@Paul_Gross I actually wasn’t worried about offending. Your explanation was actually pretty clear, but as a “layman” my mental model of level is parallel to the ground (as found with the level tool) and my model of plumb relates “hanging straight down”.
This is not at all what we mean when leveling/tramming/paralleling the print bed.
I do understand that, but declaring that plumb and level used together will automatically be clear to the layman does not match my experience. It depends on the “experiences” of what you are calling a layman.
The main argument I can see against level is that people assume they know what it means and are wrong. The main argument for tram (in the eyes of this layman, at least) is the term is unfamiliar and therefore more likely to make me ask.
Parallel seems to lie in between those extremes. But, given some of the commentary it’s still not perfect.
Tramming is probably closest to what is being done in order to insure print accuracy. If, however, that term is too obscure/archaic for most people, then maybe we should invent a term for this.
We may need to come up with new terminology to describe processes that aren’t strictly translatable from other disciplines.
Square & parallel? “Squarallel”
Or perhaps we can approach this in terms of “de-sloping” the build plate?
Your mental models of level (a spirit level I presume) and plumb (hanging straight down) are exactly the same as mine. From these agreed mental models, we then agree we will get a correct machine.
But, then you follow by saying that is not at all what you mean when leveling/tramming/paralleling the print bed - and I don’t understand why you would say this.
What do you mean by “leveling/tramming/paralleling the print bed” that contradicts those mental models?
@Paul_Gross The point is that the parts of the machine have to be adjusted with respect to one another, not with respect to gravity. A level, especially the ones that the average DIYer will have access to, is not a very precise instrument, and aligning multiple components to gravity rather than directly to one another compounds that error, not to mention the likelihood of missing one of the many measurements that would need to be made to ensure that the entire machine is properly aligned to the gravitational reference.
When people ask me about the difference between level and tram, I like to pick up a printer (usually printing at the time), turn it sideways, and ask them if the platform is still level.
Actually, the method of alignment is beside the point, because each machine has a different method for leveling the build area and plumbing the Z-axis rise.
My Printrbot will not be adjusted the same way that someones Ultimaker is, but we are both still aiming for level and plumb.
Also, if you tilt you machine sideways, you have lost both level and plumb - the two are related.
Of course, in theory, somebody could tilt a machine sideways and then still manage to align the Z-axis to move along the tilted X-Y surface normal, but that seems to be doing it the hard way, and bridging and overhang printing might suffer as well.
I think that the gravity definitions of level and plumb are simple to understand, even if a specific machine’s adjustment procedure is a bit fiddly when trying to achieve that ideal.
@Whosa_whatsis that comment about the difference between axis orthogonality and having the bed parallel to the X/Y plane is I think key. I hadn’t thought of that but now it is all of a sudden super clear. If the bed plane is parallel to the X/Y plane but your Z axis is not orthogonal, the sides of your cubes will be parallelograms, your layer height reduced by a factor cos(angle-of-slant) which will mean your correctly calibrated extrusion is a factor 1-cos(angle-of-slant) too high, et cetera. Brilliant!
Keep your printer on a level surface, or it falls to the floor.
Keep your bed parallel to the X/Y plane, or your hotend comes crashing into it.
Keep your axes square or your prints will be crooked and your extrusion rate hard to calibrate.
from a latin point of view, parallel is a status, so it can’t be used as a verb, but you should say ‘make somethings parallel’. it’s all about the 2 references.
Anyone want to tl;dr this for me? Is their a consensus? I vote for true/truing(?) given its hard to find a clear definition for it but my understanding is that something is true when it’s aligned to a given datum reference.
To muddy the waters a little, I had a ‘leg up’ on the average builder when levelling my build plate. One of the writeups suggested setting things up a precise distance above the build plate, rather than right down on it, to prevent head crashes while calibrating. They suggested using a very precise reference datum, so I grabbed a set of parallels (http://bit.ly/10L5WRF). They happened to be an inch thick, so the process for my printer, was to make sure the nozzle was 25.4mm above the build plate at all points, when I requested G0 Z25.4
This was possible because I took steps to ensure the frame was square, and the Z axis travel was perpindicular to the XY plane. It was fairly easy to do using a box frame that consisted of 20x20 aluminum extrusions with very precise lengths. (again, established using a lathe).
It’s now obvious how that situation will be different from a person making Reprap, where all of the dimensions have to be created using all-thread, when the use may not have access to high-precision measurement. Doubly so if the vertical supports may not be equidistant to the build plate, but could still be perpindicular to one axis of travel (and very hard to measure the other axis.)
But…that axis could be adjusted with an adequately precise machinist’s level, and a plumb-bob coming down from the nozzle.
So, level, plumb, and adjusted due to gravity is not the right concept, but a degree of tune could be approached, if all aspects of it are plumb and level with respect to gravity. The quality of the calibration is easier with precise measuring tools, but that’s not the only way to arrive at a calibrated machine.
“True” has some merit also, but doesn’t seem as likely to send someone in the right direction as “parallel” to me. And criticizing the proposal to use parallel as a verb to replace level is a little ironic. Level is a verb that evolved out of an adjective also.
Level just mean parallel to the surface of the earth, or more accurately perpendicular to gravity. It’s not that wrong to use Level to mean parallel to your XY gantry.
Then you make sure the instructions are clear. This is taking a topic that isn’t that hard, and making it stupid, over a silly bit of nomenclature. In the document “How to calibrate your printer”, you state “This is how you level* your printer”…you then say: Do not use a carpenter’s level - it is not the right tool for the job.
@Mike_Miller , good point. Every one of the proposed terms requires further explanation to the uninitiated. Of the 4 or 5 terms I’ve seen proposed here, the problem is the one that causes a beginner to reach for the wrong tools. So far, I think that there is only one to be avoided, even though there is a sense in which it is correct, because it leads to trouble for beginners. Would everyone be content to avoid terminology that would lead a beginner to use imprecise tools that reference gravity, whatever that terminology is?
