Printing directly on the glass

Having had a few first layer failures with the bed set to 70 and hot end at 205 then altered to 65 and 195
What are the optimum temperatures for first layer, then the rest of the print, that you're all finding for direct to glass printing?

When I print direct on glass I use 70C for all layers. I used 65C by mistake once and the print was ok. However, I find direct printing on glass works less well for shapes with lots of sharp curves in the perimeter. So I print those on dilute solvent cement instead. Also set the speed for small perimeters to a really low value in slic3r, this helps when printing a part that includes holes in the first layer.

After the bed thermistor indicates the correct temperature has been reached, it takes another 2 minutes for the temperature at the surface of the glass to stabilize.

It is really important to get the nozzle height just right before the print. Also, wash the bed in hot soapy water (not acetone) and wipe it with vinegar just before printing.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

We don't recommend printing directly on glass - it's less than reliable, though appreciate that it does work for some people. We also don't like re-applying surfaces each print, or doing too much cleaning! Which is why we print on Kapton tape. 20+ printers, printing 20 hours a day, 5 or more days a week. We clean the beds once a week with Acetone, and replace the Kapton probably no more frequently than once every 4 to 6 months. See: [reprappro.com]

Ian
RepRapPro tech support

Ian, how do you remove the print from the Kapton? When I was printing on Kapton, I often found that the print stuck too well, and for prints with low height such as the snowman I couldn't remove it without slipping a blade under it - which damaged the Kapton.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I can confirm that washing in hot soapy water then washing with vinegar solved my problem completely. I set the bed to 75 degrees having tested the bed temp with my IR thermostat and found a 5 degree difference.
Having tried both Kapton and plain glass, the ease of removing a print from glass with a bare Stanley knife blade is my preference now.
Any idea why the print layers are detached in the attached photo?
Thanks
Jon

Quote
Jon Steward
I can confirm that washing in hot soapy water then washing with vinegar solved my problem completely. I set the bed to 75 degrees having tested the bed temp with my IR thermostat and found a 5 degree difference.

I did some tests on bed temperature. With 65C commanded, when the bed temperature reported by the Duet had reached 62.5C (close enough for my firmware to consider the bed up to temperature), the top surface of the glass was at only 47C. After another 2 minutes the top surface of the glass was at 54C, with the eventual value reached being 56C. This was measured using a thermocouple taped on top of the middle of the glass. So now after the M116 command I use to wait for the bed to reach the target temperature, I have a G4 P12000 command to wait 2 more minutes.

Quote
Jon Steward
Having tried both Kapton and plain glass, the ease of removing a print from glass with a bare Stanley knife blade is my preference now.

I found that once the glass has cooled to room temperature, I don't even need a knife to remove the print - unlike when I used Kapton.

Quote
Jon Steward
Any idea why the print layers are detached in the attached photo?

Two ideas: (1) I think the aerofoils in that inlet duct are too thin, I get the same problem; (2) looking at the top surface of that print, I think you are under-extruding. I've seen the same thing recently, starting at roughly the time that I upgraded slic3r from 1.0RC2 to RC3.

PS - also I found that holes oriented in the z-axis like those come out better if I set the speed for "Small perimeters" in slic3r to a very low value. The slowest the X and Y axes will do is 15mm/sec in the current firmware, but I am thinking of reducing this.

Edited 2 time(s). Last edit at 03/29/2014 11:09AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
I often found that the print stuck too well, and for prints with low height such as the snowman I couldn't remove it without slipping a blade under it - which damaged the Kapton.

I use Kapton all the time and agree that a major issue is with removing some items. The good stickiness for printing and durability are major pluses.

Removing by hand I found difficult for anything but tall thin pieces as it is difficult to get a good grip, The strategy I use now to remove items is to use adjustable pliers (often called water pump pliers) that cover a wide range of openings. I put some kitchen paper over selected bits of the part where there is good strength and twist that part upwards away from the glass. I'm not levering against the glass but more just trying to break the seal at that bit. Often there will be a little crack noise as that starts to release. For easy parts that might be enough and it comes away. For trickier parts I sometimes have to try 2 or 3 different places. So far that has worked OK for me as I did not want to use any blade which defeats part of the objective.

I to print directly on glass
First layer: bed:60 ,Head:210 (if anything I would lover this to 200 or 205)
Other layers: bed:50 ,Head:190
I understand it is not advised to print directly on the glass but it is very convenient ;-)
sometimes (once every second week) i wash the glass in sulfo (soapy water) and apply a thin layer of hairspray
Some parts still attach to strongly (I never wait for the parts to cool unless i fear they will deform) and if have the feeling of having removed to much hairspray I apply a little extra.
This works pretty good for me so I have not done much testing with neither setting nor alternative procedures.

hihihihi I print on my Red Glass table a treat with no additives...
If it doesn't stick on the first layer it is normally down to one of these problems:-
1) Glass not scrubbed with washing up liquid, then rinsed with hot water. (In other words dirty or greasy).
2) Nozzle height to high...
3) Bed not level... (I don't use compensation here, I try to keep a flat bed). I strengthed the MDF table with 3mm composite board which is quite stiff
4) HotEnd to cold....
5) Damp Filament.
6) Printing To Fast.

