3D Printer Users with Glass Bed

[iwik]

Hi Guys,
Anyone using a printer with glass bed that they have stuck a PEI sheet too.
I have a friend who got one of these sheets from Ebay and stuck it making sure it was
squeezed when it was glued so it didnt have any bubbles left. It was perfectly flat but when
he heated the bed to do a ABS print it all bubbled and left a terrible surface behind. I think it
was ok with PLA. Anyone experienced anything like this.
Thanks
Les

[Trevor Hale]

Hi LES,
I use a PEI Sheet on glass, I stuck the PEI to the glass then use Binder clips to hold the assembly to my build plate.  I use PLA and Love it.  I haven't started with e ABS Yet, and do have a roll to try but just haven't tried it above 63 Degrees.
I will say that I love the PEI Sheet.  Now I will be cautious when printing with ABS.  Thanks for the tip

Trev

[iwik]

Trev,
I have PEI sheet on my printer and never had a problem with sticking. Love to hear if anyone has been successful  as the temp is much higher with ABS.
Les

[kattz]

I've tried it - had the same experience as your friend, but I only print in ABS, so my bed temps are HOT.

According to the spousal unit, that's the only hot thing around here...

[N4208T]

PEI sheets do not do well with high bed temps as iwik's friend found out.  There are several videos on You Tube where they talk about this.  I use primarily PLA also.  I have printed with ABS (for some car parts) and I have some TPU I am going to play with but I have found that PLA seems to work just fine for what I need.

[sagrada737]

Just a note on 3D printing ABS filament...   Keep in mind that this filament puts off toxic fumes when printing.  You don't want to breath this stuff!   When I do print ABS, I usually place a plastic shroud over the printer, turn the ceiling fan ON, and open the window, begin printing and then vacate the room.

For reliable ABS bed adhesion, I have found that making a Acetone/ABS Slurry mix works well.   I cut 1/4" pieces of ABS filament into a dish, then add a bit of acetone to dissolve the ABS.  When it become like a watery toothpaste consistency, I then spread it onto the Bed Plate.  The acetone evaporates very quickly.  This is the best bed adhesion method I have found for 3D printing of ABS.

Regarding printing TPU...   I have found it difficult to print.   Depending on its Shore Hardness, feeding TPU is like pushing a rope -- even with a direct drive setup.  What I have found that increases reliability printing TPU, is to increase the Nozzle Temperature by about 10 degrees C.   This decreases back pressure in the Heat Chamber, allowing the filament to flow easier.  I have found that this allows an increase in print speed.

Also, I use 0.6 mm nozzles, which helps to print at a faster rate.   I don't find that the surface finish to be compromised that much using a larger nozzle diameter.  I have found that the larger nozzle diameter yields better layer-to-layer adhesion, making for stronger parts.

Regarding "Wall Thickness"...   I typically print with 3 layers of wall thickness.   This allows for a stronger part, and also allows for post machining operations.

Concerning post machining of 3D printed parts...   Be sure to let your tool cool down before doing another operation, eg. drilling or reaming.   Otherwise, due to tool heat, you will gum up the tool and/or part.

All this stuff is subjective, and folks have different opinions on 3D printing.  It's best to experiment, and figure out what works best for you.

Mike

[Garys]

With printing the different types of plastics have you stuck to using brass nozzle's or have you changed over stainless?

[sagrada737]

Hey Gary,

Good question...   I have tried various kinds/types of nozzles, from Ruby nozzles to the standard brass types.   What I have settled on is a 0.6 mm from MicroSwiss.  It is their A2 hardened Tool Steel Plated nozzle that has a special coating.   These nozzles offer excellent durability when printing abrasive filament that have a mix of carbon fiber.  They are also reasonable in price.  Here's a link:

https://store.micro-swiss.com/collections/a2-hardened-steel-plated-nozzle

Mike

[Garys]

Awesome thanks Mike, I will pick one of these up. Ive only been printing with PLA but want to try some of the newer mixed fibre filaments.

[sagrada737]

Hi Gary,

I should have mentioned that when I print TPU or CarbonFiber mix (Nylon-CF; PETG-CF, etc.), I use a "Direct Drive" feed for the filament.  The typical Bowden Tube drive system is problematic for feeding TPU (flexible) and CarbonFiber (stiff) type of filaments.

Also, for printing TPU, be sure to turn Retraction OFF.

SunTop makes a very nice PLA-CF material that prints fine with the standard Bowden, and it will feed nicely through a Bowden tube.

Mike

[Garys]

Thanks for the tips Mike, I have also been reading about changing out the bowden tubing to the capricorn brand for the higher temp printing.

[sagrada737]

Hi Gary,

Changing over to the Capricorn brand tubing is not a bad choice.   One thing to consider however, is that the tubing "push-on" connections are perhaps more important than the tubing.   

This is because that during the "Retraction" cycle, which occurs many times during a typical 3D printing process, the tubing is stressed forward and backward, as the filament is forced into the tubing by the extruder gear.  Teflon type tubing helps to decrease this friction, but since the tubing flexes and turns on its way to the Hot End, there is friction buildup between the filament and the inside of the tubing.

This is more noticeable with the somewhat "sticky" nature of TPU, and the rather "stiff" nature of carbon fiber filaments.   As a result of this friction and constant flexing, the Bowden tube wants to dislodge the grip that the connector has on its outside diameter.   This constant "wiggling" of the tubing tends to compromise the grip that the connection has on the tubing, eventually causing the tubing to move back and forth during retraction cycles.   

The worst case is that the tubing simply comes loose from the connector.  More typically, this compromises the Retraction settings, potentially compromising the print result.

To help keep this from happening, use a high quality Bowden tubing.  Make sure that the connectors you are using are compatible with the tubing to ensure a reliable grip on the tubing.

As far as "high temperature" printing is concerned...   You might consider changing out your Hot End for the one that MicroSwiss sells.  It has a design that thermally isolates the heat chamber from the Bowden tubing.  This is important, as heat will compromise the connector grip on the Bowden tubing at the Hot End side.

Mike