Middle part not sticking!  

RE: Middle part not sticking!

It's common for large rectangular objects to warp. Assuming Live Z is well calibrated and the steel sheet is clean (using hot water and fragrant-free dish washing soap), here are a few approaches that have worked for me: (your comment that the ends "are not perfectly flat, but they are fine" actually make me wonder if Live z is correct...)

* Slow down print speed.

* Add mickey mouse ears to the corners. You can add a cylindrical part in PrusaSlicer, maybe 10mm diameter, change height to single layer height, then place the part at the corner. Repeat for each corner.

* Add a brim around the model, 5 mm or more.

* Use Layerneer Bed Weld ( https://www.amazon.com/Printer-Adhesive-Layerneer-Original-Filament/dp/B079984GV5/). Works better in my hands than glue stick, and you need only a thin layer.

* If you have design control over your part and it's possible considering the intended use, you can try to round the edges and/or add holes to the base of the model.

* Combination of above. Usually, brim and Layerneer works for me but large, rectangular objects can be a challenge.

RE: Middle part not sticking!

@mg-2

Looks very likely its a first layer issue as the corners look ok, and that's normally the first place a warp would occur.

Have you tried Jeff's "Life Adjust Z My Way" ?  It really makes a big difference to first layer adjustment, so much better than the standard method

life adjust Z - my way – Assembly and first prints troubleshooting – Prusa3D Forum (prusaprinters.org)

Indeed Fusher, large rectangular objects are a real pain, had a 18 hour print with corner warp that did not notice until was finished. (Thankfully was very minor so still usable)

Also, temperature drops are a likely cause if it ran overnight.

RE: Middle part not sticking!

@fuchsr

First layer look good to me, looks good right?

I have ordered layerneer, should be here tomorrow. Will do a print test and report back.

On the layerneer, you only do 1 layer, right?  and do you clean it after each print? or the same applications is used for multiple prints?

RE: Middle part not sticking!

@mg-2

Looks pretty good from where I'm sitting but telemedicine is hard 😀

Layerneer, yes, one layer should do it but I usually go one way and then one more time across. 

And though I usually dispense the advice "Clean your sheet! Clean your sheet!" I don't always follow it myself. I just have a good sense for when it's needed and when not. So if I want to be sure I'd probably put a new layer on for the next print, and when I begin to see some more visible accumulation, I'll give the sheet the hot water and soap treatment. Just don't wipe the sheet with alcohol while there's Layerneer (or glue stick) on it, or it'll create a gooey mess. 

RE: Middle part not sticking!

the corners coming up is a nagging problem for me.  I've tried magigoo, the bed weld stuff, glue, etc  I print in an enclosure so I'm not sure it's a temp drop thing.

Now that I have my MMU sort of working ok,  I was thinking about trying to solve this.  Fuchsr I'm going to go through your steps above and see if I can squash this nagging issue. 

Thanks

RE: Middle part not sticking!

@fuchsr

I tried Layerneer,  single layer...not real difference still middle part isn't sticking to the bed and getting the curved/arc on the print.

RE: Middle part not sticking!

@mg-2

So for me, with the layerneer, I apply a layer and let it dry, and then a second.  That seems to work for the corners.  I'm not sure why the middle is coming up.

But the primary thing for me is dawn platinum with a standard dish sponge(the abrasive side) before I put anything on it.  This is for smooth sheet.  for the textured sheet I used 99% IPA and nothing else.