Alternatives to Cardboard Heat Barrier Under The Heated Bed?

So far I've just been printing with PLA but soon I want to try ABS. Before I do I need to make the insulation barrier under the heated bed. I seem to remember someone posting that they used a fiber sheet/board of some type for this but now cannot find the post. It's driving me nuts that I can't find it. Am I remembering something I didn't read? I hope I'm not making it up. I thought too it was a German product. Hmmm?

Anyway, another idea that came to me was to use some leftover fiberglass cloth that is kicking around taking up space in my office. That could make for a functional and effective heat barrier. Would be light too I think and look cool. Otherwise I can surely build the cardboard heat barrier.

But, I'd be so happy if someone could point me to a post I describe above if only to help reassure me I am not losing it LOL ... thanks.

Hi Garry,

Probably part of this thread here. The keyword to search for is MTplus.

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

I think the MTplus printing surface is a fibre/resin composite that just allows the printed material to stick better at lower temperatures, rather than an insulation layer?

The purpose of the insulation is just to reduce the time it takes for the heated bed to reach the kind of temperatures you need for ABS. I print on a 3mm IKEA mirror tile at 135C/125C as read by the thermistor, which translates to 110C/100C on the surface about 50mm in from the edges (it is slightly hotter in the middle).

Without the insulation the bed takes much longer to get to this temperature - mine currently takes 10 minutes to preheat with cardboard completely filling the gap between the bed and Dibond and a cardboard "blanket" that I put over the top of the glass.

I've read elsewhere that cork is better at insulating than cardboard, so I have obtained some sheets of that but I haven't tried it yet to compare. I don't know the relative insulating properties of fiberglass cloth but anything is worth a try I suppose as long as it doesn't melt or short the bed/thermistor!

The time taken for the heated bed to get up to temperature can be significantly reduced by placing an insulator, such as a folded cloth, on top of it. Just make sure you remove it before hitting the 'print' button.

I use this technique when printing ABS rather than PLA.
Alan

Yes, definitely worth it, though I'd love to find a reliable way to automate this!

I have my bed preheat and ooze-free gcode incorporated into my slicer's start code and I usually have plenty of time between the bed reaching temperature and the nozzle coming down to meet the bed to remove my cardboard blanket.

The other day the phone rang at the precise moment that I was meant to do this (I *really* hate it when I tell someone to wait just a minute, and they reply with "oh, it won't take long, I just wanted to say...." and then bang on for ten minutes) so the nozzle hit my cardboard cover. All this did though was lift the x-carriage off the brass nuts - it only took a few minutes to sort out and get printing again. I imagine if I'd completely forgotten about it and let the print actually start then the mess would have been worse, but it's not the end of the world. Being able to do this completely unattended would be ideal.

Thanks guys. Actually I was looking for material that I thought someone used in place of the cardboard but maybe I WAS dreaming ... LOL. Anyway I am learning something because I thought the insulation was to protect the carriage etc. when in fact it is to help the glass heat quicker. Now not sure if I will use card board or something else but I definitely will try a blanket of some type on top of the glass.

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QuackingPlums
I have my bed preheat and ooze-free gcode incorporated into my slicer's start code and I usually have plenty of time between the bed reaching temperature and the nozzle coming down to meet the bed to remove my cardboard blanket.

I have been wanting to try doing the ooze-free start for Slic3r but have not felt comfortable enough yet to try. Would you mind sharing this code?

I use a 1/2" sheet of foam insulation board under the heated bed. I think another benefit of insulating is increased efficiency, because you lose less heat from the underside of the bed.

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BrianC
I use a 1/2" sheet of foam insulation board under the heated bed. I think another benefit of insulating is increased efficiency, because you lose less heat from the underside of the bed.

Is this the type of stuff you mean? Insulated Board Or something without fiberglass?

There are some insulating materials with two sides of foil but the inside is plastic-like bubble wrap but that would likely get too hot. Or maybe not? Would be more fun working with that than anything that has fiberglass in it however.

Be careful with anything that has a conductive surface - remember you have the thermistor wires as well as the main power wires to the bed under there that can be shorted.

I use the following start gcode in Slic3r for a ooze-free start (it's not quite unattended because I still have to remove my cardboard blanket):

; ***** Ooze-free start with wipe *****
G90				; Set positioning to absolute
G21				; Set units to millimeters
G28				; Home all axes
G92 E0				; Reset extruder
M42 S255 P28			; Turn on the gantry LEDs on FET 1
G1 Z200 X-45 Y95 F12000		; Move above block point
M190 S[first_layer_bed_temperature]				; Pre-heat the bed & wait as it takes 10mins
M117 Remove blanket!
M104 S[first_layer_temperature]	; Start heating the extruder before lowering the nozzle
G1 Z0.1 X-45 Y95 F12000		; Lower to block point and block nozzle
M109 S[first_layer_temperature]			; Wait for extruder to reach first layer temperature
M117 Starting in: 30
G4 S5			; Wait another 30 seconds for nozzle length to stabilise
M117 Starting in: 25
G4 S5
M117 Starting in: 20
G4 S5
M117 Starting in: 15
G4 S5
M117 Starting in: 10
G4 S1
M117 Starting in: 9
G4 S1
M117 Starting in: 8
G4 S1
M117 Starting in: 7
G4 S1
M117 Starting in: 6
G4 S1
M117 Starting in: 5
G4 S1
M117 Starting in: 4
G4 S1
M117 Starting in: 3
G4 S1
M117 Starting in: 2
G4 S1
M117 Starting in: 1
G4 S1
G1 E3				; Extrude 3 mm of filament
G1 X45 Y95 F12000			; Wipe nozzle across the bed
G1 Z1 				; Raise nozzle to 1 mm ready to begin main sequence
G92 E0				; Reset extruder
M201 X2000 Y2000 			; max acceleration in X and Y
M117 Printing...

I have a Panelolu2 with modified firmware so that the M117 commands echo useful messages to the screen (G4 commands display the message "Sleeping" by default but I overrode that). If you don't have a Panelolu2 then those commands probably do nothing - the same with the gantry LED codes.

I deliberately keep the nozzle high during bed pre-heat because it gives me more time to remove the blanket, plus the sound it makes as it lowers is a good alert for me to do it (as long as the phone doesn't ring or my 2-year old doesn't come running in!).
The time taken to drop to the bed plus the extra 30 seconds is almost a minute, which is enough for the nozzle length to stabilise.

I hope the comments make it self explanatory. If they don't then please ask!

How about a bed cover with a hinge in the middle made from tape so it can fold in half. Then attach it to a bar across the back of the machine with a spring or weight that makes it want to be vertical. You can then pull it down over the bed and attach it at the front with a hook or magnet, When the bed has heated move it forwards and the cover will be released to retract to the back out of the way.

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[www.hydraraptor.blogspot.com]

Great suggestion! I'll get right on it!

@QuackingPlums
Thank you! Cardboard it is. I'm not going to mess with things I don't fully understand. And thank you for sharing that code. I am going to work through it to understand it and might be back with questions. Best regards,

Garry

Perhaps [www.electronic-things.de] ?

I got some ceramic wool kiln insulation but I never dared to use it as it seems too much like asbestos to me. I am not sure if it is a good idea having things like fibreglass wool on a moving platform as it might create air born fibres unless it is sealed in with tape or something.

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[www.hydraraptor.blogspot.com]

Quote
Ralph Hilton
Perhaps [www.electronic-things.de] ?

Yes, this would likely be it. Thank you.

Google Translate doesn't seem to like operating on this website so I can't gain a lot using it but I wonder if this is a ceramic matte along the lines of this? Fireproof Ceramic Thermal Insulation Blanket . Or this: Superwool® Fibre blankets. If I can find this type of material easily at - maybe a pottery shop - I might try it.

