First layer question
-
@zapta said in First layer question:
Some thoughts that come to mind:
- Do you run automatic bed leveling? It helps maintaining consistent distance from the bed.
My bed leveling routine takes about 3 hours so it only gets run once in a blue moon. The resulting mesh bed map is loaded for every print.
- Isn't 230c too low for petg? I print 255c first layer and 245c for the rest of the layers. Whatever 255C and 245C mean on my printer.
It might be a little low but keep in mind that temperatures aren't absolute - they are relative to each other when you a measuring with the same setup. As you realize, 230 on my printer might be 250 on your printer.
- Slowing down will definitely help.
I just removed my latest print (with 20 mm/sec for the first layer) - it did not help
Having said that, I will go back to the standard 50% speed (25 mm/sec in this case instead of 40 mm/sec) as my default.- Is the defect always at the same location on the bed? Is the bed clean?
With PEI, once in a while I scuff it with wet 1000 grit sandpaper for better adhesion. I don't know if this is applicable for glass.
Sometimes the spot is at the same place, sometimes it is not. The print just finished had two spots at different locations.
I tried glass cleaning - sometimes it makes a difference ... but only if the glass really needed cleaning. I still get the spots with clean glass but yes, I can have more spots with glass that needs cleaning.I will run some tests with printing the same model at the same spot to verify that the spot is really moving ... just in case I don't remember things right.
- You may want to set your slicer to pause after the first layer. This way you can inspect it and cancel the print if it's defective.
That is one of my go-to things I do (watching the first layer) but it gets frustrating when you do the same first layer three times before you get a clean first print. I would really like to be able to press the 'go' button and come back to a properly finished print a few hours later.
-
Also print a temp tower and see what it wants to be printed at, as 230c (or whatever you consider that number to equate to) is considered at the very low end of the range for petg.
If bed levelling takes so long it seems one of two things: a very bad design or a bad setup.
Levelling with x3 motors takes less than 30 seconds to complete.
And this is FDM it is not yet fully at the point of press print and wait for the part to be spat out
-
The second cover plate I printed with a slow speed first layer came out perfect. It remains to be seen if this was a one-off or if the percentage of good prints is increased by a slower layer. Gut level feeling says that this will improve my prints.
I will keep printing with a slower first layer for a while and see what develops
I will not change any of the other parameters talked about until it becomes clear if changing the first layer speed gives a noticeable improvement (I just love intermittent problems - grrrrr) -
Hi,
I understand that you want a smooth build surface but I thought I would briefly mention what I went through.
I started with glass, had problems, added a build surface which worked fine but it had a texture.
Anyway, long story short, I am now using the BuildTak system and couldn't be happier.
I like being able to remove the build surface, since it is attached to the flexible plate, wave it around to cool it if desired and flex as needed to remove the print.
No longer do I have to wait for the 6mm metal bed with glass plate attached to cool before removing prints.
They have different build surfaces, one of which I think is smooth.
Frederick
-
For a time I tried different surfaces. I tried glue and I tried PEI. The PEI ended up curling at higher temperature despite being glued to the glass plate, the glue was worse than plain glass. The secret to glass (IMHO) is getting the bed temperature just right. I do need to 'preheat' the glass by making the initial temperature higher that my print temperature and dropping it just before the print (or giving a lengthy heatup period). This ensures that the glass surface temperature is warm enough.
It is annoying that the cool down takes as long as it does but I have been screwing around with print surfaces long enough that I can accept the cool down period when everything else seems to work just fine.
It would be nice to try a removable print surface but to be honest, I don't trust it to lie flat enough short of having a vacuum table. There is also the issue of the build surface being 500*500 ....
If I loose the surface of a glass plate due to getting my temperatures too high, I can turn the glass plate over and have another go but build tack is a one shot deal. There is also the question of killing the magnets by running too hot a bed.
To sum it up, I am pretty 'fiddled out' and am more into just pressing the button and let it do it's thing (a la toaster). I could be tempted to try BuildTak if there was more of an up side then just avoiding the cool-down. -
The oil in your fingerprints is an excellent barrier to bed adhesion.
A spot like that, I would expect it to be a contaminant like a fingerprint.
And be very careful with PET and glass. Get the temp too high and you will weld the PET to the glass. Like, ripping chunks out of the surface of the glass kind of welded.
Getting a perfect first layer is really hard to get consistent.
-
@theruttmeister said in First layer question:
The oil in your fingerprints is an excellent barrier to bed adhesion.
A spot like that, I would expect it to be a contaminant like a fingerprint.
Yes, a spot like that 'could' be a contaminant but in this case it was not. See my comment above about cleaning the glass plate. Also, note that two prints done on the identical spot on the build plate showed problems on one print and none on the second print.
And be very careful with PET and glass. Get the temp too high and you will weld the PET to the glass. Like, ripping chunks out of the surface of the glass kind of welded.
Been there, done that, current build surface has a big chunk missing (now on the underside)
Getting a perfect first layer is really hard to get consistent.
Yep ....
-
What are you using to clean the glass?
-
Bon Ami - works really well!
-
Another update - I have now printed three cover plates, the first one had some issues but the next two were perfect - I am very optimistic about the speed change.
Temperature was brought up as a potential issue for PETG. I dug out the details - Nozzle: 200 - 240 C, bed 75 - 85 C .... so I am right where I should be.
Thanks again to all that offered their input! To be honest, I could have stared at the settings til the cows come home and not seen that I had set it for higher than the recommended speed. I had been printing at that speed for quite some time. It's great to be able to bounce these kinds of things off the people in this forum because although it might stick out like a sore thumb to everybody else, sometimes it's difficult for the one staring at the problem to see the trees for the forest!
-
@jens55 said in First layer question:
It would be nice to try a removable print surface but to be honest, I don't trust it to lie flat enough...
I have a 300 x 300 bed and it is more than flat enough. Not sure what you would need for 500 x 500.
I cannot imagine that I will ever use glass again.
I could be tempted to try BuildTak if there was more of an up side then just avoiding the cool-down.
Don't forget the different build surfaces you can swap in/out as needed. The only part that is attached to the printer is the magnetic part.
The build surfaces are adhered to the flexible plate. I've got all of the BuildTak build surfaces but there is nothing to prevent you from attaching something else. All you need is to purchase as many flexible plates as you have build surfaces you want to use.
As to too much heat killing the magnets you would have to check with BuildTak.
Frederick
-
@jens55,
Just curious - what kind of extruder/hotend setup are you using?Cheers,
Kolbi -
Chimera clone, Volcano clone hot end. The extruder is a BMG clone. The printer is a highly modified Creality S5
