LaserUser.com Forum (formerly RDWorksLab)

Hi everybody

I just joined this forum but, can I be cheeky and ask for some advice right off the bat?

I'm thinking to buy a Chinese Red & Black 70cm x 50cm, 60w machine. I don't have room for anything bigger than that, but should I go smaller? Would a smaller machine say 60cm x 40cm be more accurate? I'm not going to use it for mass production, so not worried about high-speed operation, it's going to be super fast compared to my 3D printer anyway.

Also, should I go for 60W or spend a bit more and get 80W? Is bigger always better? I probably won't be cutting anything more than 10mm acrylic / ply / mdf etc and probably more often 4 - 6mm and thin card / paper etc. Given that you can set the laser power for the job in per cent increments, is there a downside to having more power than you need? From watching some of Russ' videos I know that the power response is non linear. But, if say 60% power on a 40W tube gives the same watts at the cutting beam as 40% on a 60W tube, would the quality of cut be the same for these tubes, all else being equal?

TIA

60W vs 80W... LOL

My 80W China Red is a 60W with an extension for the 80W tube. The power supply shipped with it will handle a 90W or a few good 100W tubes. I wish I had bought the true 80W and gotten the bigger bed. And gotten a cutting setup, and a true feed through, and a ... Well you get the gist. The two things a laser MUST have, either as shipped or with your add on, is a mA meter and a temp gauge. Personally I'd get one without the temp gauge and put my own in. You can pick up a dual digital aquarium gauge on Amazon for about $12 USD and know the delta across the tube. The rest of my over two dozen mods are mostly in the 'want' category. My DIY chiller being an exception. If you add your own temp gauges, there is a neat way to put two poly fittings togeter to give you an inline place for the sensor.

There are lots of '80W' and '100W' machines that are just the 60W with tube extension. A 60W machine with the looooong tube extension for the 100W tube is almost comical.

The size of the machine should not have an impact on accuracy. But that will be wholly depndet on how well the workers in the factory assemble the machine. So long as the Y Axis rails are parallel and the Gantry is not racked - size will not matter.

As far as which wattage is best - well there is verty little difference between 60 and 80 watts with regard to the precision of adjusting wattage for an engraving or cutting. If your primary interest will be engraving lower power machines have more resolution to adjust power.
(See Graph) There is a more significant change in miliamps in 0.5% pwr with a 35 watt machine than a 100watt machine. That gives greater control in the engraving process to finely adjust power.

If I were you I would go with the 80 watt - it will give the best of both sides of the coin - good engraving and good cutting for material under 10mm thick.

Be aware that the rating on tubes is often done by the assembler ['manufacturer' is aggrandizement in most cases] and there are two ratings, max power and max 'safe' power. The larger machines are more often described by the safe power rating but cheaper machines will often use the max rating. A tube will not last nearly as long at the max rating of course.

It is an interesting discussion about how big to go in power. In particular when you want to do fine engraving on delicate surfaces. Russ touches on it a bit across a number of his videos about the pre-ionization phase. Go to large and what is hinted at is you will lose some fine control of the Engraving side of the coin. That is the pre-ionization power of the bigger tubes is higher and more damaging so you either need to go faster (not always possible) or you will incinerate your job.

When my larger 100W Laser is done I won't be for example getting rid of my 40W one it will be instead getting a rebuild and clean for lightweight engraving and Card/Cloth work at least until I am happy the 100W tube will do the fine work.

Thank you guys for all the advice. I'm still negotiating with a couple of vendors, but hope to get it on order soon.