Settings for Cutting 0.3cm MDF

[Amos De Pasquale]

Recently I tried to cut 0.3cm MDF with my Laser Engraver, the Laser Engraver is an 80Watt Machine, similar say to a "Rabbit Laser".
Meanwhile I had quite some difficulty cutting.
Could someone give me an idea what settings to use, I was trying Speed 20 and power 30, but that was not enough, finally went to speed 10 and power 90, however, there was plenty of black burn marks along the cut.
PS I tried 4 passes each at varying strength, it was only on the last pass with speed 10 and power 90 that I finally "cut" through!!!???
Thanks, Amos:confused:

[Shane Archie]

I cut 3mm MDF using my Epilog 40w at 18 speed, 100 power. I'm guessing at 80w you should be able to cut at a greater speed.

Regards,
Shane.

[Rich Harman]

I cut 3mm MDF at about 22mm/sec, power set so that it draws 24mA on my 80W Reci using a 63.5mm lens.

[Dave Sheldrake]

The relationship between RF units and DC units is quite a wide band.

RF lasers in general have a far higher beam quality and hold a better beam mode, DC tubes tend to rely on brutal power and generally have multi-mode beams.

A 30 watt RF unit will perform *around* the same as a 60 watt DC tube.

RF tubes can be driven at 100% without too many concerns for shortening it's life, a DC tube pumped at 100% all the time may well be in an *overcurrent* situation.

For yours Amos try around 20 speed at 75% power using a 50.8mm focal lens and plenty of co-axial air. If no luck increase the power up to 90% in 5% steps and see what happens. MDF generates a LOT of carbon and CO2, both of which block radiation in the IR range very effectively. Multiple runs over the same pattern can be counter productive, once the carbon is generated each additional cut will have to overcome the IR blocking effects of the previous run.

Rich's speeds and power levels are about what I would expect from a settled in RECI 80 watt that is set up in the sweet spot.

cheers

Dave

[Amos De Pasquale]

Thanks for that advice, unfortunately, the design of my machine does not allow a lens smaller than 63.5mm, I found that out the hard way, I purchased some lens and then realized the physical improbability!!!! Even the Universal heads cannot be attached to it due to the way the original is manufactured.
Meanwhile, the suggestion of using the 63.5mm lens at 75%power or around 24mA will be tried out probably tomorrow, my mA Meter goes to 30mA, but I don't like running anything at full throttle, I think that is probably a rule of thumb, it goes for electronics, cars, and even our human bodies,; Equipment lasts longer when used in the medium range area.
I appreciate the sound advice all of you have given me. Amos

[Johan de Waal]

I cut 3mm MDF running at 65% power @25mm speed - clean cut . BUT the type of mdf makes huge difference, the mdf i use is known around here as "blond mdf" due to its lighter colour

[Dave Sheldrake]

Can you post a pic of the laser head Amos?

cheers

Dave

[Amos De Pasquale]

I tried the settings starting at 75% and 18 speed, hardly any penetration, went to 85% and 8 speed, still no good, went to 90% and 8 speed--BAD result,:eek::mad:275717275718275719275720 I will check my laser height adjustment just in case I am out of focus, meanwhile here are the photos. Thanks, Amos

[Amos De Pasquale]

What a difference the correct height makes, you can see how far out my red dot was?!! Now I can cut , I used 85% power and 12 speed, thanks for your help, ps any advice on the laser head and also red dot adjustment is welcome, Amos:)275721275722

[Johan de Waal]

Hi Amos, found the easiest way to check the focus point on the laser is to put a piece of mdf at a n angle on the work table. In other words, one side of the mdf flat on the table and the other side elevated by putting something underneath it, say 20-30mm or so. Then cut a straight line from the lowest point to the highest point on the elevated mdf. The cut line will then be very thick/wide then go thinner and become thick/ wide again. On the thinnest section that is focus point area. Without moving the mdf, manually move your head to the area where the line is the thinnest and measure the distance between the laser hed and the mdf. Use this distance always when cutting mdf. This worked the best for me. Hope it makes sense though...I removed the red dot form my laser so can't comment on setting that. With my 80W RECI I constantly cut 3mm mdf at 25mm/s and 65% power for nice clean cut. But as I said before its very dependent on the mdf type. I have found different batches of mdf requiring slower or faster cutting speeds - must be something with the glue used in manufacturing, being more or less dense I think

[Khalid Nazim]

Amos, how do you focus? Do you use a focus stick that you place between the surface that you are cutting and the laser head? If not then I suggest that you cut a few for each lens type from 3mm acrylic. The height of the focus stick would the height you will measure using the method Johan described in his email. I have attached a CDR file of the focus sticks that I use for the lenses on my machine.

Regards
KN

[Dave Sheldrake]

Hi Amos, the head is made by Shenhui, there are other versions available that will let you run with shorter focal length lens's :)

Drop Lucy Lee a line at Weike and I'm sure she will be able to advise of what one's they have available.

I'm with Johan, the red dots are just dead weight, mine went in the bin on every machine the day they got delivered :)

best wishes

Dave

[Amos De Pasquale]

I want to thank each person that has given their advice and input, it has been a great help to me, indeed, I will contact Lucy Lee at Weike; and I have downloaded the attached file from Khalid, also I will give that focusing method with angled mdf, I will post any further results from my experimenting, thanks all, Amos

[Amos De Pasquale]

Just for your info, I have ordered spare laser heads from Lucy Lee, great service. Amos