I posted before seeing yours Chris. Yes, loose bits made airborne by a shaking bed would not be cool.

Edit: Perhaps enclosing it in Kapton might work to prevent material from becoming airborne? But maybe that could compress it if not done carefully. Maybe the Kapton would negate effects of the matte? But I suspect it could be done. It might just be too much work for too little gain but that I can't say ..

Edit Again: I should have read your post fully! Oops. You had the tape idea already. Sorry.

Edited 2 time(s). Last edit at 11/30/2013 02:02PM by Garry Bartsch.

Garry - the site has a button near the top to get it in English. It does look similar, yes.

Quote
Ralph Hilton
Garry - the site has a button near the top to get it in English. It does look similar, yes.

Thanks Ralph, that worked better than trying To use Google Translate! We made the cardboard insulator yesterday and it seems to work very well and it's so light. Among others it sure does slow down the cooling of the bed when the print is done. I can really see the benefit of the cooling fan design.

I have the "standard" layer of cardboard fitted to the Dibond, which covers the screw heads etc. The remaining 4/5 layers of cardboard I have taped together with a tab that sticks out the front - this means that I can slide the thicker wad in and out easily as it doesn't snag on anything. If I'm in a hurry or I'm sitting next to my printer when a job completes then I can simply reach over and pull out the insulation, leaving the fan to cool the job in about 5 minutes. If I'm not at my desk then, well, it doesn't matter how long it takes to cool... ;-)

@QuackingPlumbs
OK, I got enough time to take a stab at beginning to understand G-Code. I don't have a Panelolu2 so stripped out bits that I think would not apply to me. Will the code below blow up the machine or does it do as you intended? Do I just put this in Slic3r start code? Thanks!

; ***** Ooze-free start with wipe *****
; ***** Original author QuackingPlumbs *****
; ***** Mangled by Garry Bartsch *****

G90								; Set positioning to absolute
G21								; Set units to millimeters
G28								; Home all axes
G92 E0							; Reset extruder
G1 Z200 X-45 Y95 F12000				; Move above block point
M190 S[first_layer_bed_temperature]		; Pre-heat the bed & wait as it takes 10mins
M104 S[first_layer_temperature]			; Start heating the extruder before lowering the nozzle
G1 Z0.1 X-45 Y95 F12000				; Lower to block point and block nozzle
M109 S[first_layer_temperature]			; Wait for extruder to reach first layer temperature
G4 S30							; Wait another 30 seconds for nozzle length to stabilise
G1 E3							; Extrude 3 mm of filament
G1 X45 Y95 F12000					; Wipe nozzle across the bed
G1 Z1 							; Raise nozzle to 1 mm ready to begin main sequence
G92 E0							; Reset extruder
M201 X2000 Y2000 					; max acceleration in X and Y

When printing ABS I usually wait for the bed to reach the first layer temperature, -5 degrees, before I set the extruder temperature.
In the time it takes for the bed to raise 5 degrees the nozzle can get up to 230 or so quite easily.

I also find a heat gun pointed at the bed for a minute (or to 100 degrees) also moves things along a lot quicker... you're going to expend the energy anyway, may as well speed up the process..

That looks good to me Garry.

Maybe I'm using an old version of Slic3r but I am unable to use formulas in my variable substitutions, so

M190 S[first_layer_bed_temperature] - 5

didn't work for me. Maybe I have the wrong syntax.

Also, if I take my cardboard off at T-5C then it takes a lot longer to get that last 5 degrees out of my bed (my first layer temps are between 125C and 135C). I know it takes a little longer but I'd rather the bed wait for the extruder than the other way round.

YMMV - I have already noticed that Chargenut's printer has slightly different heating characteristics, and we built his about two weeks before mine.

The heat gun is a good idea though. I knew that £10 special from Lidl was a good buy...