D-Bot 3D Printer

[Gina]

Having problems with a loose Precision Piezo module in the E3D extruder when hot at present but that's another matter!  I hate 3D printers at times but can't manage without!!

[tekkydave]

I thought I would ditch the borosilicate glass and try a magnetic PEI sheet.

So I bought one of these

I removed my bed from the D-Bot to make it easier to apply and gave the surface a good clean with meths.

The first part to apply is the magnetic base which sticks to the metal bed

The best method is to score the backing with a sharp knife so the first quarter can be peeled off separately and stuck down. Then clamp it to the bed so it can't slip.

Then peel off the last quarter and stick down carefully avoiding any bubbles.

Then remove the clamps and stick the remaining three-quarters down

 

The next part is the steel sheet which sticks to the magnetic sheet very well. The small tabs at the front are needed to prise it off the base.

There is a yellow PEI sheet to stick to the steel sheet. I followed the same procedure as with the magnetic sheet.

There are a few tiny bubbles on the left side of the sheet which I'm hoping will smooth out when I heat it all up.

The PEI sheet was slightly larger than the steel sheet by a few mm each side so that was trimmed off.

Finally the plate was fixed back to the z-carriage and connected back up to the controller

I'll have a go at printing something tomorrow and report back.

 

Edited October 9, 2019 by tekkydave

[Chriske]

Why ditch the glass..?
imo it is the perfect solution.

[tekkydave]

Because of the size of my bed (340x340mm) it was proving hard to keep it clamped in place. The glass is 300mm square.

I now effectively have a magnetic bed so I can try other solutions if not happy with the pei sheet that came with the kit. It is also possible to print directly on the steel sheet so I can flip it over and give that a try.

[Gina]

I tried a PEI sheet - total disaster!  Filament sticks better to clean glass when hot and releases nicely when cold.  The hot nozzle burnt the PEI when Z homing using the Precision Piezo Z probe.  I ended up removing the PEI sheet and then struggling to get the goo off, though I managed it in the end. 

Unfortunately, before the PEI disaster on the 300mm square bed I bought a PEI sheet to attach to the aluminium bed of my Giant printer when I get back to upgrading it but I probably won't be using Precision Piezo Z probing.  I tried using glass on top of the 500mm square aluminium bed but guess it was too thick as it didn't get hot enough.  I haven't decided if I shall use the 500mm square PEI sheet yet.

Edited October 9, 2019 by Gina

[Stub Mandrel]

The most satisfying thing about 3D printing is the 'crack' when the print self-releases from the borosilicate glass half an hour after the bed stops heating. Sadly I'm often too impatient to wait...

[Chriske]

I have several sheets of glass for each printer.
When a print is done I remove sheet + sticking part and install a fresh sheet of glass and continue even before the alu printbed is cold.

[tekkydave]

11 hours ago, Chriske said:

I have several sheets of glass for each printer.
When a print is done I remove sheet + sticking part and install a fresh sheet of glass and continue even before the alu printbed is cold.

How do you secure the glass to your bed? I have a gap of 20mm on the L & R sides of the glass, 30mm at the back and 10mm at the front. Foldback clips are not suitable. I like glass as a surface but since I increased the size of the bed from 300x300 to 340x340 its become an issue securing it physically.

[tekkydave]

13 hours ago, Gina said:

I tried a PEI sheet - total disaster!  Filament sticks better to clean glass when hot and releases nicely when cold.  The hot nozzle burnt the PEI when Z homing using the Precision Piezo Z probe.  I ended up removing the PEI sheet and then struggling to get the goo off, though I managed it in the end. 

How hot is your nozzle when probing? I have mine at 130 as it is soft enough to squish any filament on the nozzle.

[Chriske]

33 minutes ago, tekkydave said:

How do you secure the glass to your bed? I have a gap of 20mm on the L & R sides of the glass, 30mm at the back and 10mm at the front. Foldback clips are not suitable. I like glass as a surface but since I increased the size of the bed from 300x300 to 340x340 its become an issue securing it physically.

I use clips. But I always make the sheets of glass 15mm larger at two side, so I still can use the full printable surface.

[Gina]

49 minutes ago, tekkydave said:

How hot is your nozzle when probing? I have mine at 130 as it is soft enough to squish any filament on the nozzle.

260°C

[Stub Mandrel]

5 minutes ago, Gina said:

260°C

Yeek!

For PETG I presume?

[Gina]

Yes.

[Chriske]

I set PLA always at 235°C for a 0.4mm nozzle, 245°C for a 0.7mm nozzle and 250°C for a 1.5mm nozzle.
I always use max partscooling(powerfan) and max heatsink fan speed. For that 1.5mm(Volcano) heatsink I even use a 70(!) mm powerfan at max speed.
This allows me to print rather fast.

[Gina]

I use 240°C for PLA and 260°C for PETG except that I tried 280°C for PETG where there were steep overhangs but not sure it helped - I have some more experimenting to do.  I didn't realise a bigger nozzle wanted a higher temperature.  I tend to use a 0.4mm nozzle for higher precision parts and 0.8mm or 1.2mm for bigger, lower precision parts.  Though on my Giant printer I've been up to a 3mm nozzle plus various smaller sizes and my own design hotend.

Edited October 10, 2019 by Gina

[Chriske]

1 hour ago, Gina said:

I didn't realise a bigger nozzle wanted a higher temperature.

There's absolutely no need to raise temp using a bigger nozzle.
But as I want to combine very big nozzles and fast printing, higher temp is a absolute necessity. Standard speed of my 1.5mm nozzle is 45to50mm/s, sometimes I go even faster. Using 'SpiralVase' modus I can go as high as 55to60mm/s. To be clear: That is all done with a Volcano hotend of coarse.

[Gina]

I run at 80mm/s with 0.8mm nozzle.  Volcano hotend with 60W heater.

[tekkydave]

Printing now. I cleaned the PEI surface with what I normally use for glass :- Soap & warm water

PLA seems to be sticking quite happily to the surface so far....

I read online that it is good to rough-up the surface of a new PEI sheet with wire wool prior to first use. Any truth in that PEI fans?

 

Edited October 10, 2019 by tekkydave

[Stub Mandrel]

Crikey, I've come down to 200C for PLA. No loss of layer adhesion and less ooze.

[Chriske]

51 minutes ago, Stub Mandrel said:

Crikey, I've come down to 200C for PLA. No loss of layer adhesion and less ooze.

Funny, so everyone has it's own formula to work with...

I wouldn't even think of printing @ 200C. My steppers would stall..!

[tekkydave]

Finished!

The print was firmly stuck to the PEI sheet at the end of the print. I couldn't pull it off. Not that I would ever want to do that.

Removed the steel sheet from the magnetic build plate and flexed it a few times and.... pop... off it came.

The base isn't as shiny as with glass but its still quite a nice satin texture.

I'm OK with PEI so far and the magnetic bed. I just don't like the look of the PEI sheet supplied with the kit. I'm going to look for a steel sheet with PEI already applied I think. Black would be nice

The part is a hook that sits inside our pull-out rubbish bins in the kitchen in case you were curious   Not the best print I've ever done but still getting my Cura settings right.

[Stub Mandrel]

1 hour ago, Chriske said:

Funny, so everyone has it's own formula to work with...

I wouldn't even think of printing @ 200C. My steppers would stall..!

Maybe because I use low print speeds?

[Chriske]

190°C....😱

[Stub Mandrel]

13 hours ago, Chriske said:

190°C....😱

[Chriske]

😱😱  180°C  😱😱