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print bed flatness or lack of

Posted by AgeingHippy

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AgeingHippy

print bed flatness or lack of
December 30, 2010 06:51AM

Registered: 16 years ago
Posts: 482

Hi All

My print bed is not flat enough sad smiley

Seems it bulges slightly in the middle, by about 0.2-0.4 mm

Is it still possible to print with such a bed by using a raft to level out the unevenness?

I wonder if anyone can suggest an affordable material which would be flat enough to work. A UK source would be appreciated.

Thanks

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Greg Frost

Re: print bed flatness or lack of
December 30, 2010 07:15AM

Registered: 15 years ago
Posts: 486

I had the same problem and replaced my bed with heat-proof glass

255nevd.jpg

The glass cost 55$AU. I mounted it using some aluminium channel $4.25AU and some stick on rubber strips.

Edited 1 time(s). Last edit at 12/30/2010 07:38AM by Greg Frost.

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Nudel

Re: print bed flatness or lack of
December 30, 2010 08:04AM

Registered: 16 years ago
Posts: 689

My dibond fr got some nasty bulges in it due to a bit excessive heat gun use, so I bought some thin aluminium sheets off ebay which I clamp on. Just make sure the bulges protrude out the bottom side, and let the thin sheet level them off.
Will probably change it to a 4-6mm aluminium build plate at some point though.

--
-Nudel
Blog with RepRap Comic

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mlagana

Re: print bed flatness or lack of
December 30, 2010 08:10AM

Registered: 16 years ago
Posts: 323

you can get flat 3-4mm glass from old scanners

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AgeingHippy

Re: print bed flatness or lack of
January 29, 2011 02:55PM

Registered: 16 years ago
Posts: 482

Hi people

Seems I have managed to get flatness to within 0.1mm or thereabouts between 0 and 180mm of the bed each way.

I am guessing that is adequate?

I am loath to try sharpen it further as adjusting 1 point seems to modify the entire setting... sleeping dogs and all that.

smiling smiley

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dazed.dnc

Re: print bed flatness or lack of
January 29, 2011 05:19PM

Registered: 15 years ago
Posts: 188

As long as it doesn't vary by more than half your layer thickness, I think it should stick ok.

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AgeingHippy

Re: print bed flatness or lack of
January 29, 2011 05:27PM

Registered: 16 years ago
Posts: 482

Gosh - that gives me a good 0.2mm to play with smiling smiley

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Auzze

Re: print bed flatness or lack of
January 30, 2011 12:40AM

Registered: 15 years ago
Posts: 241

Hello

I just use a peice of 4mm glass on my 2mm Alum heated bed, I also have some small thumb wheel that I use to adjust the height. All works out well.

Auzze

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AgeingHippy

Re: print bed flatness or lack of
January 30, 2011 06:06AM

Registered: 16 years ago
Posts: 482

Hey Auzze. Is it special heat resistant glass or is it standard window glass?

cheers

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dazed.dnc

Re: print bed flatness or lack of
January 30, 2011 10:40AM

Registered: 15 years ago
Posts: 188

I don't think it has to be anything special. I'm using a sheet that was removed from an old office copier and cut down to an appropriate size. Your heat bed should only need to run at 110C tops. Most people seem to run more in the 70-100 range. If you use a heat spreader (aluminum plate) I wouldn't expect the glass to crack or anything from uneven heat and it won't come anywhere near melting at those temperatures.