MakerGear Forum

So I bought an M2 recently and after printing the test tube sample I noticed that the polyimide tape was cut by the extruder around the printed tube. Was this supposed to happen? Am I supposed to rip off the tape and apply a new sheet every time I print? I'm totally new to all of this, thanks.

http://imgur.com/LFiQcnw

Oh, Ouch! No that is not supposed to happen - the nozzle is much too close to the bed for the first layer and the heat burned right through the tape.
( i did that once. )

You have an incorrectly set Z-stop and Z-Offset for that taped surface. Replace the tape. Then please read through the new Beginner's Guide here:

viewtopic.php?f=3&t=3342

It's going to tell you step by step what you need to do to fix it.

Jules wrote:the nozzle is much too close to the bed for the first layer and the heat burned right through the tape.

Really? I thought that polyimide was more heat resistant than that. But I just looked it up online, and it's actually only rated to about 260 degrees C, which means it should be fine for PLA but one needs to be careful with PETg and especially with high-temperature filaments like ePC. Also, I have no idea how cheap brands of polyimide hold up compared to Kapton, which is what I'm used to using (from electronics, mostly, because it is a fantastically insulating material).

The Zebra plate is even worse. I melted a nice trench through mine when my nozzle came loose and dropped out of the mount plate. I hit the kill switch as fast as I could but the Zebra plate was damaged instantly. I can still use the plate on that side, though, as long as I make sure that the print is either not on top of the defect or just drawing straight lines across it.

Tim wrote:

Jules wrote:the nozzle is much too close to the bed for the first layer and the heat burned right through the tape.

Really? I thought that polyimide was more heat resistant than that. But I just looked it up online, and it's actually only rated to about 260 degrees C, which means it should be fine for PLA but one needs to be careful with PETg and especially with high-temperature filaments like ePC. Also, I have no idea how cheap brands of polyimide hold up compared to Kapton, which is what I'm used to using (from electronics, mostly, because it is a fantastically insulating material).

The Zebra plate is even worse. I melted a nice trench through mine when my nozzle came loose and dropped out of the mount plate. I hit the kill switch as fast as I could but the Zebra plate was damaged instantly. I can still use the plate on that side, though, as long as I make sure that the print is either not on top of the defect or just drawing straight lines across it.

Yeah, I probably misspoke that - might not have been the actual heat to cut it - that nozzle got literally dragged through the tape. Look at the marks it left where it tried to push the tape ahead of it and skipped. Either way - the tape is toast, it needs to be replaced. And that first layer gap needs to be adjusted.

Okay thanks for your help! I know when I first got the machine started I was testing out the X,Y, and Z movements. On the z testing, I moved the bed up too far and it made an alarm sound. It seemed like the nozzel hit the plate or it came realllly close. And I accidentally did it again trying to get the z plate down. Do you think that's what threw it off? Did I hurt the nozzel? I couldn't find anything online on what I did. The print came out fine but it just has that rough start like you seen in the picture.

Also, which part of the guide refers to incorrectly setting Z-stop and Z-Offset for that taped surface. Is it the cold setting or hotting the Z-Endstop? And am I calibrating the Z-offset? Sorry, I'm just trying to match up what you told me with the wording in the guide. I have no idea which part of the guide I should be looking at because I don't know exactly what's wrong besides the Z plate being off. A lot of the wording in the guide has to do with something with the z-plate. I'm so new with this, literally just got the printer yesterday. Thanks for all your help!

Not a problem, it's Greek at first to everyone.

First thing you want to do is take an hour and read the entire guide. (Yep - All 26 pages - ) You probably don't have to re-set the level, but you need to do the check for the Z-Stop, and everything else after that. It will help you to understand what we are talking about when we discuss certain items, and sooner or later you will need to know it to use the machine, so might as well start getting familiar with it.

1. If you don't have a set of metric feeler gauges, you will have to set the Z-stop using a business card with the Cold Method. That's the least accurate method there is, and probably why you hit the tape with it the first time. (Try Amazon or any auto parts store and get a cheap set of Metric Feeler Gauges to use to reset the Z-Stop - it's so worth it.) Once you get the feeler gauges, you can use them to set the Z-Stop using the Hot Set Method from the guide.

The Z-Stop refers to where the bed physically stops vertically in relation to the nozzle tip. In M2's the current Z=0 is at the top at the nozzle. (This is also known as the Z-Home in the software.) You start printing at Z=0, and as you finish a layer, the bed drops down a layer and prints the next layer. Took me a while to get comfortable with that, but it becomes second nature after a while.

The gap between the nozzle and the bed for that first layer is absolutely critical. If the gap is too small (the Z-Stop is set too high) you will plow the nozzle through the tape or jam it into the bed - not what you want. If it's too large of a gap (the Z-Stop is set too low) your filament won't stick for that first layer and it will warp and pop off.

2. Setting the Z-Stop is just Step One. Unless you are as expert as Ed, who sets the Z-Stop once before each roll, and then leaves it at that until the roll is finished, you are going to be printing from different spools of filament, at different temperatures, and that changes the gap.

We aren't crazy, and we don't want to have to re-set the Z-Stop every time we change the filament. So we apply a fudge factor to the starting point of the print using the software. That fudge factor is called the Z-Offset (totally different from the Z-Stop) and we determine it using a Calibration before printing.

The Z-Offset is a command that we tell the software that says "Start printing this first layer, and every other layer, xxx millimeters lower (or higher) than zero." That's because we know the likelihood of hitting that gap 100% correctly is about 0%. We just can't see that closely.
And since the gap changes with every different kind of filament, (because of the different heat expansion of the nozzle and bed), we need a way to adjust the gap without having to mess with the Z-Stop every time.

So Step Two in the process is to determine the Z-Offset for that type of filament, and that is also in the Guide.

You need to do both steps. (After you change the tape, because that tape is toast. )

Once you get the Z-Stop set fairly well once (it won't be exact), you will then use the Z-Offset to fine-tune for each type of filament. And you do need to run that Z-Offset calibration for each type of filament you print. (PLA, PETG, ABS etc.)

Couple of adjustments and you will be good to go. Once you get it set up, (until you change to a different filament), it's going to print the same.

Thank you so much for typing that up! I'll try this out and report back

Also, do you think I hurt my nozzel at all when that alarm sound went off? I think the nozzel touched the plate when I was testing the Z axis.

Spencer wrote:Also, do you think I hurt my nozzel at all when that alarm sound went off? I think the nozzel touched the plate when I was testing the Z axis.

Probably not - there are springs under the bed because it does happen once in a while. Might have just been the motor grinding a bit. (Won't hurt it.)