3D printer bed

[the_digital_dentist]

I have been looking around and found that some printers use an unheated acrylic bed for printing with PLA, and it appears they print directly to the acrylic, no kapton tape, go glass, just acrylic.  Can any of you experienced 3D printers out there tell me if other arrangements work better?

[Pete Prodoehl]

It's true... Gary is our main PLA guy, and he was printing on blue painters tape with an unheated bed. I think he's also printed on glass with success.

I've just started to see warping issues with ABS on my heated bed. I'm not sure if it's due to my larger prints, or the cold weather, or a combination of the two. I may experiment with a heat lamp, space heater, or enclosure for my printer in the coming weeks.

Pete

[Kevin Crowley]

I have been thinking that silicone baking sheets or parchment paper would make good beds.  Whether heated or unheated would be better I have no data so no opinion.  I do know that plastic I have melted in the oven on silicone or parchment has separated easily and I was able to reuse both materials.

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[Gary Kramlich]

I've been printing on heated glass, well not for awhile, new parts in this week to repair my printer.  But once I get them I'll try it on cold glass and report on how it goes.  If anyone can confirm that cold acrylic works, I'll probably go that route :)

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[Ed Hagopian]

I've been abs juicing it and its been great other than a smidge messy. 85 degree bed on 3mm glass. Pla is far more forgiving on heat but I want to make structural items and abs is better for that. But I have been contemplating going to 1.75 from 3mm filament. Just got 2 more kg so that'll have to wait a bit.

[Pete Prodoehl]

Ed, do you want a bunch of 3mm PLA?

Also, I tried ABS juice but it was just way too messy... is there any chance it helps prevent warping/shrinking of parts?


Pete

[Joe Kerman]

The entire build is dependent on how well the first layer sticks to
the bed, and its no fun if the part never comes off the bed. So you
exploit some interesting properties of the materials.

ABS's magical properties are that it sticks to COLD acrylic, and
HOT(~110C) CLEAN kapton tape, as if it were glued there. it sticks to
the acrylic so well, you will likely need a chisel to reuse the sheet.
kapton is especially magical because if you let it cool, the part
naturally un-sticks itself.

PLA's magical properties are that it sticks to COLD blue painters tape
as if it were glued there. you sometimes have to sand some of the
blue tape off the part, and replace the tape on the bed often, but it
works very well. It also sticks very well to COLD acrylic (too well,
may require chisel) HOT(~90C) CLEAN glass as well as HOT(~90C) CLEAN
kapton tape. PLA is quite... sticky, and it will stick to cold glass
as well. but that makes part removal a tad tricky :)

Cant emphasize the clean part enough. I keep a small spray bottle of
rubbing alcohol near my printer to clean the kapton. fingerprint
grease ruins its sticking properties quite a bit.

I havent printed enough with PLA to know if there are advantages to a
heated bed. I have had no trouble on an un-heated acrylic bed coated
with blue tape.

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[Ed Hagopian]

helllll yes I want some 3mm pla. :)

[Ed Hagopian]

I've used Kapton, with varying success. My bed doesn't want to go above 90c, and it's hit or miss if it sticks. However if I give it a wipe with Acetone, I can't get the piece off, I'll rip up the kapton doing so. I've been using the juice in a very diluted mix and just dabbing it on, and not only does it stick well but just pops off when cooled. Blue tape with acetone makes ABS stick insanely hard as well.

[Ed Hagopian]

Warping at the base layer usually occurs due to an over heated bed - but like I said I had mine maxed at 90c which is 20c lower than what they recommend, and I got hourglassing like crazy. With ABS juice at 85 I get almost no warping at all.

 

Picky crap this plastic I tell you...

[Kevin Crowley]

Since I use acetone to weld plastic together I recommend a looooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong wait after wiping a surface with it before trying to place molten plastic on it.

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[the_digital_dentist]

OK, so what's the consensus- what sort of bed(s) should I have on my machine?  Should I use an aluminum plate with a heater, then have exchangeable pieces of glass and acrylic to use for hot and cold printing?  

Should I spring for an invar plate for hot-bed printing?

Thanks!

On Monday, October 8, 2012 12:52:55 AM UTC-5, the_digital_dentist wrote:

[Pete Prodoehl]

Well, there is no consensus really...

I use this one:

  http://reprap.org/wiki/PCB_Heatbed

spaced above a piece of wood with 4 leveling screws, as you can see here:

  http://www.flickr.com/photos/raster/7419866678/

I then have a piece of glass covered with Kapton tape that I attach to the PCB with bulldog clips (AKA binder clips) while printing.

I actually have multiple pieces of glass so I can pull off a hot one (to allow it to cool and the part to separate) while I put on an empty one to start printing again.

As mentioned, I use 3mm ABS. I don't use PLA, and I don't print cold. My bed is heated to 110˚ Celsius (though I may try to lower it due to some warping I am seeing on larger prints.)

YMWV!


Pete

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[Kevin Crowley]

Just thinking out loud here.  Pete, what about heating the bed to 110˚ Celsius for the first layer and then lower the temp as you print to say 80˚ Celsius.  Just an Idle thought.

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[the_digital_dentist]

Now that extruders have arrived, it's time to get back to work!

My printer can accommodate up to a 12"x16" print bed.  Since 12"x12" heaters are readily available, I'm thinking of going with 12"x12" print bed.

OTOH, If I am operating unheated, the extra space on a 12"x16" bed could be useful.

So I'm thinking of using a 12"x12" piece of aluminum with heater on the bottom and clamping on a larger sheet of acrylic when operating unheated.

Any thoughts on thicknesses?

[Tom Gralewicz]

I have a sheet heater from an optics machine I brought to the space last night but forgot to mention, you might be interested.

A friend used a sheet of aluminum (about 1/4" thick) and a bunch of bolt on power resistors for his heated bed, it works great for him and you can make it any size you want.

Tom

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Tom Gralewicz
Miller Electronics Recycling
(414) 380-1716
www.deadcomputers.com

[the_digital_dentist]

How big is your heater?  Do you have voltage/current specs or a model number?

I looked into power resistors, but unless we have a bunch of them at the space, or you know a cheaper source than I have been able to find, they cost a bit too much compared to the 12x12 sheet heater that is available for $60 from qu-bd.com:

http://store.qu-bd.com/category.php?id_category=19

Thanks!

[the_digital_dentist]

Nevermind...  I did some digging and found some 25W 0.5 Ohm 1% resistors for $2.65 each at Alltronics.  I'm going to go with the 12" x 16" bed and bolt on either 16 or 20 resistors in series-parallel for 288 or 360 watts at 12V.  I'll order a 12" x 36" piece of 1/4" aluminum plate and cut it for my own printer and for the one under construction at the makerspace. The machine at the makerspace can go to 12"x20".