Speed / Power / Time / Space continuem

[Mark Kojetin]

Hi,

Can somone please explain why it is better in some cases to not run at 100% power when you you have to drop your power down to get the desired depth.
Hypothetically, if 100% power and 50% of full speed works, why would I want to drop to 90% power and have to drop my speed aswel to get the job done when that means the job takes longer to do?

[Gary Hair]

I have very few jobs that I run less than 100% power, one is powder coating. If I run it at full power it obliterates the powder even at full speed. I need to slow it down to 70% speed and 20% power to get it to melt and stick. Other than that, I almost always run at 100% power and adjust speed to suit.

Gary

[Adrian Hill]

There are reasons to keep the speed and power down. I find that when I engrave and the speed is to high, irrespective of the power setting, the line starts dark and as the head accellerates the line becomes lighter. I find that I need to keep the speed low to keep the line depth / colour constant. This of course means that my power setting is done in relation to the speed setting. Another issue is cutting MDF. If you cut MDF at a high power & speed setting it tends to char, again, i find lowering the speed in relation to the power works best. When I cut UHI and the power seting is too high it tends to leave burn marks at the bottom where the UHI sits on top of the honeycomb.

I don't think that there is an easy answer. I try to find the highest speed at the lowest power setting (provided that I get a clean, uncharred cut that doesn't show the effects of the head accelleration).

[Mike Null]

Mark

Welcome to SMC. There can be several answers to your question but the first answer deals with materials. You must vary the power, speed and resolution depending on the material you are engraving or marking. As Gary mentioned, it is quite easy to ruin a job by using too much power. Another example is engraving plastic; too much power and you can produce an image that doesn't really give you the detail you and your customer desire. Cermark and Alumamark each have their own separate requirements as does glass. You can over power anodized aluminum as well.

For best results you must match your settings to your material based on the specifications of your machine. In your example it may be that you are trying to get a darker burn, in which case a slower speed and a little lower power might help.

I encourage you to read through the thousands of posts here to see and get an idea of the techniques used and how members have experimented until they found exactly the right settings to produce great looking work.

My business is engraving but one of the things I like most about SMC is that fact that we have many hobbyists as members and frequently it is the hobbyist through experimentation who leads the way in showing us all how to achieve better results.

[Dan Hintz]

Hypothetically, if 100% power and 50% of full speed works, why would I want to drop to 90% power and have to drop my speed aswel to get the job done when that means the job takes longer to do?
You've already received some great advice, but the bolded portion is the key to another possibility. Slowing down doesn't always mean a job takes longer to do. What if the engraving is a small patch, or even worse, multiple small patches over a large area? Slowing down means the carriage has less overshoot at the end of each raster line. On a 2" wide patch, for example, I may be able to improve my time 50% by going from 100S to 50S.

Faster is not always better... but like Gary, I end up doing 90-95% of my work at 100S.

[Allan Wright]

I find when engraving light wood (basswood, birch) a high speed full power pass doesn't give me very dark coloring in the engraved portions. Slower passes with lower power gives me better 'toasting' of the wood inside the engraved areas. If that makes sense.

[Richard Rumancik]

. . .Slowing down doesn't always mean a job takes longer to do. What if the engraving is a small patch, or even worse, multiple small patches over a large area? Slowing down means the carriage has less overshoot at the end of each raster line. On a 2" wide patch, for example, I may be able to improve my time 50% by going from 100S to 50S..


Hmmm . . . I won't argue with what you are seeing, Dan, but in general I would have to say the lower the speed the longer the job. Maybe there are a few exceptions but I haven't come across them . . .


Faster is not always better... but like Mike, I end up doing 90-95% of my work at 100S.

Did Mike say that? Personally, I can't do much at 100S but then I only have 30 watts.

[Dan Hintz]

My bad... it was Gary, not Mike, that mentioned doing most of his work at 100S. I fixed my original post to reflect that.

While my reduction to 50S was likely overstating things, I do see a significant increase in job speed when I slow the carriage down for small patches (as I would expect). Selected speed may be 70S rather than 50S, but the idea behind the change is the same. It also removes control of power vs. speed from the machine's hand and puts it back in mine... not only do I feel ULS has not mastered the reduction is power versus carriage speed during ramp up/down, but some substrates simply don't respond well to a large range of powers (so keeping power within a specific band is ideal).

[Adrian Hill]

Isn't there also a relationship between the life of the tube and the power used. I try to keep the power setting as low as possible for an acceptable cut rate. I think that one could liken it to running a car at 10,000 rpm-200km/h every time you go to the shop around the corner (I'm sure that the motor's lifespan is going to be shortened)

[John Noell]

Isn't there also a relationship between the life of the tube and the power used. An interesting question but based on what people report here, probably not. The motor analogy is not a good one. In fact, it may well be that constant use of the tube extends its life, quite unlike a mechanical motor.

[Dan Hintz]

Isn't there also a relationship between the life of the tube and the power used.
In a grazing sort of manner, yes.

I try to keep the power setting as low as possible for an acceptable cut rate. I think that one could liken it to running a car at 10,000 rpm-200km/h every time you go to the shop around the corner (I'm sure that the motor's lifespan is going to be shortened)
Using the lowest setting all of the time isn't going to help you, though. Running low power for a while, slowly ramping power over a period of 15-30 minutes, the ramping down when you're done... that will help, but who has time for that nonsense? Running at full power ensures the gas mixture stays mixed.

[Mike Null]

Dan

That's very interesting. What is the scientific source of your information?

[Tammy Larrabee]

Oddly enough, the only thing I ran at 100% power was cermark, then I found out I do better running it at a much lower power, now I don't run anything over 85%

[Richard Rumancik]

Other than that, I almost always run at 100% power and adjust speed to suit.


it was Gary . . . that mentioned doing most of his work at 100S.

Dan, you are still seeing something that I don't see . . .

[Dan Hintz]

Man, I was all over the map yesterday, Richard :( Definitely read that wrong. Sorry kids!



Mike,
I have a continually growing binder(s) of journal papers and the like that I've collected over the years while writing my book. If you want, I'll try to remember to find some of the papers that discuss it and send you the titles.

[Mike Null]

Dan

The reason for the question is that I have yet to see any manufacturer postulate such a position. All of us have read countless examples of short tube life, some as short as a week and other examples of several years of tube life so there does not seem to be any contants except inconsistency.

I have had relatively good success with mine which I attributed--unscientifically-to constant moderate temperature and humidity and a relative clean environment.

I would question any such theory because of the multitude of variables involved in terms of use, location, cleanliness, temperature and humidity and certainly the care of the operator.

[Dan Hintz]

Don't get me wrong, Mike, I'm not suggesting there aren't a number of variables involved, I'm merely stating one of many possibly ways to increase the lifetime beyond that as if you had not taken the extra step. I've said many times here that stability of environment is probably the biggest contributing factor to longevity of the gas mixture. Unfortunately, none of us keep track of why tubes fail (at least no one has spoken up, and I'm just as guilty). A failed RF section can't be considered a gas failure, a dropped tube that creates a slow leak can't be considered an electrical failure, etc. The slow ramp up/down "procedure" I mentioned earlier helps keep the entire cartridge in a controlled state (the entire metal containment comes up to temp over a long period of time, reducing leakage from temporary heat-induced warping), but no one in their right mind is going to do it... it takes to long and the benefit is marginal, at best.