot bed temps. The plastic stays soft too long, the top gets heavy and squishes it. Part cooling fan is working? Check bed temps for brand of material.

4

Max insists the z axis is correct, as my first thought is it needed tweaking. Since I can only be there on Saturdays Max is always busy either teaching or prepping for class. I have located the temp setting in KISSlicer, Since I can do nothing about the z axis, any specific recommendations? I could drop the tool temp and bed temp 5 degrees or so and see what happens?

5

If Z was too low then most likely the nozzle would simply block and cause filament chaffing on the first layer.
If the issue extends beyond the first layer then it is more likely either the bed temp is too high for the filament, or the nozzle temp is too high, leaving the extrusion in a state too much like liquid.
It is a little difficult to see from the picture though how many layers are affected.
Does the printer have a heated chamber? That could also be too high of a temp.

6

Most slicers have an option to add an offset to each axis. I sometimes use this to shift the Z axis up/down without actually tweaking the printer. Looks like it’s under the ‘printer’ tab in Kiss.

See page 38 here. Printing a single layer will help give you a good idea of whether the Z axis is set correctly or not.

1 Like
7

My current plan is to drop the temperatures slightly and see if it makes a difference. I will be at the space as usual for me this Saturday. Wish me luck.

8

I dropped the temp on the tool to 210C and saw a slight improvement adjusting the bed temperature was a disaster. The first layer prints at a different temperature than the rest of the print. I have created this small test print to test various settings. The plastic I bought is rated for 210C to 240C, The link put above shows this.

I could slice this par twith a temp profile of 240C/240C at start up, then drop the main temp by 10C increments, At the moment I am asking for more ideas.

Here is the test part packed in a .zip folder…

Test Text.zip (1022 Bytes)

I’ll post how it goes.

1 Like
9

So, I got up at 6AM (Sat. Dec 21) to be at the space at 9:30AM (actually I got there around 8:45AM, but DART time differs) and started running temperature profiles until noon. I finally found one I could live with. Here are the profiles I tried using on the test print.

KISS = KISSlicer for short. The following numbers are in C.
Main Tool temperature (the tool is the extruder), 1st Layer,Warmup, bed temperature
Tool Main temperature is the main temperature used for the majority of the print.
1st Layer - since this is the part that sticks to the bed, you want it a bit hotter than the rest of the print. after the 1st layer the tool temp drops to the main tool temperature.
Warmup = help the tool stabilizes faster. most temperature control systems over shoot a bit before stabilizing the tool. KISS assumes 10 degrees, but 5 degrees is a better number(determined by watching several temp profiles during warmup).
Bed = Self Explanatory.

KISS Defaults are 250,260.180,110
print bottom smooth, over melted (om for short).
2nd attempt 220,240,180,100
3. 220,240,180,100 om
4.210,210,180,110 om
5. 200,200,180,110 om
6.190,190,170, 100 Borderline test was legible on bottom
7. 180,180,165,180,100 Temp too low, plastic failed to extrude.
8. 210,190,180,100
9. 210,190,190,110
10. 210,230,200,110 * Final profile, Good enough is enemy of the best.

Personal conclusions: Hatchbox ABS is a good brand, but this plastic melts at a substantially lower temperature than average. I’ll use #10 profile until I have to buy a new roll. The thing of it is, finding the bracket where the plastic does and does not melt is key. I t will save me time next time I have to go through this. Each print took 9 minutes to print and 5 or so minutes for the teperature to stabilize. I made a minor error on the test print, but I will redraw it and put it here for other people to try.

P.S. I also figured how to remove the plastic from the tool using one hand. With the tool still hot press (dang memory) the opposite of extrude 3 times on Octoprint. The plastic will the pull out with out having to press down on the yellow release handle.

I used to design and build precision hotplates for my old job at Alcatel as a machine maintenance tech.

All in all a good day at DMS for me.

1 Like
10

Occasionally it’s the filament - I have a spool of hatchbox gray that won’t take a print no matter what I’ve tried - brims, rafts, bed temps - you name it… - the same files work fine on 3 other spools by the same manufacturer - just different colors. :frowning:

11

I suspect someone dropped the ball in quality control with this batch, as a woman living on SSI I won’t just throw this spool away.

I would do the experiments again if it came up. It was a learning experience.

12

And, here is the new and improved test print…Test Text.zip (5.4 KB)