To fix:-
1) Wash it. Dry it with CLEAN paper towel. If you see a rainbow while drying it, then there's still grease or Washing up liquid on it still, so clean it again.
After mounting the glass, I then use clean paper towel to apply a final clean with vinager while the glass heats up. (I have found some cheap paper
towels tend to dust badly). Sometimes I just clean with vinager between prints, depending on how lazy I am.
I normaly find the print sticks very well, and can't be lifted off the glass, so I remove the glass and print and rinse under the cold tap, and the print
floats off a treat...
2) I re-check the nozzle height when homing the Z axis... If it's too high I lower it to touch the glass. Take a batch of readings from the probe using
G31 then come up with an average. Then use G31 Z0 Pxxx (where xxx is my average reading). Then re-home Z.
If the feeder starts jumping back when the print starts, then it means the HotEnd is either to cold, or the HotEnd is so low it's on the glass stopping the
plastic from coming out. (I have heard of people raising the amps on the stepper motor for the feeder, which I don't think is good myself.
I run with the original amps here).
3) Check the front bearing is located in the frame correctly. (It can be knocked out of location).
Sometimes when the printer is moved or knocked the bed can wander a little. I start at the back, working along the Y axis, then work back along the
front of the Y axis.
4) I increase the HotEnd temp by 10', but watch out for fine threads, if you get these then drop the temp by 5' untill they are gone.
5) I have found that the print picks up sometimes if the filament has absorbed moisture. I change filament, and stand the damp reel on the radiator
for a day or so which seems to sort it out. Sometimes if the filament has picked up allot of moisture then you might hear it popping as it goes through
the HotEnd where the water flashes off in to steam and makes a Pop or Crackle.
6) I try not to dabble with to many of the Slic3r settings once it's printing ok. But I did experiment increasing the speed on the first layer which didn't
go well. So I leave it as standard now.

Hope that helps people using Glass or Tape...
Kim....

Edited 1 time(s). Last edit at 03/29/2014 02:20PM by KimBrown.

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Please send me a PM if you have suggestions, or problems with Big Blue 360.
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Working Link to Big Blue 360 Complete

I've been printing all day directly to the glass.
No problem whatsoever after washing in hot soapy water first thing this morning then a light going over with vinegar between prints. (thanks DC42)
I've also recalibrated my extruder from E423 to E429 following DC's advice.
The attached photo shows before in gold and after in white.
Good progress today.
Thanks
Jon

I print on kapton.
When i remove print i spray some electric component test cooling spray on them then i can take them of whit my hand (-50 Celsius)

To remove parts from Kapton, we first drop the bed temperature to 40C, using a bed temperature command in the end gcode. Most parts will have a direction, when they're pushed, that will release them from the bed, particularly taller objects. Then it's a case of finding the correct tool to lever up a part, preferably at a corner. Sometimes it's a length of M5 rod, or an M3 screw. Other tools include a pair of long nosed pliers, and it can be useful to print two parts close together - then you can slip a screwdriver between them and lever one against the other. Even using an old printed part as a block to lever on. The main point is not to scratch the Kapton, and preferably not touch it at all; once it gets damaged, it will tear more over time. But if you're careful, it will last for ages, prints stick well (we use the same beds for ABS too) and require minimal maintenance.

Ian
RepRapPro tech support

Edited 1 time(s). Last edit at 03/29/2014 08:28PM by droftarts.

I print right to the glass. I apply a fine mist of hairspray on the glass and very tall pieces with tiny bases stick so well they cannot be pulled off even after bed cools to room temp. Pop the glass with part in the freezer for a min or two and it falls off as if magic. Once in a while, I clean off the excess hairspray with a little acetone on a paper towel. I print with the bed temp at 65 and print from nozzle being as high as a folded over paper slides loosely under it.

i print on glass with UHU glue stick

I like to print on the glass but I had an experience that I can not explain....
a day of the past week...
8.30 / 13 all morning without any problems printing on glass... after h.13 problems begin ...doesn't stick.
the same experience with two nearby printers with the same files and PLA
13.30 after several checks back to the Kapton....everything seems ok prints continue (both).
h.21..... ...doesn't stick on kapton!
I cleaned with acetone to solve the problem....

the next morning printing again on the glass without problems
I think we should have the printer in a box with controlled atmosphere to obtain reliable data..but is it possible?


Dario

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Ormerod 187
Firmware Electronics: Duet 0.6
Firmware Version:1.18.1 (2017-04-07)
Web Interface Version:1.15a
Slic3r 1.2.9a and Simplify3D 4.0.0
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