Raft required? MPCNC Tool Mount

I’ve printed up the Z motor and Z lower pieces just fine but have been having issues with the tool mount. It prints standing tall for me on the print bed but no matter where on the bed I place it, it pops off somewhere past half, 2/3 of the print and trans to spaghetti. Should I be adding a raft for this piece or “should” it be sticking fine?

Can you post a pic of the part?

For tall pieces, especially ones with small footprints, I prefer a brim. It also helps with weird corners and warping parts.

I wish I’d taken pic of the spaghetti pile (it the overnight print I promised Due I’d be right beside…and I was…I was sound asleep on the couch though). Spaghetti piles - to this point anyway - make me chuckle. These two are the ones I was printing in tandem (two up on the bed). It’s possible that the first one tipped over and started it’s spaghetti pile and it was ultimately it’s spaghetti pile that eventually knocked over the other one. I’ve since tried a second and third print but one only went halfway and the other didn’t make half. It didn’t fall over, just popped off, shifted a cm to the right and the printer kept printing with the big offset.

The tall one here might still be useable for the laser mount - I’m assuming there is little to no pressure on the laser rig since there is no contact with the workpiece.

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Those are perfect candidates for a brim. 5-10mm should keep it on there good.

I’ll give it a whirl! Do I understand correctly here:

Brim adds a connected perimeter but does not alter the bottom layer of the physical part itself.

Raft adds a full layer under the entire part thereby lifting it up the thickness of the raft.

Right. The brim can be removed with a sharp knife (or maybe a chainsaw, IDK). The raft just sort of pulls off.

The raft is better at giving you a flat bottom, or isolating you from bad bed problems. The brim is going to have whatever bed surface you’ve got on a part, but it will hold it down firmly to the bed. The brim works well because it increases the bed area but also adds an offset, so small details get rounder corners.

Good raft settings give you an easy break between the raft and the part, which is why I like a brim for this. You wouldn’t want the part to pop off the raft 3/4 of the way through the print.

Tall prints pop off because the drag has more torque.

I find it astonishing that there is any noticeable drag to be honest but I guess even a LITTLE resistance multiplied with a lever that big.

If you watched it instead of sleeping… :smiley:

What I see is something will make a little bulge, something taller than the last layer, and the nozzle will make some high speed travel move and run right into it, which will pop it off. At least, that’s what I guess it’s doing, since who can watch a printer after 4 hours of printing?

4 hours is about when I fell asleep. I bet they popped off at hour eight or nine. When I woke to the spaghetti the LCD said 10h 42min. (I was printing two at a time remember).

And so the adhesion gremlin returns. Hahaha

The brim is a good theory but if the bed can’t hold it well…

I’m letting this third attempt print run in the off chance the stars might align and the little teeny bit of brim that DID stick is JUST enough extra hold. Plus that spool is probably gonna run out on this print. (My first empty spool! Yay!!!)

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It’s always the bed adhesion gremlin. You didn’t get your printer wet did you? Did you feed it after midnight?

On a pei surface at 63C I have a hard time getting PLA off. Have you clean the surface with alcohol?

Spic and span. I’ve been wiping it down with isopropyl almost each print.

I feel like I need to preheat the machine fully fully. Like even so the bed screws warm up and do whatever expanding they need to do before it try printing. The first couple attempts the adhesion trouble was only on the right side. I monkeyed with the z endstop and got good adhesion on the right but choked the nozzle on the left. So the bed isn’t level. But it was once it warmed up more. It’s gotta be the heat transfer to the screws, no?

One thing that can happen in tall prints that I’ve run into is the wiring to the extruder/hot end can catch on something that throws things off enough to allow the nozzle to hit the print instead of gliding just over the print. That often exhibits as tall prints that almost finish but otherwise seem great. Adding a brim or raft won’t fix it though…

We’re right at the point of the last release (1:47 on the LCD) - let’s see how we do. I wonder if this has anything to do with the fact that I mounted my MP3DP on it’s side? (See pic)

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Oh, for very wide prints, I would do something different.

Still going. 2:28, not past half yet…

Something is pretty wrong about that. I am wondering if the thermistor is reading the right temp. PLA should not curl at 63C I have to let it cool so I don’t bend parts pulling them off.

The other thing to try is some Windex and a magic eraser scrub and then alcohol. If I even get a hint of a curled edge I do this (Many months between these “deep” cleanings).


Blue painter’s tape. Put a layer where you’re going to print, then wipe it down with alcohol to get your finger oils off it. I don’t think I’ve ever seen pei not stick the way yours is. It’s kinda weird. Anyway, the tape will get your stuff stuck. Sometimes you can even reuse the tape! Other times it becomes one with the print, so be advised, you might need to sand it off the bottom.

I’m still yet to understand why people use exotic stuff for their bed instead of good old glass+glue stick.

I’ve printed everyday for years with different machines only using this technique and it always works great.

That’s one of the biggest mysteries of life for me. Just like how the dinosaurs disappeared (probably a fight with space robots though).