Accuracy of time estimates

Was reading through some posts while waiting for my X-Carve, and found that Easel has a time estimation feature that is being worked on. I’ve been looking at it to get time estimates on certain project ideas, but am wondering how accurate it is.

Anyone else had a look at this? What are your thoughts on its accuracy in its current state?

The time estimates I’ve seen using other gcode sending apps have been on average reasonably accurate, but it depends a lot on what kind of project you’re doing.

The arduino and g shield take the gcode in near-real-time, but have a very small buffer. They can only hold a few commands at a time.

For example, if you were making a design with lots of little circles, each one would be several segments and each segment would be its own command. Those commands complete and exit very quickly, so a time estimate based on getting the “okays” back from the arduino would be pretty accurate. But, if you were sending a big rectangle, each line segment would be its own command so if the buffer can hold, say, 10 commands, you have to wait until the spindle has cut the rectangle twice over before dumping the buffer and getting another batch. This makes it much harder to estimate how long it will take.

And because jobs tend to be a mixture of sizes and shapes of segments, the time estimates have to be taken with a grain of salt. If you’re looking for something with up-to-the-second accuracy, you won’t find it. If you’re looking to find out if a job ought to take an hour vs. 2 hours vs say 5 hours, it should be pretty useful.

By the way, the free g-code visualizer Camotics has a time estimator built in that seems quite accurate because it actually simulates your job running and takes the feedrates into account when building the estimate.

@BradT The time estimate that exists right now (in the javascript console after clicking “Show toolpaths”) is very inaccurate. We have a refined version in the works. No info atm on when it will be available.

Thanks guys.

@Mike thanks for pointing out the software. I’ll have t take a look at that.

@EricDobroveanu Yep, that was the one I was looking at. I thought the estimates seemed a bit higher than I’d expected. Good to know. Looking forward to seeing it progress.

Just to add my results of today’s carve:

Roughing pass:
Estimated carve time: 35min
Actual carve time: 50min
15min longer

Detail pass:
Estimated carve time: 1hr2min
Actual carve time: 1hr32min
30min longer