Questions and Thoughts from a Newbie (part 2)

[SouthSideofdaSky]

(part 1 was viewtopic.php?f=8&t=1351 )

Hello again,

After a couple weeks of experimenting with the printer and software I have several more questions/requests for advice and comments to share (most of the comments will probably be things that are obvious to most of you but perhaps other newbies out there would benefit, or you can correct me on some of them)

I've been mainly printing with the MakerGear PLA so far. I've been using either Slic3r or Simpify3D to generate the G-code, then the free Pronterface/printrun thing to start the print (I like the simpler interface).

Comparing Slic3r and Simplify3D - The default settings in Simplify3D didn't seem to work very well for me, even though I loaded the MakerGear M2 V3b hotend profile. Specifically, the print wasn't sticking to the bed very well. I ended up trying Slic3r as well to compare and had almost the opposite problem...the bottom layer was almost liquid which caused the whole part to end up kind of warped and uneven. Looking through the settings I figured out that the difference was mainly in first layer height...Simplify3D had it set at 100% or greater (don't remember exact value) whereas Slic3r was literally burying the first layer in the print surface (z was negative). So after playing with different settings, 5% seems to work pretty well for me. It also seems like the slower the first layer gets put down, the better. I've been using values less than 50% for the first layer speed.

It seems that when you print through the SD card with either software, actually hitting "disconnect" once the print has started will turn the printer off. However, simply exiting the program or unplugging the USB allows the printer to continue printing. Interesting.

A code question - what is the difference between M108 and M106? A lot of the documentation on the M2 I've looked at uses M108 to turn the fan on. But turning the fan on with M108 doesn't seem to work for me. Also even when I use M106 the fan seems to be either on or off. For example if I send "M106 S255" to the printer it turns the fan on, but "M106 S100" doesn't do anything. My understanding (which could easily be wrong) was that S100 should set the speed to basically 100/255 of the full speed - 40% or whatever that is.

I've been using fine grit sandpaper to wipe my hotend clean of the filament that inevitably collects on it. It seems to work great. I'm using very light strokes but am I still in danger of eventually wearing down the nozzle? What do others use to wipe the extruder?

Now I'm trying to print ABS on Kapton tape with the hotend at 240C and the bed at 110C. Instead of re-calibrating the machine, we just measured the thickness of the Kapton tape and added that to the 5% first layer thickness, which gave us 32%. It seems to work okay most of the time but certain parts will not stick to the bed well with those settings. Should I decrease the layer thickness, turn the nozzle temp up more, or both?

Got a couple other questions already concerning ABS...
- How often do people re-apply the Kapton tape? Not after every print, right? Just whenever it's needed?
- Simplify3D isn't turning the fan on at all when working with ABS. Did you guys configure it to turn the fan on or is it better to leave it off? While I'm at it, what fan settings work best for PLA? Simplify3D was turning it on after the bottom layer and Slic3r didn't turn it on at all. This might be related to my "code question" above too...

Sorry, I know this is a lot all at once. :p thanks in advance!

[SouthSideofdaSky]

Reading through the tips thread again just now I saw the link to jsc's Simplify3D documentation page in which my fan settings question is answered...

PLA benefits from having a fan to cool down the plastic as it exits the extruder, otherwise it is prone to major curling on overhangs and sharp corners. However, you do not want cool the first layer as you want it to adhere well to the bed. ABS is much less prone to overhang and edge curling, but shrinks more than PLA and can pull so strongly as it cools that it can pull corners up off the bed, or even delaminate previously laid layers; a fan should not be used with ABS.

So with PLA, turn it on after layer 1 and with ABS, never turn it on. Still have the question about M108 vs. M106 though.

[jimc]

ok couple quick answers. m108 turn on and off the extruder fan (40mm) m106 turns off and on the bed fan (50mm). the fans need full power usually to get them spinning which would be s255. then you can turn them down to s100. it really works easiest in s3d with the fan slider for the bed cooling fan. m108 should always be on. to avoid accidents atleast for a new m2 owner....if the printer is on then the 40mm fan should be on. dont even mess with m108. as for you first layer height. in s3d if you have to have your first layer height set to 5% for it to print correctly then thats wrong. set that back to 100% and set your z stop bolt to adjust the bed height. get a set of feeler gauges and set it to .005-.006". make sure the bed is level also. try to avoid correcting for bed gap in the software unless its just to adjust for adding tape or some other material to the bed. at 100% you should be able to print correctly. download and try this to help you out.

http://www.thingiverse.com/thing:180970

[SouthSideofdaSky]

Ah, okay M108 is for the extruder fan!! That all makes a lot more sense now, haha. Yeah I don't see why I would mess with M108 then.

I will check out the height adjustment stuff. Thanks!

[SouthSideofdaSky]

Also what is everyone using for print speeds? I've been using the default 4800 mm/min but the Makergear website says it goes up to 12000 mm/min. Is it possible to increase the speed to that rate without sacrificing print quality?

[jsc]

In general, no. You can print faster, but there will be some loss in print quality, most visibly "ringing" artifacts around corners and sharp features. For certain prints, that may not matter, so you can print faster. There are always tradeoffs.

4800 mm/min (80 mm/s) is a decent middle ground speed, which gives you acceptable quality and not too slow. You will have to see what you prefer for yourself, though.

[jsc]

Regarding some of your other questions:

I just scrape off some of the worst gunk with the tweezers when the hot end is at temperature, but mostly I leave it alone. Be careful around the tip, as you don't want to go messing with the hole at all.

Kapton tape is fussy and difficult to apply. I have found glue stick superior, as it gives good adhesion without making a mess, and is very easy quick and easy to apply and washes off easily.

[Tim]

Bear in mind that melted plastic sticks very well to rough surfaces, so you don't necessarily want to go around sandpapering the nozzle too much. Occasionally I get it clean by rubbing it down with a Q-tip dipped in isopropyl alcohol.

And I agree with Jin on all counts. Kapton tape is a real pain to lay down properly without getting air bubbles in it; even if you have the technique down pat, it just can't compare to the speed and convenience of a glue stick or hairspray in a pump bottle (I suspect that the glue stick is best because you just rub it where you need it, and don't need to move the glass at all. I still use hairspray because I still have a bottle of it and it looks like it's going to last forever).

[SouthSideofdaSky]

I think I may try the hairspray or glue stick. Thanks all!