Building a 3D printer is easy. Getting the details right to build a great 3D printer is hard, as this is where most companies fail. Why?
For example, on this printer, the bed is a three-point mount (two wheels for adjustment at the front of the printbed) and the printer’s bed levelling dialogue doesn’t show the height difference that needs to be adjusted (which most 3D printers do). It does show how much it needs to be turned, and the bed levelling wheels have 1/8th turn indicators, making it easy to get it perfect.
In short, instead of an arbitrary number like 0.3mm that has no meaning to the user, they tell the user to turn this knob 1/4 of a turn. An instruction the user can follow.
** Why is this so outstanding? It doesn’t cost much, but it improves the user experience. Are companies blind to these improvements because the engineers are experienced, or is there a lack of testing during development?**
By the way, years ago I did such a fix/modification myself on a Tronxy XY2 pro by adding indicators on the wheel for 0.2mm height difference so I could convert the number to rotation: https://www.printables.com/model/301670-replacement-bed-leveling-wheel
I largely agree with what you’re saying, but was surprised to see that you called out that much variation in thread pitch. I would absolutely expect a lot of variation in the ability to measure z - especially since most printers rely on microstepping here. Thread pitch on the other hand is generally way more consistent. I am not a machinist, but it would be interesting if one chimes in. I don’t know what to ask Google to get some data here, but I strongly suspect there’s a term to use.
- If micro stepping varies that much then FDM printers (and CNC machines) wouldn’t have worked so well. Also, you can tune the micro steps, if you need 410 steps to move exactly 10mm instead of the default 400, just change it. (I just pull a random number btw, it’s been at least 5 years since I touched my Marlin firmware)
- If you’re familiar with coffee grinders, they’re basically using thread to adjust distance between 2 burrs. Even there (mid to upper-mid range ones) can’t guarantee the same grind size on the same setting for different unit of the same model, eg. setting 11 on grinder A will have slightly different result compared to another unit of grinder A on setting 11. Can it be done? Yes, one example is Commandante, that is a $300 hand grinder.
Tight tolerances will exponentially skyrocket production cost, period.
If you’re familiar with coffee grinders, they’re basically using thread to adjust distance between 2 burrs. Even there (mid to upper-mid range ones) can’t guarantee the same grind size on the same setting for different unit of the same model
While the coffee grinder example is true, this is not at all due to tolerances in the thread pitch used to adjust the distance.
This is because of the tolerances on the burrs themselves and the sideways alignment varies too much, and why it’s better on more expensive models.
Threads are controlled to a fairly tight ISO standard, which can be done very cheaply because of the simple helix shape and ridiculously large quantities.
Burrs on the other hand are much more complex shapes, in much lower quantities, which is why tight tolerances are expensive on coffee grinder burrs and not on simple thread pitches on standard bolts.
Even in millimeters, there’s a wide range in standard thread pitches. 1mm thread pitch in most common screw sizes is generally available, sure, but don’t always fit the “cheapest sufficient part” criteria.
EDIT: Dudes, the standard pitches between various sizes of metric screws does vary. This isn’t in reference to variations within a batch or whatever other garbage take 4 people apparently came up with, its just a fact.
versus:
Good lord, I could machine you a set on my lathe, easilly, but its not necessary. Just get you a tap & die:
Where am I getting the idea that these manufacturers don’t think like this and just buy the cheapest crap they can find readilly available? My siblings in christ(or whatever), how do you think we came to be on this subject? Machines are getting put out with components where the pitches are all over the place in locations where it would make more sense to match them up.
Screws of the same pitch will generally be pretty consistent regarding their specified pitch. Unless the manufacturer is randomly grabbing screws, and their matching nuts, from a mixed bin there shouldn’t be much variation.
I didn’t say anything about variation between two screws of the same pitch. There are various pitches for each length/diameter of screw on the market, and some are more common than others.
