Yeah, another writeup about 3D printing. Someday I am going to have to get my mind off this subject. Doesn’t look like that will be right now.

I am burning the midnight oil, rather my printer is. I just set up a run then go to bed. Yeah, it is that dependable. Lazy man’s work.

But there is some work in getting it set up correctly. I am still learning what all the tweaks and changes can do to a print. The fact is there are many variables and a lot of poor information available. What works for me may not work on the machine next door. It’s all the variables to consider.

What I am learning, is to look at a printing problem, then think of what is causing (for example) the rough surface. Then testing to see if my hypothesis is correct. Sometimes I find out that “standard” settings are not always the best.

Part of the problem is I don’t know what is behind the operating software. By that I mean the sequence and thinking that is the basis of operation.

For example, we are told how to set the initial height of the print head above the print surface. A gage is used (a piece of paper) to set the nozzle above the surface, say… 0.10 mm. That becomes zero height 0.00 mm on the computer control screen. But in my machine shop CNC world, because I used the gauge, that is NOT true zero to the surface. The position readout should be (read) 0.100 mm, not 0.00 mm.

I have NO IDEA where REAL zero is in the 3D print software. What were they thinking when they wrote the code?

I want (the first) layer height to be 0.30 mm. The screen will show 0.30 mm but does the software know it started at 0.10 mm above the surface? I must ASSUME it does. What if I want a 0.05 mm first layer (not a good choice)? Does the printer move Z negative by 0.05 mm, half the original 0.1 mm starting height? No idea, it’s a trade secret.

Every layer after the first just adds to the one beneath it, no issues with incremental height.

My most difficult issue is setting the initial layer height. Paper is a bit too iffy. How much “drag” is correct. For me it seems that just about zero drag is correct. Something with a harder surface and more accurate than a sheet of paper would be good. A real feeler gage. I ordered a metal tool that was reported to be 0.100 mm thick but I measured it when it came in and it is 0.40 mm thick. 4X too much!

3D printing is not exactly machine shop “tenth’s” accuracy (0.0001). It doesn’t pretend to be. It doesn’t have to be. It’s like atomic bombs and hand grenades, close is good enough. Most “made” items are not intended to be precision. However, they can be if you try hard enough.