Why Rafts are the only thing that sticks? and what are the print settings for them?

Why is it that raft work perfectly correct filament height stick well add 2 hours to the print time? every other adhesion option just peels away and is flattened and still does not stick. I have moved to using glue to help start prints and it works ok as long as the print has a good sized base. Lately I have been wanting to print things with designs against the print bed so I cant use a raft or else they come out as garbage. Also anyone know were to find the raft settings in the code I would kill to match them in the rest of my prints.

Raft is very slow, I think about 10% print speed, this takes very long if you have multiple layers in raft.

When printing a brim, does the filament not stick at all? Or does it stick on the initial pass, but get peeled off the bed by later passes? I’ve had issues with the v1 over-extruding, which forced previously adhered lines up off the bed. The problem seems to be worse at higher speeds (faster extrusion).

There are a few raft parameters for the raft that you can tweak in Luban. First, you have to customize your Printing Settings. Then you have to copy an existing profile by selecting it from the Profile drop down, then clicking the “plus” icon below it:
Screen Shot 2020-07-29 at 1.55.44 PM

Now you’ll have a Profile named #Fast Print, and it will allow you to expand the Adhesion section, switch between the different types, and control a few parameters.
Screen Shot 2020-07-29 at 1.56.56 PM
Unfortunately, pretty much the only parameter Luban allows you to change is how much larger the raft is than the print. To get more granular control, you’ll have to switch to Cura or another slicer.

But I’m hoping we can solve your adhesion problems by tuning the over/under extrustion. Using the same process to customize a print, if you open the first section titled Quality, one of the parameters you can adjust is Initial Layer Line Width. This is how much extra filament is extruded on the first layer. If you’re under extruding (nothing sticks to the bed), try increasing it and test print a brim again. If you’re over extruding (it sticks, then peels off as future filament is printed), try reducing it.

My v1 is manually calibrated to print well with Initial Layer Line Width at 100% on High Quality mode. But if I want to print with a Layer Height of 0.4mm, I have to reduce the Initial Layer Line Width to 75% (still experimenting). I don’t have a v2, but @xchrisd wrote a guide about getting started. In Section 7, there is a section named “EXTRUDER CALIBRATION”. It’s possible that this section will help you better than the Initial Layer Line Width adjustment.

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As far as raft speed I usually manually set it at 200 % speed after the first full layer is down just to cut time and set it to 1mm, I just wish i could have less than 5 layers to the raft if I am going to have to use it. The first layer either starts of not adhering and then sticks in random places or starts sticking well and then releases in other spots, some rare occasions it does not stick at all. switching to other slicers has not yielded much of a different result if i use rafts or skirts with Cura or Prusa, I get the same results. I should also mention that I do not change any calibration settings in the system between prints or remove the toolhead. I will give reducing the layer width a try thanks

With my v1, dust on the bed was a big problem. I was having issues with sticking in some locations and not others until I noticed that most of place it would stick were the places I had printed most recently (ie, the dust was cleaned off by the last print).

I don’t have an enclosure, and my office is pretty dusty (lots of books and open windows). Covering or cleaning the print bed with alcohol and a lint free cloth helped with a lot of my adhesion issues. Keeping the bed covered worked better; some fine dust was stuck in the texture of the print bed after cleaning.

After reading @ElloryJaye’s eval of the A150, it sounds like there might be some bed issues.

If you have a straight edge or ruler, can you check the print surface? Lay the straight edge of a ruler down on the bed, and shine a flash light behind the ruler. Move the ruler around, all over the surface. If you see light between the ruler and the bed, the bed is not straight.

@Dojima also had a post with similar issues. That thread actually solved the issue: The bed support structure wasn’t tightened properly and possibly the bed wasn’t secured properly.