Speed vs Power?

[Mike Audleman]

As yall may recognize, I am an inquiring type. I like to know the ins-outs of everything I can. This is another of those things....

What are yall's thoughts on power vs speed?

I mean, is it better to run 100mm/s at 100% power or go for 50mm/s at 50% (those are fictitious settings, purely hypothetical and assuming both would cut clean through)? I don;t have the experience yet to know which is better. Or are they the same as far as the material being cut goes? Does running lower power extend the life of the tube? And if so, substantially or only a little? I mean is it worth it to make a cut take longer at a lower power or speed it up and use higher power to get it done faster?

Also, anyone know if running slower with less power will produce more or less charring on materials such as wood?

[David Somers]

Mike,

On Chinese machines they often allow you to run 100% for real. The glass tubes in them will be hurt by that. And in fact, the tube manufacturers may void the warrantee if they see a tube that shows signs of running at 100%. You might think that the laser manufacturer would cap your output so you don't void your tube warrantee, but it would seem that they don't. I did a quick forum search and found a few references on this in the forum and it seems like using 85% power may be a good compromise.

Some of the Chinese control software will let you assign a reduced output to the 100% level. But as they come from the factory they let you go full throttle and you really don't want to do that or you will significantly shorten the life of your tube.

If you hunt through some of Rodney Gold's or Dave Sheldrake's posts you will see quite a few references to this.

Then....so far as the intent of your question...I think folks will suggest that from a production standpoint you want your machine to work as quickly as it is able AND produce a good end product with no fuss required afterwards. So if a high power level and high speed gets you an acceptable result then from a time is money standpoint there you are. But if that high power level and high speed creates some issues on the end product; burned edges that need to be cleaned up, damage to a surface that you have to take time to fuss with, etc, then you are probably better off changing your settings to get the cut clean the first time rather than having to deal with any cleanup.

That is just my take on that part of the question. Remember...I am still a laserless participant so I am just relating what I have been finding from hunting through the forum. As they say in TV advertisements.."I'm not a real doctor......" <grin>

Dave

[Ross Moshinsky]

On materials like coated metals or laminated plastic you want to run as fast as you can. It's either marked or it's not. So you want to run as fast as you can.

On materials like wood you need to use a bit of judgement. You want to run as fast as you can but sometimes you need to slow down a little bit so you get the right contrast. Sometimes you need to slow down the machine as ramping up the power doesn't get the results you want.

The thing most Chinese owners simply forget is your machine is slow to begin with. Max speed of 500mm/sec is 20ips. Most lasers run between 80-140ips max. So you want to engrave at 500mm/sec a huge majority of the time, assuming it puts out a quality image. The thing you're going to be adjusting most of the time is the power and to a lesser degree, scan gap.

As for keeping your tube alive, make sure you run at the proper max amps and you should be fine. I can't speak much on the subject but that's what I understand to be the case.

[Mike Audleman]

That actually explains something I had wondered about. My machine (50w ebay box) will not actually go 100%, though I call it that. On the panel, anything >98.5 is limited back to that. So if I set it to 99, it reverts back to 98. So maybe that limit is in place in my machine. I didn't know that you couldn't run the tube at 100%. Good thing its set like that for noobs like me :)


As for the original question, I was more thinking along the lines of quality differences, deeper cutting, cleaner cut, less beveling, charring, etc. Obviously if you are in business making something, if you can make it faster, that means more money and happier clients. But that wasn't my angle on the question.

I was more wondering which setting would produce better results in general. I don't know enough to be able to run controlled tests at my experience level yet. And tests of that nature need to compare apples to apples. I have had the machine less than a month and I am still firmly entrenched in the upward hill of the learning curve. And thats more of the angle of the initial question.

[Matt McCoy]

Mike: I'm far from an expert and probably not capable of giving you an academic answer, but I would be happy to pass along my real-world experiences with the 3 glass tube 40 W CO^2 lasers I have. I almost always vector cut at 100% and raster at a speed that provides the quality and engraving depth I am looking for on the particular material. I operate around 15 mA and adjust the number of passes to cut through .125 to .250" wood and acrylic. I can usually get 3,000+ hours out of a tube and I use a 5 gallon bucket of distilled water for each machine. My shop is an indoor/outdoor location in North Texas and it gets pretty summery here. I keep the lenses and mirrors as clean as as possible when I know I will be cutting at the limitations of these machines. The toughest material I have to get through is 1/4" Baltic Birch plywood. If I hit a knot, it can ruin the piece and I have to try and use it for something smaller.

My short answer to your questions are that it depends! Settings will change and require adjustment due to a lot of different factors, including the type of material and what you intend to do with it. The two years I have been messing around with a laser have been the best learning experience and involves a lot of trial and error that has filled up the recycling box.

Hope this helps.

[Kev Williams]

Rule of thumb when making money: do it as fast as possible.

In my experience, the ONLY negative I've found to engraving full blast vs. a bit slower, is the extreme left & right edge quality may suffer, usually because of power drop-off. To compensate, I'll position the work to the right of far left (usually 2"), then put in a 'dummy' graphic or letter about 1/2" to the left and right of the actual engraving. The dummy engraving is now at the extreme edges, and all of the actual engraving is nice & consistent.

As for Chinese machines limited to 500 mm/s, I've run my Triumph at 700 mm/s several times with no ill effects. The only caveat I've noticed is that the faster you go, the more left/right overrun gets 'built-in' to the raster routine, which gives it more space for the stop & turn. The extra overrun seems to prevent any extra speed shock. The only drawback I've found is the machine needs more space on the edges to compensate for the overrun, so I lose some actual engraving area to the 'artificial margins'. But since the working length is over 51", I've always had plenty of room to spare! ;)

[Bert Kemp]

I'll just add a little to what Kev said. OK first if your not in business full time with the laser if you slow the raster down some you can greatly reduce the over run and increase your usable work area. Course if your making money time is of the essence so full speed ahead, just hope your projects are small enough to have that extra space for over run. :)

[Mike Null]

You could also use the search feature to see what has been posted on this topic previously.