Time Trials

[Craig Matheny]

We all seem to be talking lately about how fast our laser is and how it cuts so well. I have attached a file here and in a different post, I thought this might be better for this. Please rune the attached file on your laser with 1/8" Baltic Birch submit your machine and wattage, speed/pwr/freq and how long it took to run the file. With this we can now talk apples to apples when we talk speed and wattage

[Craig Matheny]

Time trials pwr 100/ sp 16% / freq 150 time to run 68 seconds.

[Joe Pelonio]

I'm in the middle of cutting 2,000 ABS parts for a customer but will try it when I have time later this week. I'd really suggest another material, though. There is a big variance in the density of Baltic depending on the country of origin,
glue used, dryness etc. that can affect times. Probably basswood is a better test, though acrylic of the same brand and color might be even better. Maybe people can try a few options and others will have the same thing to try.

[Richard Rumancik]

I don't mean to discourage you, Craig, as the concept is sound. But I really think the sample file is more complex than what is really needed to do a comparison. I would suggest two shapes (separate files) - a simple square and a simple circle - would be adequate to characterize a laser's cutting speed - say 5" (127 mm) square/diameter. Joe's suggestion to use acrylic is a good one - 3 mm extruded clear acrylic is one of the most common materials and most users will have some around. There are probably some variations between manufacturers but based on past posts, baltic birch is one of the materials with a high degree of variation.

[Craig Matheny]

The concept was based off of allot of people talking about how long it takes to cut 1/2" Baltic Birch and the back and forth so if you have straight lines or soft curves you can cut faster but then it is not a true test having different degrees takes into account speeding up and down of the movement in the head. So that is why the goofy file. I personally have an interest in the Baltic Birch being I cut this stuff all day my laser would have no clue what to do with acrylic it would most likely cry.

[Michael Kowalczyk]

Richard and Joe,
I agree with Craig on this one because it is setting a base to work with since so many do use 3mm Baltic birch. Obviously everyone is probably getting it from a different mill unless of coarse they got it from me. I think this will still be somewhat educational because so many people ask me about settings and how long it takes with a 30 watt or a 45 watt to cut a tribute or ornament and I have no idea but even with a 60 watt since mine is a Trotec, my cutting speed is a different IPS than an Epilog, ULS, GCC, Vytek, Kern, or _____ (fill in the blank with yours).

My 3mm that specs out at .126" runs at 100% power and .95 speed
My 3mm that specs out at .117" runs at 100% power and 1.10 speed
now that's over a 10% difference. My hertz is at 5000. Now that only applies to a Trotec since you others have different settings. Now this is still my original 60 watt CO2 laser tube from march of 2003.

It should also be noted that so many people call 1/8"/3mm Baltic birch the same when there are many differences in glue and time of the year the logs were harvested. So for consistency, please make sure you can confirm that it is GENUINE Baltic birch, what mill it comes from (if known) probably only available to those that buy full bundles but you can ask your supplier. I will post mine with the test results.
Is a a B/BB or BB/BB?
Did it come from west coast or east coast?
How old is your laser?
If you have replaced your tube, how new is it?
What lens are you using? 1.5", 2",3.5", 4", 5" or other
make sure your lens is clean before you start
Are you using air assist or not?
How many CFM does your fume extractor have?
Does it extract from the back, bottom or both?
Has it been treated? For sake of continuity lets keep them all RAW.
is your laser tube a Synrad, Coherent, glass or other?
Does your laser use steppers or servos or both?
Is your laser room temperature controlled or a sweat house?
Are you using a honeycomb table, a pin table or other support system?
When you cut through, do you get flash back on the bottom because you use excess power, by going to slow, to get all the way through?

If anyone else can think of something else to add ( I know you want to Dan) to this list to make this as scientific as possible with out really calling it a scientific research test, feel free to add on.

I will try the test file later this week when I can and post my time and almost scientific research data back here.

[Rodne Gold]

3mm cast or excluded acrylic is a better bet , most ppl that own lasers will have some scrap of it and basically the density and composition varys very little worldwide. Any torture or thruput test must include both raster and vector graphics and have a set dpi. You can also do each individually and time them. All you are doing in this particular test that is mooted is to test relative powers or power densitys and not really speed as cutting thru stuff that requires very low speeds , where 2 lasers have the same power density , they should be more or less equal , or a higher or lower powered laser should have a time difference proportional to power.There are way too many factors that affect both materials and the particular laser to make any exact comparisons between various models and makes. One set of factors might make one machine better in one test and changing them might favour another.

[Craig Matheny]

Rodney you would think that they would be close for the same power however we have a guy stating 100% pwr 90% speed with a 35 watt zing from epilog I did a demo on a 40 watt epilog and it cut 60% then my 45 watt epilog they now make there own tubes. So the key to this is getting to understand the time it takes to do a set of cuts. The acrylic is the best product but the key is two fold understanding the Baltic Birch Market and the laser speeds to power.

[Dan Hintz]

If anyone else can think of something else to add ( I know you want to Dan) to this list to make this as scientific as possible with out really calling it a scientific research test, feel free to add on.

