Ledgend EXT Speed

[Duane Parcells]

Can't find the speed in inches per second (tech specs, raster and vector) for the Epilog Ledgend EXT. I've looked through the manual and website and yes even google'd it. Any one seen it printed somewhere? Thank you!
Duane

[Dean Carpenter]

that will vary depending on the width of your raster stroke. The longer the stroke the higher the potential for top speed.

Unfortunately, many manufacturers claim top speeds on paper that aren't achieved with the hardware and such figures never account for acceleration/deceleration/turning times.

One of the biggest speed influences is the acceleration/deceleration/turning times.

You can calculate it yourself: set your machine to 100% speed. Set a rectangle with width in a round number close to the max width of your table and 1" deep.

Set Y resolution low, like 125dpi if possible with your driver.

Now you can calulate the overall line width: 20" x 1" rectangle engraved @ 125dpi (20x125) = 2,500"

so if it takes 5 minutes (300 seconds) to process, your machine has hit an average of 8.33"/sec (2,500/300). Remember this includes acceleration/deceleration/turning time but this is a true test of a machines capable top speed for engraving.

[Mike Null]

Dean

There really aren't "many" manufacturers of laser engraving machines of the type most of us are using. Secondly, a number do not post their raster or vector speeds. I would not say those who do are not being accurate about what they do claim as I have no way to disprove them nor any reason to doubt them.

Your example though does not represent an accurate way to measure raster speed in inches per second however.

[Dean Carpenter]

to the newby (someone looking to buy their first laser) it's all-too-often incorrectly perceived that max raster speed is a benchmark to judge a machines performance by. A kind of laser version of top mph.

I get it asked of me all the time. I'm off to a show Monday and I'll bet I get it asked of me several times each day at the show

The test I described will prove one machine's potential against another so long as you minimise the number of aceleration/deceleration/turns - i.e. you use same width of raster stroke on all machines and same number of Y-steps.

It can be replicated on all machines of similar type/size and some will be a lot faster than others, thereby giving a reasonably good indication to differences in max speed of the motion system.

The question was about max raster speed and not so much about engraving quality and/or results relating to power/speed of pulse, which are other important issues.

Some machines can mechanically hit a high raster speed but other limitations mean that you can't really use full speed for some/many actual jobs.

nice to converse: Hi from 'unusually sunny' UK

[Richard Rumancik]

Dean. . . Your example though does not represent an accurate way to measure raster speed in inches per second however.

In Dean's defense, I think he is pointing out the inadequacies in using the (maximum) ips specifications. His calculation is kind of an average or "effective" raster speed.

GCC has also recognized the inadequacy in reading too much into the ips specification. On the LaserPro NA FAQ they have this:
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What is the maximum engraving speed of LaserPro?
The Spirit GX, and Explorer II are adjustable from 0.1% to 100% speed of 80 inches/second (IPS). The Spirit, and Spirit GE series are adjustable from 0.1% to 100% speed of 60 inches/second (IPS). The Venus is adjustable from 0.02% to 100% speed of 20 inches/second and the Gaia is adjustable from 0.1% to 100% of 23.6 inches/second.

IPS Speed is virtually a meaningless value. If this value was indeed a variable measurement of speed then one would expect a machine that travels at 150 IPS to be able to travel back and forth 6 times on a 25" table [in one second]. No machine is this industry can even do 2 passes in 1 second, let alone 6! A true indication of speed is throughput and engraving quality. Some machines in this industry can run fast, but not maintain their quality they produced at slower speeds. All LaserPro models are designed to be run at 100% Speed, with no sacrifice of quality, or additional wear or stress on the motion system .
---------------

I would not go so far to say that ips is meaningless, but agree that a "peak" velocity at the middle of a long straight path does not really reflect on how much work you can process with the laser. LaserPro has suggested a "throughput" measurement, but so far nobody else seems to have climbed on board. In some specs they quote: "Throughput value represents the Max. number of 8" x 10" 500DPI raster jobs that can be done per hour."

I think the idea of trying to define how much work that you can process is a valid approach to comparison. Too bad the manufacturers can't get together and adopt a standardized test protocol.

This discussion concerns raster engraving primarily but I feel that the maximum ips specs for vector cutting can also be misleading. It is only on the longest straight lines that you can hope to hit maximum speed. (And average speed will still be much less.) On short lines or on curves you will never get up to the maximum speed quoted, because it starts decelerating before it reaches peak velocity.

It's a bit like having a car that can get to 60mph in 5 seconds. If most of your driving is in the city, it really doesn't matter all that much. So the point is, you can compare the ips of different models, but be careful what conclusions you draw from them. If I was doing a model-to-model comparison, I would compare the run times for a vector cutting job and a raster engraving job. (Of course, you still need to assess the output quality between the two.)

[Dean Carpenter]

Hi Richard,

You are on my wavelength, pardon the pun!

You are right in what you say: the starting point should be the required output quality; then see how fast you can run the machine while still reaching the required quality

However, it's also not accurate to write-off IPS altogether.

Most of the main players machines all have quite good motion system design/control

You will find a machines true top speed (at good quality) is a combination of motor/belt/tollerance/laser design.

For raster speed a big limitation is the tube.

With all tubes that I have tested so far (all the main ones) beyond a raster speed of 2m/sec with a plotter mechanism shows results with deteriorating quality of output on sensitive materials.

Vector speed is another issue: other factors kick-in such as belt type and overall inertia.

[Dan Hintz]

For max IPS to be used in any meaningful way, one must also know the max acceleration/deceleration and the distance to be traveled. Give me those numbers and I'll give you an estimate of engraving time to within a few percent without breaking a sweat.

[Dave Johnson29]

For max IPS to be used in any meaningful way, one must also know the max acceleration/deceleration and the distance to be traveled.

Dan,

Surely that is what Dean was trying to get at with the test block to return a real world figure. It is not going to be accurate to the millisecond but it would give you a pretty good idea of what should be possible.

You could make several blocks of differing lengths to test and then average results based on area. The shorter blocks would be more dependent on how the acel/decel affects the timed outcome.

[Mike Null]

Dean

Pardon me, I didn't mean to be picking on you but there does not seem to be a reasonable way of measuring ips given all the variables.

Clearly there is a significant difference between machines. One consideration which must be accounted for is effective speed and that is frequently determined by power of the tube.

My machine for example has a rated speed of 140 ips. My old machine was 40ips. The new machine is not 3 and a half times faster in a raster mode simply because the power is not 3 and a half times higher.

[Dean Carpenter]

Howdy,

Sorry for the pause with my reply: I've been working away for 1 week

Mike: the general direction of the thread was motion system speed related, not about laser power. Of course, for job processing time that has a factor but the purpose of the discussion is how to benchmark mtion system speed.

Regarding acceleration/deceleration: they are as important a factor as top speed. Overall speed should, in my opinion, be calculated as a combination of all 3.

that is, the fastest machines will have short acceleration/deceleration distances and high top raster speeds.

regards to all
Dean