I know this has been asked before, and I have searched the Lightburn forums as well as various Youtube channels, but I still can’t get the Preview function to show engrave / cut times correct. I know they won’t be exactly the same but should be close. I have an XTool D1 Pro 20W and running Windows 11, with Lightburn version 1.06.03. I have gone into Device Settings and clicked on “Read from Controller” in Additional Settings tab. Doing this gave me max x speed of 300mm/s and max y speed 300mm/s, with acceleration of x=300mm/s, y=300mm/s. Actual engrave was 23min vs. 17:13min preview. XTool data shows max speed of 400mm/s. What else can I do to get Preview closer to actual? I know in the past, for bigger jobs, the difference has been over 30min longer.
The most common cause is that your laser is PHYSICALLY not able to achieve those speeds. LB calculates using theoretical values, but if your laser doesn’t reach them, the time is off.
In your case, you have many very tiny movements, so the mechanics is basically constantly accelerating and decelerating and might never reach the commanded speed. Two things you can do about this:
try to optimize laser movements, in your case you might scan 90° such that your movements are longer (though in general the x-axis is faster because it moves less mass)
reduce the speed until the theoretical time matches the actual time, then you know the actual physical speed your laser can reach.
Side note: manufacturers’ values are vastly exaggerated, usually. Even if your laser can reach 300 mm/s (I doubt that), it will only reach this if you drive from one end to the other (like 30 cm) not a few mm as in a real design. So for daily usage, take more like 100 mm/s as maximum and test from there.
I to have noticed this. What @misken says is exactly the conclusion I came to. I noticed lines were almost 100% accurate, fills not so much. Images were way off.
My rule is if it is a majority of Line paths, go with it. If is is a Fill where the head scans back and forth, double the time. If it is a full Image, multiply by 3 or 4 to get the best time estimate.
I use the Preview estimate as more of a tool to help set up conditions for the fastest burn. Click this and click that to see what lowers the time the most.
AFAIK/IME xTool D1 family of lasers (/controllers) do not support that feature, so the only option is to fine-tune the parameters by hand.
Since we do not actually know the actual acceleration and deceleration graphs, nor the actual maximum speed, it’ll always be more of an educated guess.
Cutting preview times with a low power diode laser can probably be optimized pretty accurately since the speed is rather (or very) slow to begin with, but with complex fast engraving/marking, all bets are off if fastest possible speed is the requirement.
One area that the preview time shines though is:
Even with a moderate experience about different designs, the preview reveals immediately if the DPI or LPI is too high, there’s something strange in the design one wishes to engrave, etc.
Thank you for all the replies, I will take these into consideration and do some testing based on this information. I didn’t think about all the short strokes and accel/decel speeds, but it makes perfect sense. I typically have too many irons in the fire, and use the Preview to get an idea of whether or not I have time to cut/engrave now or do it later, so I need to be more realistic with those estimates being too fast. Also, this was on a tumbler on the rotary so I’m not sure I could rotate the scan direction, but that is a potential on flat work. Thanks again!
