Cutting 125/190/250 mic Mylar film on laser - advice on machine choice

[simon kidd]

Hi,

I have just sold a G weike 60W Lc6040n. I purchased this machine to swap from a cutter plotter and carrier mats to cut my stencils. I done this in an attempt to speed things up a considerable amount. In honesty I'm getting conflicting information from various sources telling me it should of done the job. Then on the other hand, im being told im expecting too much from the machine.. Of course it cuts the mylar, but my issues are -
- uncontrollable burrs which appear where the laser passes the ridges in the honeycomb. They are small, but just not acceptable in a clean edge stencil.
- width of the cut for fine detail not so great... Focus is set correctly but its still a little on the large side.
- My last and biggest issue.... Speed the machine will not cut over 20% without poor results. Every other operation the machine does is absolutely fine. But mylar cutting over 20% is just not happening. My soul purpose of buying is to speed produce. I couldn't achieve this with it, with many hours of adjusting various settings.

Starting a fresh i really would like some input on where I went wrong, some suggestions on what machine may suit my needs so i can go forward with a bit more confidence. Or is it just not possible and I need to just stick with my plotter and continue the laborious task of peeling carrier mats! Do I need to look at fibre rather than co2? I have access to a good budget, but do I really need the height of tech and massive laser to achieve what I'm after? I don't need a bed size any larger then A3 really, possibly A2. Looking for new so I have aftercare services as I'm a novice entering laser cutting and need to have someone to turn to if all goes pear shaped again.. UK based.

Any thoughts would be greatly received.

thanks

simon

[Bert Kemp]

we need more info, what wattage was your gweiki? bed size was 600x400mm thats big enough for you I presume. to slow cutting, Sounds like you need more wattage. burrs were it passes on the honeycomb, change the bed to a knife edge or pin type bed this should help with the rough edges. You say kerf is to big. this results from improper focus, to much power and or to slow cut speed. anyone or a combination of these 3 things can cause a big kerf. The edges of mylar melts slightly when cut producing a very subtle burred edge.


'

[Andrew Holloway]

I use a 60W Trotec Speedy 100 (Bed size 600mm x 300mm) to cut Mylar stencils and I am very happy with the results. It cuts quickly (IMO) and can achieve very fine detail.
I still get the burn marks where it passes over the honeycomb, but it only affects the look of the finished stencil.

[Scott Shepherd]

we need more info, what wattage was your gweiki? bed size was 600x400mm thats big enough for you I presume. to slow cutting, Sounds like you need more wattage.


He's cutting thin mylar film. A 10W would cut mylar film. His problem is that his machine can't move fast enough, with high enough quality movement. I'm not going to recommend a machine, but I will say the problem is in your motion system, look for machines that have better motion systems that can cut quickly without losing quality.

[simon kidd]

I use a 60W Trotec Speedy 100 (Bed size 600mm x 300mm) to cut Mylar stencils and I am very happy with the results. It cuts quickly (IMO) and can achieve very fine detail.
I still get the burn marks where it passes over the honeycomb, but it only affects the look of the finished stencil.

I have been in contact with trotec, I was looking at the rayjet. But was initially looking at the speedy before. I will probably end up booking into their demo day.

I don't wish to put you out but could you possibly post some of the results you achieve with the speedy? I'd be really interested to see.

Thanks, Scott for your input. I think the answer really is buy a better quality quality machine. As I would think a number of fine tuning factors come into play with such a delicate (in laser cutting terms) material need to be controlled to a point that the g weike can't do.

Thanks Bert for the suggestions, This will help me make a more informed decision when looking at the bed types. Also the also the focus control aspect of a machine. Again going back to before mentioned, a combination of things seems to be contributing to bad results, including the control of the focus With the power delivery.

Many thanks for your replies

[Mike Null]

Until you acquire a new machine I'd advise using an acrylic grid on top of your honeycomb. Look for a 2' x 4' light grid at HD. You can cut it down to size with a saw. Be sure it is acrylic not styrene. That will eliminate the tick marks from the honeycomb.

[Scott Shepherd]

And also keep in mind that mylar uses very little power to cut through it, so you honestly can't cut it fast enough with any machine at their higher powers. There is a max speed at which all machines start to fail in vector cutting shapes. The edges will start to get wobbly, etc. That speed is going to be your limiting factor here since the power needed it so low. Which machine has the fastest "no wobble" speed, I have no idea. That would depend on the shapes you are cutting, if the curves are long, large curves, or very small, tight curves, or a combination of both. You can't vector cut at 100% speed, really, on any of them, and that's where you could be with the power you have. You'll need to take actual samples to demo and time them and see which one is the fastest at that. However, none of them are going to approach the speed of a plotter. They won't even be in the same ballpark.

[Matt McCoy]

Can you post a pic of your stencils?

[Dave Sheldrake]

Mike is on the money, use a plastic honeycomb to reduce/remove backscatter

Bottom line as Scotty says....a laser under a couple of hundred K isn't going to keep up with the power of the tube, on a chinese machine vector cutting is going to hit around 80mm per second before over runs and wobbles hit, the movement systems just aren't up to high speed.

I'd probably look at a 400mm x 400mm Galvo CO2 system, none of the wobble problems and even a 40 watt is going to cut mylar stencils quickly (albeit with an increase in spot size)

Have a look round on here for Jit Patel, he does all kinds of wonderful on paper stock so will no doubt be able to advise.

The reality is, a chinese gantry machine is the wrong tool to cut thin stock stencils.

[simon kidd]

Hi,

I thank you very much for the information supplied. Some of the comments have been extremely helpful and instantly helped me realise what I've searched hours for on google without anything coming up. Especially about the wobble that occurs at higher speeds on vector cuts. Thanks for the recommendations to search for with regards to the galvo system Dave sheldrake. Unfortunately I've binned all my bad attempts when I lost hope with the machine! If anyone does have direct experience with this type of material on laser, I'd be really interested in hearing what your set up is.

[Scott Shepherd]

Simon, what kind of dimensions are you talking about for your stencils.

[simon kidd]

Currently Cutting A4 max only but I receive a number of requests for A3. So was hoping to achieve this as well as speed up my production.

[Scott Shepherd]

You could get a Galvo CO2 with a large focal length lens and possibly get that. That would be pretty fast. That's pretty large for a galvo head though, you'd have to sacrifice beam diameter for cutting field.

[Dave Sheldrake]

Especially about the wobble that occurs at higher speeds on vector cuts.

Easiest way to look at it Si,

Accelerate from a standing start in a decent car (mercedes SLR etc)

Get up to 100 mph in this beast of the road (hell these things hold the road like glue on glue)

Now try to turn an exact right (not a curve, a literal 90 degree turn) due to the laws of motion the inertial weight of the car will try to continue in it's current direction as the force trying to change the direction is less than the force trying to continue forwards. (the back end of the car will spin out)

In essence that is the problem. at speed the motors don't have the power to force a change of direction. The higher the speed, the bigger the radius of the turn has to be to stay within the power rating of the motors.