Speed changes depending on engraving direction

[Kathy Madan]

I am noticing a curious change in engraving speeds on the same product.

I set up a job with multiple pieces on a sheet of material. I determined that I could get 7 across and 4 down if I rotated the engraving 90 degrees rather than 9 across and 3 down in an upright position.

I sent the job over and found that rotated the job seemed to be running much slower than the 20 speed and 50 power that I sent it on. In addition, I discovered that the entire sheet took about 3 times what I had anticipated for run time.

So on the next sheet I decided to rotate back to the original design. I figured I had enough material to more than make up for the difference in time. I haven't finished the run time yet, but I am certain it is going to be closer to the ballpark time I thought it should be.

My question is, if you rotate your text, does it slow down the physical time even if the settings are exactly the same? This is a simple text job, no graphics, just text inside a box to be cut out.

[Richard Rumancik]

If you posted the raster image it would be easier to guess what has happened. I'm thinking that a) you don't have a border around the text and b) that there are "blank" lines between the text.

IF that is the case, then what is happening is this: with the left-right reading text the laser driver "sees" the blank line, and jumps down to the next actual engraving line. It won't waste time "engraving" white space. But if you rotate the text, then there probably isn't any blank lines. There might be some shorter ones, but it will require a lot more passes as you effectively have given it a fairly dense graphic to plot.

That would not explain the fact that you sense it is engraving slower. I suspect it is engraving at the same linear speed, but the total job time is longer.

As I said - a pic would help as I could be off base.

[Doug Griffith]

If the machine is running at a different speed the engraving results would be different. With increased passes, you increase the quantity of ramp-up and ramp-down moves which are at each end of the pass. These moves are slower than the engraving speed and will affect the time to run the job quite a bit.

[Joe Pelonio]

If it's mostly text, horizontal layout will always be faster. The head moves
a lot faster on the x axis than on the y, and text goes left to right.

[Mike Null]

I think Richard's explanation is closer to the mark. You are increasing the raster time by changing the orientation of the graphic.

[Scott Shepherd]

Richard's got it. To expand on it, if you have 3 sentences, 6" long, with 1/4" high letters, you have 3/4" of an inch of engraving in the Y, and 6" in the X. 3/4" divided by your resolution, which probably moves about .004" per pass, = 187 passes back and forth.

Turn it side ways, you now have 6" in the Y, so that's 6" divided by .004" per pass, or 1,500 passes back and forth, so you can see it will take a LOT longer to do 1,500 instead of 187, even though the 1,500 passes would be shorter.

[Doug Griffith]

The thing is, you are still engraving the same square inches and laying down the same amount of dots. Ramp-up and ramp-down along the x-axis affects the time far more than the slower "rapid movements" between the the lines on the y axis. Put a horizontal paragraph of text inside a square engraved border and the results will be close to the same whichever way you rotate it.

So Richard is correct when he noted that there must not be a border around the text.