3D Printing 3D printer plunge

[cwbullet]

Nice Prusa.

 

[TurbulentSphere]

Bigger threads are generally easier to print than smaller ones. I did some on a nose cone/payload bay assembly that was ~2 inches in diameter. I found that I needed about 40 thou of clearance between the major diameters of the internal and external threads, so it would be a good idea to make some test pieces to play with tolerances first.

 

[matthewdlaudato]

Nice Prusa.

Thanks. It was fun to build, took me about 10 hours at my usual ‘check twice, do once’ pace. Seems to print great, but I’m at the bottom of the learning curve, so...

 

[Tobor]

Bigger threads are generally easier to print than smaller ones. I did some on a nose cone/payload bay assembly that was ~2 inches in diameter. I found that I needed about 40 thou of clearance between the major diameters of the internal and external threads, so it would be a good idea to make some test pieces to play with tolerances first.

Thx for the info.

 

[Alan R]

Got my new Ender 3 a couple of days ago, but so far things have been coming out like this because the PETG aint sticking. (I just let that print run when I went to bed last night.)
I cut that new shiny bed this morning from an old mirror. Hoping it will work better than the included bed.

 

[matthewdlaudato]

Got my new Ender 3 a couple of days ago, but so far things have been coming out like this because the PETG aint sticking. (I just let that print run when I went to bed last night.)
I cut that new shiny bed this morning from an old mirror. Hoping it will work better than the included bed.

I just did my first PETG print on the stock PEI sheet that came with the Prusa. Used glue stick - very good adhesion.

 

[Alan R]

Just tried the hairspray on the glass - no good.
Blue tape on the glass - no good.
Glue stick on the blue tape --- printing now --- seems to be working so far.
Next experiment will be just the glue stick on the glass.

It's a small piece so i added a little wider brim in Cura also.

I didnt want to mess up the build surface that came with the printer, so I've refrained from putting any adhesives on it so far. Not sure if it's PEI or Buildtak or just something similar

 

[cwbullet]

PETG is very sensitive to the right live Z. I recommend PEI cleaned with isopropyl alcohol. If you have a headed bed: Once the bed reaches 10 degrees from final bed temp, clean with with Windex.

I am near 90% success with this.

 

[matthewdlaudato]

PETG is very sensitive to the right live Z. I recommend PEI cleaned with isopropyl alcohol. If you have a headed bed: Once the bed reaches 10 degrees from final bed temp, clean with with Windex.

I am near 90% success with this.

Good tips Chuck.

I also adjusted my live Z for the PETG - it’s softer and stringier than PLA from what I can tell, so I brought the head down closer to the bed, around 0.8mm on my machine. Still experimenting.

 

[KC3KNM]

PETG is very sensitive to the right live Z. I recommend PEI cleaned with isopropyl alcohol. If you have a headed bed: Once the bed reaches 10 degrees from final bed temp, clean with with Windex.

I am near 90% success with this.

That’s a great point, the Z offset is super critical. A well leveled bed makes a big difference as well. I’ve gotten into the habit of indexing my head to the bed using a dial indicator, then I adjust the Z offset in Simplfy3D for the proper Z height. A cheap indicator off Amazon should be sufficient for this purpose. You can also use it for straightness compensation on your machine.

I just started using PEI and I’ve really liked it. All I do is clean it with alcohol and I’ve had no issues with first layer adhesion. It’s great how easy parts are to remove after cooling as well.

 

[Alan R]

so I brought the head down closer to the bed, around 0.8mm on my machine. Still experimenting.

.8 ?? sounds really high. Large nozzle?

also sounds like I need a PEI bed. thank goodness for amazon gift cards.

Good thing I have some priming and sanding to do while I wait.

 

[matthewdlaudato]

.8 ?? sounds really high. Large nozzle?

also sounds like I need a PEI bed. thank goodness for amazon gift cards.

Good thing I have some priming and sanding to do while I wait.

-.800. Like I said I’m still experimenting. Doing a print right now at -.950.

 

[matthewdlaudato]

Today’s output (minus a bunch of experimental throw-aways). 24mm engine block, 4 29-24 centering rings and a nose cone. I had these LOC 29 and 24 tubes laying around so I’m making a long skinny D powered rocket.

Calipers plus patience/practice in Autodesk Fusion 360 = excellent, perfect fitting parts.

 

[cwbullet]

That’s a great point, the Z offset is super critical. A well leveled bed makes a big difference as well. I’ve gotten into the habit of indexing my head to the bed using a dial indicator, then I adjust the Z offset in Simplfy3D for the proper Z height. A cheap indicator off Amazon should be sufficient for this purpose. You can also use it for straightness compensation on your machine.

I just started using PEI and I’ve really liked it. All I do is clean it with alcohol and I’ve had no issues with first layer adhesion. It’s great how easy parts are to remove after cooling as well.

Depending on the bed type, Windex increases or decreases adhesion. On a powder coated, it increases adhesion. On PEI sheets, it decreases adhesion. If you ever use PETG on PEI with a highly tuned live-Z, you will know why less adhesion might be desired.

 

[KC3KNM]

Depending on the bed type, Windex increases or decreases adhesion. On a powder coated, it increases adhesion. On PEI sheets, it decreases adhesion. If you ever use PETG on PEI with a highly tuned live-Z, you will know why less adhesion might be desired.

I haven’t had any issues with PETG on PEI. I did switch from thicker PEI sheets to the thin adhesive lined PEI that lulzbot sells. It’s more expensive, but works without issue. The thicker PEI always came warped and never quite sat flat on my bed. I’m not sure if the difference was the material itself or that the thinner stuff sat flatter/was more consistent in thickness, but PETG pops off as easily as PLA for me.

I’m not sure what you mean by highly tuned live Z, though. It’s possible to find that balance between proper first layer adhesion and layer height/finish. Playing around with slower feedrates and extrusion settings gave me good results.

 

[cwbullet]

Highly Tuned: If your live-z is too positive, you get poor adhesion. If it is too negative, you get stringing and clumps. You can find a balance, but getting perfect will result in better print quality. You can get strings with either, but it is worse with overly humified PETG or too negative a live-Z.

I did buy a food dehydrator to dehumidify my filament. It was cheap and has seemed to reduce stringing. I use it and then store the filament with desiccant in 5-gallon buckets.

 

[gorillamotors]

If it is too negative, you get stringing and clumps.

These clumps you are referring to are they like 'boogers'?

Jim

 

[cwbullet]

Yes, sometimes.

 

[gorillamotors]

I found this on the prusa forum and I tried it and it appears to be working. I don't have any problems with boogers on PETG but on PLA. I am using Simplify 3D on my MK3.

Try these settings, works for me and many others ...
Retract Length = 0.4
Lift Z = 0
Retract Speed = 35

Jim

 

[cwbullet]

Thanks.

I have tried that. The Live-Z tuning was what worked for me.

 

[KC3KNM]

Highly Tuned: If your live-z is too positive, you get poor adhesion. If it is too negative, you get stringing and clumps. You can find a balance, but getting perfect will result in better print quality. You can get strings with either, but it is worse with overly humified PETG or too negative a live-Z.

I did buy a food dehydrator to dehumidify my filament. It was cheap and has seemed to reduce stringing. I use it and then store the filament with desiccant in 5-gallon buckets.

Sounds more like properly setup than highly tuned .

 

[cwbullet]

Depends. Not tunning in the LIVE Z on a Prusa is the number on reason for poor adhesion and poor print quality. What works for one bed and filament may be different from filament to filament and bed to bed.

 

[KC3KNM]

Depends. Not tunning in the LIVE Z on a Prusa is the number on reason for poor adhesion and poor print quality. What works for one bed and filament may be different from filament to filament and bed to bed.

Z offset is important on anything that has a Z .

Even two of the same machines will have differences with the same bed and filament. Everyone loves to get into software settings and bed materials, but I find it odd there isn’t much attention paid to machine setup itself. Things out of square, improper belt tensions/lead screws improperly aligned or not lubricated, backlash issues, warped surfaces... there’s a ton that can cause issues with print quality. Sometimes the issues can be mitigated with software adjustments, but you’re not going to have the repeatability and precision you would with a well maintained and setup machine.

 

[matthewdlaudato]

Z offset is important on anything that has a Z .

Even two of the same machines will have differences with the same bed and filament. Everyone loves to get into software settings and bed materials, but I find it odd there isn’t much attention paid to machine setup itself. Things out of square, improper belt tensions/lead screws improperly aligned or not lubricated, backlash issues, warped surfaces... there’s a ton that can cause issues with print quality. Sometimes the issues can be mitigated with software adjustments, but you’re not going to have the repeatability and precision you would with a well maintained and setup machine.

+1 for a well setup and maintained machine. Mine appears square and true; the calibration metrics were spot-on. Prusa has the following, to which I’d add belt inspection and re-tensioning.

https://help.prusa3d.com/l/en/article/sVQHD6vtfm-bearings-maintenance

 

[jnobels]

Just tried the hairspray on the glass - no good.
Blue tape on the glass - no good.
Glue stick on the blue tape --- printing now --- seems to be working so far.
Next experiment will be just the glue stick on the glass.

It's a small piece so i added a little wider brim in Cura also.

I didnt want to mess up the build surface that came with the printer, so I've refrained from putting any adhesives on it so far. Not sure if it's PEI or Buildtak or just something similar

Most painters tape has a coating that prevents adhesion. Give it a good clean with alcohol before you print. This is my go-to setup. Without cleaning it, it doesn’t work at all. I can usually get a few prints before I need to change the tape.

 

[matthewdlaudato]

The Prusa plain PEI bed seems to have good adhesion al by itself for PETG (Amazon Basics brand). I tried Chuck’s tip of using a bit of Windex as the bed approaches final temp - way too much adhesion. Simply cleaning the bed with alcohol and printing is showing good first layer adhesion and easy release. For now anyway.

 

[cwbullet]

The Prusa plain PEI bed seems to have good adhesion al by itself for PETG (Amazon Basics brand). I tried Chuck’s tip of using a bit of Windex as the bed approaches final temp - way too much adhesion. Simply cleaning the bed with alcohol and printing is showing good first layer adhesion and easy release. For now anyway.

Like I said above, it is filament dependent. One brand of filament is different from another. I had trouble with Hatch box white until I used Windex. It works perfectly now. Some do not like Hatchbox because of this. I like it because I can get it for $13 a spool.

I recommend you keep Windex in mind as you find PETG filaments that are hard to stick. I typically only use it on the textured powder coated bed for the PRUSA.

 

[Alan R]

glue stick on glass - no good.
my PEI sheet arrives tomorrow

question: do you stick your PEI sheet directly to the aluminum bed, or do you stick it to glass on top of the bed? I'm not sure I want to stick something directly to the aluminum.
was thinking I would stick it to a piece of glass on top of the aluminum.

 

[cwbullet]

I have spring steel sheets that attach to the bed with magnets. I attach the PEI to the steel sheets. I would attach the PEI to one side of your glass.

One other bed is very sticky - Buildtak. Does one hell of a job with ABS.

 

[matthewdlaudato]

A nifty shock cord mount that I printed. Sits in the top of the motor tube. If the Kevlar ever breaks, a new strand could be threaded through.