<chuckle> I was skimming the list in about 3 seconds when that sentence caught my eye ;-)

I think a lot of the items mentioned could better be boiled down to "What's the actual output power of the tube being used." and "How fast can the carriage move in both vector or raster modes.". From a power standpoint, it's (mostly) irrelevant whether or not the tube is glass (DC) or metal (RF), domestic or foreign, age of tube, steppers or servos, etc. Start out with max carriage speed and beam power at the carriage. If you want to get more complicated, pay attention to ramp up/down speeds of the carriage (Trotec, for example, obviously does a better job at this than the others). But I think the first-order test of max speed and max power should be good enough for government work.

[Mike Null]

I think projects such as this are largely efforts in futility but at least there ought to be a constant. Plywood is in no way a constant; those who suggest acrylic are much closer to the mark.

That should be clear acrylic of a specified thickness and type.

[Richard Rumancik]

Perhaps I misunderstood the reason for the test - I assumed it was to compare lasers, so that one could have some confidence that their laser is operating properly. Otherwise, we have someone saying "why does my GCC cut at 2% speed and an Epilog cuts at 20% speed". Seems to me if you want to characterize the laser's capability/functioning, you need a constant substrate to test on. As I noted recently in another post, % speed is not transferable between laser systems. But if we all cut 20 linear inches of 3mm acrylic, the job time is a meaningful comparison.

On the other hand, if you want to characterize the Baltic Birch on the market, you need a constant laser system. One person can do this investigation and hopefully find the best baltic birch. But collectively we don't have constant laser systems so I don't see how using variable laser systems on variable baltic birch samples, and comparing the results, will tell us much. You can only have one independent variable in an experiment.

If baltic birch is not cutting properly on a system, then I would want to know if the laser is operating properly in general. The best way to do this is to test on a material which lasers well. That material is acrylic. Whether you make parts from acrylic or not, the first objective is to find out if your system will cut acrylic properly (with speed comparable to other users that have similar wattages of machines). Once that is established, then the baltic birch can be introduced into the experiment. Then it becomes an exercise in finding the best baltic birch on the market on the basis as to how well it lasers. That has much more to do with the product than with the lasers.

I suggested 3mm clear extruded acrylic as a test substrate because it is inexpensive and readily available, and it can be cut in one pass using the lowest power (25 watt) systems. I prefer the use of extruded over cast, because the thickness tolerance on extruded is tighter than on cast material. I might add one more parameter - use a 2" FL lens for the test. If you use something else, a comparison will be difficult and results ambigious. Parameters such as PPI should be set to the optimum value.

You could take an alternate approach to comparing systems and just look at the numbers - get a power meter and measure output power, determine maximum speed, measure spot size, etc. But in the end the only thing that matters is throughput. How fast can the laser cut a 5" circle in 3mm clear acrylic? Once a user is satisfied that the system is optimized, then they can try to cut baltic birch or rubber or carbon fibre knowing that their system is as good as it will be.

[Michael Kowalczyk]

Yes I agree that 3mm acrylic would be better for a real test but this particular post stemmed from people having issues with Baltic Birch. So since Craig, the OP, started this time test with Baltic Birch, I think it should stay the topic of this post. If 3mm acrylic is requested as the test material, then a new post should be started for it, since results & settings will be different. This way if someone reads this archived post in 17 years there will be less confusion.

Dan, I thought you'd get a out of it. Yes it could be but I was just throwing out items that could be relevant if taken to the next level. Not everyone has a power meter or would be willing to pay to rent one for a day. So that is a hard item to put in the equation, though it is a good one. Each one of the items I listed may or may not effect the output of the laser but each one is a variable that if a newbie or a seasoned laserer finds their settings may be able to be tweaked a little to get better results, then it was worth mentioning.

Craig,
You have 1/2" BB in your post (2 above) and I think it should be 1/8"/3mm.

[Neil Pabia]

Not too sure what it is going to prove, but I was bored and ran the test 3 times.
test 1 100 power, 35 speed, 150 freq., 58 seconds
test 2 100 power, 40 speed, 150 freq,. 54 seconds
test 3 100 power, 45 speed, 150 freq,. 52 seconds didn't cut completely in 2 small spots
Hope that helps some.

[Ron Chapellaz]

we have a guy stating 100% pwr 90% speed with a 35 watt zing from epilog.

I'm that guy, and today I did Craig's test. Here are my results with my zing 35W.
Test 1: 85 speed, 100 power 500 freq. 52 seconds
Test 2: 95 speed, 100 power 500 freq. 51 seconds
Test 3: 100 speed, 100 power, 500 freq. 49 seconds.

Every test yielded a complete cut through the wood. I haven't played with the freq setting so I'm not sure if that would improve the speed or not.

I'm not that far off from Neil's time but then again he has a 60W. It is obvoius that Neil's machine should be able to beat me in a speed race as he was going on his last test at 45 speed compared to me at 100.

There could be a few reasons as to why our machines come in at about the same time such as the machine's actual wattage, quality of the wood, extractor, lens condition, and more as Michael has suggested in his above post.

I'd like to see how others compare. It is an interesting topic!

[Martin Boekers]

[QUOTE=Dan Hintz;1744038x should be good enough for government work.[/QUOTE]

Hey, Hey Hey....... Some of us take Government work to a whole new level!