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Cheap Chinese Laser Cutter

experiences with a Chinese laser cutter

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Andy Joyce27/01/2020 18:26:19
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260 forum posts
54 photos

Noticed on AliExpress there is a 7 or 15W laser with a fan assisted driver. Link. Has anyone tried one of these?

FlyinFlynn28/01/2020 13:48:16
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150 forum posts
95 photos

That looks interesting, with the inclusion of the fan it would appear to be of a higher power than the run of the mill offerings, but bear in mind it is Chinese, so perhaps the specs might be a tad optimistic. Best order one before the prices go up on Saturday frown

Andy Joyce29/01/2020 19:14:39
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260 forum posts
54 photos

Anyone else found a good buy on higher powered lasers?

adrian garnham29/01/2020 19:37:58
22 forum posts

I'm getting good results with this one .... gone down by £10 since I bought it

**LINK**

I'm just getting to grips with the focusing, feed rate, power and air assist but cuts through 3mm soft balsa in 2 passes.

Once I've fully sorted it I'll post some videos etc.

Phil Olson - Model Technics07/02/2020 14:24:24
44 forum posts
1 photos

two questions

1 I'm using GRBL 0.9i (according to arduino ide) - should I update to 1.1f ?

2 when setting to servo mode the servo does nothing, but when in laser mode it twitches during the cut

I'm using the Elemaker A3 and eleksmaker software. I'm still at the testing stage so I've not actually used the laser, I've just put a pencil in place to check direction and size etc

Phil Olson - Model Technics07/02/2020 17:34:28
44 forum posts
1 photos

I think I may have solved both as I took a spare Nano and put 1.1h on it and it now seems to work the servo OK

FlyinFlynn08/02/2020 11:32:21
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150 forum posts
95 photos

You should be aware that 1.1h introduces self squaring gantry homing at the expense of variable spindle/laser mode on the cheaper versions of the cnc shield. what this basically means is that if you have bought and used one of the chinese clones of Protoneers 'cncshields' you will not be able to use laser mode or control the laser intensity using the spindle speed commands. more info in the release notes for grbl on github. If that is going to be a problem for you then I would suggest you download ver 1.1f and go with that. Servo control was added to GRBL around 0.9i, or at least some versions of 0.9i so you may have just been unlucky with your version, your servo should work fine with 1.1f

adrian garnham19/02/2020 20:38:45
22 forum posts

Hi all

I have finished building a 5W laser cutter which is a hybrid between the FlyinFlynn and Geoff Gardiner machines (thanks to you both for your input as I don't think I would have been able to complete it without your help)

I am more than happy with the results for cutting balsa but not so impressed with ply so I have almost finished making a CNC router with a 500W spindle motor.

What type of cutter should I use for cutting up to 6 mm birch plywood ?

Geoff Gardiner19/02/2020 22:57:27
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540 forum posts
914 photos

Hi Adrian.

Glad to have been of any help.

I use a Dremel for my routing and these are the bits that I use - I have been using the 1mm bit.

Geoff...

Martyn K06/04/2020 17:01:17
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5083 forum posts
3678 photos

It's a while since there has been a post on this thread. I am still plodding on but I have a couple of questions.

Software is Lightburn

The firmware on my LED Laser controller is grbl1.1h and it does indeed reduce laser power as it slows down for the bends.

However, the power reduction is too high. For example, I now need 5 passes as 600mm/sec at 100% power to cut through 1.5mm balsa. If I switch to the 1.1e driver, 100% power at 600mm/sec sets fire to the balsa on the first pass.

I would guess I am only running at 50% power. Drawing a circle doesn't even mark the wood as the power only seems to be about 25%. I cant see a way of increasing the power and wonder whether I have overlooked anything.

Any magic that I have overlooked?

I would welcome any suggestions, I am using a hell of a lot of wood trying to cut very few parts.

Thanks

Martyn

Barrie Lever06/04/2020 18:35:53
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233 forum posts
46 photos

Martyn

I have a 40W K40 laser cutter, I would generally cut 1.5mm balsa at about 30mm/sec and maybe 25% power.

Are you sure that you are using 600mm/sec? that is an engraving speed in my book.

I would look at slowing the feed rate down and also lowering the power.

In the video below, I had everything set perfectly and only cut at 100mm/sec.

https://www.youtube.com/watch?v=RVHL3ECXSeM

Is there anyway or need on your machine to set the focal length? My K40 needs the length setting at 36mm from the lens to the top of the work piece, if this is wrong the cutting performance is very badly effected.

I went to have a demo of a £20K Austrian Trotec cutter (only about 700x400mm) and even that needed the focal length setting, albeit it was a semi automated process.

Is there a test firing button, fires the laser without the carriage moving?

Barrie

Martyn K06/04/2020 21:25:00
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5083 forum posts
3678 photos

Apologies, that should have been 600mm per minute.

This is the problem with it slowing too much. There is a vid on YouTube https://youtu.be/b5-vxgoqpUI

What appears to happen is that it is pausing at each non linear curve start and stop rather than reading the data stream and processing it smoothly. But even the large wheel circles have not cut evenly. They have had 5 passes each and always pause at the same point.. However, the smaller wheel hub has cut perfectly. I thought it may be a USB problem but I am having the same issue on a more powerful and more modern system

dsc_1641.jpg

Tim C06/04/2020 21:58:43
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514 forum posts
273 photos

Martin,

is your PSU supplying enough current.? I had a similar problem when I ramped up the power setting to 100%, I solved mine by junking the supplied psu and connecting it up to my bench supply, a converted ATX psu from a computer

Barrie Lever06/04/2020 22:11:31
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233 forum posts
46 photos

Martyn

I will have to bow out on this one as I have no experience of your type of laser cutter, but I guess the reason it has to slow down significantly is due to carrying the mass of the laser around.

