Glass Bed (Page 7 of 9)

I got it now. Man that screw is in a tough spot. I needed basically to screw it in more.

I got three 8X8 mirrors to use on the bed. Put the thumb screws on to level the bed. I then found out that mirrors aren't necessarily flat as I had assumed. I adjusted the right and left sides for about .1mm and then checked the center and the nozzle was dragging. Don't assume mirrors are flat. Cut glass should be.

I think .3 is too high. I use a piece of paper that is .11 thick to set mine up. With some ABS I give it a little slack to probably .15. Last night I almost couldn't get my model off of the glass and hair spray.

In my limited experience of 1 week, I have been using a set of 5mm x 200mm x 200mm mirrors that I got from the bathroom section of the hardware store. Clipped them on in 3 places using medium sized binder clips (1 at the back and left, 1 front and left, and 1 right side and front), making sure not to catch any wires under the aluminium bed and in places that will not interfere with the extruder in most circumstances. The bed and the z axis screw were adjusted to give a total 5mm downward adjustment. (The bed cannot go down too much, otherwise it will pinch on the wires underneath). I printed a z axis screw extender to avoid having to screw it down all the way.

The mirrors work great - totally flat, no warping, very smooth surface. I use some generic hairspray I got from the dollar store. I had troubles with the hairspray drying out to a hard film, but after a lot of trial and error, I get the most consistent results by spraying a film of hairspray, letting it dry while the bed and extruder heats up, then about 30 seconds before you are ready to print, spraying the area with some isopropyl alcohol to dissolve it a little and spraying another light layer of hairspray. (If done too soon it will harden again before the 1st layer is printed) The bed also needs to be at about 85-88 C for ABS to stick properly. The prints usually stick well enough for the whole job, but will come off with a bit of finger pressure.

At some stage, there will be too much hairspray on the surface to be effective, but the mirrors can be swapped out easily and washed in warm soapy water for a clean surface again.

I tried out a glass bed as of last weekend, and it works beautifully. I got around the warping of my aluminum slab by applying layers of copper tape to the bed and to the bottom of the glass - extra layers at the sides, where the bed is lower, yielding a shiny and beauteous print platform thanks to the nicely conductive copper.  A small roll of "Slug and Snail Cooper Tape Barrier" from the garden section of the hardware store cost me about $7, if I recall, and it was reasonably easy to work with.

I used standard glass, which the guy at the hardware store told me would not change shape at temperatures in the neighborhood of 100C. According to the glass guy, it would require something much, much, much higher than that. Also, that part was not expensive, and the guy at OSH kindly cut it in 6" squares for me.

I'm sure that would work.  I was worried about losing z depth as well so I never printed the thumb screws.  I just take a pair of pliers and grab the lowest part of the screw and make my adjustments.

That's a good idea.

For my fellow Australians...I had to hunt a little for Borosilicate Glass to suit and though I found some on Ebay I also found a glass supplier who could provide it for a good price. I'm going to pop the details in Buy/Sell/Trade.

This was one of the first mods I did on  how I print,

1. I went to my local glass shop where they cut me two pieces glass 7.75" by 8" out of scrap and rounded all the edges for free.
2. I then bought some of the black 1.5"  binder clips.  to hold the glass on. I use three when I'm printing. Just got to be care full the nozzle of the extruder doesn't run in to them (no damage as far as I know, Just have restart print and move clamp)
3. print off three of the the adjustment knobs for the print bed, I super glued mine on after about 4 revolutions. (They are nice if you don't use glass)
4. move Print bed all the way down to get at the Z-stop screw. Note the length. Take it out and screw it in from the bottom this should give you enough to zero your print bed.
5. Adjust Z-stop screw to where print bed should level with very little adjustments (don't clamp glass down at this point, slide glass in and out till Z-stop is close.
6. Level print bed.
7. Put hair spray on glass (it seems to help the plastic stick to glass.
8. Heat up print bed a little longer then normal (more mass to heat up and print is futher away from temp sensor.
9. Print you test part and have fun.

Hope this helps.. This is what I did...
Print screw knobs for bed leveling
buy glass, hairspray, binder clips

and your ready to rock.

I just tonight had a print that curled quite a bit and didn't hardly stick at all (I changed from SD to Octave filament for what it's worth) and wanted to try to glass mod. I have the glass precut already and sprayed it with aquanet. Is there a waiting period for the hair spray to become sticky on glass, and will the heat of the print bed adversely effect the stickness once things get going?

and wow.. to really glue somethng to the glass use acetone abs slurry! I used it for one piece and the remnants have been holding other print jobs ever since. My advice, use sparingly!