Nozzle tip to bed gap height?

I'll admit first off, I'm in the process of building from scratch a Prusa I3 rework and I have parts on order. I'm new (technically a virgin) to 3D printing but not computers or electronics. (Former electronics and calibration tech in the Navy and currently Systems Administrator.) Being mechanically minded and all I thought this would be a fun exercise. That and I heard I can earn a ton of cash by whipping out plastic junk. (The internet said so! )

Having watched a ton of videos and instructions, I've not actually seen any reference to what the actual gap is between the nozzle tip and the actual surface of the bed. All I've read is a smidgen, gap, splinter etc. Not precise measurements in my book (and I can understand why as there will be variations in tolerances per unit). My question is what's a reasonable starting point? I thought a feeler gauge would be a tremendous assist in the alignment phase of the build.

So if anyone could lend their expertise as to the approximate gap size between nozzle tip and bed other than a splinter, I'd appreciate it.

Thanks.

Hi,

i use and 0,05mm (5/100mm) feeler gauge. Some use paper but if you dont fit it very tight its a gap thats to big.

Try using one of these. Then print something with a skirt and measure the skirt. It its your first layer height then its ok.

Thanks, I'll do that!

Make sure both the hot-end and bed are at print temperature when you set the zero point for the Z axis. The extruder nozzle always has a little plastic in it and if it isn't soft you won't set the zero point right. Many print beds tend to warp a little at print temperature so you want to make sure it's in print state when you zero.

In general, clean the bed at room temperature prior to printing, level and zero the bed at print temperatures.

Hadn't thought of that.... thanks!

The following works well for me.

Select a piece of drill steel or silver steel or a long shanked drill bit of a known diameter - about 2mm is good
Get the bed and hotend up to temperature and allow about 10 minutes to stabilize.
Home the Z axis and lift to the diameter of the previously selected steel rod minus about 0.05mm
Move the hotend directly over (or as close to directly over as you can get)one of the bed adjusters and slide the steel rod under the nozzle. When correctly adjusted there should be only a slight drag on the rod.
Repeat for each of the other adjusters. If you have three adjusters it should now be good - if you have four you may have to go around several times.

The feel with a rod is much better than with a feeler gauge and an accuracy of 0.025mm (0.001") is easy to achieve. I work on the belief that zero on the z axis should mean zero - not a smidgeon, sliver or piece of paper.

Mike

Edited 1 time(s). Last edit at 04/11/2015 02:36PM by leadinglights.

Yeah, that's good too, but the real flakyness comes in when you adjust the screw to trip the zero switch. There is mechanical hysteresis built into the switch so you're never exactly sure what spacing you're going to get until you try printing.

I use metal feeler gauges.
Always with bed and nozzle at printing heat and filament retracted and wiped off.
0.08mm for my 0.3mm nozzle.
0.1mm for my 0.5mm nozzle.

Once you get a feel for feeler guages they are very accurate.

Gordon

Quote
Lord_Vader
Hi, I use and 0,05mm (5/100mm) feeler gauge. Some use paper but if you dont fit it very tight its a gap thats to big.

Try using one of these. Then print something with a skirt and measure the skirt. It its your first layer height then its ok.

That is an interesting idea. I never considered measuring the first layer before.

I always home te nozzle, then slip a piece of tissue paper under the nozzle. Then I adjust that corner of the bed until I can feel friction from the nozzle. I will then repeat this for each corner, and then repeat the process again. As the print starts, I like to manually adjust the leadscrew during the skirt so it is a good height.

I must be crazy then as I use a feeler gage for spark plug gaps and use .010 or ten thousandths of an inch, works great for me ;-)

I use a piece of paper, and have ordered some feeler gauges. I shoot for about 200micron. I use a thick layer of abs good in the 100-150 micron thickness. This ensures a warp free print.

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