All the laser cutters I have worked with have a laser tube mounted in the back of the machine firing through mirrors to a focus lens over the work piece, they can move at incredible speeds when engraving due to the low mass.

Regards

B.

Edited By Barrie Lever on 06/04/2020 22:12:12

Martyn K06/04/2020 23:21:24
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5083 forum posts
3678 photos

Thanks both

I think the psu is OK. If I run the gcode using an early version of grbl1.1 which doesn't support variable laser power with speed then it will happily set fire to the balsa with 100% and 600mm per minute the laser still hesitates, the laser is about twice as bright.

I think the underlying issue is that the processor can't process the gcode fast enough. I just wonder whether anyone else with the banggood laser has experienced this.

Martyn

Gervaise Vernon Retail manager StarLoc07/04/2020 09:06:31
8 forum posts

I dont use this type of laser ours is a co2 one but , Are you joining the lines together to form one line in the cad pack you are using, the line type can cause problems spline or non spline curves, one doesn't cut it cuts in stages, depending on the speed it can power up you can with some led lasers get gaps.

The burning, unless you cut at very low power a few times you will burn the wood, cut at high power as the power goes up if you hit softer parts of the wood it will suddenly flame up and set the piece on fire,

The cure is `air assist` to run a tube to point at the cutting dot and blow air down it we have 50psi from a big oilless compressor , we disabled the fancy air assist nozzle that our co2 lasers have as ithey are not as good, we blow down a piece of 2mm id nylon tube and get no flames,

The air also removes dust from in the cut allowing you to cut faster and deeper in one pass as you remove the dust that otherwise blocks the laser as you cut.

Rob Ashley07/04/2020 09:16:06
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256 forum posts
86 photos
Posted by adrian garnham on 19/02/2020 20:38:45:

Hi all

I have finished building a 5W laser cutter which is a hybrid between the FlyinFlynn and Geoff Gardiner machines (thanks to you both for your input as I don't think I would have been able to complete it without your help)

I am more than happy with the results for cutting balsa but not so impressed with ply so I have almost finished making a CNC router with a 500W spindle motor.

What type of cutter should I use for cutting up to 6 mm birch plywood ?

Adrian,

I have found that 1mm end mills, as shown by Geoff Gardiner, are perfect for cutting balsa and ply (you can also use larger). I found its is best in ply to cut no more than 3.2 mm each pass so 2 passes for 6mm ply. Balsa can be cut in 1 pass. Your total depth limit is the length of the cutter - so a 3mm bit with a 3mm shank can cut 20mm thick material.The main thing is not to stress the cutter and clearing the swarf is essential to reduce heat. I often use 0.8mm mills for balsa and even 0.3mm engraving bits for extra fine work.

Feed rate is also important so for ply I find 250 mm/min works well and 300-350m/min works great for balsa. You can go faster but I like to reduce the stress on the cutter - they last longer and you get a much better cut.

For aluminium and mild steel use decent end mills and I find 1,2 & 3mm proxxon bits are awesome.

Others may have their own methods/ideas that work - the info I have I found from personal experience and there is always something to learn. It is quite a fascinating part of the hobby for me and I have been CNC machining/routing for over 10 yrs now making everything from single parts to kits to engine parts. I hope you have fun with it as it can be quite absorbing.

Rob

FlyinFlynn08/04/2020 08:44:59
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150 forum posts
95 photos

Martyn - Your description of the machine pausing at the end of every arc is precisely what laser mode was designed to overcome. In a router the x and y axis must pause at the start and end of each linear movement to allow changes on spindle speed to take effect, when using a laser, spindle speed changes happen all the time to change the laser intensity. Are you sure you have laser mode set to ON in your GRBL settings? ($32 = 1)

Barrie Lever08/04/2020 11:33:04
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233 forum posts
46 photos
Posted by FlyinFlynn on 08/04/2020 08:44:59:

Martyn -

. In a router the x and y axis must pause at the start and end of each linear movement to allow changes on spindle speed to take effect,

FF

Are you sure about this sentence? I programme many different routers and CNC machines from hobby types to full on £140K industrial machines on an almost daily basis and none slow the spindle down when coming to changes of directions.

In CNC routers and mills there is deacceleration and reaccelerating at severe changes of direction but that is to allow the mechanical movements to keep in kilter, flexible low powered machines require longer deacceleration/reacceleration times than stiff powerful industrial machines, but no spindle speed changes.

With the laser cutter we are discussing I could see some sense in the laser power reducing as it slowed down as it had some serious motion pauses at which point the laser would have still been burning away, even cheap Chinese Ebay Co2 lasers have quite a swift motion control, see my Co2 laser machine cutting in the link below.

https://www.youtube.com/watch?v=qKs25VGW8tU

Surely Martyn is looking at a motion control issue?

Regards

B.

Stephen Smith 1408/04/2020 12:39:47
210 forum posts

Barrie thats a really nice head on your K40 what make is it and where did you get it from would like one on mine.

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