First layer adhesion

Hello.

I'm very new to 3D printing, I'm still assembling my RepRap, but already printed some parts.
I'm using a piece of glass over the heatbed.
I've seen much people complaining about poor adhesion of first layer and I had an idea.
If I scratch the glass with a sandpaper, this would help in the first layer?
I believe it will using the "logic of the things", but, is it a good idea?
Please tell me what you think.

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If I scratch the glass with a sandpaper, this would help in the first layer?

not one bit will that help...
your option are kapton tape you get a mirror like finish but not 100% prints can/may curl and lift, glue stick another had a lot of success with pla but it gets messy over time..
the best option and one I stick with is thermal plastic build plate from andornot build plate there other brands with pei sheets like gecko... now the problem with these thermal plastic sheets they work extremely well , where you can end up fighting and wrecking the Z axis, not so much of problem for you if stick with glass and plastic sheet but the other option with makes removing prints child play flexible bed thou am not sure how good that is with ABS or the higher temp filament.

Edited 2 time(s). Last edit at 10/09/2018 02:52AM by jinx.

no

you create lots of ^^^^ on the glass, giving even less surface area to stick to

clean your glass with isopropyl alcohol and make sure your bed is level and first layer is correct height.

finger print on the glass will make it lift every time.

Edited 1 time(s). Last edit at 10/09/2018 02:51AM by Dust.

I print PLA on plain glass on one of my printers. Scrub it in clean hot soapy water and dry it with a paper towel, then install it in the printer without finger marking the top surface. Before each print, wipe it with paper towel moistened in distilled malt vinegar. Don't use acetone or isopropanol to clean it, just vinegar. Heat it to about 50C for printing. After printing, let it cool and the print just pops off.

This works well for several brands of PLA that I have tried, including RigidInk and eSun.

Alternatively, stick a sheet of PEI or PrintBite on top of the glass.

Edited 1 time(s). Last edit at 10/09/2018 02:58AM 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].

I've run though few different options now and the one I finally settled on is a plain glass piece from Lowes. The trick is to keep it clean. Remember that fan is blowing air across the glass the entire time so it gets a film of dust/dirt stuck to it pretty easy.

I am sure vinegar or alcohol work great but I found that buying a bottle of eye glasses lens cleaner and a micro fiber towel from Walmart vision shop works great. It doesn't leave a residue, it isn't strong smelling and as a bonus it reminds me to clean my glasses occasionally. Just remember the hot end will melt the microfiber cloth.

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The Lazy Fat Guy!

Printing on plain glass is not as simple as getting it clean. When I first started printing I was happy with plain glass for ABS - until it stopped working for no apparent reason. Cleaning with acetone, alcohol, glass cleaner, dishwasher liquid and even mechanical cleaning wth fine wire wool had little effect - what improvement was obtained was only temporary. Leaving the glass plate out exposed to sunshine did improve things a lot but still not as good as new glass.
Then I picked up the vinegar method from dc42 and now have no problems. My method is:-

1. Clean the glass with fine wire wool
2. Put it in the dishwasher on a hot wash (alternatively hand dishwasher and rinse with boiling water)
3. Wipe with distilled malt vinegar. - don't use kitchen tissue as it contains oils to make surfaces gleam.

I think that the reason that glass is so tricky is that the adhesion is down to stuff that happens at a molecular level and most cleaning methods poison the surface.

Mike

Doug gave me a piece of polycarbonate and I have to say, wow.
No more adhesion problems.
In fact, I needed to sand it with 60 grit to slightly reduce the actual touching surface. No heat, it just sticks.
Used it with PLA, ABS and PETg so far. Oh and Ninjaflex.
Totally trouble free.

Also, because he was so kind as to give me some magnetic film with it, it is easy to pop off the parts.

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Lykle
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Co-creator of the Zesty Nimble, worlds lightest Direct Drive extruder.
[zesty.tech]

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Lykle
Doug gave me a piece of polycarbonate and I have to say, wow.
No more adhesion problems.
In fact, I needed to sand it with 60 grit to slightly reduce the actual touching surface. No heat, it just sticks.
Used it with PLA, ABS and PETg so far. Oh and Ninjaflex.
Totally trouble free.

Also, because he was so kind as to give me some magnetic film with it, it is easy to pop off the parts.

There is no problem with the heat from the heatbed?

No, because I don't have to heat the bed. Bed is at room temp for all materials.
But the magnetic foil is pretty heat resistant, Doug has had it up to 80C with no loss of strength.

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Lykle
________________________________________________

Co-creator of the Zesty Nimble, worlds lightest Direct Drive extruder.
[zesty.tech]

Couple you possibly post a picture of your print bed lykle?

How thick is your poly carbonate sheet? You mount it magnetically to a different surface? Etc ?