1 Topic by Staffordknot

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Topic: Bed levelling... How do other printers do it?

As with many of you, you've probably thought or have built your own printer... I'm considering the same but i wanted some sort of self levelling or perhaps digitally controlled self leveling.

I was wanting to level the bed using steppers to rotate a threaded bar similar to the existing way just electronic. I've seen the fantastic auto sensing and software fix for the bed on here but its important that the print head is perpendicular to the bed to print components that have right angled edges between print bed and the vertical.

So how do more expensive / cheaper printers do it? Are four screws better then three? Or should two points be sprung fixed and only rotate two points using the steppers?

How do professional models do it or cnc machines?

Just a brainstorming exercise. Cheers

2 Reply by elmoret (edited by elmoret 2014-01-12 20:46:51)

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Re: Bed levelling... How do other printers do it?

Most DIY printers are manual. Three screws are better than 4. A plane is over constrained by 4 points.

I can't remember the last time I leveled the bed. It was easily 500 prints/6 months ago.

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3 Reply by Claghorn

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Re: Bed levelling... How do other printers do it?

I haven't made the final firmware changes for this yet, but I have high hopes for using the extruder nozzle as a bed level sensor in combination with a force sensitive resistor:

http://home.comcast.net/~tomhorsley/har … level.html

(most recent results are at the bottom of that rather long drawn out web page :-).

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4 Reply by Staffordknot

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Re: Bed levelling... How do other printers do it?

Elmoret,  I'm looking at quite a big print bed, but printing the same object multiple times at once using say 4 or six hotends all on the same head but spaced sufficiently apart so i'm a little worried that even a little bit out of level might become an issue when your hotends are say 4 inch apart and from one end to the other hotend maybe 300mm.

Hmm thats a lot of prints without levelling. I am looking to lift the glass off between prints as it takes to long for the whole thing to cool down and when printing in abs i am sometimes putting my bed under undue pressure to remove the print. (Out of impatience usually)

5 Reply by spapadim

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Re: Bed levelling... How do other printers do it?

elmoret wrote:

I can't remember the last time I leveled the bed. It was easily 500 prints/6 months ago.

+1 (with glass bed, and provided screws are properly tensioned - which on SD they are, not rocket science anyway smile

6 Reply by elmoret

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Re: Bed levelling... How do other printers do it?

Staffordknot wrote:

Elmoret,  I'm looking at quite a big print bed, but printing the same object multiple times at once using say 4 or six hotends all on the same head but spaced sufficiently apart so i'm a little worried that even a little bit out of level might become an issue when your hotends are say 4 inch apart and from one end to the other hotend maybe 300mm.

Hmm thats a lot of prints without levelling. I am looking to lift the glass off between prints as it takes to long for the whole thing to cool down and when printing in abs i am sometimes putting my bed under undue pressure to remove the print. (Out of impatience usually)

I never let it cool, in fact I usually let the extruder head bash it off as it starts the next print. I'm probably just lucky or found the magic combination of hairspray and print footprint/height. Its Filastruder hoppers, for what its worth.

Anyway, I've printed 180mm parts before on the bed with no warp, ABS. I use a full enclosure and a 4 foot blanket around the SD. It just works, so I don't mess with it.

Filastruder - the robust, inexpensive filament extruder
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7 Reply by Staffordknot

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Re: Bed levelling... How do other printers do it?

I have to practically cut my prints off my glass bed, i dont use hairspray just a light wash of watered down abs glue.

8 Reply by spapadim (edited by spapadim 2014-01-14 09:59:49)

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Re: Bed levelling... How do other printers do it?

elmoret wrote:

I'm probably just lucky or found the magic combination of hairspray and print footprint/height.

Indeed. smile. ABS (hairspray on glass) I always had to let cool. PLA I could bash off, but after recalibrating everything (E3D install.. smile ), it sticks like hell. Go figure. Richrap was probably right when he said, some time ago, that understanding adhesion properties is top of his list.

9 Reply by Tomek

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Re: Bed levelling... How do other printers do it?

Staffordknot wrote:

I have to practically cut my prints off my glass bed, i dont use hairspray just a light wash of watered down abs glue.

To me that reads like "I don't use small kitchen knifes, just a light saber or machete"

Abs glue is more heavy-guns than hairspray. Hairspray is much easier apply lightly and sticks less than ABS glue [for me.]

10 Reply by Staffordknot

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Re: Bed levelling... How do other printers do it?

I didn't like removing the glass to apply the hair spray, if i left it in place it clogged everything up. Plus it just didn't stick enough on large flat prints reliably enough. If i do get some curl i squirt a small amount of glue on and push it down and it solves it. I use a 35mm paint scraper to remove the print but will consider a machete haha