Relative speed and power settings (help please)


#1

I have had the chance to use someone else’s laser recently, and will again soon. So far I’ve only used 1/8th inch clear acrylic. Next session I’m going to cut some solid dark blue acrylic, some quarter inch clear acrylic, and if I have time, some 1/8 and 1/4 mdf from fleetfarm.

The laser is an 80w co2, and the current owner of the machine just got it from a good friend recently, and hasn’t figured it all out yet. For the 1/8 clear acrylic we found that 18mm/sec speed at 90% power was perfect for cutting through.

But how would those other materials relate? Should i expect the same settings for the blue acrylic? Would i want to lower the power when cutting the wood? I know most machines are differrent and most mdf is differrent, but could anyone throw a few suggestions for starting point?


#2

A good place to start is the manufacturer of the laser in question. Most will have a set of suggested settings for various materials. Try googling for “rabbit laser settings,” “epilog laser settings,” etc.

It’s important to note that different makers refer to power settings as either straight wattage, a percentage of max, or a relative stepped scale (e.g. 1-255).

Testing is critical! Always test your settings on a scrap (of the exact same material!), or if not available, in a section of your material that would otherwise be discarded.

Good luck!


#3

Ive tried googling, not coming up with anything. It rates in percantage, but was hoping for an answer of something like "i run acrylic through at x power and y speed, but when i switch to mdf/hardboard i can keep same speed but go with a third less power, etc.

Guess I’ll just have to burn through some material til i get it right.


#4

Lacking definitive details from the manufacturer, the next best thing is to find settings for the same wattage. In this case, googling “80w laser cutting settings” returned some potentially helpful links. Here are the first 6:

  1. http://www.rabbitlaserusa.com/manuals/speedsfeeds_RL.pdf
  2. http://wiki.makeitlabs.com/training/laser/laser-settings-80w
  3. https://www.bosslaser.com/laser-settings
  4. https://www.epiloglaser.com/assets/downloads/whitepapers/settings_whitepaper.pdf
  5. http://www.front-cut.com/wp-content/uploads/2015/11/CO2-Laser-Machine-Parameters-Setting.pdf
  6. https://rowmark.com/MARK/LaserandRotarySettingsGuide/Laser%20Setting%20Guide%2010.11.pdf

Also keep in mind that your friend’s laser has a maximum output of 80w - you will almost never use 100% power for acrylic or mdf, so if you find settings for a 40w laser, simply scale the output value. 85% of 40w = 56.6% of 60w = 42.5% of 80w (34w in each case).

Speed need not be converted - 12 mm/sec is 12 mm/sec, period. However, you might need a unit conversion, depending on the driver software (metric vs imperial, etc.).

Please keep in mind that any published settings are just a starting place! You will indeed burn through material to find the perfect settings, only to find that the next batch of mdf, bamboo, acrylic, etc. is slightly different.

Hope this helps…


#5

Unfortunately the “percentage” has a nonlinear relationship with the actual output power on every laser I’ve used. Also, strangely, colored acrylic seems to cut differently than clear - and different colors differently. Cast and extruded also be have quite differently.

I’d be prepared to cut a lot of test pieces to dial in the right settings.


#6

Right, and prepared to waste material I am, but what I was curious about was- generally speaking, does it require more “laser effort” to cut mdf vs clear acrylic, or generally less “laser effort”.

Being able to quantify that would be a bonus, “twice as much, half as much, about a third more, a bit less”…not talking in absolutes, just generalizations here.

I understand the question is flawed an cannot produce the information requested, I am sorry for the undue stress.


#7

@dan I know the GF will identify any material that is bought from you, but it there going to be a way to look up suggested starting setting when testing a on a new material?


#8

@Sawa: Ah. Assuming the same thickness, these would be my very intuitive, very misleading, purely for entertainment’s sake estimates:
Acrylic is x - 2x
Hardwoods are x - infinity
Plywood is 1.5x - infinity
MDF is 2x - infinity
where X is a given power setting per unit time, and this is extremely vague estimates for typical CO2 lasers (and not in any way glowforge or power specific).

Basically, some woods and acrylics are easy… but glue (that’s in plywood and MDF) varies wildly, with (in my experience) a minority of the materials on the market qualifying as “cutting well” (on the low end of the range).

@ianauch: as you may surmise from this answer, the most likely outcome of any advice we give will be frustrated beginners who complain that our recommendations don’t work, so we won’t try to give what will ultimately be bad advice. Rather, our advice is to either buy material that’s known to work, or to educate yourself on material properties so you can profile your own. The forums here will no doubt be a fountain of knowledge for those who want to profile their own materials.


#9

Thanks @dan, that is helpful. I do have some good info for ant other neophyte thinking/wondering the same as I was.

Redsail 80w co2 cuts paperbacked clear 1/8 (.118 real) acrylic fastest at 18mm/sec at 90% power (with stability).

Home depot tempered hardboard in true 1/8 did not cut through until we did it at 15 mm/sec at 90% power, and the same place true 1/4 got almost all the way through at 7mm/sec and 90% power.

I actually will not have wasted any materials-- the shallow cuts where i didn’t cut all the way through on the hardboard i will hit again with a hand razor cutter.


#10

Along these lines, I have a related question (yes, I’m a noob when it comes to laser cutting, but anxiously waiting to learn on my new GF :slight_smile: ).

I would imagine that, for a given material/thickness, there are a range of power-rate combinations that would work. That is, you might be able to cut at 90% power and 25 mm/s, but could also achieve the same result at 70% power and a slower rate. Obviously, the higher speed would finish quicker, but is there an appreciable benefit to ‘wear and tear’ on the tube, motors, linear bearings, etc. to operating at a slower speed?


#11

Depending on the cooling system and other supportive elements, there may be more, or not.

Something burning high for long time should depreciate faster, but if the cooling system is keeping it all very chill, there should be minimal stress to the machine. Power supply too, as long as it is keeping up with demand, the least amount of wear should occur.

I really had to get my stuff done as soon as possible, i was on borrowed laser time. Slowing it down and going less power may provide some slight changes.

I would think it would slightly lessen the melting kerf on acrylic or make less of a scorch mark on papers/woods… or i would guess it may do the opposite and make it worse for being on the material longer. (Or maybe no difference at all, i think this is a good question.


#12

Saw this photo today and it reminded me that laser printers aren’t the only machines that need calibration.


#13

Obligatory Last Leaf video link: