Some observations with LB's Preview, Estimated Run Time, and Rotary

LightBurn Software Questions
1

When working with flat plywood, the estimated run time is accurate with rare occasions being off a couple of seconds. Really nothing to worry about.

Now that I’ve installed a rotary, I noticed the estimated run time is way off, around double the time from the estimate shown.

I know different rotaries have different steps per mm, mine has 160 so that is what I’ll be using.

As we know, 360 is a full circle.

So, 160 ÷ 360 = 0.4444444. Read that as a percentage

Since LB only accepts only to a tenth of a percentage I rounded down to 44.4%

Now go to:
Device Settings > Additional Settings >

(If you haven’t done so already click on [Read From Controller], this will install the settings form your laser.)

Now go to:
Cut Speed Scale and change 100% to 44.4%

Click on Ok

Now the Estimated Run Time is now off by a couple of seconds.

I hope someone finds this useful.

PS: I don’t think there is a setting for LB to do this automatically, if it does please let me know.

LB31
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2

It’ll be the Y axis (the one the rotary is connected to) because the maximum speed and acceleration for the rotary axis will be dramatically slower than the stock Y axis of the machine. If you adjusted those values to match the rotary axis the preview accuracy would improve.

At some point I want to have “rotary profiles” that you can switch between. Having it auto-update these motion parameters along with it would be a nice improvement I hadn’t thought of.

1 Like
3

Ok… interesting.
I’m guessing you are referring to [Maximum Speed] for Y:
Maybe I’m wrong but those numbers don’t look like percentages

If they are not, my cutting speed is 4000 mm/min what numbers do I plug in?

LB32
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4

You’d enter the maximum “surface travel” speed that axis can move, or accelerate. For a roller rotary those numbers will be constant, but for a chuck they’ll vary with the diameter of the object.

Ideally they’d be in angular units, since that’s what the rotary works in, but the preview wasn’t set up to handle rotaries. We could add settings for the rotational axis and have LightBurn do the math internally.

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5

:+1:
Sounds like a plan