Why will raft stick but first layer won't

[scienceelf]

I am using PetG at 245 degrees printing on Buildtak heated to 100 degrees. I use a raft and print with no problems. Without a raft the first layer will not stick. Am using maker desktop to print with my Flashforge Creator Pro.

It doesnt matter if the surface area of the print is large or small. I am printing first layer at 30mm/s (same as raft printing speed). I have leveled and re-leveled with a piece of paper barely able to slip under printhead with the slightest resistance.

Why will the raft stick but a non raft first layer not? What logic am I missing in my settings?

Thanks in advance.

Nathan

[AxxAxx]

That sounds stange. I never use the raft feature, no matter of platstic, (ABS, PLA, Ninjaflex, Nylon, Pet).

If the temperature and print speed is the same for raft/no raft and the buildplate is level the only factor left I can think of is the 0 height calibration.

Do you subtract the thickness of the paper (0,1 mm for normal 80g/m^2 printer paper) after you have calibrated?
The raft layer often use a higher layer height and width to acceive a better adhesion to unlevel beds.

Could that be one factor?

[scienceelf]

I appreciate that advice Axx, will give that a try.

Nathan

[AxxAxx]

Good luck!
Which slicer software are you using?

[scienceelf]

Maker Desktop has its own slicer built in but I am very close to biting the bullet and buying Simplify3D. Have used MatterControl in the past and liked it but don't think the Flashforge creator pro is supported.

[Marm]

Try using a "zero" thickness surface, like glue stick or hair spray, and see if your results change. I too hate rafts as I can never get them off the print cleanly.

[LambdaFF]

Hi, since the glass transition temp of PET is 70°C, you should not heat your bed plate over that. Try a much lower bed temp, something like 65°C or 60°C.

[curious aardvark]

the answer is simple.

When printing a raft makerware slows the print speed down - much slower than the set speed.
When not printing with araft it doesn't slow the first layer down at all.

You need to create a custom profile with a slower first layer and it should work :-)

Don't have makerware on this one anymore or I'd show you what you need to change in the profile.

But yep - that was the single biggest issue I had with makerware. Once I figured out how to change the speed of the first layer - everything stuck without araft :-)

[scienceelf]

Thanks for all of the advice. I think the problem is that my hobbled bolt was full of shavings and I was underextruding. With a thick raft it would work, with a regular 1st layer it wasn't enough filament to stick. I lowered the gap between base and hotend a tiny bit and cleaned out my bolt. Seems to be working well now.

Will bump the platform temp down a bit for my PetG and create a profile that has a first layer at 20mm

Thanks,

[3dex ltd]

Im glad you managed to get your printer working!