Laserscript user forum

The other day my new tube died, 1 month old, air bubble - disaster.

So I went back to an old tube that I had cutting at a very slow rate, as i didn't have a spare in stock.

I mainly cut 3mm MDF and my setting for a new tube are approx. 17mm at 85% power (40W tube)

As the tube gets older I reduce the speed.

Anyway put this old tube in and sure enough I had the speed down at 6mm power 85% and it was barely cutting.

Then I started cutting some oak not sure about settings and set the power to 50% and speed to 10mm, I indented to cut 2 or 3 times, until the job was done, it cut on first pass.

So I started cutting some 3mm MDF again and now I'm cutting it at 50% power speed 14mm, this tube was barely cutting a 6mm power 85%.

Hope that all makes sense.

Whats going on there then?

And will this tube last a good while yet or is it nearly dead?

My son discovered some time ago that our machines cut better with the power at 60 instead of 80. Rarely go above 60 now!

Most timber, ply and mdf cuts better with less power

My suspicion is that MDF is quite peculiar compared with other materials.

Because it generates so much smoke, the harder you cut it, the more smoke it produces, so the worse it cuts. I've spent many, many hours messing around with MDF settings. Sometimes MDF doesn't cut well in a horizontal straight line. I'm wondering whether the action of the laser and the air pump creates a microscopic "bow wave" of smoke in some directions, so that a whole design will cut... apart from one line. A horizontal and a vertical line cut differently (if you're scoring grids, this becomes quite clear).

A couple of years ago I did a big project where I had to cut 6000 fine, complex items from MDF in just a month. I employed a guy to help me, and he was... kinda obsessive. He observed how you could have the same design repeated across a sheet, and just some of the copies wouldn't cut right. But not because the bed wasn't level, or the laser not aligned. We ended up realising that it was to do with the position of the head before each repeat started cutting. In some cases, the head would float smoke across the target zone, reducing the power on that particular iteration. (Obviously, maximising the cut speed was a major consideration with so many repeats.)

Rather than reducing the cut speed, we ended up putting a zero percent power circle (yes, zero percent) into the designs, so that the head would waft around for a second or two before going on to the next cut. Problem solved.

Bottom line - there's much more going on in the cutting process than just linear relationships.

Cheers,

James

I agree James - I've found the same with mdf and sometimes ply - if going from engraving to cut sometimes the cut is not as good as the rest so I put in a small waste cut in between.

Good air extraction and upgrading the air assist both help and give you a bit more scope to adjust.

Best
Dave