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Z0 is where the bed is but where / how far away is the hot end nozzle. I have used 0.05 mm feeler gauge at the 4 points on the bed (each tower and centre), sorted out the delta radius.

Do I subtract the 0.05mm to set the Z0 or is this taken into account by the slic3r software for the first layer from the XYZ tower heights. I am having issues with getting a good first layer down with PLA, it appears to be too high and extruding but not adhering to eitherthe glass (65 degrees C), blue tape (cold and 65 degrees) and paper.

Bluemalu wrote:Z0 is where the bed is but where / how far away is the hot end nozzle. I have used 0.05 mm feeler gauge at the 4 points on the bed (each tower and centre), sorted out the delta radius.

Do I subtract the 0.05mm to set the Z0 or is this taken into account by the slic3r software for the first layer from the XYZ tower heights. I am having issues with getting a good first layer down with PLA, it appears to be too high and extruding but not adhering to eitherthe glass (65 degrees C), blue tape (cold and 65 degrees) and paper.

Good question, I use a paper and the paper is 0.1mm thick, I set it then move the nozzle 1mm down to take up the difference and it help allot with my first layer. I was getting some skipping, but now it is flat and even. other can chime in on what they do. This may affect your overall part height, check it wit calipers and see if you can live with it. providing your machine is dialed in. I may use a 123 block and check mine and see if I get the true movement and may adjust the steps per to test it.

I had trouble getting PLA to stick too. Try rubbing some isopropyl alcohol on the blue tape and see if it helps. Did wonders for me and have yet to have a problem that way.

If you're in Repetier, move your Z all the way down. If you're at Z=0 and you can put that feeler gauge underneath it and it feels just right, then you're probably right in the ballpark of where you want it to be. You obviously don't want the nozzle right on the bed or you won't be able to extrude. Try changing the extrusion width in Slic3r to see if it helps. In the Printer Settings tab, go to the Advanced option on the left. For the first layer, try setting it to '0.7' or '200%' and see if it makes a difference for you.

As I mentioned though, try something with the blue tape. I notice a lot of guys have no problems with the blue tape at all, but I really think it depends on the manufacturer of the tape or even the manufacturer of the filament. My blue tape is made by 3M and it wouldn't stick if my life depended on it. It would just peel away and stick to the end of the extruder. Printing right on the borosilicate glass was no different. Tried hot and cold. My suggestion is the alcohol. It's cheap and you can pick it up at pretty well any drug store.

Tinyhead wrote:I had trouble getting PLA to stick too. Try rubbing some isopropyl alcohol on the blue tape and see if it helps. Did wonders for me and have yet to have a problem that way.

If you're in Repetier, move your Z all the way down. If you're at Z=0 and you can put that feeler gauge underneath it and it feels just right, then you're probably right in the ballpark of where you want it to be. You obviously don't want the nozzle right on the bed or you won't be able to extrude. Try changing the extrusion width in Slic3r to see if it helps. In the Printer Settings tab, go to the Advanced option on the left. For the first layer, try setting it to '0.7' or '200%' and see if it makes a difference for you.

As I mentioned though, try something with the blue tape. I notice a lot of guys have no problems with the blue tape at all, but I really think it depends on the manufacturer of the tape or even the manufacturer of the filament. My blue tape is made by 3M and it wouldn't stick if my life depended on it. It would just peel away and stick to the end of the extruder. Printing right on the borosilicate glass was no different. Tried hot and cold. My suggestion is the alcohol. It's cheap and you can pick it up at pretty well any drug store.

One thing I've always found peculiar is *why* don't we want z=0 to be the nozzle sitting on the bed? Because in Slic3r (I'm not sure about other slicers), you tell it the height of the first layer (e.g. 0.3mm). So I would expect that it would position the nozzle at Z=0.3mm. But if when calibrating, Z=0 is not directly on the bed, the Z=0.3 in Slic3r would mean something like Z=0.31 or whatever, basically adding in the offset that the nozzle was from the bed when calibrating.

More than anything else I suspect it's because you don't want the head coming down and smashing into the glass at the start of the job. Most people don't have feeler gauges but do have paper, and it's accurate enough given that things will warp and move around a bit anyway.

So this is just a tiny bit of clearance.

Rather than setting your extrusion multiplier for the first layer smaller, try setting it to 1.2 and running 0.25mm first layer. More noodle coming out tends, I've found, to smoosh the layer down into the bed a little more convincingly and bed adhesion improved enormously when I did this.

Z=0 is assumed by the slicer to be on the bed. You can trivially validate this by looking at the GCode from the Slicer. For what ever reason old versions of skeinforge used to assume that the first layer should be printed at Z=0, but no other slicer I'm aware of has ever done that.
IME if using something like paper as a gauge the amount you should add to the home position is something of a crap shoot, it's going to be in the 0.05 to 0.1 range. By far the best test for correct 0 setting is looking at the first layer, but it requires you know what your looking for.
I personally now use a feeler gauge and just add the width to the Z Home position when I calibrate, it's usually pretty much dead on.

Thanks for all the opinions, reset my Z0 to be 'potentially' the hot end striking the glass. Used the 3M blue tape with isopropynol alcohol (even more fun when the bed is heated). Adheres well with PLA @ 170 and heatbed 60 degrees C for the first layer then let it cool.

Now it's repeatable, it's time to sort out the extruder volume and learn more about Slic3r settings.