Metric vs Imperial

Continuing the discussion from Discussion of March 2018 Update:

Really? Just for that? A lot of us here in the states actually think in metric, for various reasons (mine is that I work in health care, and we’re primarily metric), but it wouldn’t have occurred to me to see that as a barrier to buying a GF. It’s not that big a deal to do conversions. I flip back and forth from mm to inches all the time in Inkscape, since I like to design in mm but have it set to default inches for the GF stuff. My micrometer flips back and forth just as easily.

If you’re an American company expecting most of your sales to be in the US, where construction tools, fasteners, lumber and other materials are measured and sold using the Imperial system, it wouldn’t make sense to set your system up to use metric. It needs to be compatible with the things it’s used with.

If I buy a product from EU I expect it to be metric, so it seems to me that if you buy an American product, it shouldn’t be a surprise that it uses American measurements.

Think of it as exercise for your brain. As I tell my patients, “the more you have to lose, the longer it takes to lose it.” Doing calculations for your GF projects will help you stave off dementia. :wink:


Oh man…I knew I was doing it wrong. :smile:

(Excellent points to live by. And I do the metric-imperial shuffle on a daily basis as well. I cook and drive in imperial, design in metric, don’t bother to convert it, and the GFUI handles it just fine, and perfectly accurately. The only thing that requires inches is the thickness measurement for non-PG materials, and a measuring device takes care of that.)


If I recall, someone (maybe @scott.wiederhold) had posted a while back that the internals of the GF use metric, it’s only the GFUI that relies on imperial, and as @jules states, only for the thickness measurement. I create 99% of my designs in metric and have absolutely no problem with it on the GF, so I don’t know why anyone would claim that it is “based on the Imperial system;” and, it’s certainly not arrogant, because they picked a measurement system for the GFUI that would be usable by the most people that would receive the GF first once it started shipping.

Unless I missed something, the software/GFUI is still in Beta, and adding metric to the interface I believe is “in the hopper.” Of all things to complain about–delays, non-standard definitions for certain features, etc–this seems like an argument looking for an excuse.


Is the UI metric for non US shipped ‘Forges? I really expected the UI to give us the option to use either when international units started shipping.


I think the UI is the same for everyone.

The hardware is definitely metric - as in the belts, pulleys, and rack and pinion gears.

The firmware seems to work purely in step counts, which are 0.01875 mm (0.0007381889764…") on the X/Y (I don’t recall the Z, but it’s floating around here in the forums somewhere).

It would make sense to work in metric in the background, but only GF could say for sure if they do.

1 Like

Other than specifying material thickness, I’m struggling to think of where else it makes any difference.


PG settings from the server are metric and speed is actually speed, etc. Focus is an offset from the surface.

The Z steps, despite using a metric rack, are irrational numbers because they involve pi.

Mod 0.5 rack with 9 tooth pinion and 40 step motor gives 0.353429173528852mm.

1 Like

As others have pointed out there is one other place inches are used:

Engraving: Lines per Inch (LPI).

1 Like

It just occurred to me that the real reason management changed to a unitless Speed was to avoid the metric/imperial issue. :wink: I wonder why they didn’t do the same for LPI and focus. :stuck_out_tongue_winking_eye:


Considering LPI is a drop-down, it may as well be a numbered list or descriptors starting at fastest and ending at longest, oh my god so looooong. The scales running on the side of the GFUI is in inches, but really they’re just evenly spaced numbers unless you’re resizing your design inside the GFUI. That idea just makes me shudder.


Regarding power, it seems to me that the way GF has it set up with their own scale (besides governing the power so the tube can’t be overdriven) is that so owners of both basic and pro can share the settings and they would be equivalent up to 100%, and the only difference would be “Full” between the 40w and the 45w machines.


If power was in watts you could just as easily share settings. 0-40W would be the same on both machines. They would just have to stick below 40W for PG engrave settings.


This never made sense to me.

What if you are a Pro owner?

You are restricted between 2 settings at the top of the power range? 40w and 45w?

No 42w? Douglas Adams would be disappointed…


Just curious, do laser printers (and I mean real laser printers like an HP laser jet) and desktop publishing software use something other than DPI for printouts outside the US? While I realize the the PI=per inch, but I never think about it in inch terms, it’s more like I know what 1200dpi vs. 600dpi means (in reality dpi could stand for Duck per Ingot of toner and it would work just as well) - it’s really a quality marker

1 Like

Dunno. Folks who live in countries other that the US would have to chime in here. And of course that extends to scaling bitmaps in applications like PostScript to print at the printer’s natural resolution.

I’ve been looking at the settings provide by Glowforge a lot this week and they are different. It appears that pro machines are about 18% faster at cutting, amongst other things. I’ve been wanting to make a spreadsheet to make comparing these values easier though I haven’t had the time.

Please note that the speed settings are not the standard 1-500 values that we see in the UI they are translated before being displayed.

Basic Settings:

    "Medium Maple Hardwood Settings,"
      "power": 100
      "speed": 965

    "Medium Walnut Hardwood Settings"
      "power": 100
      "speed": 965

    "Medium Teal Acrylic"
      "power": 100
      "speed": 584

Pro Settings:

    "Medium Maple Hardwood Settings, Pro"
      "power": 100
      "speed": 1168

    "Medium Walnut Hardwood Settings, Pro"
      "power": 100
      "speed": 1168

    "Medium Teal Acrylic, Pro"
      "power": 100
      "speed": 711

We’ve known this for a while. They are faster because of the additional power available on the “Full” setting. They are the same speed as the Basic when cutting in the 0-100% range, and when engraving.

They are also supposed to be faster due to some yet unidentified and yet to be enabled ‘linear component upgrades’.

1 Like

When I was in college, my photography/digital imaging professor said some people tried to make pixels per cm and dots per cm happen for a while, but according to him it never really caught on. But this was, like, a decade ago (oi vey) so maybe thats changed by now.

Also I am old.


How much has this actually been tested? Do we have side by side comparisons of similar material cut times on different models? If the difference is only when using max power then it has to be handled server side. Programmatically, the UI sees 100 as Max Power, 99 as 100, 98 as 99, and so on.

I’m not really sure how much this actually matters. If the laser can’t cut it at its current full speed/power, going faster isn’t going to help.