Rookie questions

[Dweldz 4]

Hello

I want to thank everyone on this forum for all the learning I was able to do before my machine showed up a week ago.

I have already used up 1/2 the PLA spool that came with my UM2+ extended.

Some rookie questions.

Can I pull the SD card out of the printer once a part has started printing?

Bottom/ top layer height, I'm wanting to get a very smooth first layer, its not bad but would like to improve it.

If I am printing a .10 layer height and set the top/bot thickness at say .85 that works out to 8.5 layer thicknesses

My question is how does Cura handle this.

Does it make the first layer .05 thick (I'm hoping to get more squish against the build plate)?

Or does it just end up putting down a .90 thick bottom even though you asked for .85?

This there anyway to tell Cura to pause the print at a given layer number or at least be able to see which layer is being printed at the time? I want to try dropping a threaded metal insert into the part during printing and then print over most of it, so I would need to do this at the correct layer count during the print.

Thanks

Dweldz

[SandervG 1,521]

Welcome to the forum!

Hopefully you have learned a lot, and you'll also give back some of the knowledge you have gained and will gain down the line

About your questions:

Can I pull the SD card out of the printer once a part has started printing?

Nope. It will stop/cancel/ruin your print.

First layer:

You probably need to reconsider your bed levelling.

Pictures are always good! If you can add a picture from your first layer we could probably give you some good pointers.

Originally, your first layer should be 0.3. It is also set so in Cura. Did you change this?

It is best to keep your top layer a multitude of your layer height.

So either go for 0.8 or 0.9

There is a Pause feature that can pause your print at Z. Check Cura plugins for this feature.

Good luck!

[gr5 2,270]

If you pull the SD card out it will stop - the computer in the printer is an arduino and only stores about 12 commands ahead.

For the layer height question - it will do 0.9 layer height. If bottom layer is .3mm (default) then that's a total of 7 layers (a .3 thick layer and 6 .3 thick layers). For this question you can ask Cura instead of humans and just look at it in layer view.

To get extra smooth bottoms some people found it helps to print a thinner bottom layer - say .2mm or even .1mm. Also if you spread glue on the glass, you should use a wet tissue to spread the glue - if the glue is lumpy the bottom of the part will also be lumpy. If you print a bottom layer of .1mm then you need leveling all that muich better. Don't use the procedure but instead just adjust the 3 knobs while it's printing. Eventually you will get it perfect.

There is a "pause at Z" plugin. It's fantastic - get it. It's meant for exactly this kind of thing - changing filaments at a given layer or inserting a part. Make sure the part doesn't stick up!

If you want to do it the hard way, get tinker marlin - it's very very simple and easy to use and it gives you much more functionality including continuing a failed print, or showing the current Z position during a print. Having the Z value lets you sit by the printer until it is at the right height.

[Dweldz 4]

Thank you

I seem to have had an issue replying but believe this is sorted out now.

I reset the bed, turned initial layer down to .1 and its doing much better.

I have been measuring the brim thickness on ABS parts and its pretty consistent around the whole brim so I think I have the leveling fairly dialed in.

I measure the calibration card at .14 MM

Is the actual target nozzle to bed clearance .15?

On adjusting the layer height during the print.

Sounds a bit daunting

Is there a video you could steer me toward?

I'm looking forward to playing with the stop at Z plug in.

But I'm going thru the ABS learning curve at the moment.

Thanks again

[gr5 2,270]

You want it squished a bit. Here is an example where it is squished maybe a little too much - but still quite good. If it's more transparent (can see right through it and have trouble telling what color the filament it is) then it's squished too much).

There is a tradeoff. If you level it such that it doesn't squish much the part doesn't stick well to the glass. If it squishes a bit more and is as much as this photo you get really good sticking on the bottom layer but the bottom layer sticks out a little bit so if it is a part that needs to be dimensionally perfect you might want to squish it slightly less so you don't have to file off the outer edge of the bottom layer. note that this is 2 passes on the skirt - not just one pass:

[gr5 2,270]

This skirt was squished too much - see how it is transparent in spots?

[Dweldz 4]

Its appears to be a fine line.

I re leveled the bed carefully to a .1mm gap.

And adjusted the screws while printing and seemed to work out.

I think part of my problem was there was just a bit of filament poking out of the nozzle, which I really couldn't see and this threw off the gap toward the high side.

I heated the nozzle and wiped it off then reset.

Lots to learn

Thanks

[SandervG 1,521]

Hi Dweldz, that is very much possible.

Next time you could heat up your nozzle to remove the filament or just snap it of with your fingers/knife/pliers.

Good that you found the source and you can now continue 3D printing.

[gr5 2,270]

The leveling procedure gets you close but I always level it again when it starts printing - live - by the seat of my pants so to speak. Just twist those knobs. The first time you may panic. Just take a deep breath. Take your time. Think about if you want the bed to go up or down, then think about which way to turn the knobs, then turn all 3 the same amount.

The first time you may be too late to help the first layer much. But if you do this at the start of EVERY print you will quickly become an expert.

[Dweldz 4]

I'm getting the live leveling.

Just have to remember which way to turn the screws and how the bed moves around three points

New glasses might help too....

Thanks

[gr5 2,270]

It takes practice. Eventually you do it without thinking.